Re: [PATCH] mmc: sdhci-xenon: add gpio hard reset support

[Jisheng Zhang <jszhang@marvell.com>]

On Mon, 14 Aug 2017 15:19:16 -0700 Zhoujie Wu wrote:

> On some platforms, like armada3700,  SD card need to
> do hard reset by gpio toggling to make it work properly
> after warm reset the board.
> Add gpio hard reset feature for this purpose.
> 
> Signed-off-by: Zhoujie Wu <zjwu@marvell.com>
> ---
>  drivers/mmc/host/sdhci-xenon.c | 49 +++++++++++++++++++++++++++++++++++++++---
>  drivers/mmc/host/sdhci-xenon.h |  4 ++++
>  2 files changed, 50 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/mmc/host/sdhci-xenon.c b/drivers/mmc/host/sdhci-xenon.c
> index edd4d915..54a7057 100644
> --- a/drivers/mmc/host/sdhci-xenon.c
> +++ b/drivers/mmc/host/sdhci-xenon.c
> @@ -18,6 +18,8 @@
>  #include <linux/ktime.h>
>  #include <linux/module.h>
>  #include <linux/of.h>
> +#include <linux/of_gpio.h>
> +
>  
>  #include "sdhci-pltfm.h"
>  #include "sdhci-xenon.h"
> @@ -210,12 +212,25 @@ static void xenon_set_uhs_signaling(struct sdhci_host *host,
>  	sdhci_writew(host, ctrl_2, SDHCI_HOST_CONTROL2);
>  }
>  
> +static void xenon_hw_reset(struct sdhci_host *host)
> +{
> +	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> +	struct xenon_priv *priv = sdhci_pltfm_priv(pltfm_host);
> +
> +	if (priv->reset_gpio) {
> +		gpiod_set_value_cansleep(priv->reset_gpio, 0);
> +		msleep(30);
> +		gpiod_set_value_cansleep(priv->reset_gpio, 1);

Does setting the pin to low means assert reset in your HW? You'd better
invert the logic in the DT.

As for reset gpio, logic "1" means assert the reset, logic "0" means
de-assert the reset.

> +	}
> +}
> +
>  static const struct sdhci_ops sdhci_xenon_ops = {
>  	.set_clock		= sdhci_set_clock,
>  	.set_bus_width		= sdhci_set_bus_width,
>  	.reset			= xenon_reset,
>  	.set_uhs_signaling	= xenon_set_uhs_signaling,
>  	.get_max_clock		= sdhci_pltfm_clk_get_max_clock,
> +	.hw_reset		= xenon_hw_reset,
>  };
>  
>  static const struct sdhci_pltfm_data sdhci_xenon_pdata = {
> @@ -373,10 +388,15 @@ static int xenon_probe_dt(struct platform_device *pdev)
>  	struct device_node *np = pdev->dev.of_node;
>  	struct sdhci_host *host = platform_get_drvdata(pdev);
>  	struct mmc_host *mmc = host->mmc;
> +	struct device *dev = mmc_dev(mmc);
>  	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
>  	struct xenon_priv *priv = sdhci_pltfm_priv(pltfm_host);
>  	u32 sdhc_id, nr_sdhc;
>  	u32 tuning_count;
> +	int reset_gpio, ret;
> +	enum of_gpio_flags flags;
> +	char *reset_name;
> +	unsigned long gpio_flags;
>  
>  	/* Disable HS200 on Armada AP806 */
>  	if (of_device_is_compatible(np, "marvell,armada-ap806-sdhci"))
> @@ -387,7 +407,7 @@ static int xenon_probe_dt(struct platform_device *pdev)
>  		nr_sdhc = sdhci_readl(host, XENON_SYS_CFG_INFO);
>  		nr_sdhc &= XENON_NR_SUPPORTED_SLOT_MASK;
>  		if (unlikely(sdhc_id > nr_sdhc)) {
> -			dev_err(mmc_dev(mmc), "SDHC Index %d exceeds Number of SDHCs %d\n",
> +			dev_err(dev, "SDHC Index %d exceeds Number of SDHCs %d\n",

is this related with "add gpio hard reset support"? You'd better put this
change into a separate patch.

>  				sdhc_id, nr_sdhc);
>  			return -EINVAL;
>  		}
> @@ -398,14 +418,37 @@ static int xenon_probe_dt(struct platform_device *pdev)
>  	if (!of_property_read_u32(np, "marvell,xenon-tun-count",
>  				  &tuning_count)) {
>  		if (unlikely(tuning_count >= XENON_TMR_RETUN_NO_PRESENT)) {
> -			dev_err(mmc_dev(mmc), "Wrong Re-tuning Count. Set default value %d\n",
> +			dev_err(dev, "Wrong Re-tuning Count. Set default value %d\n",

ditto 

>  				XENON_DEF_TUNING_COUNT);
>  			tuning_count = XENON_DEF_TUNING_COUNT;
>  		}
>  	}
>  	priv->tuning_count = tuning_count;
>  
> -	return xenon_phy_parse_dt(np, host);
> +	ret = xenon_phy_parse_dt(np, host);
> +
> +	reset_gpio = of_get_named_gpio_flags(np, "reset-gpios", 0, &flags);
> +	if (gpio_is_valid(reset_gpio)) {
> +		if (flags & OF_GPIO_ACTIVE_LOW)
> +			gpio_flags = GPIOF_ACTIVE_LOW | GPIOF_OUT_INIT_HIGH;
> +		else
> +			gpio_flags = GPIOF_OUT_INIT_LOW;
> +
> +		reset_name = devm_kasprintf(dev, GFP_KERNEL, "%s-reset",
> +						dev_name(dev));
> +		if (!reset_name)
> +			return -ENOMEM;
> +		ret = devm_gpio_request_one(dev, reset_gpio, gpio_flags,
> +					    reset_name);
> +		if (ret) {
> +			dev_err(dev, "Failed to request reset gpio\n");
> +			return ret;
> +		}
> +
> +		priv->reset_gpio = gpio_to_desc(reset_gpio);
> +	}

is devm_gpiod_get_optional() better?

> +
> +	return ret;
>  }
>  
>  static int xenon_sdhc_prepare(struct sdhci_host *host)
> diff --git a/drivers/mmc/host/sdhci-xenon.h b/drivers/mmc/host/sdhci-xenon.h
> index 73debb4..cffb0fe 100644
> --- a/drivers/mmc/host/sdhci-xenon.h
> +++ b/drivers/mmc/host/sdhci-xenon.h
> @@ -90,6 +90,10 @@ struct xenon_priv {
>  	 */
>  	void		*phy_params;
>  	struct xenon_emmc_phy_regs *emmc_phy_regs;
> +	/*
> +	 * gpio pin for hw reset
> +	 */
> +	struct gpio_desc *reset_gpio;
>  };
>  
>  int xenon_phy_adj(struct sdhci_host *host, struct mmc_ios *ios);