[PATCH 3/8] sdhci: sdhci-esdhc-imx: support real clock on and off for imx6q

[Shawn Guo]

On Wed, Sep 04, 2013 at 08:54:12PM +0800, Dong Aisheng wrote:
> The signal voltage switch follow requires to shutdown and output

s/follow/flow

> clock in a specific sequence according to standard host controller
> v3.0 spec. In that timing, the card must really receive clock or not.
> 
> However, for i.MX6Q, the uSDHC will not output clock even the clock
> is enabled until there is command or data in transfer on the bus,
> which will then cause singal voltage switch always to fail.
> 
> For i.MX6Q, we clear ESDHC_VENDOR_SPEC_FRC_SDCLK_ON bit to let
> controller to gate off clock automatically and set that bit
> to force clock output if clock is on.
> 
> This is required by SD3.0 support.
> 
> Signed-off-by: Dong Aisheng <b29396 at freescale.com>
> ---
>  drivers/mmc/host/sdhci-esdhc-imx.c |    3 ---
>  drivers/mmc/host/sdhci-esdhc.h     |   29 ++++++++++++++++++++++++++---
>  2 files changed, 26 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/mmc/host/sdhci-esdhc-imx.c b/drivers/mmc/host/sdhci-esdhc-imx.c
> index 1dd5ba8..3118a82 100644
> --- a/drivers/mmc/host/sdhci-esdhc-imx.c
> +++ b/drivers/mmc/host/sdhci-esdhc-imx.c
> @@ -31,9 +31,6 @@
>  #include "sdhci-esdhc.h"
>  
>  #define	ESDHC_CTRL_D3CD			0x08
> -/* VENDOR SPEC register */
> -#define ESDHC_VENDOR_SPEC		0xc0
> -#define  ESDHC_VENDOR_SPEC_SDIO_QUIRK	(1 << 1)
>  #define ESDHC_WTMK_LVL			0x44
>  #define ESDHC_MIX_CTRL			0x48
>  #define  ESDHC_MIX_CTRL_AC23EN		(1 << 7)
> diff --git a/drivers/mmc/host/sdhci-esdhc.h b/drivers/mmc/host/sdhci-esdhc.h
> index a2a0642..86fcd5b 100644
> --- a/drivers/mmc/host/sdhci-esdhc.h
> +++ b/drivers/mmc/host/sdhci-esdhc.h
> @@ -14,6 +14,8 @@
>  #ifndef _DRIVERS_MMC_SDHCI_ESDHC_H
>  #define _DRIVERS_MMC_SDHCI_ESDHC_H
>  
> +#include <linux/of.h>
> +
>  /*
>   * Ops and quirks for the Freescale eSDHC controller.
>   */
> @@ -33,6 +35,12 @@
>  #define ESDHC_CLOCK_HCKEN	0x00000002
>  #define ESDHC_CLOCK_IPGEN	0x00000001
>  
> +/* VENDOR SPEC register */
> +#define ESDHC_VENDOR_SPEC		0xc0
> +#define  ESDHC_VENDOR_SPEC_SDIO_QUIRK	(1 << 1)
> +#define  ESDHC_VENDOR_SPEC_VSELECT	(1 << 1)

It would be better to introduce the macro only when it's actually being
used.

> +#define  ESDHC_VENDOR_SPEC_FRC_SDCLK_ON (1 << 8)
> +
>  /* pltfm-specific */
>  #define ESDHC_HOST_CONTROL_LE	0x20
>  
> @@ -52,12 +60,20 @@
>  static inline void esdhc_set_clock(struct sdhci_host *host, unsigned int clock,
>  				   unsigned int host_clock)
>  {
> +	struct device *dev;
>  	int pre_div = 2;
>  	int div = 1;
> -	u32 temp;
> -
> -	if (clock == 0)
> +	u32 temp, val;
> +
> +	dev = mmc_dev(host->mmc);
> +	if (clock == 0) {
> +		if (of_device_is_compatible(dev->of_node, "fsl,imx6q-usdhc")) {
> +			val = readl(host->ioaddr + ESDHC_VENDOR_SPEC);
> +			writel(val & ~ESDHC_VENDOR_SPEC_FRC_SDCLK_ON,
> +				host->ioaddr + ESDHC_VENDOR_SPEC);
> +		}

To me, maintaining this esdhc_set_clock() for both imx and powerpc makes
no sense now.  I think it might be the time to have different versions
of the function for imx and powerpc, just in esdhc_pltfm_set_clock() and
esdhc_of_set_clock() respectively.

Shawn

>  		goto out;
> +	}
>  
>  	temp = sdhci_readl(host, ESDHC_SYSTEM_CONTROL);
>  	temp &= ~(ESDHC_CLOCK_IPGEN | ESDHC_CLOCK_HCKEN | ESDHC_CLOCK_PEREN
> @@ -81,6 +97,13 @@ static inline void esdhc_set_clock(struct sdhci_host *host, unsigned int clock,
>  		| (div << ESDHC_DIVIDER_SHIFT)
>  		| (pre_div << ESDHC_PREDIV_SHIFT));
>  	sdhci_writel(host, temp, ESDHC_SYSTEM_CONTROL);
> +
> +	if (of_device_is_compatible(dev->of_node, "fsl,imx6q-usdhc")) {
> +		val = readl(host->ioaddr + ESDHC_VENDOR_SPEC);
> +		writel(val | ESDHC_VENDOR_SPEC_FRC_SDCLK_ON,
> +			host->ioaddr + ESDHC_VENDOR_SPEC);
> +	}
> +
>  	mdelay(1);
>  out:
>  	host->clock = clock;
> -- 
> 1.7.1
> 
>