On 01/18/2018 08:33 AM, Alexander Graf wrote:
> The BCM2835 family of SoCs has 2 different SD controllers: One based on
> the SDHCI spec and a custom, home-grown one.
> 
> This patch implements a driver for the latter based on the Linux driver.
> This is needed so that we can make use of device trees that assume driver
> presence of both SD controllers.
> 
> Signed-off-by: Alexander Graf <ag...@suse.de>
> 
> ---
> 
> v1 -> v2:
> 
>   - Remove hand written pinctrl support
>   - Checkpatch fixes
> ---
>  MAINTAINERS                  |   1 +
>  drivers/mmc/Kconfig          |  14 +
>  drivers/mmc/Makefile         |   1 +
>  drivers/mmc/bcm2835_sdhost.c | 994 
> +++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 1010 insertions(+)
>  create mode 100644 drivers/mmc/bcm2835_sdhost.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 1f2545191b..728d38aebf 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -97,6 +97,7 @@ S:  Orphaned (Since 2017-07)
>  F:   arch/arm/mach-bcm283x/
>  F:   drivers/gpio/bcm2835_gpio.c
>  F:   drivers/mmc/bcm2835_sdhci.c
> +F:   drivers/mmc/bcm2835_sdhost.c
>  F:   drivers/serial/serial_bcm283x_mu.c
>  F:   drivers/video/bcm2835.c
>  F:   include/dm/platform_data/serial_bcm283x_mu.h
> diff --git a/drivers/mmc/Kconfig b/drivers/mmc/Kconfig
> index ab0627a8af..9b90db908b 100644
> --- a/drivers/mmc/Kconfig
> +++ b/drivers/mmc/Kconfig
> @@ -256,6 +256,20 @@ config MMC_UNIPHIER
>         This selects support for the Matsushita SD/MMC Host Controller on
>         SocioNext UniPhier and Renesas RCar SoCs.
>  
> +config MMC_BCM2835
> +     bool "BCM2835 family custom SD/MMC Host Controller support"
> +     depends on ARCH_BCM283X
> +     depends on BLK && DM_MMC
> +     depends on OF_CONTROL
> +     default y
> +     help
> +       This selects support for the custom SD host controller in the BCM2835
> +       family of devices.
> +
> +       If you have a BCM2835 platform with SD or MMC devices, say Y here.
> +
> +       If unsure, say N.
> +
>  config MMC_SANDBOX
>       bool "Sandbox MMC support"
>       depends on SANDBOX
> diff --git a/drivers/mmc/Makefile b/drivers/mmc/Makefile
> index 64b6f21c61..42113e2603 100644
> --- a/drivers/mmc/Makefile
> +++ b/drivers/mmc/Makefile
> @@ -64,3 +64,4 @@ obj-$(CONFIG_MMC_SDHCI_ZYNQ)                += zynq_sdhci.o
>  
>  obj-$(CONFIG_MMC_SUNXI)                      += sunxi_mmc.o
>  obj-$(CONFIG_MMC_UNIPHIER)           += uniphier-sd.o
> +obj-$(CONFIG_MMC_BCM2835)            += bcm2835_sdhost.o
> diff --git a/drivers/mmc/bcm2835_sdhost.c b/drivers/mmc/bcm2835_sdhost.c
> new file mode 100644
> index 0000000000..ad9c7adb5a
> --- /dev/null
> +++ b/drivers/mmc/bcm2835_sdhost.c
> @@ -0,0 +1,994 @@
> +/*
> + * bcm2835 sdhost driver.
> + *
> + * The 2835 has two SD controllers: The Arasan sdhci controller
> + * (supported by the iproc driver) and a custom sdhost controller
> + * (supported by this driver).
> + *
> + * The sdhci controller supports both sdcard and sdio.  The sdhost
> + * controller supports the sdcard only, but has better performance.
> + * Also note that the rpi3 has sdio wifi, so driving the sdcard with
> + * the sdhost controller allows to use the sdhci controller for wifi
> + * support.
> + *
> + * The configuration is done by devicetree via pin muxing.  Both
> + * SD controller are available on the same pins (2 pin groups = pin 22
> + * to 27 + pin 48 to 53).  So it's possible to use both SD controllers
> + * at the same time with different pin groups.
> + *
> + * This code was ported to U-Boot by
> + *  Alexander Graf <ag...@suse.de>
> + * and is based on drivers/mmc/host/bcm2835.c in Linux which is written by
> + *  Phil Elwell <p...@raspberrypi.org>
> + *  Copyright (C) 2015-2016 Raspberry Pi (Trading) Ltd.
> + * which is 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/>.

Can be replaced to SPDX-License-Identifier?

> + */
> +#include <common.h>
> +#include <clk.h>
> +#include <fdtdec.h>
> +#include <mmc.h>
> +#include <dm.h>
> +#include <linux/compat.h>
> +#include <linux/io.h>
> +#include <linux/iopoll.h>
> +#include <linux/sizes.h>
> +#include <power/regulator.h>
> +#include <asm/unaligned.h>
> +#include <mach/gpio.h>
> +#include <asm/arch/msg.h>

Ordering.

> +
> +DECLARE_GLOBAL_DATA_PTR;
> +
> +#define msleep(a) udelay(a * 1000)
> +
> +#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/W */
> +#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 */

Remove unnecessary comment. What is 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 SDVDD_POWER_OFF              0
> +#define SDVDD_POWER_ON               1
> +
> +#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
> +
> +struct bcm2835_plat {
> +     struct mmc_config cfg;
> +     struct mmc mmc;
> +};
> +
> +struct bcm2835_host {
> +     void __iomem            *ioaddr;
> +     u32                     phys_addr;
> +
> +     int                     clock;          /* Current clock speed */
> +     unsigned int            max_clk;        /* Max possible freq */
> +     unsigned int            blocks;         /* remaining PIO blocks */
> +     int                     irq;            /* Device IRQ */
> +
> +     u32                     ns_per_fifo_word;
> +
> +     /* cached registers */
> +     u32                     hcfg;
> +     u32                     cdiv;
> +
> +     struct mmc_cmd  *cmd;           /* Current command */
> +     struct mmc_data         *data;          /* Current data request */
> +     bool                    data_complete:1;/* Data finished before cmd */
> +     bool                    use_busy:1;     /* Wait for busy interrupt */
> +     bool                    wait_data_complete:1;   /* Wait for data */
> +
> +     /* for threaded irq handler */
> +     bool                    irq_block;
> +     bool                    irq_busy;
> +     bool                    irq_data;
> +
> +     struct udevice          *dev;
> +     struct mmc              *mmc;
> +     struct bcm2835_plat     *plat;
> +};
> +
> +static void bcm2835_dumpregs(struct bcm2835_host *host)
> +{
> +     dev_dbg(dev, "=========== REGISTER DUMP ===========\n");
> +     dev_dbg(dev, "SDCMD  0x%08x\n", readl(host->ioaddr + SDCMD));
> +     dev_dbg(dev, "SDARG  0x%08x\n", readl(host->ioaddr + SDARG));
> +     dev_dbg(dev, "SDTOUT 0x%08x\n", readl(host->ioaddr + SDTOUT));
> +     dev_dbg(dev, "SDCDIV 0x%08x\n", readl(host->ioaddr + SDCDIV));
> +     dev_dbg(dev, "SDRSP0 0x%08x\n", readl(host->ioaddr + SDRSP0));
> +     dev_dbg(dev, "SDRSP1 0x%08x\n", readl(host->ioaddr + SDRSP1));
> +     dev_dbg(dev, "SDRSP2 0x%08x\n", readl(host->ioaddr + SDRSP2));
> +     dev_dbg(dev, "SDRSP3 0x%08x\n", readl(host->ioaddr + SDRSP3));
> +     dev_dbg(dev, "SDHSTS 0x%08x\n", readl(host->ioaddr + SDHSTS));
> +     dev_dbg(dev, "SDVDD  0x%08x\n", readl(host->ioaddr + SDVDD));
> +     dev_dbg(dev, "SDEDM  0x%08x\n", readl(host->ioaddr + SDEDM));
> +     dev_dbg(dev, "SDHCFG 0x%08x\n", readl(host->ioaddr + SDHCFG));
> +     dev_dbg(dev, "SDHBCT 0x%08x\n", readl(host->ioaddr + SDHBCT));
> +     dev_dbg(dev, "SDHBLC 0x%08x\n", readl(host->ioaddr + SDHBLC));
> +     dev_dbg(dev, "===========================================\n");
> +}
> +
> +static void bcm2835_reset_internal(struct bcm2835_host *host)
> +{
> +     u32 temp;
> +
> +     writel(SDVDD_POWER_OFF, host->ioaddr + SDVDD);
> +     writel(0, host->ioaddr + SDCMD);
> +     writel(0, host->ioaddr + SDARG);
> +     writel(0xf00000, host->ioaddr + SDTOUT);
> +     writel(0, host->ioaddr + SDCDIV);
> +     writel(0x7f8, host->ioaddr + SDHSTS); /* Write 1s to clear */

What is 0xf00000 and 0x7f8? it's magic number. Don't use the magic number.

> +     writel(0, host->ioaddr + SDHCFG);
> +     writel(0, host->ioaddr + SDHBCT);
> +     writel(0, host->ioaddr + SDHBLC);
> +
> +     /* Limit fifo usage due to silicon bug */
> +     temp = readl(host->ioaddr + 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);
> +     writel(temp, host->ioaddr + SDEDM);
> +     msleep(20);
> +     writel(SDVDD_POWER_ON, host->ioaddr + SDVDD);
> +     msleep(20);

Why need to sleep at here? Could you add the some comments?
like /* Wait for stable power. */ ?

> +     host->clock = 0;
> +     writel(host->hcfg, host->ioaddr + SDHCFG);
> +     writel(host->cdiv, host->ioaddr + SDCDIV);
> +}
> +
> +static int bcm2835_finish_command(struct bcm2835_host *host);
> +
> +static void bcm2835_wait_transfer_complete(struct bcm2835_host *host)
> +{
> +     int timediff;
> +     u32 alternate_idle;
> +
> +     alternate_idle = (host->data->flags & MMC_DATA_READ) ?
> +             SDEDM_FSM_READWAIT : SDEDM_FSM_WRITESTART1;
> +
> +     timediff = 0;
> +
> +     while (1) {
> +             u32 edm, fsm;
> +
> +             edm = readl(host->ioaddr + SDEDM);
> +             fsm = edm & SDEDM_FSM_MASK;
> +
> +             if ((fsm == SDEDM_FSM_IDENTMODE) ||
> +                 (fsm == SDEDM_FSM_DATAMODE))
> +                     break;
> +             if (fsm == alternate_idle) {
> +                     writel(edm | SDEDM_FORCE_DATA_MODE,
> +                            host->ioaddr + SDEDM);
> +                     break;
> +             }
> +
> +             timediff++;
> +             if (timediff == 100000) {

timediff is 100000?

> +                     dev_err(host->dev,
> +                             "wait_transfer_complete - still waiting after 
> %d retries\n",
> +                             timediff);
> +                     bcm2835_dumpregs(host);
> +                     return;
> +             }
> +     }
> +}
> +
> +static int bcm2835_transfer_block_pio(struct bcm2835_host *host, bool 
> is_read)
> +{
> +     size_t blksize;
> +     struct mmc_data *data = host->data;
> +
> +     blksize = data->blocksize;
> +
> +     while (blksize) {
> +             int copy_words;
> +             u32 hsts = 0;
> +             size_t len;
> +             u32 *buf;
> +
> +             len = blksize;
> +             if (len % 4)
> +                     return -EINVAL;
> +
> +             blksize -= len;
> +
> +             buf = is_read ? (u32 *)data->dest : (u32 *)data->src;
> +
> +             if (is_read)
> +                     data->dest += len;
> +             else
> +                     data->src += len;
> +
> +             copy_words = len / 4;
> +
> +             while (copy_words) {
> +                     int burst_words, words;
> +                     u32 edm;
> +
> +                     burst_words = min(SDDATA_FIFO_PIO_BURST, copy_words);
> +                     edm = readl(host->ioaddr + SDEDM);
> +                     if (is_read)
> +                             words = ((edm >> 4) & 0x1f);
> +                     else
> +                             words = SDDATA_FIFO_WORDS - ((edm >> 4) & 0x1f);

0x1f also is magic number. align?

> +
> +                     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 = readl(host->ioaddr + SDHSTS);
> +                                     printf("fsm %x, hsts %08x\n",
> +                                            fsm_state, hsts);
> +                                     if (hsts & SDHSTS_ERROR_MASK)
> +                                             break;
> +                             }
> +
> +                             continue;
> +                     } else if (words > copy_words) {
> +                             words = copy_words;
> +                     }
> +
> +                     copy_words -= words;
> +
> +                     while (words) {
> +                             if (is_read)
> +                                     *(buf++) = readl(host->ioaddr + SDDATA);
> +                             else
> +                                     writel(*(buf++), host->ioaddr + SDDATA);
> +                             words--;
> +                     }
> +             }
> +
> +             if (hsts & SDHSTS_ERROR_MASK)
> +                     break;
> +     }

hmm.. 
while() {
        while() {

                while() { }
        }
}


> +
> +     return 0;
> +}
> +
> +static int bcm2835_transfer_pio(struct bcm2835_host *host)
> +{
> +     u32 sdhsts;
> +     bool is_read;
> +     int r = 0;

r? Coud you use the meaningful variable naming?

> +
> +     is_read = (host->data->flags & MMC_DATA_READ) != 0;
> +     r = bcm2835_transfer_block_pio(host, is_read);
> +
> +     if (host->wait_data_complete)
> +             bcm2835_wait_transfer_complete(host);
> +
> +     sdhsts = readl(host->ioaddr + SDHSTS);
> +     if (sdhsts & (SDHSTS_CRC16_ERROR |
> +                   SDHSTS_CRC7_ERROR |
> +                   SDHSTS_FIFO_ERROR)) {
> +             printf("%s transfer error - HSTS %08x\n",
> +                    is_read ? "read" : "write", sdhsts);
> +             r =  -EILSEQ;
> +     } else if ((sdhsts & (SDHSTS_CMD_TIME_OUT |
> +                           SDHSTS_REW_TIME_OUT))) {
> +             printf("%s timeout error - HSTS %08x\n",
> +                    is_read ? "read" : "write", sdhsts);
> +             r = -ETIMEDOUT;
> +     }
> +
> +     return r;
> +}
> +
> +static void bcm2835_set_transfer_irqs(struct bcm2835_host *host)
> +{
> +     u32 all_irqs = SDHCFG_DATA_IRPT_EN | SDHCFG_BLOCK_IRPT_EN |
> +             SDHCFG_BUSY_IRPT_EN;
> +
> +     host->hcfg = (host->hcfg & ~all_irqs) |
> +             SDHCFG_DATA_IRPT_EN |
> +             SDHCFG_BUSY_IRPT_EN;
> +
> +     writel(host->hcfg, host->ioaddr + SDHCFG);
> +}
> +
> +static
> +void bcm2835_prepare_data(struct bcm2835_host *host, struct mmc_cmd *cmd,
> +                       struct mmc_data *data)
> +{
> +     WARN_ON(host->data);
> +
> +     host->data = data;
> +     if (!data)
> +             return;
> +
> +     host->wait_data_complete = cmd->cmdidx != MMC_CMD_READ_MULTIPLE_BLOCK;
> +     host->data_complete = false;
> +
> +     /* Use PIO */
> +     host->blocks = data->blocks;
> +
> +     bcm2835_set_transfer_irqs(host);
> +
> +     writel(data->blocksize, host->ioaddr + SDHBCT);
> +     writel(data->blocks, host->ioaddr + SDHBLC);
> +}
> +
> +static u32 bcm2835_read_wait_sdcmd(struct bcm2835_host *host, u32 max_ms)

Does it need to pass the max_ms? When i have checked this driver, max_ms is 
always 100.
Then just can use the define value like below 

#define SDHST_TIMEOUT_MAX_MSEC  100000 ?

> +{
> +     u32 value;
> +     int ret;
> +     int timeout_us = (max_ms * 1000);
> +
> +     ret = readl_poll_timeout(host->ioaddr + SDCMD, value,
> +                              !(value & SDCMD_NEW_FLAG), 10);
> +     if (ret == -ETIMEDOUT)
> +             /* if it takes a while make poll interval bigger */
> +             ret = readl_poll_timeout(host->ioaddr + SDCMD, value,
> +                                      !(value & SDCMD_NEW_FLAG),
> +                                      timeout_us);

Why don't use the timeout_us at first time?

> +     if (ret == -ETIMEDOUT)
> +             printf("%s: timeout (%d ms)\n", __func__, max_ms);> +
> +     return value;
> +}
> +
> +static int bcm2835_send_command(struct bcm2835_host *host, struct mmc_cmd 
> *cmd,
> +                             struct mmc_data *data)
> +{
> +     u32 sdcmd, sdhsts;
> +
> +     WARN_ON(host->cmd);
> +
> +     sdcmd = bcm2835_read_wait_sdcmd(host, 100);
> +     if (sdcmd & SDCMD_NEW_FLAG) {
> +             printf("previous command never completed.\n");
> +             bcm2835_dumpregs(host);
> +             return -EILSEQ;

"Previous command never completed" means "busy state"?
It's not illegal sequence error..can be to -EBUSY?

> +     }
> +
> +     host->cmd = cmd;
> +
> +     /* Clear any error flags */
> +     sdhsts = readl(host->ioaddr + SDHSTS);
> +     if (sdhsts & SDHSTS_ERROR_MASK)
> +             writel(sdhsts, host->ioaddr + SDHSTS);
> +
> +     if ((cmd->resp_type & MMC_RSP_136) && (cmd->resp_type & MMC_RSP_BUSY)) {
> +             printf("unsupported response type!\n");
> +             return -EINVAL;
> +     }

If didn't suport these resp_types, can be located to top place.

> +
> +     bcm2835_prepare_data(host, cmd, data);
> +
> +     writel(cmd->cmdarg, host->ioaddr + SDARG);
> +
> +     sdcmd = cmd->cmdidx & SDCMD_CMD_MASK;
> +
> +     host->use_busy = false;
> +     if (!(cmd->resp_type & MMC_RSP_PRESENT)) {
> +             sdcmd |= SDCMD_NO_RESPONSE;
> +     } else {
> +             if (cmd->resp_type & MMC_RSP_136)
> +                     sdcmd |= SDCMD_LONG_RESPONSE;
> +             if (cmd->resp_type & MMC_RSP_BUSY) {
> +                     sdcmd |= SDCMD_BUSYWAIT;
> +                     host->use_busy = true;
> +             }
> +     }
> +
> +     if (data) {
> +             if (data->flags & MMC_DATA_WRITE)
> +                     sdcmd |= SDCMD_WRITE_CMD;
> +             if (data->flags & MMC_DATA_READ)
> +                     sdcmd |= SDCMD_READ_CMD;
> +     }
> +
> +     writel(sdcmd | SDCMD_NEW_FLAG, host->ioaddr + SDCMD);
> +
> +     return 0;
> +}
> +
> +static int bcm2835_transfer_complete(struct bcm2835_host *host)
> +{
> +     int r = 0;
> +
> +     WARN_ON(!host->data_complete);
> +
> +     host->data = NULL;
> +
> +     return r;
> +}
> +
> +static void bcm2835_finish_data(struct bcm2835_host *host)
> +{
> +     host->hcfg &= ~(SDHCFG_DATA_IRPT_EN | SDHCFG_BLOCK_IRPT_EN);
> +     writel(host->hcfg, host->ioaddr + SDHCFG);
> +
> +     host->data_complete = true;
> +
> +     if (host->cmd) {
> +             /* Data managed to finish before the
> +              * command completed. Make sure we do
> +              * things in the proper order.
> +              */
> +             dev_dbg(dev, "Finished early - HSTS %08x\n",
> +                     readl(host->ioaddr + SDHSTS));
> +     } else {
> +             bcm2835_transfer_complete(host);
> +     }
> +}
> +
> +static int bcm2835_finish_command(struct bcm2835_host *host)
> +{
> +     struct mmc_cmd *cmd = host->cmd;
> +     u32 sdcmd;
> +     int r = 0;
> +
> +     sdcmd = bcm2835_read_wait_sdcmd(host, 100);
> +
> +     /* Check for errors */
> +     if (sdcmd & SDCMD_NEW_FLAG) {
> +             printf("command never completed.\n");
> +             bcm2835_dumpregs(host);
> +             return -EIO;
> +     } else if (sdcmd & SDCMD_FAIL_FLAG) {
> +             u32 sdhsts = readl(host->ioaddr + SDHSTS);
> +
> +             /* Clear the errors */
> +             writel(SDHSTS_ERROR_MASK, host->ioaddr + SDHSTS);
> +
> +             if (!(sdhsts & SDHSTS_CRC7_ERROR) ||
> +                 (host->cmd->cmdidx != MMC_CMD_SEND_OP_COND)) {
> +                     if (sdhsts & SDHSTS_CMD_TIME_OUT) {
> +                             r = -ETIMEDOUT;
> +                     } else {
> +                             printf("unexpected command %d error\n",
> +                                    host->cmd->cmdidx);
> +                             bcm2835_dumpregs(host);
> +                             r = -EILSEQ;
> +                     }
> +
> +                     return r;
> +             }
> +     }
> +
> +     if (cmd->resp_type & MMC_RSP_PRESENT) {
> +             if (cmd->resp_type & MMC_RSP_136) {
> +                     int i;
> +
> +                     for (i = 0; i < 4; i++) {
> +                             cmd->response[3 - i] =
> +                                     readl(host->ioaddr + SDRSP0 + i * 4);
> +                     }
> +             } else {
> +                     cmd->response[0] = readl(host->ioaddr + SDRSP0);
> +             }
> +     }
> +
> +     /* Processed actual command. */
> +     host->cmd = NULL;
> +     if (host->data && host->data_complete)
> +             r = bcm2835_transfer_complete(host);
> +
> +     return r;
> +}
> +
> +static int bcm2835_check_cmd_error(struct bcm2835_host *host, u32 intmask)
> +{
> +     int r = -EINVAL;

int ret.

> +
> +     if (!(intmask & SDHSTS_ERROR_MASK))
> +             return 0;
> +
> +     if (!host->cmd)
> +             return -EINVAL;
> +
> +     printf("sdhost_busy_irq: intmask %08x\n", intmask);
> +     if (intmask & SDHSTS_CRC7_ERROR) {
> +             r = -EILSEQ;
> +     } else if (intmask & (SDHSTS_CRC16_ERROR |
> +                           SDHSTS_FIFO_ERROR)) {
> +             r = -EILSEQ;
> +     } else if (intmask & SDHSTS_REW_TIME_OUT) {
> +             r = -ETIMEDOUT;
> +     } else if (intmask & SDHSTS_CMD_TIME_OUT) {
> +             r = -ETIMEDOUT;

else if (intmask & (SDHST_CMD_TIMEOUT | SDHST_REW_TIME_OUT) {
                ret = -ETIMEOUT;
}

> +     }
> +     bcm2835_dumpregs(host);
> +     return r;
> +}
> +
> +static int bcm2835_check_data_error(struct bcm2835_host *host, u32 intmask)
> +{
> +     int r = 0;

ditto

> +
> +     if (!host->data)
> +             return 0;
> +     if (intmask & (SDHSTS_CRC16_ERROR | SDHSTS_FIFO_ERROR))
> +             r = -EILSEQ;
> +     if (intmask & SDHSTS_REW_TIME_OUT)
> +             r = -ETIMEDOUT;
> +
> +     if (r)
> +             printf("%s:%d %d\n", __func__, __LINE__, r);
> +
> +     return r;
> +}
> +
> +static void bcm2835_busy_irq(struct bcm2835_host *host)
> +{
> +     if (WARN_ON(!host->cmd)) {
> +             bcm2835_dumpregs(host);
> +             return;
> +     }
> +
> +     if (WARN_ON(!host->use_busy)) {
> +             bcm2835_dumpregs(host);
> +             return;
> +     }

Really need to use WARN_ON? for what?

> +     host->use_busy = false;
> +
> +     bcm2835_finish_command(host);
> +}
> +
> +static void bcm2835_data_irq(struct bcm2835_host *host, u32 intmask)
> +{
> +     int r;
> +
> +     /* 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.
> +      */

/*
 * There are...
 */

> +     if (!host->data)
> +             return;
> +
> +     r = bcm2835_check_data_error(host, intmask);
> +     if (r)
> +             goto finished;
> +
> +     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;
> +             writel(host->hcfg, host->ioaddr + SDHCFG);
> +             bcm2835_transfer_pio(host);
> +     } else {
> +             bcm2835_transfer_pio(host);
> +             host->blocks--;
> +             if ((host->blocks == 0))
> +                     goto finished;
> +     }
> +     return;
> +
> +finished:
> +     host->hcfg &= ~(SDHCFG_DATA_IRPT_EN | SDHCFG_BLOCK_IRPT_EN);
> +     writel(host->hcfg, host->ioaddr + SDHCFG);
> +}
> +
> +static void bcm2835_data_threaded_irq(struct bcm2835_host *host)
> +{
> +     if (!host->data)
> +             return;
> +     if ((host->blocks == 0))
> +             bcm2835_finish_data(host);
> +}
> +
> +static void bcm2835_block_irq(struct bcm2835_host *host)
> +{
> +     if (WARN_ON(!host->data)) {
> +             bcm2835_dumpregs(host);
> +             return;
> +     }
> +
> +     WARN_ON(!host->blocks);
> +     if ((--host->blocks == 0))
> +             bcm2835_finish_data(host);
> +     else
> +             bcm2835_transfer_pio(host);
> +}
> +
> +static irqreturn_t bcm2835_irq(int irq, void *dev_id)
> +{
> +     irqreturn_t result = IRQ_NONE;
> +     struct bcm2835_host *host = dev_id;
> +     u32 intmask;
> +
> +     intmask = readl(host->ioaddr + SDHSTS);
> +
> +     writel(SDHSTS_BUSY_IRPT |
> +            SDHSTS_BLOCK_IRPT |
> +            SDHSTS_SDIO_IRPT |
> +            SDHSTS_DATA_FLAG,
> +            host->ioaddr + SDHSTS);
> +
> +     if (intmask & SDHSTS_BLOCK_IRPT) {
> +             bcm2835_check_data_error(host, intmask);
> +             host->irq_block = true;
> +             result = IRQ_WAKE_THREAD;
> +     }
> +
> +     if (intmask & SDHSTS_BUSY_IRPT) {
> +             if (!bcm2835_check_cmd_error(host, intmask)) {
> +                     host->irq_busy = true;
> +                     result = IRQ_WAKE_THREAD;
> +             } else {
> +                     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_data_irq(host, intmask);
> +             host->irq_data = true;
> +             result = IRQ_WAKE_THREAD;
> +     }
> +
> +     return result;
> +}
> +
> +static irqreturn_t bcm2835_threaded_irq(int irq, void *dev_id)
> +{
> +     struct bcm2835_host *host = dev_id;
> +     bool block, busy, data;
> +
> +     block = host->irq_block;
> +     busy  = host->irq_busy;
> +     data  = host->irq_data;
> +     host->irq_block = false;
> +     host->irq_busy  = false;
> +     host->irq_data  = false;
> +
> +     if (block)
> +             bcm2835_block_irq(host);
> +     if (busy)
> +             bcm2835_busy_irq(host);
> +     if (data)
> +             bcm2835_data_threaded_irq(host);

if (host->irq_block) {
        host->irq_block = false;
        bcm2835_block_irq(); 
}

Then you can remove the "bool block, busy, data".

> +
> +     return IRQ_HANDLED;
> +}
> +
> +static void bcm2835_irq_poll(struct bcm2835_host *host)
> +{
> +     u32 intmask;
> +
> +     while (1) {
> +             intmask = readl(host->ioaddr + SDHSTS);
> +             if (intmask & (SDHSTS_BUSY_IRPT | SDHSTS_BLOCK_IRPT |
> +                            SDHSTS_SDIO_IRPT | SDHSTS_DATA_FLAG)) {
> +                     bcm2835_irq(0, host);
> +                     bcm2835_threaded_irq(0, host);
> +                     return;
> +             }
> +     }
> +}
> +
> +static void bcm2835_set_clock(struct bcm2835_host *host, unsigned int clock)
> +{
> +     int div;
> +
> +     /* 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.
> +      */
> +
> +     if (clock < 100000) {
> +             /* Can't stop the clock, but make it as slow as possible
> +              * to show willing
> +              */
> +             host->cdiv = SDCDIV_MAX_CDIV;
> +             writel(host->cdiv, host->ioaddr + 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->clock = clock;
> +
> +     /* Calibrate some delays */
> +
> +     host->ns_per_fifo_word = (1000000000 / clock) *
> +             ((host->mmc->card_caps & MMC_MODE_4BIT) ? 8 : 32);
> +
> +     host->cdiv = div;
> +     writel(host->cdiv, host->ioaddr + SDCDIV);
> +
> +     /* Set the timeout to 500ms */
> +     writel(host->mmc->clock / 2, host->ioaddr + SDTOUT);
> +}
> +
> +static inline int is_power_of_2(u64 x)
> +{
> +     return !(x & (x - 1));
> +}
> +
> +static int bcm2835_send_cmd(struct udevice *dev, struct mmc_cmd *cmd,
> +                         struct mmc_data *data)
> +{
> +     struct bcm2835_host *host = dev_get_priv(dev);
> +     u32 edm, fsm;
> +     int r = 0;
> +
> +     if (data && !is_power_of_2(data->blocksize)) {
> +             printf("unsupported block size (%d bytes)\n", data->blocksize);
> +
> +             if (cmd)
> +                     return -EINVAL;
> +     }
> +
> +     edm = readl(host->ioaddr + SDEDM);
> +     fsm = edm & SDEDM_FSM_MASK;
> +
> +     if ((fsm != SDEDM_FSM_IDENTMODE) &&
> +         (fsm != SDEDM_FSM_DATAMODE) &&
> +         (cmd && cmd->cmdidx != MMC_CMD_STOP_TRANSMISSION)) {
> +             printf("previous command (%d) not complete (EDM %08x)\n",
> +                    readl(host->ioaddr + SDCMD) & SDCMD_CMD_MASK, edm);
> +             bcm2835_dumpregs(host);
> +
> +             if (cmd)
> +                     return -EILSEQ;
> +
> +             return 0;
> +     }
> +
> +     if (cmd) {
> +             r = bcm2835_send_command(host, cmd, data);
> +             if (!r && !host->use_busy)
> +                     r = bcm2835_finish_command(host);
> +     }
> +
> +     /* Wait for completion of busy signal or data transfer */
> +     while (host->use_busy || host->data)
> +             bcm2835_irq_poll(host);
> +
> +     return r;
> +}
> +
> +static int bcm2835_set_ios(struct udevice *dev)
> +{
> +     struct bcm2835_host *host = dev_get_priv(dev);
> +     struct mmc *mmc = mmc_get_mmc_dev(dev);
> +
> +     if (!mmc->clock || mmc->clock != host->clock) {
> +             bcm2835_set_clock(host, mmc->clock);
> +             host->clock = mmc->clock;
> +     }
> +
> +     /* set bus width */
> +     host->hcfg &= ~SDHCFG_WIDE_EXT_BUS;
> +     if (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;
> +
> +     writel(host->hcfg, host->ioaddr + SDHCFG);
> +
> +     return 0;
> +}
> +
> +static int bcm2835_add_host(struct bcm2835_host *host)
> +{
> +     struct mmc_config *cfg = &host->plat->cfg;
> +
> +     cfg->f_max = host->max_clk;
> +     cfg->f_min = host->max_clk / SDCDIV_MAX_CDIV;
> +     cfg->b_max = 65535;
> +
> +     dev_dbg(dev, "f_max %d, f_min %d\n",
> +             cfg->f_max, cfg->f_min);
> +
> +     /* host controller capabilities */
> +     cfg->host_caps = MMC_MODE_4BIT | MMC_MODE_HS | MMC_MODE_HS_52MHz;
> +
> +     /* report supported voltage ranges */
> +     cfg->voltages = MMC_VDD_32_33 | MMC_VDD_33_34;
> +
> +     /* Set interrupt enables */
> +     host->hcfg = SDHCFG_BUSY_IRPT_EN;
> +
> +     bcm2835_reset_internal(host);
> +
> +     return 0;
> +}
> +
> +static int bcm2835_probe(struct udevice *dev)
> +{
> +     struct bcm2835_plat *plat = dev_get_platdata(dev);
> +     struct bcm2835_host *host = dev_get_priv(dev);
> +     struct mmc *mmc = mmc_get_mmc_dev(dev);
> +     struct mmc_uclass_priv *upriv = dev_get_uclass_priv(dev);
> +     int ret;
> +
> +     host->dev = dev;
> +     host->mmc = mmc;
> +     host->plat = plat;
> +     upriv->mmc = &plat->mmc;
> +     plat->cfg.name = dev->name;
> +
> +     host->phys_addr = devfdt_get_addr(dev);
> +     if (host->phys_addr == FDT_ADDR_T_NONE)
> +             return -EINVAL;
> +
> +     host->ioaddr = devm_ioremap(dev, host->phys_addr, SZ_256);
> +     if (!host->ioaddr)
> +             return -ENOMEM;
> +
> +     host->max_clk = bcm2835_get_mmc_clock();
> +
> +     ret = bcm2835_add_host(host);
> +     if (ret)
> +             goto err;

bcm2835_add_host is always returned to 0.
Never go to err...

> +
> +     dev_dbg(dev, "%s -> OK\n", __func__);
> +
> +     return 0;
> +
> +err:
> +     dev_dbg(dev, "%s -> err %d\n", __func__, ret);
> +
> +     return ret;
> +}
> +
> +static const struct udevice_id bcm2835_match[] = {
> +     { .compatible = "brcm,bcm2835-sdhost" },
> +     { }
> +};
> +
> +static const struct dm_mmc_ops bcm2835_ops = {
> +     .send_cmd = bcm2835_send_cmd,
> +     .set_ios = bcm2835_set_ios,
> +};
> +
> +static int bcm2835_bind(struct udevice *dev)
> +{
> +     struct bcm2835_plat *plat = dev_get_platdata(dev);
> +
> +     return mmc_bind(dev, &plat->mmc, &plat->cfg);
> +}
> +
> +U_BOOT_DRIVER(bcm2835_sdhost) = {
> +     .name = "bcm2835-sdhost",
> +     .id = UCLASS_MMC,
> +     .of_match = bcm2835_match,
> +     .bind = bcm2835_bind,
> +     .probe = bcm2835_probe,
> +     .priv_auto_alloc_size = sizeof(struct bcm2835_host),
> +     .platdata_auto_alloc_size = sizeof(struct bcm2835_plat),
> +     .ops = &bcm2835_ops,
> +};
> 

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