Jagan, > -----Original Message----- > From: Jagan Teki [mailto:jt...@openedev.com] > Sent: Thursday, October 29, 2015 10:34 AM > To: Tom Warren <twar...@nvidia.com> > Cc: u-boot@lists.denx.de; Stephen Warren <swar...@nvidia.com>; > tomcwarren3...@gmail.com > Subject: Re: [U-Boot] [PATCH v5] Tegra: T210: Add QSPI driver > > On 28 October 2015 at 21:25, Tom Warren <twar...@nvidia.com> wrote: > > Jagan, > > > >> -----Original Message----- > >> From: Tom Warren > >> Sent: Monday, October 26, 2015 1:56 PM > >> To: u-boot@lists.denx.de > >> Cc: Stephen Warren <swar...@nvidia.com>; tomcwarren3...@gmail.com; > >> jt...@openedev.com; Yen Lin <ye...@nvidia.com>; Tom Warren > >> <twar...@nvidia.com> > >> Subject: [PATCH v5] Tegra: T210: Add QSPI driver > >> > >> This is the normal Tegra SPI driver modified to work with the QSPI > >> controller in Tegra210. It does not do 2x/4x transfers or any other QSPI > protocol. > >> > >> Signed-off-by: Yen Lin <ye...@nvidia.com> > >> Signed-off-by: Tom Warren <twar...@nvidia.com> > > Reviewed-by: Jagan Teki <jt...@openedev.com> > > >> --- > >> Changes in v2: > >> - Drop defconfig and pinmux files, this is a driver-only patch. > >> - If/when pinmux tables have been updated for P2371/P2571, another > >> - patch will be sent to enable the QSPI driver on those boards. > >> Changes in v3: > >> - removed status reg write/clear in claim_bus(), done in xfer() Changes in > v4: > >> - added timeout in wait for FIFO flush status in xfer() > >> - used BIT and GENMASK macros throughout > >> - minor changes in copyright message in driver and Kconfig help > >> Changes in v5: > >> - commented on reason for udelay before setting GO bit, as per Yen Lin. > > > > Can you PTAL and see if this meets all your requests? Thanks. > > OK with this? Can you point the dts and config patch for this driver - I > couldn't > find it either. The intent is to only upstream the driver. The DTS already contains the QSPI node (see spi@0,70410000), and the defconfig/pinmux-config.h changes won't be merged since there's no T210 board (from Nvidia) that has a SPI part on the QSPI controller currently. There is a customer with their own board that needs this driver upstreamed so they can pull it down into their custom U-Boot repo. However, if you search the list for my original patch ('[PATCH] Tegra210: add QSPI driver'), you'll see examples of the p2571 def_config/pinmux configs that can be used if someone does wish to pop a SPI chip on their T210 board, etc.
So with that in mind, will you take this in to the SPI repo, or can I take it in via the Tegra repo instead? I'm fine with either course. Tom -- nvpublic > > > > > And do you want to take this in, or can I take it in via the Tegra repo? > > > > Tom > > -- > > nvpublic > >> > >> drivers/spi/Kconfig | 7 + > >> drivers/spi/Makefile | 1 + > >> drivers/spi/tegra210_qspi.c | 417 > >> ++++++++++++++++++++++++++++++++++++++++++++ > >> 3 files changed, 425 insertions(+) > >> create mode 100644 drivers/spi/tegra210_qspi.c > >> > >> diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig index > >> 2f8cf19..95286da > >> 100644 > >> --- a/drivers/spi/Kconfig > >> +++ b/drivers/spi/Kconfig > >> @@ -123,6 +123,13 @@ config TEGRA20_SLINK > >> be used to access the SPI NOR flash on platforms embedding this > >> nVidia Tegra20/Tegra30 IP cores. > >> > >> +config TEGRA210_QSPI > >> + bool "nVidia Tegra210 QSPI driver" > >> + help > >> + Enable the Tegra Quad-SPI (QSPI) driver for T210. This driver > >> + be used to access SPI chips on platforms embedding this > >> + NVIDIA Tegra210 IP core. > >> + > >> config XILINX_SPI > >> bool "Xilinx SPI driver" > >> help > >> diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile index > >> de241be..209a41e > >> 100644 > >> --- a/drivers/spi/Makefile > >> +++ b/drivers/spi/Makefile > >> @@ -46,6 +46,7 @@ obj-$(CONFIG_SH_QSPI) += sh_qspi.o > >> obj-$(CONFIG_TEGRA114_SPI) += tegra114_spi.o > >> obj-$(CONFIG_TEGRA20_SFLASH) += tegra20_sflash.o > >> obj-$(CONFIG_TEGRA20_SLINK) += tegra20_slink.o > >> +obj-$(CONFIG_TEGRA210_QSPI) += tegra210_qspi.o > >> obj-$(CONFIG_TI_QSPI) += ti_qspi.o > >> obj-$(CONFIG_XILINX_SPI) += xilinx_spi.o > >> obj-$(CONFIG_ZYNQ_SPI) += zynq_spi.o diff --git > >> a/drivers/spi/tegra210_qspi.c b/drivers/spi/tegra210_qspi.c new file > >> mode 100644 index 0000000..6bbbe93 > >> --- /dev/null > >> +++ b/drivers/spi/tegra210_qspi.c > >> @@ -0,0 +1,417 @@ > >> +/* > >> + * NVIDIA Tegra210 QSPI controller driver > >> + * > >> + * (C) Copyright 2015 NVIDIA Corporation <www.nvidia.com> > >> + * > >> + * SPDX-License-Identifier: GPL-2.0+ > >> + */ > >> + > >> +#include <common.h> > >> +#include <dm.h> > >> +#include <asm/io.h> > >> +#include <asm/arch/clock.h> > >> +#include <asm/arch-tegra/clk_rst.h> > >> +#include <spi.h> > >> +#include <fdtdec.h> > >> +#include "tegra_spi.h" > >> + > >> +DECLARE_GLOBAL_DATA_PTR; > >> + > >> +/* COMMAND1 */ > >> +#define QSPI_CMD1_GO BIT(31) > >> +#define QSPI_CMD1_M_S BIT(30) > >> +#define QSPI_CMD1_MODE_MASK GENMASK(1,0) > >> +#define QSPI_CMD1_MODE_SHIFT 28 > >> +#define QSPI_CMD1_CS_SEL_MASK GENMASK(1,0) > >> +#define QSPI_CMD1_CS_SEL_SHIFT 26 > >> +#define QSPI_CMD1_CS_POL_INACTIVE0 BIT(22) > >> +#define QSPI_CMD1_CS_SW_HW BIT(21) > >> +#define QSPI_CMD1_CS_SW_VAL BIT(20) > >> +#define QSPI_CMD1_IDLE_SDA_MASK GENMASK(1,0) > >> +#define QSPI_CMD1_IDLE_SDA_SHIFT 18 > >> +#define QSPI_CMD1_BIDIR BIT(17) > >> +#define QSPI_CMD1_LSBI_FE BIT(16) > >> +#define QSPI_CMD1_LSBY_FE BIT(15) > >> +#define QSPI_CMD1_BOTH_EN_BIT BIT(14) > >> +#define QSPI_CMD1_BOTH_EN_BYTE BIT(13) > >> +#define QSPI_CMD1_RX_EN BIT(12) > >> +#define QSPI_CMD1_TX_EN BIT(11) > >> +#define QSPI_CMD1_PACKED BIT(5) > >> +#define QSPI_CMD1_BITLEN_MASK GENMASK(4,0) > >> +#define QSPI_CMD1_BITLEN_SHIFT 0 > >> + > >> +/* COMMAND2 */ > >> +#define QSPI_CMD2_TX_CLK_TAP_DELAY BIT(6) > >> +#define QSPI_CMD2_TX_CLK_TAP_DELAY_MASK GENMASK(11,6) > >> +#define QSPI_CMD2_RX_CLK_TAP_DELAY BIT(0) > >> +#define QSPI_CMD2_RX_CLK_TAP_DELAY_MASK GENMASK(5,0) > >> + > >> +/* TRANSFER STATUS */ > >> +#define QSPI_XFER_STS_RDY BIT(30) > >> + > >> +/* FIFO STATUS */ > >> +#define QSPI_FIFO_STS_CS_INACTIVE BIT(31) > >> +#define QSPI_FIFO_STS_FRAME_END BIT(30) > >> +#define QSPI_FIFO_STS_RX_FIFO_FLUSH BIT(15) #define > >> +QSPI_FIFO_STS_TX_FIFO_FLUSH BIT(14) > >> +#define QSPI_FIFO_STS_ERR BIT(8) > >> +#define QSPI_FIFO_STS_TX_FIFO_OVF BIT(7) > >> +#define QSPI_FIFO_STS_TX_FIFO_UNR BIT(6) > >> +#define QSPI_FIFO_STS_RX_FIFO_OVF BIT(5) > >> +#define QSPI_FIFO_STS_RX_FIFO_UNR BIT(4) > >> +#define QSPI_FIFO_STS_TX_FIFO_FULL BIT(3) > >> +#define QSPI_FIFO_STS_TX_FIFO_EMPTY BIT(2) > >> +#define QSPI_FIFO_STS_RX_FIFO_FULL BIT(1) > >> +#define QSPI_FIFO_STS_RX_FIFO_EMPTY BIT(0) > >> + > >> +#define QSPI_TIMEOUT 1000 > >> + > >> +struct qspi_regs { > >> + u32 command1; /* 000:QSPI_COMMAND1 register */ > >> + u32 command2; /* 004:QSPI_COMMAND2 register */ > >> + u32 timing1; /* 008:QSPI_CS_TIM1 register */ > >> + u32 timing2; /* 00c:QSPI_CS_TIM2 register */ > >> + u32 xfer_status;/* 010:QSPI_TRANS_STATUS register */ > >> + u32 fifo_status;/* 014:QSPI_FIFO_STATUS register */ > >> + u32 tx_data; /* 018:QSPI_TX_DATA register */ > >> + u32 rx_data; /* 01c:QSPI_RX_DATA register */ > >> + u32 dma_ctl; /* 020:QSPI_DMA_CTL register */ > >> + u32 dma_blk; /* 024:QSPI_DMA_BLK register */ > >> + u32 rsvd[56]; /* 028-107 reserved */ > >> + u32 tx_fifo; /* 108:QSPI_FIFO1 register */ > >> + u32 rsvd2[31]; /* 10c-187 reserved */ > >> + u32 rx_fifo; /* 188:QSPI_FIFO2 register */ > >> + u32 spare_ctl; /* 18c:QSPI_SPARE_CTRL register */ }; > >> + > >> +struct tegra210_qspi_priv { > >> + struct qspi_regs *regs; > >> + unsigned int freq; > >> + unsigned int mode; > >> + int periph_id; > >> + int valid; > >> + int last_transaction_us; > >> +}; > >> + > >> +static int tegra210_qspi_ofdata_to_platdata(struct udevice *bus) { > >> + struct tegra_spi_platdata *plat = bus->platdata; > >> + const void *blob = gd->fdt_blob; > >> + int node = bus->of_offset; > >> + > >> + plat->base = dev_get_addr(bus); > >> + plat->periph_id = clock_decode_periph_id(blob, node); > >> + > >> + if (plat->periph_id == PERIPH_ID_NONE) { > >> + debug("%s: could not decode periph id %d\n", __func__, > >> + plat->periph_id); > >> + return -FDT_ERR_NOTFOUND; > >> + } > >> + > >> + /* Use 500KHz as a suitable default */ > >> + plat->frequency = fdtdec_get_int(blob, node, "spi-max-frequency", > >> + 500000); > >> + plat->deactivate_delay_us = fdtdec_get_int(blob, node, > >> + "spi-deactivate-delay", 0); > >> + debug("%s: base=%#08lx, periph_id=%d, max-frequency=%d, > >> deactivate_delay=%d\n", > >> + __func__, plat->base, plat->periph_id, plat->frequency, > >> + plat->deactivate_delay_us); > >> + > >> + return 0; > >> +} > >> + > >> +static int tegra210_qspi_probe(struct udevice *bus) { > >> + struct tegra_spi_platdata *plat = dev_get_platdata(bus); > >> + struct tegra210_qspi_priv *priv = dev_get_priv(bus); > >> + > >> + priv->regs = (struct qspi_regs *)plat->base; > >> + > >> + priv->last_transaction_us = timer_get_us(); > >> + priv->freq = plat->frequency; > >> + priv->periph_id = plat->periph_id; > >> + > >> + return 0; > >> +} > >> + > >> +static int tegra210_qspi_claim_bus(struct udevice *bus) { > >> + struct tegra210_qspi_priv *priv = dev_get_priv(bus); > >> + struct qspi_regs *regs = priv->regs; > >> + > >> + /* Change SPI clock to correct frequency, PLLP_OUT0 source */ > >> + clock_start_periph_pll(priv->periph_id, CLOCK_ID_PERIPH, > >> + priv->freq); > >> + > >> + debug("%s: FIFO STATUS = %08x\n", __func__, > >> +readl(®s->fifo_status)); > >> + > >> + /* Set master mode and sw controlled CS */ > >> + setbits_le32(®s->command1, QSPI_CMD1_M_S | > >> QSPI_CMD1_CS_SW_HW | > >> + (priv->mode << QSPI_CMD1_MODE_SHIFT)); > >> + debug("%s: COMMAND1 = %08x\n", __func__, readl(®s- > >> >command1)); > >> + > >> + return 0; > >> +} > >> + > >> +/** > >> + * Activate the CS by driving it LOW > >> + * > >> + * @param slave Pointer to spi_slave to which controller has to > >> + * communicate with > >> + */ > >> +static void spi_cs_activate(struct udevice *dev) { > >> + struct udevice *bus = dev->parent; > >> + struct tegra_spi_platdata *pdata = dev_get_platdata(bus); > >> + struct tegra210_qspi_priv *priv = dev_get_priv(bus); > >> + > >> + /* If it's too soon to do another transaction, wait */ > >> + if (pdata->deactivate_delay_us && > >> + priv->last_transaction_us) { > >> + ulong delay_us; /* The delay completed so far */ > >> + delay_us = timer_get_us() - priv->last_transaction_us; > >> + if (delay_us < pdata->deactivate_delay_us) > >> + udelay(pdata->deactivate_delay_us - delay_us); > >> + } > >> + > >> + clrbits_le32(&priv->regs->command1, QSPI_CMD1_CS_SW_VAL); } > >> + > >> +/** > >> + * Deactivate the CS by driving it HIGH > >> + * > >> + * @param slave Pointer to spi_slave to which controller has to > >> + * communicate with > >> + */ > >> +static void spi_cs_deactivate(struct udevice *dev) { > >> + struct udevice *bus = dev->parent; > >> + struct tegra_spi_platdata *pdata = dev_get_platdata(bus); > >> + struct tegra210_qspi_priv *priv = dev_get_priv(bus); > >> + > >> + setbits_le32(&priv->regs->command1, QSPI_CMD1_CS_SW_VAL); > >> + > >> + /* Remember time of this transaction so we can honour the bus > >> + delay > >> */ > >> + if (pdata->deactivate_delay_us) > >> + priv->last_transaction_us = timer_get_us(); > >> + > >> + debug("Deactivate CS, bus '%s'\n", bus->name); } > >> + > >> +static int tegra210_qspi_xfer(struct udevice *dev, unsigned int bitlen, > >> + const void *data_out, void *data_in, > >> + unsigned long flags) { > >> + struct udevice *bus = dev->parent; > >> + struct tegra210_qspi_priv *priv = dev_get_priv(bus); > >> + struct qspi_regs *regs = priv->regs; > >> + u32 reg, tmpdout, tmpdin = 0; > >> + const u8 *dout = data_out; > >> + u8 *din = data_in; > >> + int num_bytes, tm, ret; > >> + > >> + debug("%s: slave %u:%u dout %p din %p bitlen %u\n", > >> + __func__, bus->seq, spi_chip_select(dev), dout, din, bitlen); > >> + if (bitlen % 8) > >> + return -1; > >> + num_bytes = bitlen / 8; > >> + > >> + ret = 0; > >> + > >> + /* clear all error status bits */ > >> + reg = readl(®s->fifo_status); > >> + writel(reg, ®s->fifo_status); > >> + > >> + /* flush RX/TX FIFOs */ > >> + setbits_le32(®s->fifo_status, > >> + (QSPI_FIFO_STS_RX_FIFO_FLUSH | > >> + QSPI_FIFO_STS_TX_FIFO_FLUSH)); > >> + > >> + tm = QSPI_TIMEOUT; > >> + while ((tm && readl(®s->fifo_status) & > >> + (QSPI_FIFO_STS_RX_FIFO_FLUSH | > >> + QSPI_FIFO_STS_TX_FIFO_FLUSH))) { > >> + tm--; > >> + udelay(1); > >> + } > >> + > >> + if (!tm) { > >> + printf("%s: timeout during QSPI FIFO flush!\n", > >> + __func__); > >> + return -1; > >> + } > >> + > >> + /* > >> + * Notes: > >> + * 1. don't set LSBY_FE, so no need to swap bytes from/to TX/RX > >> FIFOs; > >> + * 2. don't set RX_EN and TX_EN yet. > >> + * (SW needs to make sure that while programming the blk_size, > >> + * tx_en and rx_en bits must be zero) > >> + * [TODO] I (Yen Lin) have problems when both RX/TX EN bits are > >> set > >> + * i.e., both dout and din are not NULL. > >> + */ > >> + clrsetbits_le32(®s->command1, > >> + (QSPI_CMD1_LSBI_FE | QSPI_CMD1_LSBY_FE | > >> + QSPI_CMD1_RX_EN | QSPI_CMD1_TX_EN), > >> + (spi_chip_select(dev) << > >> + QSPI_CMD1_CS_SEL_SHIFT)); > >> + > >> + /* set xfer size to 1 block (32 bits) */ > >> + writel(0, ®s->dma_blk); > >> + > >> + if (flags & SPI_XFER_BEGIN) > >> + spi_cs_activate(dev); > >> + > >> + /* handle data in 32-bit chunks */ > >> + while (num_bytes > 0) { > >> + int bytes; > >> + > >> + tmpdout = 0; > >> + bytes = (num_bytes > 4) ? 4 : num_bytes; > >> + > >> + if (dout != NULL) { > >> + memcpy((void *)&tmpdout, (void *)dout, bytes); > >> + dout += bytes; > >> + num_bytes -= bytes; > >> + writel(tmpdout, ®s->tx_fifo); > >> + setbits_le32(®s->command1, QSPI_CMD1_TX_EN); > >> + } > >> + > >> + if (din != NULL) > >> + setbits_le32(®s->command1, QSPI_CMD1_RX_EN); > >> + > >> + /* clear ready bit */ > >> + setbits_le32(®s->xfer_status, QSPI_XFER_STS_RDY); > >> + > >> + clrsetbits_le32(®s->command1, > >> + QSPI_CMD1_BITLEN_MASK << > >> QSPI_CMD1_BITLEN_SHIFT, > >> + (bytes * 8 - 1) << > >> + QSPI_CMD1_BITLEN_SHIFT); > >> + > >> + /* Need to stabilize other reg bits before GO bit set. > >> + * As per the TRM: > >> + * "For successful operation at various freq combinations, > >> + * a minimum of 4-5 spi_clk cycle delay might be required > >> + * before enabling the PIO or DMA bits. The worst case delay > >> + * calculation can be done considering slowest qspi_clk as > >> + * 1MHz. Based on that 1us delay should be enough before > >> + * enabling PIO or DMA." Padded another 1us for safety. > >> + */ > >> + udelay(2); > >> + setbits_le32(®s->command1, QSPI_CMD1_GO); > >> + udelay(1); > >> + > >> + /* > >> + * Wait for SPI transmit FIFO to empty, or to time out. > >> + * The RX FIFO status will be read and cleared last > >> + */ > >> + for (tm = 0; tm < QSPI_TIMEOUT; ++tm) { > >> + u32 fifo_status, xfer_status; > >> + > >> + xfer_status = readl(®s->xfer_status); > >> + if (!(xfer_status & QSPI_XFER_STS_RDY)) > >> + continue; > >> + > >> + fifo_status = readl(®s->fifo_status); > >> + if (fifo_status & QSPI_FIFO_STS_ERR) { > >> + debug("%s: got a fifo error: ", __func__); > >> + if (fifo_status & QSPI_FIFO_STS_TX_FIFO_OVF) > >> + debug("tx FIFO overflow "); > >> + if (fifo_status & QSPI_FIFO_STS_TX_FIFO_UNR) > >> + debug("tx FIFO underrun "); > >> + if (fifo_status & QSPI_FIFO_STS_RX_FIFO_OVF) > >> + debug("rx FIFO overflow "); > >> + if (fifo_status & QSPI_FIFO_STS_RX_FIFO_UNR) > >> + debug("rx FIFO underrun "); > >> + if (fifo_status & QSPI_FIFO_STS_TX_FIFO_FULL) > >> + debug("tx FIFO full "); > >> + if (fifo_status & > >> QSPI_FIFO_STS_TX_FIFO_EMPTY) > >> + debug("tx FIFO empty "); > >> + if (fifo_status & > >> QSPI_FIFO_STS_RX_FIFO_FULL) > >> + debug("rx FIFO full "); > >> + if (fifo_status & > >> QSPI_FIFO_STS_RX_FIFO_EMPTY) > >> + debug("rx FIFO empty "); > >> + debug("\n"); > >> + break; > >> + } > >> + > >> + if (!(fifo_status & QSPI_FIFO_STS_RX_FIFO_EMPTY)) { > >> + tmpdin = readl(®s->rx_fifo); > >> + if (din != NULL) { > >> + memcpy(din, &tmpdin, bytes); > >> + din += bytes; > >> + num_bytes -= bytes; > >> + } > >> + } > >> + break; > >> + } > >> + > >> + if (tm >= QSPI_TIMEOUT) > >> + ret = tm; > >> + > >> + /* clear ACK RDY, etc. bits */ > >> + writel(readl(®s->fifo_status), ®s->fifo_status); > >> + } > >> + > >> + if (flags & SPI_XFER_END) > >> + spi_cs_deactivate(dev); > >> + > >> + debug("%s: transfer ended. Value=%08x, fifo_status = %08x\n", > >> + __func__, tmpdin, readl(®s->fifo_status)); > >> + > >> + if (ret) { > >> + printf("%s: timeout during SPI transfer, tm %d\n", > >> + __func__, ret); > >> + return -1; > >> + } > >> + > >> + return ret; > >> +} > >> + > >> +static int tegra210_qspi_set_speed(struct udevice *bus, uint speed) { > >> + struct tegra_spi_platdata *plat = bus->platdata; > >> + struct tegra210_qspi_priv *priv = dev_get_priv(bus); > >> + > >> + if (speed > plat->frequency) > >> + speed = plat->frequency; > >> + priv->freq = speed; > >> + debug("%s: regs=%p, speed=%d\n", __func__, priv->regs, > >> + priv->freq); > >> + > >> + return 0; > >> +} > >> + > >> +static int tegra210_qspi_set_mode(struct udevice *bus, uint mode) { > >> + struct tegra210_qspi_priv *priv = dev_get_priv(bus); > >> + > >> + priv->mode = mode; > >> + debug("%s: regs=%p, mode=%d\n", __func__, priv->regs, > >> + priv->mode); > >> + > >> + return 0; > >> +} > >> + > >> +static const struct dm_spi_ops tegra210_qspi_ops = { > >> + .claim_bus = tegra210_qspi_claim_bus, > >> + .xfer = tegra210_qspi_xfer, > >> + .set_speed = tegra210_qspi_set_speed, > >> + .set_mode = tegra210_qspi_set_mode, > >> + /* > >> + * cs_info is not needed, since we require all chip selects to be > >> + * in the device tree explicitly > >> + */ > >> +}; > >> + > >> +static const struct udevice_id tegra210_qspi_ids[] = { > >> + { .compatible = "nvidia,tegra210-qspi" }, > >> + { } > >> +}; > >> + > >> +U_BOOT_DRIVER(tegra210_qspi) = { > >> + .name = "tegra210-qspi", > >> + .id = UCLASS_SPI, > >> + .of_match = tegra210_qspi_ids, > >> + .ops = &tegra210_qspi_ops, > >> + .ofdata_to_platdata = tegra210_qspi_ofdata_to_platdata, > >> + .platdata_auto_alloc_size = sizeof(struct tegra_spi_platdata), > >> + .priv_auto_alloc_size = sizeof(struct tegra210_qspi_priv), > >> + .per_child_auto_alloc_size = sizeof(struct spi_slave), > >> + .probe = tegra210_qspi_probe, > >> +}; > >> -- > >> 1.8.2.1.610.g562af5b > > thanks! > -- > Jagan | openedev. _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot