The 2835 has two SD controllers: The Arasan SDHCI controller that we
currently use, and a custom SD controller.  The custom one runs faster
at 16.7MB/sec reads on PIO (according to hdparm -t on a Pi 2B) instead
of 10.15MB/sec, and up to 18.45MB/sec with DMA enabled.

The code was originally written by Phil Elwell in the downstream
Rasbperry Pi tree, and I did a major cleanup on it (+319, -721 lines
out of the original 2055) for inclusion.

Signed-off-by: Eric Anholt <e...@anholt.net>
---
 drivers/mmc/host/Kconfig          |    9 +
 drivers/mmc/host/Makefile         |    1 +
 drivers/mmc/host/bcm2835-sdhost.c | 1652 +++++++++++++++++++++++++++++++++++++
 3 files changed, 1662 insertions(+)
 create mode 100644 drivers/mmc/host/bcm2835-sdhost.c

diff --git a/drivers/mmc/host/Kconfig b/drivers/mmc/host/Kconfig
index 1526b8a..b991a21 100644
--- a/drivers/mmc/host/Kconfig
+++ b/drivers/mmc/host/Kconfig
@@ -778,6 +778,15 @@ config MMC_TOSHIBA_PCI
        depends on PCI
        help
 
+config MMC_BCM2835_SDHOST
+       tristate "platform support for the BCM2835 SDHOST MMC Controller"
+       depends on ARCH_BCM2835 || COMPILE_TEST
+       help
+         This selects the BCM2835 SDHOST MMC controller. If you have a BCM2835
+         platform with SD or MMC devices, say Y or M here.
+
+         If unsure, say N.
+
 config MMC_MTK
        tristate "MediaTek SD/MMC Card Interface support"
        depends on HAS_DMA
diff --git a/drivers/mmc/host/Makefile b/drivers/mmc/host/Makefile
index 3595f83..b31b994 100644
--- a/drivers/mmc/host/Makefile
+++ b/drivers/mmc/host/Makefile
@@ -57,6 +57,7 @@ obj-$(CONFIG_MMC_MOXART)      += moxart-mmc.o
 obj-$(CONFIG_MMC_SUNXI)                += sunxi-mmc.o
 obj-$(CONFIG_MMC_USDHI6ROL0)   += usdhi6rol0.o
 obj-$(CONFIG_MMC_TOSHIBA_PCI)  += toshsd.o
+obj-$(CONFIG_MMC_BCM2835_SDHOST)       += bcm2835-sdhost.o
 
 obj-$(CONFIG_MMC_REALTEK_PCI)  += rtsx_pci_sdmmc.o
 obj-$(CONFIG_MMC_REALTEK_USB)  += rtsx_usb_sdmmc.o
diff --git a/drivers/mmc/host/bcm2835-sdhost.c 
b/drivers/mmc/host/bcm2835-sdhost.c
new file mode 100644
index 0000000..a84f675
--- /dev/null
+++ b/drivers/mmc/host/bcm2835-sdhost.c
@@ -0,0 +1,1652 @@
+/*
+ * BCM2835 SD host driver.
+ *
+ * Author:      Phil Elwell <p...@raspberrypi.org>
+ *              Copyright (C) 2015-2016 Raspberry Pi (Trading) Ltd.
+ *
+ * Based on
+ *  mmc-bcm2835.c by Gellert Weisz
+ * which is, in turn, based on
+ *  sdhci-bcm2708.c by Broadcom
+ *  sdhci-bcm2835.c by Stephen Warren and Oleksandr Tymoshenko
+ *  sdhci.c and sdhci-pci.c by Pierre Ossman
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/delay.h>
+#include <linux/module.h>
+#include <linux/io.h>
+#include <linux/mmc/mmc.h>
+#include <linux/mmc/host.h>
+#include <linux/mmc/sd.h>
+#include <linux/scatterlist.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/clk.h>
+#include <linux/platform_device.h>
+#include <linux/err.h>
+#include <linux/blkdev.h>
+#include <linux/dmaengine.h>
+#include <linux/dma-mapping.h>
+#include <linux/of_dma.h>
+#include <linux/time.h>
+#include <linux/workqueue.h>
+
+#define SDCMD  0x00 /* Command to SD card              - 16 R/W */
+#define SDARG  0x04 /* Argument to SD card             - 32 R/W */
+#define SDTOUT 0x08 /* Start value for timeout counter - 32 R/W */
+#define SDCDIV 0x0c /* Start value for clock divider   - 11 R/W */
+#define SDRSP0 0x10 /* SD card response (31:0)         - 32 R   */
+#define SDRSP1 0x14 /* SD card response (63:32)        - 32 R   */
+#define SDRSP2 0x18 /* SD card response (95:64)        - 32 R   */
+#define SDRSP3 0x1c /* SD card response (127:96)       - 32 R   */
+#define SDHSTS 0x20 /* SD host status                  - 11 R   */
+#define SDVDD  0x30 /* SD card power control           -  1 R/W */
+#define SDEDM  0x34 /* Emergency Debug Mode            - 13 R/W */
+#define SDHCFG 0x38 /* Host configuration              -  2 R/W */
+#define SDHBCT 0x3c /* Host byte count (debug)         - 32 R/W */
+#define SDDATA 0x40 /* Data to/from SD card            - 32 R/W */
+#define SDHBLC 0x50 /* Host block count (SDIO/SDHC)    -  9 R/W */
+
+#define SDCMD_NEW_FLAG                  0x8000
+#define SDCMD_FAIL_FLAG                 0x4000
+#define SDCMD_BUSYWAIT                  0x800
+#define SDCMD_NO_RESPONSE               0x400
+#define SDCMD_LONG_RESPONSE             0x200
+#define SDCMD_WRITE_CMD                 0x80
+#define SDCMD_READ_CMD                  0x40
+#define SDCMD_CMD_MASK                  0x3f
+
+#define SDCDIV_MAX_CDIV                 0x7ff
+
+#define SDHSTS_BUSY_IRPT                0x400
+#define SDHSTS_BLOCK_IRPT               0x200
+#define SDHSTS_SDIO_IRPT                0x100
+#define SDHSTS_REW_TIME_OUT             0x80
+#define SDHSTS_CMD_TIME_OUT             0x40
+#define SDHSTS_CRC16_ERROR              0x20
+#define SDHSTS_CRC7_ERROR               0x10
+#define SDHSTS_FIFO_ERROR               0x08
+/* Reserved */
+/* Reserved */
+#define SDHSTS_DATA_FLAG                0x01
+
+#define SDHSTS_TRANSFER_ERROR_MASK      (SDHSTS_CRC7_ERROR | \
+                                        SDHSTS_CRC16_ERROR | \
+                                        SDHSTS_REW_TIME_OUT | \
+                                        SDHSTS_FIFO_ERROR)
+
+#define SDHSTS_ERROR_MASK               (SDHSTS_CMD_TIME_OUT | \
+                                        SDHSTS_TRANSFER_ERROR_MASK)
+
+#define SDHCFG_BUSY_IRPT_EN     BIT(10)
+#define SDHCFG_BLOCK_IRPT_EN    BIT(8)
+#define SDHCFG_SDIO_IRPT_EN     BIT(5)
+#define SDHCFG_DATA_IRPT_EN     BIT(4)
+#define SDHCFG_SLOW_CARD        BIT(3)
+#define SDHCFG_WIDE_EXT_BUS     BIT(2)
+#define SDHCFG_WIDE_INT_BUS     BIT(1)
+#define SDHCFG_REL_CMD_LINE     BIT(0)
+
+#define SDEDM_FORCE_DATA_MODE   BIT(19)
+#define SDEDM_CLOCK_PULSE       BIT(20)
+#define SDEDM_BYPASS            BIT(21)
+
+#define SDEDM_WRITE_THRESHOLD_SHIFT 9
+#define SDEDM_READ_THRESHOLD_SHIFT 14
+#define SDEDM_THRESHOLD_MASK     0x1f
+
+#define SDEDM_FSM_MASK           0xf
+#define SDEDM_FSM_IDENTMODE      0x0
+#define SDEDM_FSM_DATAMODE       0x1
+#define SDEDM_FSM_READDATA       0x2
+#define SDEDM_FSM_WRITEDATA      0x3
+#define SDEDM_FSM_READWAIT       0x4
+#define SDEDM_FSM_READCRC        0x5
+#define SDEDM_FSM_WRITECRC       0x6
+#define SDEDM_FSM_WRITEWAIT1     0x7
+#define SDEDM_FSM_POWERDOWN      0x8
+#define SDEDM_FSM_POWERUP        0x9
+#define SDEDM_FSM_WRITESTART1    0xa
+#define SDEDM_FSM_WRITESTART2    0xb
+#define SDEDM_FSM_GENPULSES      0xc
+#define SDEDM_FSM_WRITEWAIT2     0xd
+#define SDEDM_FSM_STARTPOWDOWN   0xf
+
+#define SDDATA_FIFO_WORDS        16
+
+#define FIFO_READ_THRESHOLD     4
+#define FIFO_WRITE_THRESHOLD    4
+#define SDDATA_FIFO_PIO_BURST   8
+#define CMD_DALLY_US            1
+
+struct bcm2835_host {
+       spinlock_t              lock;
+
+       void __iomem            *ioaddr;
+       u32                     phys_addr;
+
+       struct mmc_host         *mmc;
+
+       u32                     pio_timeout;    /* In jiffies */
+
+       int                     clock;          /* Current clock speed */
+
+       unsigned int            max_clk;        /* Max possible freq */
+
+       struct tasklet_struct   finish_tasklet; /* Tasklet structures */
+
+       struct work_struct      cmd_wait_wq;    /* Workqueue function */
+
+       struct timer_list       timer;          /* Timer for timeouts */
+
+       struct sg_mapping_iter  sg_miter;       /* SG state for PIO */
+       unsigned int            blocks;         /* remaining PIO blocks */
+
+       int                     irq;            /* Device IRQ */
+
+       u32                     cmd_quick_poll_retries;
+       u32                     ns_per_fifo_word;
+
+       /* cached registers */
+       u32                     hcfg;
+       u32                     cdiv;
+
+       /* Current request */
+       struct mmc_request              *mrq;
+       /* Current command */
+       struct mmc_command              *cmd;
+       /* Current data request */
+       struct mmc_data                 *data;
+       /* Data finished before cmd */
+       bool                            data_complete:1;
+       /* Drain the fifo when finishing */
+       bool                            flush_fifo:1;
+       /* Wait for busy interrupt */
+       bool                            use_busy:1;
+       /* Send CMD23 */
+       bool                            use_sbc:1;
+
+       /*DMA part*/
+       struct dma_chan                 *dma_chan_rx;
+       struct dma_chan                 *dma_chan_tx;
+       /* Channel in use */
+       struct dma_chan                 *dma_chan;
+       struct dma_async_tx_descriptor  *dma_desc;
+       u32                             dma_dir;
+       u32                             drain_words;
+       struct page                     *drain_page;
+       u32                             drain_offset;
+
+       bool                            use_dma;
+       /*end of DMA part*/
+       /* maximum length of time spent waiting */
+       int                             max_delay;
+       /* Maximum block count for PIO (0 = always DMA) */
+       u32                             pio_limit;
+};
+
+static inline void bcm2835_sdhost_write(struct bcm2835_host *host,
+                                       u32 val, int reg)
+{
+       writel(val, host->ioaddr + reg);
+}
+
+static inline u32 bcm2835_sdhost_read(struct bcm2835_host *host, int reg)
+{
+       return readl(host->ioaddr + reg);
+}
+
+static inline u32 bcm2835_sdhost_read_relaxed(struct bcm2835_host *host,
+                                             int reg)
+{
+       return readl_relaxed(host->ioaddr + reg);
+}
+
+static void bcm2835_sdhost_dumpcmd(struct bcm2835_host *host,
+                                  struct mmc_command *cmd,
+                                  const char *label)
+{
+       if (!cmd)
+               return;
+
+       pr_err("%s:%c%s op %d arg 0x%x flags 0x%x - resp %08x %08x %08x %08x, 
err %d\n",
+              mmc_hostname(host->mmc),
+              (cmd == host->cmd) ? '>' : ' ',
+              label, cmd->opcode, cmd->arg, cmd->flags,
+              cmd->resp[0], cmd->resp[1], cmd->resp[2], cmd->resp[3],
+              cmd->error);
+}
+
+static void bcm2835_sdhost_dumpregs(struct bcm2835_host *host)
+{
+       if (host->mrq) {
+               bcm2835_sdhost_dumpcmd(host, host->mrq->sbc, "sbc");
+               bcm2835_sdhost_dumpcmd(host, host->mrq->cmd, "cmd");
+               if (host->mrq->data) {
+                       pr_err("%s: data blocks %x blksz %x - err %d\n",
+                              mmc_hostname(host->mmc),
+                              host->mrq->data->blocks,
+                              host->mrq->data->blksz,
+                              host->mrq->data->error);
+               }
+               bcm2835_sdhost_dumpcmd(host, host->mrq->stop, "stop");
+       }
+
+       pr_err("%s: =========== REGISTER DUMP ===========\n",
+              mmc_hostname(host->mmc));
+
+       pr_err("%s: SDCMD  0x%08x\n",
+              mmc_hostname(host->mmc),
+              bcm2835_sdhost_read(host, SDCMD));
+       pr_err("%s: SDARG  0x%08x\n",
+              mmc_hostname(host->mmc),
+              bcm2835_sdhost_read(host, SDARG));
+       pr_err("%s: SDTOUT 0x%08x\n",
+              mmc_hostname(host->mmc),
+              bcm2835_sdhost_read(host, SDTOUT));
+       pr_err("%s: SDCDIV 0x%08x\n",
+              mmc_hostname(host->mmc),
+              bcm2835_sdhost_read(host, SDCDIV));
+       pr_err("%s: SDRSP0 0x%08x\n",
+              mmc_hostname(host->mmc),
+              bcm2835_sdhost_read(host, SDRSP0));
+       pr_err("%s: SDRSP1 0x%08x\n",
+              mmc_hostname(host->mmc),
+              bcm2835_sdhost_read(host, SDRSP1));
+       pr_err("%s: SDRSP2 0x%08x\n",
+              mmc_hostname(host->mmc),
+              bcm2835_sdhost_read(host, SDRSP2));
+       pr_err("%s: SDRSP3 0x%08x\n",
+              mmc_hostname(host->mmc),
+              bcm2835_sdhost_read(host, SDRSP3));
+       pr_err("%s: SDHSTS 0x%08x\n",
+              mmc_hostname(host->mmc),
+              bcm2835_sdhost_read(host, SDHSTS));
+       pr_err("%s: SDVDD  0x%08x\n",
+              mmc_hostname(host->mmc),
+              bcm2835_sdhost_read(host, SDVDD));
+       pr_err("%s: SDEDM  0x%08x\n",
+              mmc_hostname(host->mmc),
+              bcm2835_sdhost_read(host, SDEDM));
+       pr_err("%s: SDHCFG 0x%08x\n",
+              mmc_hostname(host->mmc),
+              bcm2835_sdhost_read(host, SDHCFG));
+       pr_err("%s: SDHBCT 0x%08x\n",
+              mmc_hostname(host->mmc),
+              bcm2835_sdhost_read(host, SDHBCT));
+       pr_err("%s: SDHBLC 0x%08x\n",
+              mmc_hostname(host->mmc),
+              bcm2835_sdhost_read(host, SDHBLC));
+
+       pr_err("%s: ===========================================\n",
+              mmc_hostname(host->mmc));
+}
+
+static void bcm2835_sdhost_set_power(struct bcm2835_host *host, bool on)
+{
+       bcm2835_sdhost_write(host, on ? 1 : 0, SDVDD);
+}
+
+static void bcm2835_sdhost_reset_internal(struct bcm2835_host *host)
+{
+       u32 temp;
+
+       bcm2835_sdhost_set_power(host, false);
+
+       bcm2835_sdhost_write(host, 0, SDCMD);
+       bcm2835_sdhost_write(host, 0, SDARG);
+       bcm2835_sdhost_write(host, 0xf00000, SDTOUT);
+       bcm2835_sdhost_write(host, 0, SDCDIV);
+       bcm2835_sdhost_write(host, 0x7f8, SDHSTS); /* Write 1s to clear */
+       bcm2835_sdhost_write(host, 0, SDHCFG);
+       bcm2835_sdhost_write(host, 0, SDHBCT);
+       bcm2835_sdhost_write(host, 0, SDHBLC);
+
+       /* Limit fifo usage due to silicon bug */
+       temp = bcm2835_sdhost_read(host, SDEDM);
+       temp &= ~((SDEDM_THRESHOLD_MASK << SDEDM_READ_THRESHOLD_SHIFT) |
+                 (SDEDM_THRESHOLD_MASK << SDEDM_WRITE_THRESHOLD_SHIFT));
+       temp |= (FIFO_READ_THRESHOLD << SDEDM_READ_THRESHOLD_SHIFT) |
+               (FIFO_WRITE_THRESHOLD << SDEDM_WRITE_THRESHOLD_SHIFT);
+       bcm2835_sdhost_write(host, temp, SDEDM);
+       mdelay(10);
+       bcm2835_sdhost_set_power(host, true);
+       mdelay(10);
+       host->clock = 0;
+       bcm2835_sdhost_write(host, host->hcfg, SDHCFG);
+       bcm2835_sdhost_write(host, host->cdiv, SDCDIV);
+}
+
+static void bcm2835_sdhost_reset(struct mmc_host *mmc)
+{
+       struct bcm2835_host *host = mmc_priv(mmc);
+       unsigned long flags;
+
+       spin_lock_irqsave(&host->lock, flags);
+       bcm2835_sdhost_reset_internal(host);
+       spin_unlock_irqrestore(&host->lock, flags);
+}
+
+static void bcm2835_sdhost_set_ios(struct mmc_host *mmc, struct mmc_ios *ios);
+
+static void bcm2835_sdhost_init(struct bcm2835_host *host, int soft)
+{
+       pr_debug("bcm2835_sdhost_init(%d)\n", soft);
+
+       /* Set interrupt enables */
+       host->hcfg = SDHCFG_BUSY_IRPT_EN;
+
+       bcm2835_sdhost_reset_internal(host);
+
+       if (soft) {
+               /* force clock reconfiguration */
+               host->clock = 0;
+               bcm2835_sdhost_set_ios(host->mmc, &host->mmc->ios);
+       }
+}
+
+static void bcm2835_sdhost_wait_transfer_complete(struct bcm2835_host *host)
+{
+       int timediff;
+       u32 alternate_idle;
+       u32 edm;
+
+       alternate_idle = (host->mrq->data->flags & MMC_DATA_READ) ?
+               SDEDM_FSM_READWAIT : SDEDM_FSM_WRITESTART1;
+
+       edm = bcm2835_sdhost_read(host, SDEDM);
+
+       timediff = 0;
+
+       while (1) {
+               u32 fsm = edm & SDEDM_FSM_MASK;
+
+               if ((fsm == SDEDM_FSM_IDENTMODE) ||
+                   (fsm == SDEDM_FSM_DATAMODE))
+                       break;
+               if (fsm == alternate_idle) {
+                       bcm2835_sdhost_write(host,
+                                            edm | SDEDM_FORCE_DATA_MODE,
+                                            SDEDM);
+                       break;
+               }
+
+               timediff++;
+               if (timediff == 100000) {
+                       pr_err("%s: wait_transfer_complete - still waiting 
after %d retries\n",
+                              mmc_hostname(host->mmc),
+                              timediff);
+                       bcm2835_sdhost_dumpregs(host);
+                       host->mrq->data->error = -ETIMEDOUT;
+                       return;
+               }
+               cpu_relax();
+               edm = bcm2835_sdhost_read(host, SDEDM);
+       }
+}
+
+static void bcm2835_sdhost_finish_data(struct bcm2835_host *host);
+
+static void bcm2835_sdhost_dma_complete(void *param)
+{
+       struct bcm2835_host *host = param;
+       struct mmc_data *data = host->data;
+       unsigned long flags;
+
+       spin_lock_irqsave(&host->lock, flags);
+
+       if (host->dma_chan) {
+               dma_unmap_sg(host->dma_chan->device->dev,
+                            data->sg, data->sg_len,
+                            host->dma_dir);
+
+               host->dma_chan = NULL;
+       }
+
+       if (host->drain_words) {
+               void *page;
+               u32 *buf;
+
+               page = kmap_atomic(host->drain_page);
+               buf = page + host->drain_offset;
+
+               while (host->drain_words) {
+                       u32 edm = bcm2835_sdhost_read(host, SDEDM);
+
+                       if ((edm >> 4) & 0x1f)
+                               *(buf++) = bcm2835_sdhost_read(host,
+                                                              SDDATA);
+                       host->drain_words--;
+               }
+
+               kunmap_atomic(page);
+       }
+
+       bcm2835_sdhost_finish_data(host);
+
+       spin_unlock_irqrestore(&host->lock, flags);
+}
+
+static void bcm2835_sdhost_transfer_block_pio(struct bcm2835_host *host,
+                                             bool is_read)
+{
+       unsigned long flags;
+       size_t blksize, len;
+       u32 *buf;
+       unsigned long wait_max;
+
+       blksize = host->data->blksz;
+
+       wait_max = jiffies + msecs_to_jiffies(host->pio_timeout);
+
+       local_irq_save(flags);
+
+       while (blksize) {
+               int copy_words;
+               u32 hsts = 0;
+
+               if (!sg_miter_next(&host->sg_miter)) {
+                       host->data->error = -EINVAL;
+                       break;
+               }
+
+               len = min(host->sg_miter.length, blksize);
+               if (len % 4) {
+                       host->data->error = -EINVAL;
+                       break;
+               }
+
+               blksize -= len;
+               host->sg_miter.consumed = len;
+
+               buf = (u32 *)host->sg_miter.addr;
+
+               copy_words = len / 4;
+
+               while (copy_words) {
+                       int burst_words, words;
+                       u32 edm;
+
+                       burst_words = SDDATA_FIFO_PIO_BURST;
+                       if (burst_words > copy_words)
+                               burst_words = copy_words;
+                       edm = bcm2835_sdhost_read(host, SDEDM);
+                       if (is_read)
+                               words = ((edm >> 4) & 0x1f);
+                       else
+                               words = SDDATA_FIFO_WORDS - ((edm >> 4) & 0x1f);
+
+                       if (words < burst_words) {
+                               int fsm_state = (edm & SDEDM_FSM_MASK);
+
+                               if ((is_read &&
+                                    (fsm_state != SDEDM_FSM_READDATA &&
+                                     fsm_state != SDEDM_FSM_READWAIT &&
+                                     fsm_state != SDEDM_FSM_READCRC)) ||
+                                   (!is_read &&
+                                    (fsm_state != SDEDM_FSM_WRITEDATA &&
+                                     fsm_state != SDEDM_FSM_WRITESTART1 &&
+                                     fsm_state != SDEDM_FSM_WRITESTART2))) {
+                                       hsts = bcm2835_sdhost_read(host,
+                                                                  SDHSTS);
+                                       pr_err("%s: fsm %x, hsts %x\n",
+                                              mmc_hostname(host->mmc),
+                                              fsm_state, hsts);
+                                       if (hsts & SDHSTS_ERROR_MASK)
+                                               break;
+                               }
+
+                               if (time_after(jiffies, wait_max)) {
+                                       pr_err("%s: PIO %s timeout - EDM %x\n",
+                                              is_read ? "read" : "write",
+                                              mmc_hostname(host->mmc),
+                                              edm);
+                                       hsts = SDHSTS_REW_TIME_OUT;
+                                       break;
+                               }
+                               ndelay((burst_words - words) *
+                                      host->ns_per_fifo_word);
+                               continue;
+                       } else if (words > copy_words) {
+                               words = copy_words;
+                       }
+
+                       copy_words -= words;
+
+                       while (words) {
+                               if (is_read) {
+                                       *(buf++) = bcm2835_sdhost_read(host,
+                                                                      SDDATA);
+                               } else {
+                                       bcm2835_sdhost_write(host, *(buf++),
+                                                            SDDATA);
+                               }
+                               words--;
+                       }
+               }
+
+               if (hsts & SDHSTS_ERROR_MASK)
+                       break;
+       }
+
+       sg_miter_stop(&host->sg_miter);
+
+       local_irq_restore(flags);
+}
+
+static void bcm2835_sdhost_transfer_pio(struct bcm2835_host *host)
+{
+       u32 sdhsts;
+       bool is_read;
+
+       is_read = (host->data->flags & MMC_DATA_READ) != 0;
+       bcm2835_sdhost_transfer_block_pio(host, is_read);
+
+       sdhsts = bcm2835_sdhost_read(host, SDHSTS);
+       if (sdhsts & (SDHSTS_CRC16_ERROR |
+                     SDHSTS_CRC7_ERROR |
+                     SDHSTS_FIFO_ERROR)) {
+               pr_err("%s: %s transfer error - HSTS %x\n",
+                      mmc_hostname(host->mmc),
+                      is_read ? "read" : "write",
+                      sdhsts);
+               host->data->error = -EILSEQ;
+       } else if ((sdhsts & (SDHSTS_CMD_TIME_OUT |
+                             SDHSTS_REW_TIME_OUT))) {
+               pr_err("%s: %s timeout error - HSTS %x\n",
+                      mmc_hostname(host->mmc),
+                      is_read ? "read" : "write",
+                      sdhsts);
+               host->data->error = -ETIMEDOUT;
+       }
+}
+
+static void bcm2835_sdhost_prepare_dma(struct bcm2835_host *host,
+                                      struct mmc_data *data)
+{
+       int len, dir_data, dir_slave;
+       struct dma_async_tx_descriptor *desc = NULL;
+       struct dma_chan *dma_chan;
+
+       pr_debug("bcm2835_sdhost_prepare_dma()\n");
+
+       if (data->flags & MMC_DATA_READ) {
+               dma_chan = host->dma_chan_rx;
+               dir_data = DMA_FROM_DEVICE;
+               dir_slave = DMA_DEV_TO_MEM;
+       } else {
+               dma_chan = host->dma_chan_tx;
+               dir_data = DMA_TO_DEVICE;
+               dir_slave = DMA_MEM_TO_DEV;
+       }
+
+       /* The block doesn't manage the FIFO DREQs properly for
+        * multi-block transfers, so don't attempt to DMA the final
+        * few words.  Unfortunately this requires the final sg entry
+        * to be trimmed.  N.B. This code demands that the overspill
+        * is contained in a single sg entry.
+        */
+
+       host->drain_words = 0;
+       if ((data->blocks > 1) && (dir_data == DMA_FROM_DEVICE)) {
+               struct scatterlist *sg;
+               u32 len;
+               int i;
+
+               len = min((u32)(FIFO_READ_THRESHOLD - 1) * 4,
+                         (u32)data->blocks * data->blksz);
+
+               for_each_sg(data->sg, sg, data->sg_len, i) {
+                       if (sg_is_last(sg)) {
+                               WARN_ON(sg->length < len);
+                               sg->length -= len;
+                               host->drain_page = (struct page *)sg->page_link;
+                               host->drain_offset = sg->offset + sg->length;
+                       }
+               }
+               host->drain_words = len / 4;
+       }
+
+       len = dma_map_sg(dma_chan->device->dev, data->sg, data->sg_len,
+                        dir_data);
+
+       if (len > 0) {
+               desc = dmaengine_prep_slave_sg(dma_chan, data->sg,
+                                              len, dir_slave,
+                                              DMA_PREP_INTERRUPT |
+                                              DMA_CTRL_ACK);
+       }
+
+       if (desc) {
+               desc->callback = bcm2835_sdhost_dma_complete;
+               desc->callback_param = host;
+               host->dma_desc = desc;
+               host->dma_chan = dma_chan;
+               host->dma_dir = dir_data;
+       }
+}
+
+static void bcm2835_sdhost_start_dma(struct bcm2835_host *host)
+{
+       dmaengine_submit(host->dma_desc);
+       dma_async_issue_pending(host->dma_chan);
+}
+
+static void bcm2835_sdhost_set_transfer_irqs(struct bcm2835_host *host)
+{
+       u32 all_irqs = SDHCFG_DATA_IRPT_EN | SDHCFG_BLOCK_IRPT_EN |
+               SDHCFG_BUSY_IRPT_EN;
+
+       if (host->dma_desc) {
+               host->hcfg = (host->hcfg & ~all_irqs) |
+                       SDHCFG_BUSY_IRPT_EN;
+       } else {
+               host->hcfg = (host->hcfg & ~all_irqs) |
+                       SDHCFG_DATA_IRPT_EN |
+                       SDHCFG_BUSY_IRPT_EN;
+       }
+
+       bcm2835_sdhost_write(host, host->hcfg, SDHCFG);
+}
+
+static void bcm2835_sdhost_prepare_data(struct bcm2835_host *host,
+                                       struct mmc_command *cmd)
+{
+       struct mmc_data *data = cmd->data;
+
+       WARN_ON(host->data);
+
+       host->data = data;
+       if (!data)
+               return;
+
+       /* Sanity checks */
+       WARN_ON(data->blksz * data->blocks > 524288);
+       WARN_ON(data->blksz > host->mmc->max_blk_size);
+       WARN_ON(data->blocks > 65535);
+
+       host->data_complete = false;
+       host->flush_fifo = false;
+       host->data->bytes_xfered = 0;
+
+       if (!host->dma_desc) {
+               /* Use PIO */
+               int flags = SG_MITER_ATOMIC;
+
+               if (data->flags & MMC_DATA_READ)
+                       flags |= SG_MITER_TO_SG;
+               else
+                       flags |= SG_MITER_FROM_SG;
+               sg_miter_start(&host->sg_miter, data->sg, data->sg_len, flags);
+               host->blocks = data->blocks;
+       }
+
+       bcm2835_sdhost_set_transfer_irqs(host);
+
+       bcm2835_sdhost_write(host, data->blksz, SDHBCT);
+       bcm2835_sdhost_write(host, data->blocks, SDHBLC);
+}
+
+bool bcm2835_sdhost_send_command(struct bcm2835_host *host,
+                                struct mmc_command *cmd)
+{
+       u32 sdcmd, sdhsts;
+       unsigned long timeout;
+       int delay;
+
+       WARN_ON(host->cmd);
+
+       if (cmd->data) {
+               pr_debug("%s: send_command %d 0x%x (flags 0x%x) - %s %d*%d\n",
+                        mmc_hostname(host->mmc),
+                        cmd->opcode, cmd->arg, cmd->flags,
+                        (cmd->data->flags & MMC_DATA_READ) ?
+                        "read" : "write", cmd->data->blocks,
+                        cmd->data->blksz);
+       } else {
+               pr_debug("%s: send_command %d 0x%x (flags 0x%x)\n",
+                        mmc_hostname(host->mmc),
+                        cmd->opcode, cmd->arg, cmd->flags);
+       }
+
+       /* Wait max 100 ms */
+       timeout = 10000;
+
+       while (bcm2835_sdhost_read(host, SDCMD) & SDCMD_NEW_FLAG) {
+               if (timeout == 0) {
+                       pr_err("%s: previous command never completed.\n",
+                              mmc_hostname(host->mmc));
+                       bcm2835_sdhost_dumpregs(host);
+                       cmd->error = -EILSEQ;
+                       tasklet_schedule(&host->finish_tasklet);
+                       return false;
+               }
+               timeout--;
+               udelay(10);
+       }
+
+       delay = (10000 - timeout) / 100;
+       if (delay > host->max_delay) {
+               host->max_delay = delay;
+               pr_warn("%s: controller hung for %d ms\n",
+                       mmc_hostname(host->mmc),
+                       host->max_delay);
+       }
+
+       timeout = jiffies;
+       if (!cmd->data && cmd->busy_timeout > 9000)
+               timeout += DIV_ROUND_UP(cmd->busy_timeout, 1000) * HZ + HZ;
+       else
+               timeout += 10 * HZ;
+       mod_timer(&host->timer, timeout);
+
+       host->cmd = cmd;
+
+       /* Clear any error flags */
+       sdhsts = bcm2835_sdhost_read(host, SDHSTS);
+       if (sdhsts & SDHSTS_ERROR_MASK)
+               bcm2835_sdhost_write(host, sdhsts, SDHSTS);
+
+       if ((cmd->flags & MMC_RSP_136) && (cmd->flags & MMC_RSP_BUSY)) {
+               pr_err("%s: unsupported response type!\n",
+                      mmc_hostname(host->mmc));
+               cmd->error = -EINVAL;
+               tasklet_schedule(&host->finish_tasklet);
+               return false;
+       }
+
+       bcm2835_sdhost_prepare_data(host, cmd);
+
+       bcm2835_sdhost_write(host, cmd->arg, SDARG);
+
+       sdcmd = cmd->opcode & SDCMD_CMD_MASK;
+
+       host->use_busy = false;
+       if (!(cmd->flags & MMC_RSP_PRESENT)) {
+               sdcmd |= SDCMD_NO_RESPONSE;
+       } else {
+               if (cmd->flags & MMC_RSP_136)
+                       sdcmd |= SDCMD_LONG_RESPONSE;
+               if (cmd->flags & MMC_RSP_BUSY) {
+                       sdcmd |= SDCMD_BUSYWAIT;
+                       host->use_busy = true;
+               }
+       }
+
+       if (cmd->data) {
+               if (cmd->data->flags & MMC_DATA_WRITE)
+                       sdcmd |= SDCMD_WRITE_CMD;
+               if (cmd->data->flags & MMC_DATA_READ)
+                       sdcmd |= SDCMD_READ_CMD;
+       }
+
+       bcm2835_sdhost_write(host, sdcmd | SDCMD_NEW_FLAG, SDCMD);
+
+       return true;
+}
+
+static void bcm2835_sdhost_finish_command(struct bcm2835_host *host,
+                                         unsigned long *irq_flags);
+
+static void bcm2835_sdhost_transfer_complete(struct bcm2835_host *host)
+{
+       struct mmc_data *data;
+
+       WARN_ON(!host->data_complete);
+
+       data = host->data;
+       host->data = NULL;
+
+       pr_debug("transfer_complete(error %d, stop %d)\n",
+                data->error, data->stop ? 1 : 0);
+
+       /* Need to send CMD12 if -
+        * a) open-ended multiblock transfer (no CMD23)
+        * b) error in multiblock transfer
+        */
+       if (host->mrq->stop && (data->error || !host->use_sbc)) {
+               if (bcm2835_sdhost_send_command(host, host->mrq->stop)) {
+                       /* No busy, so poll for completion */
+                       if (!host->use_busy)
+                               bcm2835_sdhost_finish_command(host, NULL);
+               }
+       } else {
+               bcm2835_sdhost_wait_transfer_complete(host);
+               tasklet_schedule(&host->finish_tasklet);
+       }
+}
+
+static void bcm2835_sdhost_finish_data(struct bcm2835_host *host)
+{
+       struct mmc_data *data;
+
+       data = host->data;
+
+       pr_debug("finish_data(error %d, stop %d, sbc %d)\n",
+                data->error, data->stop ? 1 : 0,
+                host->mrq->sbc ? 1 : 0);
+
+       host->hcfg &= ~(SDHCFG_DATA_IRPT_EN | SDHCFG_BLOCK_IRPT_EN);
+       bcm2835_sdhost_write(host, host->hcfg, SDHCFG);
+
+       data->bytes_xfered = data->error ? 0 : (data->blksz * data->blocks);
+
+       host->data_complete = true;
+
+       if (host->cmd) {
+               /* Data managed to finish before the
+                * command completed. Make sure we do
+                * things in the proper order.
+                */
+               pr_debug("Finished early - HSTS %x\n",
+                        bcm2835_sdhost_read(host, SDHSTS));
+       } else {
+               bcm2835_sdhost_transfer_complete(host);
+       }
+}
+
+/* If irq_flags is valid, the caller is in a thread context and is
+ * allowed to sleep
+ */
+static void bcm2835_sdhost_finish_command(struct bcm2835_host *host,
+                                         unsigned long *irq_flags)
+{
+       u32 sdcmd;
+       u32 retries;
+
+       pr_debug("finish_command(%x)\n", bcm2835_sdhost_read(host, SDCMD));
+
+       /* Poll quickly at first */
+
+       retries = host->cmd_quick_poll_retries;
+       if (!retries) {
+               /* Work out how many polls take 1us by timing 10us */
+               struct timeval start, now;
+               int us_diff;
+
+               retries = 1;
+               do {
+                       int i;
+
+                       retries *= 2;
+
+                       do_gettimeofday(&start);
+
+                       for (i = 0; i < retries; i++) {
+                               cpu_relax();
+                               sdcmd = bcm2835_sdhost_read(host, SDCMD);
+                       }
+
+                       do_gettimeofday(&now);
+                       us_diff = (now.tv_sec - start.tv_sec) * 1000000 +
+                               (now.tv_usec - start.tv_usec);
+               } while (us_diff < 10);
+
+               host->cmd_quick_poll_retries =
+                       ((retries * us_diff + 9) * CMD_DALLY_US) / 10 + 1;
+               retries = 1; /* We've already waited long enough this time */
+       }
+
+       retries = host->cmd_quick_poll_retries;
+       for (sdcmd = bcm2835_sdhost_read(host, SDCMD);
+            (sdcmd & SDCMD_NEW_FLAG) && !(sdcmd & SDCMD_FAIL_FLAG) && retries;
+            retries--) {
+               cpu_relax();
+               sdcmd = bcm2835_sdhost_read(host, SDCMD);
+       }
+
+       if (!retries) {
+               unsigned long wait_max;
+
+               if (!irq_flags) {
+                       /* Schedule the work */
+                       schedule_work(&host->cmd_wait_wq);
+                       return;
+               }
+
+               /* Wait max 100 ms */
+               wait_max = jiffies + msecs_to_jiffies(100);
+               while (time_before(jiffies, wait_max)) {
+                       spin_unlock_irqrestore(&host->lock, *irq_flags);
+                       usleep_range(1, 10);
+                       spin_lock_irqsave(&host->lock, *irq_flags);
+                       sdcmd = bcm2835_sdhost_read(host, SDCMD);
+                       if (!(sdcmd & SDCMD_NEW_FLAG) ||
+                           (sdcmd & SDCMD_FAIL_FLAG))
+                               break;
+               }
+       }
+
+       /* Check for errors */
+       if (sdcmd & SDCMD_NEW_FLAG) {
+               pr_err("%s: command never completed.\n",
+                      mmc_hostname(host->mmc));
+               bcm2835_sdhost_dumpregs(host);
+               host->cmd->error = -EIO;
+               tasklet_schedule(&host->finish_tasklet);
+               return;
+       } else if (sdcmd & SDCMD_FAIL_FLAG) {
+               u32 sdhsts = bcm2835_sdhost_read(host, SDHSTS);
+
+               /* Clear the errors */
+               bcm2835_sdhost_write(host, SDHSTS_ERROR_MASK, SDHSTS);
+
+               if (!(sdhsts & SDHSTS_CRC7_ERROR) ||
+                   (host->cmd->opcode != 1)) {
+                       if (sdhsts & SDHSTS_CMD_TIME_OUT) {
+                               host->cmd->error = -ETIMEDOUT;
+                       } else {
+                               pr_err("%s: unexpected command %d error\n",
+                                      mmc_hostname(host->mmc),
+                                      host->cmd->opcode);
+                               bcm2835_sdhost_dumpregs(host);
+                               host->cmd->error = -EILSEQ;
+                       }
+                       tasklet_schedule(&host->finish_tasklet);
+                       return;
+               }
+       }
+
+       if (host->cmd->flags & MMC_RSP_PRESENT) {
+               if (host->cmd->flags & MMC_RSP_136) {
+                       int i;
+
+                       for (i = 0; i < 4; i++) {
+                               host->cmd->resp[3 - i] =
+                                       bcm2835_sdhost_read(host,
+                                                           SDRSP0 + i * 4);
+                       }
+
+                       pr_debug("%s: finish_command %08x %08x %08x %08x\n",
+                                mmc_hostname(host->mmc),
+                                host->cmd->resp[0], host->cmd->resp[1],
+                                host->cmd->resp[2], host->cmd->resp[3]);
+               } else {
+                       host->cmd->resp[0] = bcm2835_sdhost_read(host, SDRSP0);
+                       pr_debug("%s: finish_command %08x\n",
+                                mmc_hostname(host->mmc),
+                                host->cmd->resp[0]);
+               }
+       }
+
+       if (host->cmd == host->mrq->sbc) {
+               /* Finished CMD23, now send actual command. */
+               host->cmd = NULL;
+               if (bcm2835_sdhost_send_command(host, host->mrq->cmd)) {
+                       if (host->data && host->dma_desc)
+                               /* DMA transfer starts now, PIO starts
+                                * after irq
+                                */
+                               bcm2835_sdhost_start_dma(host);
+
+                       if (!host->use_busy)
+                               bcm2835_sdhost_finish_command(host, NULL);
+               }
+       } else if (host->cmd == host->mrq->stop) {
+               /* Finished CMD12 */
+               tasklet_schedule(&host->finish_tasklet);
+       } else {
+               /* Processed actual command. */
+               host->cmd = NULL;
+               if (!host->data)
+                       tasklet_schedule(&host->finish_tasklet);
+               else if (host->data_complete)
+                       bcm2835_sdhost_transfer_complete(host);
+       }
+}
+
+static void bcm2835_sdhost_timeout(unsigned long data)
+{
+       struct bcm2835_host *host;
+       unsigned long flags;
+
+       host = (struct bcm2835_host *)data;
+
+       spin_lock_irqsave(&host->lock, flags);
+
+       if (host->mrq) {
+               pr_err("%s: timeout waiting for hardware interrupt.\n",
+                      mmc_hostname(host->mmc));
+               bcm2835_sdhost_dumpregs(host);
+
+               if (host->data) {
+                       host->data->error = -ETIMEDOUT;
+                       bcm2835_sdhost_finish_data(host);
+               } else {
+                       if (host->cmd)
+                               host->cmd->error = -ETIMEDOUT;
+                       else
+                               host->mrq->cmd->error = -ETIMEDOUT;
+
+                       pr_debug("timeout_timer tasklet_schedule\n");
+                       tasklet_schedule(&host->finish_tasklet);
+               }
+       }
+
+       spin_unlock_irqrestore(&host->lock, flags);
+}
+
+static void bcm2835_sdhost_busy_irq(struct bcm2835_host *host, u32 intmask)
+{
+       if (!host->cmd) {
+               pr_err("%s: got command busy interrupt 0x%08x even though no 
command operation was in progress.\n",
+                      mmc_hostname(host->mmc), (unsigned)intmask);
+               bcm2835_sdhost_dumpregs(host);
+               return;
+       }
+
+       if (!host->use_busy) {
+               pr_err("%s: got command busy interrupt 0x%08x even though not 
expecting one.\n",
+                      mmc_hostname(host->mmc), (unsigned)intmask);
+               bcm2835_sdhost_dumpregs(host);
+               return;
+       }
+       host->use_busy = false;
+
+       if (intmask & SDHSTS_ERROR_MASK) {
+               pr_err("sdhost_busy_irq: intmask %x, data %p\n",
+                      intmask, host->mrq->data);
+               if (intmask & SDHSTS_CRC7_ERROR) {
+                       host->cmd->error = -EILSEQ;
+               } else if (intmask & (SDHSTS_CRC16_ERROR |
+                                   SDHSTS_FIFO_ERROR)) {
+                       if (host->mrq->data)
+                               host->mrq->data->error = -EILSEQ;
+                       else
+                               host->cmd->error = -EILSEQ;
+               } else if (intmask & SDHSTS_REW_TIME_OUT) {
+                       if (host->mrq->data)
+                               host->mrq->data->error = -ETIMEDOUT;
+                       else
+                               host->cmd->error = -ETIMEDOUT;
+               } else if (intmask & SDHSTS_CMD_TIME_OUT) {
+                       host->cmd->error = -ETIMEDOUT;
+               }
+
+               bcm2835_sdhost_dumpregs(host);
+       } else {
+               bcm2835_sdhost_finish_command(host, NULL);
+       }
+}
+
+static void bcm2835_sdhost_data_irq(struct bcm2835_host *host, u32 intmask)
+{
+       /* There are no dedicated data/space available interrupt
+        * status bits, so it is necessary to use the single shared
+        * data/space available FIFO status bits. It is therefore not
+        * an error to get here when there is no data transfer in
+        * progress.
+        */
+       if (!host->data)
+               return;
+
+       if (intmask & (SDHSTS_CRC16_ERROR |
+                      SDHSTS_FIFO_ERROR |
+                      SDHSTS_REW_TIME_OUT)) {
+               if (intmask & (SDHSTS_CRC16_ERROR |
+                              SDHSTS_FIFO_ERROR))
+                       host->data->error = -EILSEQ;
+               else
+                       host->data->error = -ETIMEDOUT;
+       }
+
+       if (host->data->error) {
+               bcm2835_sdhost_finish_data(host);
+       } else if (host->data->flags & MMC_DATA_WRITE) {
+               /* Use the block interrupt for writes after the first block */
+               host->hcfg &= ~(SDHCFG_DATA_IRPT_EN);
+               host->hcfg |= SDHCFG_BLOCK_IRPT_EN;
+               bcm2835_sdhost_write(host, host->hcfg, SDHCFG);
+               bcm2835_sdhost_transfer_pio(host);
+       } else {
+               bcm2835_sdhost_transfer_pio(host);
+               host->blocks--;
+               if ((host->blocks == 0) || host->data->error)
+                       bcm2835_sdhost_finish_data(host);
+       }
+}
+
+static void bcm2835_sdhost_block_irq(struct bcm2835_host *host, u32 intmask)
+{
+       if (!host->data) {
+               pr_err("%s: got block interrupt 0x%08x even though no data 
operation was in progress.\n",
+                      mmc_hostname(host->mmc), (unsigned)intmask);
+               bcm2835_sdhost_dumpregs(host);
+               return;
+       }
+
+       if (intmask & (SDHSTS_CRC16_ERROR |
+                      SDHSTS_FIFO_ERROR |
+                      SDHSTS_REW_TIME_OUT)) {
+               if (intmask & (SDHSTS_CRC16_ERROR |
+                              SDHSTS_FIFO_ERROR))
+                       host->data->error = -EILSEQ;
+               else
+                       host->data->error = -ETIMEDOUT;
+       }
+
+       if (!host->dma_desc) {
+               WARN_ON(!host->blocks);
+               if (host->data->error || (--host->blocks == 0))
+                       bcm2835_sdhost_finish_data(host);
+               else
+                       bcm2835_sdhost_transfer_pio(host);
+       } else if (host->data->flags & MMC_DATA_WRITE) {
+               bcm2835_sdhost_finish_data(host);
+       }
+}
+
+static irqreturn_t bcm2835_sdhost_irq(int irq, void *dev_id)
+{
+       irqreturn_t result = IRQ_NONE;
+       struct bcm2835_host *host = dev_id;
+       u32 intmask;
+
+       spin_lock(&host->lock);
+
+       intmask = bcm2835_sdhost_read(host, SDHSTS);
+
+       bcm2835_sdhost_write(host,
+                            SDHSTS_BUSY_IRPT |
+                            SDHSTS_BLOCK_IRPT |
+                            SDHSTS_SDIO_IRPT |
+                            SDHSTS_DATA_FLAG,
+                            SDHSTS);
+
+       if (intmask & SDHSTS_BLOCK_IRPT) {
+               bcm2835_sdhost_block_irq(host, intmask);
+               result = IRQ_HANDLED;
+       }
+
+       if (intmask & SDHSTS_BUSY_IRPT) {
+               bcm2835_sdhost_busy_irq(host, intmask);
+               result = IRQ_HANDLED;
+       }
+
+       /* There is no true data interrupt status bit, so it is
+        * necessary to qualify the data flag with the interrupt
+        * enable bit.
+        */
+       if ((intmask & SDHSTS_DATA_FLAG) &&
+           (host->hcfg & SDHCFG_DATA_IRPT_EN)) {
+               bcm2835_sdhost_data_irq(host, intmask);
+               result = IRQ_HANDLED;
+       }
+
+       spin_unlock(&host->lock);
+
+       return result;
+}
+
+void bcm2835_sdhost_set_clock(struct bcm2835_host *host, unsigned int clock)
+{
+       int div = 0; /* Initialized for compiler warning */
+
+       /* The SDCDIV register has 11 bits, and holds (div - 2).  But
+        * in data mode the max is 50MHz wihout a minimum, and only
+        * the bottom 3 bits are used. Since the switch over is
+        * automatic (unless we have marked the card as slow...),
+        * chosen values have to make sense in both modes.  Ident mode
+        * must be 100-400KHz, so can range check the requested
+        * clock. CMD15 must be used to return to data mode, so this
+        * can be monitored.
+        *
+        * clock 250MHz -> 0->125MHz, 1->83.3MHz, 2->62.5MHz, 3->50.0MHz
+        *                 4->41.7MHz, 5->35.7MHz, 6->31.3MHz, 7->27.8MHz
+        *
+        *               623->400KHz/27.8MHz
+        *               reset value (507)->491159/50MHz
+        *
+        * BUT, the 3-bit clock divisor in data mode is too small if
+        * the core clock is higher than 250MHz, so instead use the
+        * SLOW_CARD configuration bit to force the use of the ident
+        * clock divisor at all times.
+        */
+
+       host->mmc->actual_clock = 0;
+
+       if (clock < 100000) {
+               /* Can't stop the clock, but make it as slow as possible
+                * to show willing
+                */
+               host->cdiv = SDCDIV_MAX_CDIV;
+               bcm2835_sdhost_write(host, host->cdiv, SDCDIV);
+               return;
+       }
+
+       div = host->max_clk / clock;
+       if (div < 2)
+               div = 2;
+       if ((host->max_clk / div) > clock)
+               div++;
+       div -= 2;
+
+       if (div > SDCDIV_MAX_CDIV)
+               div = SDCDIV_MAX_CDIV;
+
+       clock = host->max_clk / (div + 2);
+       host->mmc->actual_clock = clock;
+
+       /* Calibrate some delays */
+
+       host->ns_per_fifo_word = (1000000000 / clock) *
+               ((host->mmc->caps & MMC_CAP_4_BIT_DATA) ? 8 : 32);
+
+       host->cdiv = div;
+       bcm2835_sdhost_write(host, host->cdiv, SDCDIV);
+
+       /* Set the timeout to 500ms */
+       bcm2835_sdhost_write(host, host->mmc->actual_clock / 2, SDTOUT);
+}
+
+static void bcm2835_sdhost_request(struct mmc_host *mmc,
+                                  struct mmc_request *mrq)
+{
+       struct bcm2835_host *host;
+       unsigned long flags;
+       u32 edm, fsm;
+
+       host = mmc_priv(mmc);
+
+       /* Reset the error statuses in case this is a retry */
+       if (mrq->sbc)
+               mrq->sbc->error = 0;
+       if (mrq->cmd)
+               mrq->cmd->error = 0;
+       if (mrq->data)
+               mrq->data->error = 0;
+       if (mrq->stop)
+               mrq->stop->error = 0;
+
+       if (mrq->data && !is_power_of_2(mrq->data->blksz)) {
+               pr_err("%s: unsupported block size (%d bytes)\n",
+                      mmc_hostname(mmc), mrq->data->blksz);
+               mrq->cmd->error = -EINVAL;
+               mmc_request_done(mmc, mrq);
+               return;
+       }
+
+       if (host->use_dma && mrq->data &&
+           (mrq->data->blocks > host->pio_limit))
+               bcm2835_sdhost_prepare_dma(host, mrq->data);
+
+       spin_lock_irqsave(&host->lock, flags);
+
+       WARN_ON(host->mrq);
+       host->mrq = mrq;
+
+       edm = bcm2835_sdhost_read(host, SDEDM);
+       fsm = edm & SDEDM_FSM_MASK;
+
+       if ((fsm != SDEDM_FSM_IDENTMODE) &&
+           (fsm != SDEDM_FSM_DATAMODE)) {
+               pr_err("%s: previous command (%d) not complete (EDM %x)\n",
+                      mmc_hostname(host->mmc),
+                      bcm2835_sdhost_read(host, SDCMD) & SDCMD_CMD_MASK,
+                      edm);
+               bcm2835_sdhost_dumpregs(host);
+               mrq->cmd->error = -EILSEQ;
+               tasklet_schedule(&host->finish_tasklet);
+               spin_unlock_irqrestore(&host->lock, flags);
+               return;
+       }
+
+       host->use_sbc = !!mrq->sbc && (host->mrq->data->flags & MMC_DATA_READ);
+       if (host->use_sbc) {
+               if (bcm2835_sdhost_send_command(host, mrq->sbc)) {
+                       if (!host->use_busy)
+                               bcm2835_sdhost_finish_command(host, &flags);
+               }
+       } else if (bcm2835_sdhost_send_command(host, mrq->cmd)) {
+               if (host->data && host->dma_desc) {
+                       /* DMA transfer starts now, PIO starts after irq */
+                       bcm2835_sdhost_start_dma(host);
+               }
+
+               if (!host->use_busy)
+                       bcm2835_sdhost_finish_command(host, &flags);
+       }
+
+       spin_unlock_irqrestore(&host->lock, flags);
+}
+
+static void bcm2835_sdhost_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
+{
+       struct bcm2835_host *host = mmc_priv(mmc);
+       unsigned long flags;
+
+       spin_lock_irqsave(&host->lock, flags);
+
+       if (!ios->clock || ios->clock != host->clock) {
+               bcm2835_sdhost_set_clock(host, ios->clock);
+               host->clock = ios->clock;
+       }
+
+       /* set bus width */
+       host->hcfg &= ~SDHCFG_WIDE_EXT_BUS;
+       if (ios->bus_width == MMC_BUS_WIDTH_4)
+               host->hcfg |= SDHCFG_WIDE_EXT_BUS;
+
+       host->hcfg |= SDHCFG_WIDE_INT_BUS;
+
+       /* Disable clever clock switching, to cope with fast core clocks */
+       host->hcfg |= SDHCFG_SLOW_CARD;
+
+       bcm2835_sdhost_write(host, host->hcfg, SDHCFG);
+
+       spin_unlock_irqrestore(&host->lock, flags);
+}
+
+static struct mmc_host_ops bcm2835_sdhost_ops = {
+       .request = bcm2835_sdhost_request,
+       .set_ios = bcm2835_sdhost_set_ios,
+       .hw_reset = bcm2835_sdhost_reset,
+};
+
+static void bcm2835_sdhost_cmd_wait_work(struct work_struct *work)
+{
+       struct bcm2835_host *host;
+       unsigned long flags;
+
+       host = container_of(work, struct bcm2835_host, cmd_wait_wq);
+
+       spin_lock_irqsave(&host->lock, flags);
+
+       /* If this tasklet gets rescheduled while running, it will
+        * be run again afterwards but without any active request.
+        */
+       if (!host->mrq) {
+               spin_unlock_irqrestore(&host->lock, flags);
+               return;
+       }
+
+       bcm2835_sdhost_finish_command(host, &flags);
+
+       spin_unlock_irqrestore(&host->lock, flags);
+}
+
+static void bcm2835_sdhost_tasklet_finish(unsigned long param)
+{
+       struct bcm2835_host *host;
+       unsigned long flags;
+       struct mmc_request *mrq;
+       struct dma_chan *terminate_chan = NULL;
+
+       host = (struct bcm2835_host *)param;
+
+       spin_lock_irqsave(&host->lock, flags);
+
+       /* If this tasklet gets rescheduled while running, it will
+        * be run again afterwards but without any active request.
+        */
+       if (!host->mrq) {
+               spin_unlock_irqrestore(&host->lock, flags);
+               return;
+       }
+
+       del_timer(&host->timer);
+
+       mrq = host->mrq;
+
+       host->mrq = NULL;
+       host->cmd = NULL;
+       host->data = NULL;
+
+       host->dma_desc = NULL;
+       terminate_chan = host->dma_chan;
+       host->dma_chan = NULL;
+
+       spin_unlock_irqrestore(&host->lock, flags);
+
+       if (terminate_chan) {
+               int err = dmaengine_terminate_all(terminate_chan);
+
+               if (err)
+                       pr_err("%s: failed to terminate DMA (%d)\n",
+                              mmc_hostname(host->mmc), err);
+       }
+
+       mmc_request_done(host->mmc, mrq);
+}
+
+int bcm2835_sdhost_add_host(struct bcm2835_host *host)
+{
+       struct mmc_host *mmc;
+       struct dma_slave_config cfg;
+       char pio_limit_string[20];
+       int ret;
+
+       mmc = host->mmc;
+
+       bcm2835_sdhost_reset_internal(host);
+
+       mmc->f_max = host->max_clk;
+       mmc->f_min = host->max_clk / SDCDIV_MAX_CDIV;
+
+       mmc->max_busy_timeout = ~0 / (mmc->f_max / 1000);
+
+       pr_debug("f_max %d, f_min %d, max_busy_timeout %d\n",
+                mmc->f_max, mmc->f_min, mmc->max_busy_timeout);
+
+       /* host controller capabilities */
+       mmc->caps |=
+               MMC_CAP_SD_HIGHSPEED | MMC_CAP_MMC_HIGHSPEED |
+               MMC_CAP_NEEDS_POLL | MMC_CAP_HW_RESET | MMC_CAP_ERASE |
+               MMC_CAP_CMD23;
+
+       spin_lock_init(&host->lock);
+
+       if (IS_ERR_OR_NULL(host->dma_chan_tx) ||
+           IS_ERR_OR_NULL(host->dma_chan_rx)) {
+               pr_err("%s: unable to initialise DMA channels. Falling back to 
PIO\n",
+                      mmc_hostname(mmc));
+               host->use_dma = false;
+       } else {
+               host->use_dma = true;
+
+               cfg.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
+               cfg.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
+               cfg.slave_id = 13;              /* DREQ channel */
+
+               cfg.direction = DMA_MEM_TO_DEV;
+               cfg.src_addr = 0;
+               cfg.dst_addr = host->phys_addr + SDDATA;
+               ret = dmaengine_slave_config(host->dma_chan_tx, &cfg);
+               if (ret)
+                       host->use_dma = false;
+
+               cfg.direction = DMA_DEV_TO_MEM;
+               cfg.src_addr = host->phys_addr + SDDATA;
+               cfg.dst_addr = 0;
+               ret = dmaengine_slave_config(host->dma_chan_rx, &cfg);
+               if (ret)
+                       host->use_dma = false;
+       }
+
+       mmc->max_segs = 128;
+       mmc->max_req_size = 524288;
+       mmc->max_seg_size = mmc->max_req_size;
+       mmc->max_blk_size = 512;
+       mmc->max_blk_count =  65535;
+
+       /* report supported voltage ranges */
+       mmc->ocr_avail = MMC_VDD_32_33 | MMC_VDD_33_34;
+
+       tasklet_init(&host->finish_tasklet,
+                    bcm2835_sdhost_tasklet_finish, (unsigned long)host);
+
+       INIT_WORK(&host->cmd_wait_wq, bcm2835_sdhost_cmd_wait_work);
+
+       setup_timer(&host->timer, bcm2835_sdhost_timeout,
+                   (unsigned long)host);
+
+       bcm2835_sdhost_init(host, 0);
+
+       ret = request_irq(host->irq, bcm2835_sdhost_irq, 0 /*IRQF_SHARED*/,
+                         mmc_hostname(mmc), host);
+       if (ret) {
+               pr_err("%s: failed to request IRQ %d: %d\n",
+                      mmc_hostname(mmc), host->irq, ret);
+               goto untasklet;
+       }
+
+       mmc_add_host(mmc);
+
+       pio_limit_string[0] = '\0';
+       if (host->use_dma && (host->pio_limit > 0))
+               sprintf(pio_limit_string, " (>%d)", host->pio_limit);
+       pr_info("%s: loaded - DMA %s%s\n",
+               mmc_hostname(mmc),
+               host->use_dma ? "enabled" : "disabled",
+               pio_limit_string);
+
+       return 0;
+
+untasklet:
+       tasklet_kill(&host->finish_tasklet);
+
+       return ret;
+}
+
+static int bcm2835_sdhost_probe(struct platform_device *pdev)
+{
+       struct device *dev = &pdev->dev;
+       struct clk *clk;
+       struct resource *iomem;
+       struct bcm2835_host *host;
+       struct mmc_host *mmc;
+       int ret;
+
+       pr_debug("bcm2835_sdhost_probe\n");
+       mmc = mmc_alloc_host(sizeof(*host), dev);
+       if (!mmc)
+               return -ENOMEM;
+
+       mmc->ops = &bcm2835_sdhost_ops;
+       host = mmc_priv(mmc);
+       host->mmc = mmc;
+       host->cmd_quick_poll_retries = 0;
+       host->pio_timeout = msecs_to_jiffies(500);
+       host->pio_limit = 1;
+       host->max_delay = 1; /* Warn if over 1ms */
+       spin_lock_init(&host->lock);
+
+       iomem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+       host->ioaddr = devm_ioremap_resource(dev, iomem);
+       if (IS_ERR(host->ioaddr)) {
+               ret = PTR_ERR(host->ioaddr);
+               goto err;
+       }
+
+       /* Parse OF address directly to get the physical address for
+        * DMA to our registers.
+        */
+       host->phys_addr = be32_to_cpup(of_get_address(pdev->dev.of_node, 0,
+                                                     NULL, NULL));
+
+       pr_debug(" - ioaddr %lx, iomem->start %lx, phys_addr %lx\n",
+                (unsigned long)host->ioaddr,
+                (unsigned long)iomem->start,
+                (unsigned long)host->phys_addr);
+
+       host->dma_chan = NULL;
+       host->dma_desc = NULL;
+
+       host->dma_chan_tx = dma_request_slave_channel(dev, "tx");
+       host->dma_chan_rx = dma_request_slave_channel(dev, "rx");
+
+       clk = devm_clk_get(dev, NULL);
+       if (IS_ERR(clk)) {
+               ret = PTR_ERR(clk);
+               if (ret != -EPROBE_DEFER)
+                       dev_err(dev, "could not get clk: %d\n", ret);
+               goto err;
+       }
+
+       host->max_clk = clk_get_rate(clk);
+
+       host->irq = platform_get_irq(pdev, 0);
+       if (host->irq <= 0) {
+               dev_err(dev, "get IRQ failed\n");
+               ret = -EINVAL;
+               goto err;
+       }
+
+       pr_debug(" - max_clk %lx, irq %d\n",
+                (unsigned long)host->max_clk,
+                (int)host->irq);
+
+       mmc_of_parse(mmc);
+
+       ret = bcm2835_sdhost_add_host(host);
+       if (ret)
+               goto err;
+
+       platform_set_drvdata(pdev, host);
+
+       pr_debug("bcm2835_sdhost_probe -> OK\n");
+
+       return 0;
+
+err:
+       pr_debug("bcm2835_sdhost_probe -> err %d\n", ret);
+       mmc_free_host(mmc);
+
+       return ret;
+}
+
+static int bcm2835_sdhost_remove(struct platform_device *pdev)
+{
+       struct bcm2835_host *host = platform_get_drvdata(pdev);
+
+       pr_debug("bcm2835_sdhost_remove\n");
+
+       mmc_remove_host(host->mmc);
+
+       bcm2835_sdhost_set_power(host, false);
+
+       free_irq(host->irq, host);
+
+       del_timer_sync(&host->timer);
+
+       tasklet_kill(&host->finish_tasklet);
+
+       mmc_free_host(host->mmc);
+       platform_set_drvdata(pdev, NULL);
+
+       pr_debug("bcm2835_sdhost_remove - OK\n");
+       return 0;
+}
+
+static const struct of_device_id bcm2835_sdhost_match[] = {
+       { .compatible = "brcm,bcm2835-sdhost" },
+       { }
+};
+MODULE_DEVICE_TABLE(of, bcm2835_sdhost_match);
+
+static struct platform_driver bcm2835_sdhost_driver = {
+       .probe      = bcm2835_sdhost_probe,
+       .remove     = bcm2835_sdhost_remove,
+       .driver     = {
+               .name           = "sdhost-bcm2835",
+               .of_match_table = bcm2835_sdhost_match,
+       },
+};
+module_platform_driver(bcm2835_sdhost_driver);
+
+MODULE_ALIAS("platform:sdhost-bcm2835");
+MODULE_DESCRIPTION("BCM2835 SDHost driver");
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Phil Elwell");
-- 
2.7.0


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