Re: [PATCH v10 3/3] mmc: Add driver for LiteX's LiteSDCard interface

From: Gabriel L. Somlo
Date: Sun Jan 09 2022 - 11:56:51 EST

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In reply to: Andy Shevchenko: "Re: [PATCH v10 3/3] mmc: Add driver for LiteX's LiteSDCard interface"
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On Sun, Jan 09, 2022 at 05:06:20PM +0200, Andy Shevchenko wrote:
> On Sun, Jan 9, 2022 at 4:56 PM Gabriel Somlo <gsomlo@xxxxxxxxx> wrote:
> >
> > LiteX (https://github.com/enjoy-digital/litex) is a SoC framework
> > that targets FPGAs. LiteSDCard is a small footprint, configurable
> > SDCard core commonly used in LiteX designs.
> >
> > The driver was first written in May 2020 and has been maintained
> > cooperatively by the LiteX community. Thanks to all contributors!
>
> LGTM, thanks!
> FWIW,
> Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>

Thanks for spending the time reviewing it, much appreciated!

> One thing that may be improved later is the interrupt handler. I don't
> think it's correct to return IRQ_HANDLED in case there was no CMD or
> CD event, but I don't know the hardware either.

The only interrupt sources ever enabled elsewhere in the driver are
SDIRQ_CARD_DETECT and SDIRQ_CMD_DONE, so it's unlikely (impossible?)
for `pending` to have any other flags set besides those two.

I guess one could rewrite the whole thing to read like:

{
...
> irqreturn_t ret = IRQ_NONE;

/* Check for card change interrupt */
if (pending & SDIRQ_CARD_DETECT) {
litex_write32(host->sdirq + LITEX_IRQ_PENDING,
SDIRQ_CARD_DETECT);
mmc_detect_change(mmc, msecs_to_jiffies(10));
> ret = IRQ_HANDLED;
}

/* Check for command completed */
if (pending & SDIRQ_CMD_DONE) {
/* Disable it so it doesn't keep interrupting */
litex_write32(host->sdirq + LITEX_IRQ_ENABLE,
SDIRQ_CARD_DETECT);
complete(&host->cmd_done);
> ret = IRQ_HANDLED;
}

> return ret;
}

but that'd be only for defensive/paranoid code reasons, and I don't
expect it to ever end up returning IRQ_NONE given how the driver is
currently coded to work.

What do you think?

Thanks again,
--Gabriel

> > Co-developed-by: Kamil Rakoczy <krakoczy@xxxxxxxxxxxx>
> > Signed-off-by: Kamil Rakoczy <krakoczy@xxxxxxxxxxxx>
> > Co-developed-by: Maciej Dudek <mdudek@xxxxxxxxxxxxxxxxxxxxxxxx>
> > Signed-off-by: Maciej Dudek <mdudek@xxxxxxxxxxxxxxxxxxxxxxxx>
> > Co-developed-by: Paul Mackerras <paulus@xxxxxxxxxx>
> > Signed-off-by: Paul Mackerras <paulus@xxxxxxxxxx>
> > Signed-off-by: Gabriel Somlo <gsomlo@xxxxxxxxx>
> > Reviewed-by: Joel Stanley <joel@xxxxxxxxx>
> > ---
> >
> > New in v10:
> > drivers/mmc/host/litex_mmc.c:
> > - group `linux/mmc/*` includes by themselves
> > - clean-up of `return` style (multiple locations throughout source)
> > - create `mmc_free_host()` wrapper for use with
> > `devm_add_action_or_reset()`
> > - use GFP_KERNEL with `dmam_alloc_coherent()`
> >
> > >New in v9:
> > >drivers/mmc/host/Kconfig:
> > > - fix OF dependency
> > >drivers/mmc/host/litex_mmc.c:
> > > - remove `linux/of.h` include, no longer needed since dropping
> > > `of_match_ptr()`
> > > - add `linux/mod_devicetable.h` include
> > > - use devm_action_or_reset() to devm-ify mmc_alloc_host(), and obviate
> > > the need to call mmc_free_host() explicitly during either probe()
> > > error path or during remove()
> > >
> > >>New in v8:
> > >> - remove `Cc:` lines from commit blurb
> > >>drivers/mmc/host/litex_mmc.c:
> > >> - fix file header comment (for real, this time)
> > >> - add explicit `bits.h` include
> > >> - remove `of_match_ptr()` wrapper from around .of_match_table argument
> > >> - fix devm ordering issues: use `devm_request_irq()`, which precludes
> > >> the need to call `free_irq()` on `probe()` error path or from `remove()`
> > >>
> > >>>New in v7:
> > >>>drivers/mmc/host/Kconfig:
> > >>> - added module name in LiteSDCard Kconfig entry
> > >>>drivers/mmc/host/litex_mmc.c:
> > >>> - fixed comment formatting, ordering, and capitalization throughout
> > >>> the entire file
> > >>> - sorted header #include statements
> > >>> - removed redundant parantheses in readx_poll_timeout() condition
> > >>> - explicit handling of readx_poll_timeout() timeout scenarios
> > >>> - dev_err() used in litex_mmc_sdcard_wait_done()
> > >>> - use memcpy_fromio() to grab command response
> > >>> - no need to apply 0xffff mask to a 32-bit value right-shifted by 16
> > >>> (host->resp[3])
> > >>> - use clamp() instead of min(max(...)...)
> > >>> - reworked platform_get_irq_optional() error handling logic
> > >>> - no need to explicitly zero host->irq, kzalloc() does that already
> > >>> - added missing free_irq() in litex_mmc_probe() error path
> > >>> - reordered calls inside litex_mmc_remove() (calling mmc_free_host()
> > >>> before free_irq()
> > >>>
> > >>>>New in v6:
> > >>>> - fix handling of deferred probe vs. platform_get_irq_optional()
> > >>>> - don't #ifdef dma_set_mask_and_coherent(), since it automatically
> > >>>> does the right thing on both 32- and 64-bit DMA capable arches
> > >>>> - remove MMC_CAP2_FULL_PWR_CYCLE, add MMC_CAP2_NO_MMC to list of
> > >>>> hardcoded capabilities during litex_mmc_probe()
> > >>>> - hardcode mmc->ocr_avail to the full 2.7-3.6V range allowed by the
> > >>>> SDCard spec (the LiteSDCard device doesn't accept software
> > >>>> configuration)
> > >>>>
> > >>>>>New in v5:
> > >>>>> - shorter #define constant names (cosmetic, make them less unwieldy)
> > >>>>> - picked up reviewed-by Joel
> > >>>>>
> > >>>>>>New in v4:
> > >>>>>> - struct litex_mmc_host fields re-ordered so that `pahole` reports
> > >>>>>> no holes on either 32- or 64-bit builds
> > >>>>>> - litex_mmc_set_bus_width() now encapsulates check for
> > >>>>>> host->is_bus_width_set
> > >>>>>> - litex_mmc_request() - factor out dma data setup into separate
> > >>>>>> helper function: litex_mmc_do_dma()
> > >>>>>>
> > >>>>>>> New in v3:
> > >>>>>>> - fixed function signature (no line split), and naming (litex_mmc_*)
> > >>>>>>> - more informative MODULE_AUTHOR() entries
> > >>>>>>> - also added matching "Copyright" entries in file header
> > >>>>>>> - fixed description and dependencies in Kconfig
> > >>>>>>> - removed magic constants
> > >>>>>>> - removed litex_map_status(), have sdcard_wait_done() return *real*
> > >>>>>>> error codes directly instead.
> > >>>>>>> - streamlined litex_mmc_reponse_len()
> > >>>>>>> - call litex_mmc_set_bus_width() only once, and ensure it returns
> > >>>>>>> correct error code(s)
> > >>>>>>> - use readx_poll_timeout() -- more concise -- instead of
> > >>>>>>> read_poll_timeout()
> > >>>>>>> - use dev_err() in litex_mmc_send_cmd() (instead of pr_err())
> > >>>>>>> - litex_mmc_setclk() will update host->clock before returning
> > >>>>>>> - separate irq initialization into its own function,
> > >>>>>>> litex_mmc_irq_init()
> > >>>>>>> - document rationale for f_min, f_max
> > >>>>>>> - use dmam_alloc_coherent(), which simplifies cleanup significantly
> > >>>>>>> - bump dma_set_mask_and_coherent() to 64-bits on suitable
> > >>>>>>> architectures
> > >>>>>>> - clock source picked up from dedicated DT clock reference property
> > >>>>>>> - remove gpio card-detect logic (needs testing and a dt binding
> > >>>>>>> example before being eligible for upstream inclusion)
> > >>>>>>> - large `if (data) { ... }` block in litex_mmc_request() left as-is,
> > >>>>>>> there are too many variables shared with the rest of the parent
> > >>>>>>> function body to easily separate (e.g., `len`, `transfer`, `direct`).
> > >>>>>>> If this is indeed a blocker, I can take another shot at refactoring
> > >>>>>>> it in a future revision!
> >
> > drivers/mmc/host/Kconfig | 9 +
> > drivers/mmc/host/Makefile | 1 +
> > drivers/mmc/host/litex_mmc.c | 655 +++++++++++++++++++++++++++++++++++
> > 3 files changed, 665 insertions(+)
> > create mode 100644 drivers/mmc/host/litex_mmc.c
> >
> > diff --git a/drivers/mmc/host/Kconfig b/drivers/mmc/host/Kconfig
> > index 5af8494c31b5..8f661f52b502 100644
> > --- a/drivers/mmc/host/Kconfig
> > +++ b/drivers/mmc/host/Kconfig
> > @@ -1093,3 +1093,12 @@ config MMC_OWL
> >
> > config MMC_SDHCI_EXTERNAL_DMA
> > bool
> > +
> > +config MMC_LITEX
> > + tristate "LiteX MMC Host Controller support"
> > + depends on ((PPC_MICROWATT || LITEX) && OF) || COMPILE_TEST
> > + help
> > + This selects support for the MMC Host Controller found in LiteX SoCs.
> > +
> > + To compile this driver as a module, choose M here: the
> > + module will be called litex_mmc.
> > diff --git a/drivers/mmc/host/Makefile b/drivers/mmc/host/Makefile
> > index ea36d379bd3c..4e4ceb32c4b4 100644
> > --- a/drivers/mmc/host/Makefile
> > +++ b/drivers/mmc/host/Makefile
> > @@ -101,6 +101,7 @@ obj-$(CONFIG_MMC_CQHCI) += cqhci.o
> > cqhci-y += cqhci-core.o
> > cqhci-$(CONFIG_MMC_CRYPTO) += cqhci-crypto.o
> > obj-$(CONFIG_MMC_HSQ) += mmc_hsq.o
> > +obj-$(CONFIG_MMC_LITEX) += litex_mmc.o
> >
> > ifeq ($(CONFIG_CB710_DEBUG),y)
> > CFLAGS-cb710-mmc += -DDEBUG
> > diff --git a/drivers/mmc/host/litex_mmc.c b/drivers/mmc/host/litex_mmc.c
> > new file mode 100644
> > index 000000000000..db1858e343c7
> > --- /dev/null
> > +++ b/drivers/mmc/host/litex_mmc.c
> > @@ -0,0 +1,655 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * LiteX LiteSDCard driver
> > + *
> > + * Copyright (C) 2019-2020 Antmicro <contact@xxxxxxxxxxxx>
> > + * Copyright (C) 2019-2020 Kamil Rakoczy <krakoczy@xxxxxxxxxxxx>
> > + * Copyright (C) 2019-2020 Maciej Dudek <mdudek@xxxxxxxxxxxxxxxxxxxxxxxx>
> > + * Copyright (C) 2020 Paul Mackerras <paulus@xxxxxxxxxx>
> > + * Copyright (C) 2020-2021 Gabriel Somlo <gsomlo@xxxxxxxxx>
> > + */
> > +
> > +#include <linux/bits.h>
> > +#include <linux/clk.h>
> > +#include <linux/delay.h>
> > +#include <linux/dma-mapping.h>
> > +#include <linux/interrupt.h>
> > +#include <linux/iopoll.h>
> > +#include <linux/litex.h>
> > +#include <linux/mod_devicetable.h>
> > +#include <linux/module.h>
> > +#include <linux/platform_device.h>
> > +
> > +#include <linux/mmc/host.h>
> > +#include <linux/mmc/mmc.h>
> > +#include <linux/mmc/sd.h>
> > +
> > +#define LITEX_PHY_CARDDETECT 0x00
> > +#define LITEX_PHY_CLOCKERDIV 0x04
> > +#define LITEX_PHY_INITIALIZE 0x08
> > +#define LITEX_PHY_WRITESTATUS 0x0C
> > +#define LITEX_CORE_CMDARG 0x00
> > +#define LITEX_CORE_CMDCMD 0x04
> > +#define LITEX_CORE_CMDSND 0x08
> > +#define LITEX_CORE_CMDRSP 0x0C
> > +#define LITEX_CORE_CMDEVT 0x1C
> > +#define LITEX_CORE_DATEVT 0x20
> > +#define LITEX_CORE_BLKLEN 0x24
> > +#define LITEX_CORE_BLKCNT 0x28
> > +#define LITEX_BLK2MEM_BASE 0x00
> > +#define LITEX_BLK2MEM_LEN 0x08
> > +#define LITEX_BLK2MEM_ENA 0x0C
> > +#define LITEX_BLK2MEM_DONE 0x10
> > +#define LITEX_BLK2MEM_LOOP 0x14
> > +#define LITEX_MEM2BLK_BASE 0x00
> > +#define LITEX_MEM2BLK_LEN 0x08
> > +#define LITEX_MEM2BLK_ENA 0x0C
> > +#define LITEX_MEM2BLK_DONE 0x10
> > +#define LITEX_MEM2BLK_LOOP 0x14
> > +#define LITEX_MEM2BLK 0x18
> > +#define LITEX_IRQ_STATUS 0x00
> > +#define LITEX_IRQ_PENDING 0x04
> > +#define LITEX_IRQ_ENABLE 0x08
> > +
> > +#define SD_CTL_DATA_XFER_NONE 0
> > +#define SD_CTL_DATA_XFER_READ 1
> > +#define SD_CTL_DATA_XFER_WRITE 2
> > +
> > +#define SD_CTL_RESP_NONE 0
> > +#define SD_CTL_RESP_SHORT 1
> > +#define SD_CTL_RESP_LONG 2
> > +#define SD_CTL_RESP_SHORT_BUSY 3
> > +
> > +#define SD_BIT_DONE BIT(0)
> > +#define SD_BIT_WR_ERR BIT(1)
> > +#define SD_BIT_TIMEOUT BIT(2)
> > +#define SD_BIT_CRC_ERR BIT(3)
> > +
> > +#define SD_SLEEP_US 5
> > +#define SD_TIMEOUT_US 20000
> > +
> > +#define SDIRQ_CARD_DETECT 1
> > +#define SDIRQ_SD_TO_MEM_DONE 2
> > +#define SDIRQ_MEM_TO_SD_DONE 4
> > +#define SDIRQ_CMD_DONE 8
> > +
> > +#define LITEX_MMC_OCR (MMC_VDD_27_28 | MMC_VDD_28_29 | MMC_VDD_29_30 | \
> > + MMC_VDD_30_31 | MMC_VDD_31_32 | MMC_VDD_32_33 | \
> > + MMC_VDD_33_34 | MMC_VDD_34_35 | MMC_VDD_35_36)
> > +
> > +struct litex_mmc_host {
> > + struct mmc_host *mmc;
> > + struct platform_device *dev;
> > +
> > + void __iomem *sdphy;
> > + void __iomem *sdcore;
> > + void __iomem *sdreader;
> > + void __iomem *sdwriter;
> > + void __iomem *sdirq;
> > +
> > + void *buffer;
> > + size_t buf_size;
> > + dma_addr_t dma;
> > +
> > + struct completion cmd_done;
> > + int irq;
> > +
> > + unsigned int ref_clk;
> > + unsigned int sd_clk;
> > +
> > + u32 resp[4];
> > + u16 rca;
> > +
> > + bool is_bus_width_set;
> > + bool app_cmd;
> > +};
> > +
> > +static int litex_mmc_sdcard_wait_done(void __iomem *reg, struct device *dev)
> > +{
> > + u8 evt;
> > + int ret;
> > +
> > + ret = readx_poll_timeout(litex_read8, reg, evt, evt & SD_BIT_DONE,
> > + SD_SLEEP_US, SD_TIMEOUT_US);
> > + if (ret)
> > + return ret;
> > + if (evt == SD_BIT_DONE)
> > + return 0;
> > + if (evt & SD_BIT_WR_ERR)
> > + return -EIO;
> > + if (evt & SD_BIT_TIMEOUT)
> > + return -ETIMEDOUT;
> > + if (evt & SD_BIT_CRC_ERR)
> > + return -EILSEQ;
> > + dev_err(dev, "%s: unknown error (evt=%x)\n", __func__, evt);
> > + return -EINVAL;
> > +}
> > +
> > +static int litex_mmc_send_cmd(struct litex_mmc_host *host,
> > + u8 cmd, u32 arg, u8 response_len, u8 transfer)
> > +{
> > + struct device *dev = mmc_dev(host->mmc);
> > + void __iomem *reg;
> > + int ret;
> > + u8 evt;
> > +
> > + litex_write32(host->sdcore + LITEX_CORE_CMDARG, arg);
> > + litex_write32(host->sdcore + LITEX_CORE_CMDCMD,
> > + cmd << 8 | transfer << 5 | response_len);
> > + litex_write8(host->sdcore + LITEX_CORE_CMDSND, 1);
> > +
> > + /*
> > + * Wait for an interrupt if we have an interrupt and either there is
> > + * data to be transferred, or if the card can report busy via DAT0.
> > + */
> > + if (host->irq > 0 &&
> > + (transfer != SD_CTL_DATA_XFER_NONE ||
> > + response_len == SD_CTL_RESP_SHORT_BUSY)) {
> > + reinit_completion(&host->cmd_done);
> > + litex_write32(host->sdirq + LITEX_IRQ_ENABLE,
> > + SDIRQ_CMD_DONE | SDIRQ_CARD_DETECT);
> > + wait_for_completion(&host->cmd_done);
> > + }
> > +
> > + ret = litex_mmc_sdcard_wait_done(host->sdcore + LITEX_CORE_CMDEVT, dev);
> > + if (ret) {
> > + dev_err(dev, "Command (cmd %d) error, status %d\n", cmd, ret);
> > + return ret;
> > + }
> > +
> > + if (response_len != SD_CTL_RESP_NONE) {
> > + /*
> > + * NOTE: this matches the semantics of litex_read32()
> > + * regardless of underlying arch endianness!
> > + */
> > + memcpy_fromio(host->resp,
> > + host->sdcore + LITEX_CORE_CMDRSP, 0x10);
> > + }
> > +
> > + if (!host->app_cmd && cmd == SD_SEND_RELATIVE_ADDR)
> > + host->rca = (host->resp[3] >> 16);
> > +
> > + host->app_cmd = (cmd == MMC_APP_CMD);
> > +
> > + if (transfer == SD_CTL_DATA_XFER_NONE)
> > + return ret; /* OK from prior litex_mmc_sdcard_wait_done() */
> > +
> > + ret = litex_mmc_sdcard_wait_done(host->sdcore + LITEX_CORE_DATEVT, dev);
> > + if (ret) {
> > + dev_err(dev, "Data xfer (cmd %d) error, status %d\n", cmd, ret);
> > + return ret;
> > + }
> > +
> > + /* Wait for completion of (read or write) DMA transfer */
> > + reg = (transfer == SD_CTL_DATA_XFER_READ) ?
> > + host->sdreader + LITEX_BLK2MEM_DONE :
> > + host->sdwriter + LITEX_MEM2BLK_DONE;
> > + ret = readx_poll_timeout(litex_read8, reg, evt, evt & SD_BIT_DONE,
> > + SD_SLEEP_US, SD_TIMEOUT_US);
> > + if (ret)
> > + dev_err(dev, "DMA timeout (cmd %d)\n", cmd);
> > +
> > + return ret;
> > +}
> > +
> > +static int litex_mmc_send_app_cmd(struct litex_mmc_host *host)
> > +{
> > + return litex_mmc_send_cmd(host, MMC_APP_CMD, host->rca << 16,
> > + SD_CTL_RESP_SHORT, SD_CTL_DATA_XFER_NONE);
> > +}
> > +
> > +static int litex_mmc_send_set_bus_w_cmd(struct litex_mmc_host *host, u32 width)
> > +{
> > + return litex_mmc_send_cmd(host, SD_APP_SET_BUS_WIDTH, width,
> > + SD_CTL_RESP_SHORT, SD_CTL_DATA_XFER_NONE);
> > +}
> > +
> > +static int litex_mmc_set_bus_width(struct litex_mmc_host *host)
> > +{
> > + bool app_cmd_sent;
> > + int ret;
> > +
> > + if (host->is_bus_width_set)
> > + return 0;
> > +
> > + /* Ensure 'app_cmd' precedes 'app_set_bus_width_cmd' */
> > + app_cmd_sent = host->app_cmd; /* was preceding command app_cmd? */
> > + if (!app_cmd_sent) {
> > + ret = litex_mmc_send_app_cmd(host);
> > + if (ret)
> > + return ret;
> > + }
> > +
> > + /* LiteSDCard only supports 4-bit bus width */
> > + ret = litex_mmc_send_set_bus_w_cmd(host, MMC_BUS_WIDTH_4);
> > + if (ret)
> > + return ret;
> > +
> > + /* Re-send 'app_cmd' if necessary */
> > + if (app_cmd_sent) {
> > + ret = litex_mmc_send_app_cmd(host);
> > + if (ret)
> > + return ret;
> > + }
> > +
> > + host->is_bus_width_set = true;
> > +
> > + return 0;
> > +}
> > +
> > +static int litex_mmc_get_cd(struct mmc_host *mmc)
> > +{
> > + struct litex_mmc_host *host = mmc_priv(mmc);
> > + int ret;
> > +
> > + if (!mmc_card_is_removable(mmc))
> > + return 1;
> > +
> > + ret = !litex_read8(host->sdphy + LITEX_PHY_CARDDETECT);
> > + if (ret)
> > + return ret;
> > +
> > + /* Ensure bus width will be set (again) upon card (re)insertion */
> > + host->is_bus_width_set = false;
> > +
> > + return 0;
> > +}
> > +
> > +static irqreturn_t litex_mmc_interrupt(int irq, void *arg)
> > +{
> > + struct mmc_host *mmc = arg;
> > + struct litex_mmc_host *host = mmc_priv(mmc);
> > + u32 pending = litex_read32(host->sdirq + LITEX_IRQ_PENDING);
> > +
> > + /* Check for card change interrupt */
> > + if (pending & SDIRQ_CARD_DETECT) {
> > + litex_write32(host->sdirq + LITEX_IRQ_PENDING,
> > + SDIRQ_CARD_DETECT);
> > + mmc_detect_change(mmc, msecs_to_jiffies(10));
> > + }
> > +
> > + /* Check for command completed */
> > + if (pending & SDIRQ_CMD_DONE) {
> > + /* Disable it so it doesn't keep interrupting */
> > + litex_write32(host->sdirq + LITEX_IRQ_ENABLE,
> > + SDIRQ_CARD_DETECT);
> > + complete(&host->cmd_done);
> > + }
> > +
> > + return IRQ_HANDLED;
> > +}
> > +
> > +static u32 litex_mmc_response_len(struct mmc_command *cmd)
> > +{
> > + if (cmd->flags & MMC_RSP_136)
> > + return SD_CTL_RESP_LONG;
> > + if (!(cmd->flags & MMC_RSP_PRESENT))
> > + return SD_CTL_RESP_NONE;
> > + if (cmd->flags & MMC_RSP_BUSY)
> > + return SD_CTL_RESP_SHORT_BUSY;
> > + return SD_CTL_RESP_SHORT;
> > +}
> > +
> > +static void litex_mmc_do_dma(struct litex_mmc_host *host, struct mmc_data *data,
> > + unsigned int *len, bool *direct, u8 *transfer)
> > +{
> > + struct device *dev = mmc_dev(host->mmc);
> > + dma_addr_t dma;
> > + int sg_count;
> > +
> > + /*
> > + * Try to DMA directly to/from the data buffer.
> > + * We can do that if the buffer can be mapped for DMA
> > + * in one contiguous chunk.
> > + */
> > + dma = host->dma;
> > + *len = data->blksz * data->blocks;
> > + sg_count = dma_map_sg(dev, data->sg, data->sg_len,
> > + mmc_get_dma_dir(data));
> > + if (sg_count == 1) {
> > + dma = sg_dma_address(data->sg);
> > + *len = sg_dma_len(data->sg);
> > + *direct = true;
> > + } else if (*len > host->buf_size)
> > + *len = host->buf_size;
> > +
> > + if (data->flags & MMC_DATA_READ) {
> > + litex_write8(host->sdreader + LITEX_BLK2MEM_ENA, 0);
> > + litex_write64(host->sdreader + LITEX_BLK2MEM_BASE, dma);
> > + litex_write32(host->sdreader + LITEX_BLK2MEM_LEN, *len);
> > + litex_write8(host->sdreader + LITEX_BLK2MEM_ENA, 1);
> > + *transfer = SD_CTL_DATA_XFER_READ;
> > + } else if (data->flags & MMC_DATA_WRITE) {
> > + if (!*direct)
> > + sg_copy_to_buffer(data->sg, data->sg_len,
> > + host->buffer, *len);
> > + litex_write8(host->sdwriter + LITEX_MEM2BLK_ENA, 0);
> > + litex_write64(host->sdwriter + LITEX_MEM2BLK_BASE, dma);
> > + litex_write32(host->sdwriter + LITEX_MEM2BLK_LEN, *len);
> > + litex_write8(host->sdwriter + LITEX_MEM2BLK_ENA, 1);
> > + *transfer = SD_CTL_DATA_XFER_WRITE;
> > + } else {
> > + dev_warn(dev, "Data present w/o read or write flag.\n");
> > + /* Continue: set cmd status, mark req done */
> > + }
> > +
> > + litex_write16(host->sdcore + LITEX_CORE_BLKLEN, data->blksz);
> > + litex_write32(host->sdcore + LITEX_CORE_BLKCNT, data->blocks);
> > +}
> > +
> > +static void litex_mmc_request(struct mmc_host *mmc, struct mmc_request *mrq)
> > +{
> > + struct litex_mmc_host *host = mmc_priv(mmc);
> > + struct device *dev = mmc_dev(mmc);
> > + struct mmc_command *cmd = mrq->cmd;
> > + struct mmc_command *sbc = mrq->sbc;
> > + struct mmc_data *data = mrq->data;
> > + struct mmc_command *stop = mrq->stop;
> > + unsigned int retries = cmd->retries;
> > + unsigned int len = 0;
> > + bool direct = false;
> > + u32 response_len = litex_mmc_response_len(cmd);
> > + u8 transfer = SD_CTL_DATA_XFER_NONE;
> > +
> > + /* First check that the card is still there */
> > + if (!litex_mmc_get_cd(mmc)) {
> > + cmd->error = -ENOMEDIUM;
> > + mmc_request_done(mmc, mrq);
> > + return;
> > + }
> > +
> > + /* Send set-block-count command if needed */
> > + if (sbc) {
> > + sbc->error = litex_mmc_send_cmd(host, sbc->opcode, sbc->arg,
> > + litex_mmc_response_len(sbc),
> > + SD_CTL_DATA_XFER_NONE);
> > + if (sbc->error) {
> > + host->is_bus_width_set = false;
> > + mmc_request_done(mmc, mrq);
> > + return;
> > + }
> > + }
> > +
> > + if (data) {
> > + /*
> > + * LiteSDCard only supports 4-bit bus width; therefore, we MUST
> > + * inject a SET_BUS_WIDTH (acmd6) before the very first data
> > + * transfer, earlier than when the mmc subsystem would normally
> > + * get around to it!
> > + */
> > + cmd->error = litex_mmc_set_bus_width(host);
> > + if (cmd->error) {
> > + dev_err(dev, "Can't set bus width!\n");
> > + mmc_request_done(mmc, mrq);
> > + return;
> > + }
> > +
> > + litex_mmc_do_dma(host, data, &len, &direct, &transfer);
> > + }
> > +
> > + do {
> > + cmd->error = litex_mmc_send_cmd(host, cmd->opcode, cmd->arg,
> > + response_len, transfer);
> > + } while (cmd->error && retries-- > 0);
> > +
> > + if (cmd->error) {
> > + /* Card may be gone; don't assume bus width is still set */
> > + host->is_bus_width_set = false;
> > + }
> > +
> > + if (response_len == SD_CTL_RESP_SHORT) {
> > + /* Pull short response fields from appropriate host registers */
> > + cmd->resp[0] = host->resp[3];
> > + cmd->resp[1] = host->resp[2] & 0xFF;
> > + } else if (response_len == SD_CTL_RESP_LONG) {
> > + cmd->resp[0] = host->resp[0];
> > + cmd->resp[1] = host->resp[1];
> > + cmd->resp[2] = host->resp[2];
> > + cmd->resp[3] = host->resp[3];
> > + }
> > +
> > + /* Send stop-transmission command if required */
> > + if (stop && (cmd->error || !sbc)) {
> > + stop->error = litex_mmc_send_cmd(host, stop->opcode, stop->arg,
> > + litex_mmc_response_len(stop),
> > + SD_CTL_DATA_XFER_NONE);
> > + if (stop->error)
> > + host->is_bus_width_set = false;
> > + }
> > +
> > + if (data) {
> > + dma_unmap_sg(dev, data->sg, data->sg_len,
> > + mmc_get_dma_dir(data));
> > + }
> > +
> > + if (!cmd->error && transfer != SD_CTL_DATA_XFER_NONE) {
> > + data->bytes_xfered = min(len, mmc->max_req_size);
> > + if (transfer == SD_CTL_DATA_XFER_READ && !direct) {
> > + sg_copy_from_buffer(data->sg, sg_nents(data->sg),
> > + host->buffer, data->bytes_xfered);
> > + }
> > + }
> > +
> > + mmc_request_done(mmc, mrq);
> > +}
> > +
> > +static void litex_mmc_setclk(struct litex_mmc_host *host, unsigned int freq)
> > +{
> > + struct device *dev = mmc_dev(host->mmc);
> > + u32 div;
> > +
> > + div = freq ? host->ref_clk / freq : 256U;
> > + div = roundup_pow_of_two(div);
> > + div = clamp(div, 2U, 256U);
> > + dev_dbg(dev, "sd_clk_freq=%d: set to %d via div=%d\n",
> > + freq, host->ref_clk / div, div);
> > + litex_write16(host->sdphy + LITEX_PHY_CLOCKERDIV, div);
> > + host->sd_clk = freq;
> > +}
> > +
> > +static void litex_mmc_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
> > +{
> > + struct litex_mmc_host *host = mmc_priv(mmc);
> > +
> > + /*
> > + * NOTE: Ignore any ios->bus_width updates; they occur right after
> > + * the mmc core sends its own acmd6 bus-width change notification,
> > + * which is redundant since we snoop on the command flow and inject
> > + * an early acmd6 before the first data transfer command is sent!
> > + */
> > +
> > + /* Update sd_clk */
> > + if (ios->clock != host->sd_clk)
> > + litex_mmc_setclk(host, ios->clock);
> > +}
> > +
> > +static const struct mmc_host_ops litex_mmc_ops = {
> > + .get_cd = litex_mmc_get_cd,
> > + .request = litex_mmc_request,
> > + .set_ios = litex_mmc_set_ios,
> > +};
> > +
> > +static int litex_mmc_irq_init(struct litex_mmc_host *host)
> > +{
> > + struct device *dev = mmc_dev(host->mmc);
> > + int ret;
> > +
> > + ret = platform_get_irq_optional(host->dev, 0);
> > + if (ret < 0 && ret != -ENXIO)
> > + return ret;
> > + if (ret > 0)
> > + host->irq = ret;
> > + else {
> > + dev_warn(dev, "Failed to get IRQ, using polling\n");
> > + goto use_polling;
> > + }
> > +
> > + host->sdirq = devm_platform_ioremap_resource_byname(host->dev, "irq");
> > + if (IS_ERR(host->sdirq))
> > + return PTR_ERR(host->sdirq);
> > +
> > + ret = devm_request_irq(dev, host->irq, litex_mmc_interrupt, 0,
> > + "litex-mmc", host->mmc);
> > + if (ret < 0) {
> > + dev_warn(dev, "IRQ request error %d, using polling\n", ret);
> > + goto use_polling;
> > + }
> > +
> > + /* Clear & enable card-change interrupts */
> > + litex_write32(host->sdirq + LITEX_IRQ_PENDING, SDIRQ_CARD_DETECT);
> > + litex_write32(host->sdirq + LITEX_IRQ_ENABLE, SDIRQ_CARD_DETECT);
> > +
> > + return 0;
> > +
> > +use_polling:
> > + host->mmc->caps |= MMC_CAP_NEEDS_POLL;
> > + return 0;
> > +}
> > +
> > +static void litex_mmc_free_host_wrapper(void *mmc)
> > +{
> > + mmc_free_host(mmc);
> > +}
> > +
> > +static int litex_mmc_probe(struct platform_device *pdev)
> > +{
> > + struct device *dev = &pdev->dev;
> > + struct litex_mmc_host *host;
> > + struct mmc_host *mmc;
> > + struct clk *clk;
> > + int ret;
> > +
> > + /*
> > + * NOTE: defaults to max_[req,seg]_size=PAGE_SIZE, max_blk_size=512,
> > + * and max_blk_count accordingly set to 8;
> > + * If for some reason we need to modify max_blk_count, we must also
> > + * re-calculate `max_[req,seg]_size = max_blk_size * max_blk_count;`
> > + */
> > + mmc = mmc_alloc_host(sizeof(struct litex_mmc_host), dev);
> > + if (!mmc)
> > + return -ENOMEM;
> > +
> > + ret = devm_add_action_or_reset(dev, litex_mmc_free_host_wrapper, mmc);
> > + if (ret)
> > + return dev_err_probe(dev, ret,
> > + "Can't register mmc_free_host action\n");
> > +
> > + host = mmc_priv(mmc);
> > + host->mmc = mmc;
> > + host->dev = pdev;
> > +
> > + /* Initialize clock source */
> > + clk = devm_clk_get(dev, NULL);
> > + if (IS_ERR(clk))
> > + return dev_err_probe(dev, PTR_ERR(clk), "can't get clock\n");
> > + host->ref_clk = clk_get_rate(clk);
> > + host->sd_clk = 0;
> > +
> > + /*
> > + * LiteSDCard only supports 4-bit bus width; therefore, we MUST inject
> > + * a SET_BUS_WIDTH (acmd6) before the very first data transfer, earlier
> > + * than when the mmc subsystem would normally get around to it!
> > + */
> > + host->is_bus_width_set = false;
> > + host->app_cmd = false;
> > +
> > + /* LiteSDCard can support 64-bit DMA addressing */
> > + ret = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(64));
> > + if (ret)
> > + return ret;
> > +
> > + host->buf_size = mmc->max_req_size * 2;
> > + host->buffer = dmam_alloc_coherent(dev, host->buf_size,
> > + &host->dma, GFP_KERNEL);
> > + if (host->buffer == NULL)
> > + return -ENOMEM;
> > +
> > + host->sdphy = devm_platform_ioremap_resource_byname(pdev, "phy");
> > + if (IS_ERR(host->sdphy))
> > + return PTR_ERR(host->sdphy);
> > +
> > + host->sdcore = devm_platform_ioremap_resource_byname(pdev, "core");
> > + if (IS_ERR(host->sdcore))
> > + return PTR_ERR(host->sdcore);
> > +
> > + host->sdreader = devm_platform_ioremap_resource_byname(pdev, "reader");
> > + if (IS_ERR(host->sdreader))
> > + return PTR_ERR(host->sdreader);
> > +
> > + host->sdwriter = devm_platform_ioremap_resource_byname(pdev, "writer");
> > + if (IS_ERR(host->sdwriter))
> > + return PTR_ERR(host->sdwriter);
> > +
> > + /* Ensure DMA bus masters are disabled */
> > + litex_write8(host->sdreader + LITEX_BLK2MEM_ENA, 0);
> > + litex_write8(host->sdwriter + LITEX_MEM2BLK_ENA, 0);
> > +
> > + init_completion(&host->cmd_done);
> > + ret = litex_mmc_irq_init(host);
> > + if (ret)
> > + return ret;
> > +
> > + /* Allow full generic 2.7-3.6V range; no software tuning available */
> > + mmc->ocr_avail = LITEX_MMC_OCR;
> > +
> > + mmc->ops = &litex_mmc_ops;
> > +
> > + /*
> > + * Set default sd_clk frequency range based on empirical observations
> > + * of LiteSDCard gateware behavior on typical SDCard media
> > + */
> > + mmc->f_min = 12.5e6;
> > + mmc->f_max = 50e6;
> > +
> > + ret = mmc_of_parse(mmc);
> > + if (ret)
> > + return ret;
> > +
> > + /* Force 4-bit bus_width (only width supported by hardware) */
> > + mmc->caps &= ~MMC_CAP_8_BIT_DATA;
> > + mmc->caps |= MMC_CAP_4_BIT_DATA;
> > +
> > + /* Set default capabilities */
> > + mmc->caps |= MMC_CAP_WAIT_WHILE_BUSY |
> > + MMC_CAP_DRIVER_TYPE_D |
> > + MMC_CAP_CMD23;
> > + mmc->caps2 |= MMC_CAP2_NO_WRITE_PROTECT |
> > + MMC_CAP2_NO_SDIO |
> > + MMC_CAP2_NO_MMC;
> > +
> > + platform_set_drvdata(pdev, host);
> > +
> > + return mmc_add_host(mmc);
> > +}
> > +
> > +static int litex_mmc_remove(struct platform_device *pdev)
> > +{
> > + struct litex_mmc_host *host = platform_get_drvdata(pdev);
> > +
> > + mmc_remove_host(host->mmc);
> > + return 0;
> > +}
> > +
> > +static const struct of_device_id litex_match[] = {
> > + { .compatible = "litex,mmc" },
> > + { }
> > +};
> > +MODULE_DEVICE_TABLE(of, litex_match);
> > +
> > +static struct platform_driver litex_mmc_driver = {
> > + .probe = litex_mmc_probe,
> > + .remove = litex_mmc_remove,
> > + .driver = {
> > + .name = "litex-mmc",
> > + .of_match_table = litex_match,
> > + },
> > +};
> > +module_platform_driver(litex_mmc_driver);
> > +
> > +MODULE_DESCRIPTION("LiteX SDCard driver");
> > +MODULE_AUTHOR("Antmicro <contact@xxxxxxxxxxxx>");
> > +MODULE_AUTHOR("Kamil Rakoczy <krakoczy@xxxxxxxxxxxx>");
> > +MODULE_AUTHOR("Maciej Dudek <mdudek@xxxxxxxxxxxxxxxxxxxxxxxx>");
> > +MODULE_AUTHOR("Paul Mackerras <paulus@xxxxxxxxxx>");
> > +MODULE_AUTHOR("Gabriel Somlo <gsomlo@xxxxxxxxx>");
> > +MODULE_LICENSE("GPL v2");
> > --
> > 2.31.1
> >
>
>
> --
> With Best Regards,
> Andy Shevchenko

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