Re: [PATCH v2 2/5] mmc: sdhci-pxav3: enable usage of DAT3 pin as HW card detect

[Jisheng Zhang]

On Fri, 9 Oct 2015 03:03:52 +0200
Marcin Wojtas <mw@xxxxxxxxxxxx> wrote:

> Marvell Armada 38x SDHCI controller enable using DAT3 pin as a hardware
> card detection. According to the SD sdandard this signal can be used for
> this purpose combined with a pull-up resistor, implying inverted (active
> low) polarization of a card detect. MMC standard does not support this
> feature and does not operate with such connectivity of DAT3.
> 
> When using DAT3-based detection Armada 38x SDIO IP expects its internal
> clock to be always on, which had to be ensured twofold:

What happen if runtime suspend disables its core clk and axi clk? I guess
dat3-based detection isn't compatible with runtime pm. If so, do we also
need to disable runtime pm in probe function?

> - Each time controller is reset by updating appropriate registers. On the
>   occasion of adding new register @0x104, register @0x100 name is modified
>   in order to the be aligned with Armada 38x documentation.
> - Leaving the clock enabled despite power-down. For this purpose a new
>   quirk had to be added to SDHCI subsystem - SDHCI_QUIRK2_KEEP_INT_CLK_ON.

As seen from other mails, Ulf calls for no more quirks...

Thanks,
Jisheng

> 
> In addition to the changes above this commit adds a new property to Armada
> 38x SDHCI node ('dat3-cd') with an according binding documentation update.
> 
> Signed-off-by: Marcin Wojtas <mw@xxxxxxxxxxxx>
> ---
>  .../devicetree/bindings/mmc/sdhci-pxa.txt          |  5 +++
>  drivers/mmc/host/sdhci-pxav3.c                     | 38 ++++++++++++++++++++--
>  drivers/mmc/host/sdhci.c                           |  5 ++-
>  drivers/mmc/host/sdhci.h                           |  3 ++
>  4 files changed, 47 insertions(+), 4 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/mmc/sdhci-pxa.txt b/Documentation/devicetree/bindings/mmc/sdhci-pxa.txt
> index 3d1b449..ffd6b14 100644
> --- a/Documentation/devicetree/bindings/mmc/sdhci-pxa.txt
> +++ b/Documentation/devicetree/bindings/mmc/sdhci-pxa.txt
> @@ -23,6 +23,11 @@ Required properties:
>  
>  Optional properties:
>  - mrvl,clk-delay-cycles: Specify a number of cycles to delay for tuning.
> +- dat3-cd: use DAT3 pin as hardware card detect - option available for
> +  "marvell,armada-380-sdhci" only. The detection is supposed to work with
> +  active high polarity, which implies usage of "cd-inverted" property.
> +  Note that according to the specifications DAT3-based card detection can be
> +  used with SD cards only. MMC standard doesn't support this feature.
>  
>  Example:
>  
> diff --git a/drivers/mmc/host/sdhci-pxav3.c b/drivers/mmc/host/sdhci-pxav3.c
> index 76b9a70..352c5eb 100644
> --- a/drivers/mmc/host/sdhci-pxav3.c
> +++ b/drivers/mmc/host/sdhci-pxav3.c
> @@ -46,10 +46,14 @@
>  #define SDCLK_DELAY_SHIFT	9
>  #define SDCLK_DELAY_MASK	0x1f
>  
> -#define SD_CFG_FIFO_PARAM       0x100
> +#define SD_EXTRA_PARAM_REG	0x100
>  #define SDCFG_GEN_PAD_CLK_ON	(1<<6)
>  #define SDCFG_GEN_PAD_CLK_CNT_MASK	0xFF
>  #define SDCFG_GEN_PAD_CLK_CNT_SHIFT	24
> +#define SD_FIFO_PARAM_REG	0x104
> +#define SD_USE_DAT3		BIT(7)
> +#define SD_OVRRD_CLK_OEN	BIT(11)
> +#define SD_FORCE_CLK_ON		BIT(12)
>  
>  #define SD_SPI_MODE          0x108
>  #define SD_CE_ATA_1          0x10C
> @@ -163,6 +167,15 @@ static int armada_38x_quirks(struct platform_device *pdev,
>  	}
>  	host->caps1 &= ~(SDHCI_SUPPORT_SDR104 | SDHCI_USE_SDR50_TUNING);
>  
> +	/*
> +	 * The interface clock enable is also used as control
> +	 * for the A38x SDIO IP, so it can't be powered down
> +	 * when using HW-based card detection.
> +	 */
> +	if (of_property_read_bool(np, "dat3-cd") &&
> +	    !of_property_read_bool(np, "broken-cd"))
> +		host->quirks2 |= SDHCI_QUIRK2_KEEP_INT_CLK_ON;
> +
>  	return 0;
>  }
>  
> @@ -170,6 +183,8 @@ static void pxav3_reset(struct sdhci_host *host, u8 mask)
>  {
>  	struct platform_device *pdev = to_platform_device(mmc_dev(host->mmc));
>  	struct sdhci_pxa_platdata *pdata = pdev->dev.platform_data;
> +	struct device_node *np = pdev->dev.of_node;
> +	u32 reg_val;
>  
>  	sdhci_reset(host, mask);
>  
> @@ -187,6 +202,22 @@ static void pxav3_reset(struct sdhci_host *host, u8 mask)
>  			tmp |= SDCLK_SEL;
>  			writew(tmp, host->ioaddr + SD_CLOCK_BURST_SIZE_SETUP);
>  		}
> +
> +		if (of_device_is_compatible(np, "marvell,armada-380-sdhci") &&
> +		    host->quirks2 & SDHCI_QUIRK2_KEEP_INT_CLK_ON) {
> +			reg_val = sdhci_readl(host, SD_FIFO_PARAM_REG);
> +			reg_val |= SD_USE_DAT3 | SD_OVRRD_CLK_OEN |
> +				   SD_FORCE_CLK_ON;
> +			sdhci_writel(host, reg_val, SD_FIFO_PARAM_REG);
> +
> +			/*
> +			 * For HW detection based on DAT3 pin keep internal
> +			 * clk switched on after controller reset.
> +			 */
> +			reg_val = sdhci_readl(host, SDHCI_CLOCK_CONTROL);
> +			reg_val |= SDHCI_CLOCK_INT_EN;
> +			sdhci_writel(host, reg_val, SDHCI_CLOCK_CONTROL);
> +		}
>  	}
>  }
>  
> @@ -214,9 +245,9 @@ static void pxav3_gen_init_74_clocks(struct sdhci_host *host, u8 power_mode)
>  		writew(tmp, host->ioaddr + SD_CE_ATA_2);
>  
>  		/* start sending the 74 clocks */
> -		tmp = readw(host->ioaddr + SD_CFG_FIFO_PARAM);
> +		tmp = readw(host->ioaddr + SD_EXTRA_PARAM_REG);
>  		tmp |= SDCFG_GEN_PAD_CLK_ON;
> -		writew(tmp, host->ioaddr + SD_CFG_FIFO_PARAM);
> +		writew(tmp, host->ioaddr + SD_EXTRA_PARAM_REG);
>  
>  		/* slowest speed is about 100KHz or 10usec per clock */
>  		udelay(740);
> @@ -410,6 +441,7 @@ static int sdhci_pxav3_probe(struct platform_device *pdev)
>  		sdhci_get_of_property(pdev);
>  		pdata = pxav3_get_mmc_pdata(dev);
>  		pdev->dev.platform_data = pdata;
> +
>  	} else if (pdata) {
>  		/* on-chip device */
>  		if (pdata->flags & PXA_FLAG_CARD_PERMANENT)
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index 64b7fdb..cfed695 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -1159,7 +1159,10 @@ void sdhci_set_clock(struct sdhci_host *host, unsigned int clock)
>  
>  	host->mmc->actual_clock = 0;
>  
> -	sdhci_writew(host, 0, SDHCI_CLOCK_CONTROL);
> +	/* Some controllers need to keep internal clk always enabled */
> +	if (host->quirks2 & SDHCI_QUIRK2_KEEP_INT_CLK_ON)
> +		clk = SDHCI_CLOCK_INT_EN;
> +	sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL);
>  
>  	if (clock == 0)
>  		return;
> diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
> index 7c02ff4..c751b78 100644
> --- a/drivers/mmc/host/sdhci.h
> +++ b/drivers/mmc/host/sdhci.h
> @@ -412,6 +412,9 @@ struct sdhci_host {
>  #define SDHCI_QUIRK2_ACMD23_BROKEN			(1<<14)
>  /* Broken Clock divider zero in controller */
>  #define SDHCI_QUIRK2_CLOCK_DIV_ZERO_BROKEN		(1<<15)
> +/* Do not disable internal clk on power-off */
> +#define SDHCI_QUIRK2_KEEP_INT_CLK_ON			(1<<16)
> +
>  
>  	int irq;		/* Device IRQ */
>  	void __iomem *ioaddr;	/* Mapped address */

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