[PATCH] mmc: sdhci-sirf: add sirf tuning function (cmd 19)

[Ulf Hansson]

On 11 November 2014 16:47, Barry Song <21cnbao at gmail.com> wrote:
> From: Minda Chen <Minda.Chen at csr.com>
>
> Add manual tuning function in CSR atlas7 SoC. It is mainly used
> for the UHS-I SD card working SDR50 SDR104 mode.
>
> The tuning principle can be seen in SD spec part1 v3.01 4.2.4.5
> (tuning command).
>
> SD host send the cmd19 and set the delay value(0-127).
> and the sdcard return 64 bytes data. If the data is same with
> the tuning data. The delay value is valid. Execute this commmand
> 128 times. And calculate the longest window of the valid values.
> The value in the middle of this window is the best value.
>
> Signed-off-by: Minda Chen <Minda.Chen at csr.com>
> Signed-off-by: Barry Song <Baohua.Song at csr.com>
> ---
>  drivers/mmc/host/sdhci-sirf.c | 105 +++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 104 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mmc/host/sdhci-sirf.c b/drivers/mmc/host/sdhci-sirf.c
> index dd29d47..c71cf4e 100644
> --- a/drivers/mmc/host/sdhci-sirf.c
> +++ b/drivers/mmc/host/sdhci-sirf.c
> @@ -8,14 +8,18 @@
>
>  #include <linux/delay.h>
>  #include <linux/device.h>
> -#include <linux/mmc/host.h>
>  #include <linux/module.h>
>  #include <linux/of.h>
>  #include <linux/of_gpio.h>
> +#include <linux/slab.h>
> +#include <linux/mmc/host.h>
> +#include <linux/mmc/mmc.h>
>  #include <linux/mmc/slot-gpio.h>
>  #include "sdhci-pltfm.h"
>
> +#define SDHCI_CLK_DELAY_SETTING 0x4C
>  #define SDHCI_SIRF_8BITBUS BIT(3)
> +#define SIRF_TUNING_COUNT 128
>
>  struct sdhci_sirf_priv {
>         struct clk *clk;
> @@ -49,7 +53,106 @@ static void sdhci_sirf_set_bus_width(struct sdhci_host *host, int width)
>         sdhci_writeb(host, ctrl, SDHCI_HOST_CONTROL);
>  }
>
> +static int sdhci_sirf_execute_tuning(struct sdhci_host *host, u32 opcode)
> +{
> +       int tuning_seq_cnt = 3;
> +       u8 phase, *data_buf, tuned_phases[SIRF_TUNING_COUNT];
> +       u8 tuned_phase_cnt = 0;
> +       const u8 *tuning_block_pattern = tuning_blk_pattern_4bit;
> +       int size = sizeof(tuning_blk_pattern_4bit);
> +       int rc, longest_range = 0;
> +       int start = -1, end, tuning_value = -1, range = 0;
> +       u16 clock_setting;
> +       struct mmc_host *mmc = host->mmc;
> +
> +       data_buf = kmalloc(size, GFP_KERNEL);
> +       if (!data_buf)
> +               return -ENOMEM;
> +
> +       clock_setting = sdhci_readw(host, SDHCI_CLK_DELAY_SETTING);
> +       clock_setting &= ~0x3fff;
> +
> +retry:
> +       phase = 0;
> +       do {
> +               struct mmc_command cmd = { 0 };
> +               struct mmc_data data = { 0 };
> +               struct mmc_request mrq = {
> +                       .cmd = &cmd,
> +                       .data = &data
> +               };
> +               struct scatterlist sg;
> +
> +               sdhci_writel(host,
> +                       clock_setting | phase | (phase << 7) | (phase << 16),
> +                       SDHCI_CLK_DELAY_SETTING);
> +
> +               cmd.opcode = opcode;
> +               cmd.flags = MMC_RSP_R1 | MMC_CMD_ADTC;
> +
> +               data.blksz = size;
> +               data.blocks = 1;
> +               data.flags = MMC_DATA_READ;
> +               data.timeout_ns = NSEC_PER_SEC; /* 1 second */
> +
> +               data.sg = &sg;
> +               data.sg_len = 1;
> +               sg_init_one(&sg, data_buf, size);
> +               memset(data_buf, 0, size);
> +               mmc_wait_for_req(mmc, &mrq);

These piece of code, which sends the tuning command don't belong in
the host driver. Instead I would like this to be handled from a helper
function from the mmc core.

I realize that there already a few existing host drivers that
implemented similar code and I don't like it. We should convert them
to use a common helper function from the core instead.

> +
> +               if (!cmd.error && !data.error &&
> +                   !memcmp(data_buf, tuning_block_pattern, size)) {
> +                       /* Tuning is successful at this tuning point */
> +                       tuned_phases[tuned_phase_cnt++] = phase;
> +                       dev_dbg(mmc_dev(mmc), "%s: Found good phase = %d\n",
> +                                mmc_hostname(mmc), phase);
> +                       if (start == -1)
> +                               start = phase;
> +                       end = phase;
> +                       range++;
> +                       if (phase == (SIRF_TUNING_COUNT - 1)
> +                               && range > longest_range)
> +                               tuning_value = (start + end) / 2;
> +               } else {
> +                       dev_dbg(mmc_dev(mmc), "%s: Found bad phase = %d\n",
> +                                mmc_hostname(mmc), phase);
> +                       if (range > longest_range) {
> +                               tuning_value = (start + end) / 2;
> +                               longest_range = range;
> +                       }
> +                       start = -1;
> +                       end = range = 0;
> +               }
> +       } while (++phase < ARRAY_SIZE(tuned_phases));
> +
> +       if (tuned_phase_cnt && tuning_value > 0) {
> +               /*
> +                * Finally set the selected phase in delay
> +                * line hw block.
> +                */
> +               phase = tuning_value;
> +               sdhci_writel(host,
> +                       clock_setting | phase | (phase << 7) | (phase << 16),
> +                       SDHCI_CLK_DELAY_SETTING);
> +
> +               dev_dbg(mmc_dev(mmc), "%s: Setting the tuning phase to %d\n",
> +                        mmc_hostname(mmc), phase);
> +       } else {
> +               if (--tuning_seq_cnt)
> +                       goto retry;
> +               /* Tuning failed */
> +               dev_dbg(mmc_dev(mmc), "%s: No tuning point found\n",
> +                      mmc_hostname(mmc));
> +               rc = -EIO;
> +       }
> +
> +       kfree(data_buf);
> +       return rc;
> +}
> +
>  static struct sdhci_ops sdhci_sirf_ops = {
> +       .platform_execute_tuning = sdhci_sirf_execute_tuning,
>         .set_clock = sdhci_set_clock,
>         .get_max_clock  = sdhci_sirf_get_max_clk,
>         .set_bus_width = sdhci_sirf_set_bus_width,
> --
> 2.1.1
>

Kind regards
Uffe