Re: [RFC PATCH] mmc: sdhci-of-arasan: Add auto tuning support for ZynqMP Platform

[Adrian Hunter]

On 30/01/18 20:14, Manish Narani wrote:
> This patch adds support of SD auto tuning for ZynqMP platform. Auto
> tuning sequence sends tuning block to card when operating in UHS-1
> modes. This resets the DLL and sends CMD19/CMD21 as a part of the auto
> tuning process. Once the auto tuning process gets completed, reset the
> DLL to load the newly obtained SDHC tuned tap value.

How is this different from:
	1. reset the dll
	2. call sdhci_execute_tuning
	3. reset the dll

> 
> Signed-off-by: Manish Narani <mnarani@xxxxxxxxxx>
> ---
>  .../devicetree/bindings/mmc/arasan,sdhci.txt       |   1 +
>  drivers/mmc/host/sdhci-of-arasan.c                 | 219 ++++++++++++++++++++-
>  2 files changed, 219 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/devicetree/bindings/mmc/arasan,sdhci.txt b/Documentation/devicetree/bindings/mmc/arasan,sdhci.txt
> index 60481bf..7d29751 100644
> --- a/Documentation/devicetree/bindings/mmc/arasan,sdhci.txt
> +++ b/Documentation/devicetree/bindings/mmc/arasan,sdhci.txt
> @@ -14,6 +14,7 @@ Required Properties:
>      - "arasan,sdhci-4.9a": generic Arasan SDHCI 4.9a PHY
>      - "arasan,sdhci-5.1": generic Arasan SDHCI 5.1 PHY
>      - "rockchip,rk3399-sdhci-5.1", "arasan,sdhci-5.1": rk3399 eMMC PHY
> +    - "xlnx,zynqmp-8.9a": Xilinx ZynqMP 8.9a PHY
>        For this device it is strongly suggested to include arasan,soc-ctl-syscon.
>    - reg: From mmc bindings: Register location and length.
>    - clocks: From clock bindings: Handles to clock inputs.
> diff --git a/drivers/mmc/host/sdhci-of-arasan.c b/drivers/mmc/host/sdhci-of-arasan.c
> index 0720ea7..7673db4 100644
> --- a/drivers/mmc/host/sdhci-of-arasan.c
> +++ b/drivers/mmc/host/sdhci-of-arasan.c
> @@ -24,15 +24,18 @@
>  #include <linux/module.h>
>  #include <linux/of_device.h>
>  #include <linux/phy/phy.h>
> +#include <linux/mmc/mmc.h>
>  #include <linux/regmap.h>
>  #include "sdhci-pltfm.h"
>  #include <linux/of.h>
> +#include <linux/firmware/xilinx/zynqmp/firmware.h>
> 
>  #define SDHCI_ARASAN_VENDOR_REGISTER   0x78
> 
>  #define VENDOR_ENHANCED_STROBE         BIT(0)
> 
>  #define PHY_CLK_TOO_SLOW_HZ            400000
> +#define MAX_TUNING_LOOP                        40
> 
>  /*
>   * On some SoCs the syscon area has a feature where the upper 16-bits of
> @@ -88,6 +91,7 @@ struct sdhci_arasan_data {
>         struct sdhci_host *host;
>         struct clk      *clk_ahb;
>         struct phy      *phy;
> +       u32             device_id;
>         bool            is_phy_on;
> 
>         struct clk_hw   sdcardclk_hw;
> @@ -157,6 +161,213 @@ static int sdhci_arasan_syscon_write(struct sdhci_host *host,
>         return ret;
>  }
> 
> +/**
> + * arasan_zynqmp_dll_reset - Issue the DLL reset.
> + * @deviceid:          Unique Id of device
> + */
> +void zynqmp_dll_reset(u8 deviceid)
> +{
> +       const struct zynqmp_eemi_ops *eemi_ops = get_eemi_ops();
> +
> +       if (!eemi_ops || !eemi_ops->ioctl)
> +               return;
> +
> +       /* Issue DLL Reset */
> +       if (deviceid == 0)
> +               eemi_ops->ioctl(NODE_SD_0, IOCTL_SD_DLL_RESET,
> +                               PM_DLL_RESET_PULSE, 0, NULL);
> +       else
> +               eemi_ops->ioctl(NODE_SD_1, IOCTL_SD_DLL_RESET,
> +                               PM_DLL_RESET_PULSE, 0, NULL);
> +}
> +
> +static void arasan_zynqmp_dll_reset(struct sdhci_host *host, u8 deviceid)
> +{
> +       u16 clk;
> +       unsigned long timeout;
> +
> +       clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
> +       clk &= ~(SDHCI_CLOCK_CARD_EN | SDHCI_CLOCK_INT_EN);
> +       sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL);
> +
> +       /* Issue DLL Reset */
> +       zynqmp_dll_reset(deviceid);
> +
> +       clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
> +       clk |= SDHCI_CLOCK_INT_EN;
> +       sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL);
> +
> +       /* Wait max 20 ms */
> +       timeout = 20;
> +       while (!((clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL))
> +                               & SDHCI_CLOCK_INT_STABLE)) {
> +               if (timeout == 0) {
> +                       dev_err(mmc_dev(host->mmc),
> +                               ": Internal clock never stabilised.\n");
> +                       return;
> +               }
> +               timeout--;
> +               mdelay(1);
> +       }
> +
> +       clk |= SDHCI_CLOCK_CARD_EN;
> +       sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL);
> +}
> +
> +static int arasan_zynqmp_execute_tuning(struct sdhci_host *host, u32 opcode)
> +{
> +       struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> +       struct sdhci_arasan_data *sdhci_arasan = sdhci_pltfm_priv(pltfm_host);
> +       struct mmc_host *mmc = host->mmc;
> +       u16 ctrl;
> +       int tuning_loop_counter = MAX_TUNING_LOOP;
> +       int err = 0;
> +       unsigned long flags;
> +       unsigned int tuning_count = 0;
> +
> +       spin_lock_irqsave(&host->lock, flags);
> +
> +       if (host->tuning_mode == SDHCI_TUNING_MODE_1)
> +               tuning_count = host->tuning_count;
> +
> +       ctrl = sdhci_readw(host, SDHCI_HOST_CONTROL2);
> +       ctrl |= SDHCI_CTRL_EXEC_TUNING;
> +       if (host->quirks2 & SDHCI_QUIRK2_TUNING_WORK_AROUND)
> +               ctrl |= SDHCI_CTRL_TUNED_CLK;
> +       sdhci_writew(host, ctrl, SDHCI_HOST_CONTROL2);
> +
> +       mdelay(1);
> +
> +       arasan_zynqmp_dll_reset(host, sdhci_arasan->device_id);
> +
> +       /*
> +        * As per the Host Controller spec v3.00, tuning command
> +        * generates Buffer Read Ready interrupt, so enable that.
> +        *
> +        * Note: The spec clearly says that when tuning sequence
> +        * is being performed, the controller does not generate
> +        * interrupts other than Buffer Read Ready interrupt. But
> +        * to make sure we don't hit a controller bug, we _only_
> +        * enable Buffer Read Ready interrupt here.
> +        */
> +       sdhci_writel(host, SDHCI_INT_DATA_AVAIL, SDHCI_INT_ENABLE);
> +       sdhci_writel(host, SDHCI_INT_DATA_AVAIL, SDHCI_SIGNAL_ENABLE);
> +
> +       /*
> +        * Issue CMD19 repeatedly till Execute Tuning is set to 0 or the number
> +        * of loops reaches 40 times or a timeout of 150ms occurs.
> +        */
> +       do {
> +               struct mmc_command cmd = {0};
> +               struct mmc_request mrq = {NULL};
> +
> +               cmd.opcode = opcode;
> +               cmd.arg = 0;
> +               cmd.flags = MMC_RSP_R1 | MMC_CMD_ADTC;
> +               cmd.retries = 0;
> +               cmd.data = NULL;
> +               cmd.mrq = &mrq;
> +               cmd.error = 0;
> +
> +               if (tuning_loop_counter-- == 0)
> +                       break;
> +
> +               mrq.cmd = &cmd;
> +
> +               /*
> +                * In response to CMD19, the card sends 64 bytes of tuning
> +                * block to the Host Controller. So we set the block size
> +                * to 64 here.
> +                */
> +               if (cmd.opcode == MMC_SEND_TUNING_BLOCK_HS200) {
> +                       if (mmc->ios.bus_width == MMC_BUS_WIDTH_8) {
> +                               sdhci_writew(host, SDHCI_MAKE_BLKSZ(7, 128),
> +                                            SDHCI_BLOCK_SIZE);
> +                       } else if (mmc->ios.bus_width == MMC_BUS_WIDTH_4) {
> +                               sdhci_writew(host, SDHCI_MAKE_BLKSZ(7, 64),
> +                                            SDHCI_BLOCK_SIZE);
> +                       }
> +               } else {
> +                       sdhci_writew(host, SDHCI_MAKE_BLKSZ(7, 64),
> +                                    SDHCI_BLOCK_SIZE);
> +               }
> +
> +               /*
> +                * The tuning block is sent by the card to the host controller.
> +                * So we set the TRNS_READ bit in the Transfer Mode register.
> +                * This also takes care of setting DMA Enable and Multi Block
> +                * Select in the same register to 0.
> +                */
> +               sdhci_writew(host, SDHCI_TRNS_READ, SDHCI_TRANSFER_MODE);
> +
> +               sdhci_send_command(host, &cmd);
> +
> +               host->cmd = NULL;
> +
> +               spin_unlock_irqrestore(&host->lock, flags);
> +               /* Wait for Buffer Read Ready interrupt */
> +               wait_event_interruptible_timeout(host->buf_ready_int,
> +                                       (host->tuning_done == 1),
> +                                       msecs_to_jiffies(50));
> +               spin_lock_irqsave(&host->lock, flags);
> +
> +               if (!host->tuning_done) {
> +                       dev_warn(mmc_dev(host->mmc),
> +                                ": Timeout for Buffer Read Ready interrupt, back to fixed sampling clock\n");
> +                       ctrl = sdhci_readw(host, SDHCI_HOST_CONTROL2);
> +                       ctrl &= ~SDHCI_CTRL_TUNED_CLK;
> +                       ctrl &= ~SDHCI_CTRL_EXEC_TUNING;
> +                       sdhci_writew(host, ctrl, SDHCI_HOST_CONTROL2);
> +
> +                       err = -EIO;
> +                       goto out;
> +               }
> +
> +               host->tuning_done = 0;
> +
> +               ctrl = sdhci_readw(host, SDHCI_HOST_CONTROL2);
> +
> +               /* eMMC spec does not require a delay between tuning cycles */
> +               if (opcode == MMC_SEND_TUNING_BLOCK)
> +                       mdelay(1);
> +       } while (ctrl & SDHCI_CTRL_EXEC_TUNING);
> +
> +       /*
> +        * The Host Driver has exhausted the maximum number of loops allowed,
> +        * so use fixed sampling frequency.
> +        */
> +       if (tuning_loop_counter < 0) {
> +               ctrl &= ~SDHCI_CTRL_TUNED_CLK;
> +               sdhci_writew(host, ctrl, SDHCI_HOST_CONTROL2);
> +       }
> +       if (!(ctrl & SDHCI_CTRL_TUNED_CLK)) {
> +               dev_warn(mmc_dev(host->mmc),
> +                        ": Tuning failed, back to fixed sampling clock\n");
> +               err = -EIO;
> +       } else {
> +               arasan_zynqmp_dll_reset(host, sdhci_arasan->device_id);
> +       }
> +
> +out:
> +       /*
> +        * In case tuning fails, host controllers which support
> +        * re-tuning can try tuning again at a later time, when the
> +        * re-tuning timer expires.  So for these controllers, we
> +        * return 0. Since there might be other controllers who do not
> +        * have this capability, we return error for them.
> +        */
> +       if (tuning_count)
> +               err = 0;
> +
> +       host->mmc->retune_period = err ? 0 : tuning_count;
> +
> +       sdhci_writel(host, host->ier, SDHCI_INT_ENABLE);
> +       sdhci_writel(host, host->ier, SDHCI_SIGNAL_ENABLE);
> +       spin_unlock_irqrestore(&host->lock, flags);
> +
> +       return err;
> +}
> +
>  static void sdhci_arasan_set_clock(struct sdhci_host *host, unsigned int clock)
>  {
>         struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> @@ -262,7 +473,7 @@ static int sdhci_arasan_voltage_switch(struct mmc_host *mmc,
>         return -EINVAL;
>  }
> 
> -static const struct sdhci_ops sdhci_arasan_ops = {
> +static struct sdhci_ops sdhci_arasan_ops = {
>         .set_clock = sdhci_arasan_set_clock,
>         .get_max_clock = sdhci_pltfm_clk_get_max_clock,
>         .get_timeout_clock = sdhci_pltfm_clk_get_max_clock,
> @@ -371,6 +582,7 @@ static const struct of_device_id sdhci_arasan_of_match[] = {
>         { .compatible = "arasan,sdhci-8.9a" },
>         { .compatible = "arasan,sdhci-5.1" },
>         { .compatible = "arasan,sdhci-4.9a" },
> +       { .compatible = "xlnx,zynqmp-8.9a" },
> 
>         { /* sentinel */ }
>  };
> @@ -642,6 +854,11 @@ static int sdhci_arasan_probe(struct platform_device *pdev)
>                 goto unreg_clk;
>         }
> 
> +       if (of_device_is_compatible(pdev->dev.of_node, "xlnx,zynqmp-8.9a")) {
> +               sdhci_arasan_ops.platform_execute_tuning =
> +                       arasan_zynqmp_execute_tuning;
> +       }
> +
>         sdhci_arasan->phy = ERR_PTR(-ENODEV);
>         if (of_device_is_compatible(pdev->dev.of_node,
>                                     "arasan,sdhci-5.1")) {
> --
> 2.7.4
> 
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