Re: [PATCH v1 4/5] mmc: sdhci-msm: Add ops to do sdhc register write

[Adrian Hunter]

On 30/08/17 15:51, Vijay Viswanath wrote:
> Register writes which change voltage of IO lines or turn the IO bus
> on/off require controller to be ready before progressing further. When
> the controller is ready, it will generate a power irq which needs to be
> handled. The thread which initiated the register write should wait for
> power irq to complete. This will be done through the new sdhc msm write
> APIs which will check whether the particular write can trigger a power
> irq and wait for it with a timeout if it is expected.
> The SDHC core power control IRQ gets triggered when -
> * There is a state change in power control bit (bit 0)
>   of SDHCI_POWER_CONTROL register.
> * There is a state change in 1.8V enable bit (bit 3) of
>   SDHCI_HOST_CONTROL2 register.
> * Bit 1 of SDHCI_SOFTWARE_RESET is set.
> 
> Signed-off-by: Vijay Viswanath <vviswana@xxxxxxxxxxxxxx>

Acked-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>

> ---
>  drivers/mmc/host/sdhci-msm.c | 69 +++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 68 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c
> index e3e385e..a4a78b5 100644
> --- a/drivers/mmc/host/sdhci-msm.c
> +++ b/drivers/mmc/host/sdhci-msm.c
> @@ -1070,7 +1070,6 @@ static void sdhci_msm_check_power_status(struct sdhci_host *host, u32 req_type)
>  			__WARN_printf("%s: pwr_irq for req: (%d) timed out\n",
>  					mmc_hostname(host->mmc), req_type);
>  	}
> -	msm_host->pwr_irq_flag = 0;
>  	pr_debug("%s: %s: request %d done\n", mmc_hostname(host->mmc),
>  			__func__, req_type);
>  }
> @@ -1250,6 +1249,70 @@ static void sdhci_msm_set_clock(struct sdhci_host *host, unsigned int clock)
>  	__sdhci_msm_set_clock(host, clock);
>  }
>  
> +#ifdef CONFIG_MMC_SDHCI_IO_ACCESSORS
> +/*
> + * Platform specific register write functions. This is so that, if any
> + * register write needs to be followed up by platform specific actions,
> + * they can be added here. These functions can go to sleep when writes
> + * to certain registers are done.
> + * These functions are relying on sdhci_set_ios not using spinlock.
> + */
> +static int __sdhci_msm_check_write(struct sdhci_host *host, u16 val, int reg)
> +{
> +	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> +	struct sdhci_msm_host *msm_host = sdhci_pltfm_priv(pltfm_host);
> +	u32 req_type = 0;
> +
> +	switch (reg) {
> +	case SDHCI_HOST_CONTROL2:
> +		req_type = (val & SDHCI_CTRL_VDD_180) ? REQ_IO_LOW :
> +			REQ_IO_HIGH;
> +		break;
> +	case SDHCI_SOFTWARE_RESET:
> +		if (host->pwr && (val & SDHCI_RESET_ALL))
> +			req_type = REQ_BUS_OFF;
> +		break;
> +	case SDHCI_POWER_CONTROL:
> +		req_type = !val ? REQ_BUS_OFF : REQ_BUS_ON;
> +		break;
> +	}
> +
> +	if (req_type) {
> +		msm_host->pwr_irq_flag = 0;
> +		/*
> +		 * Since this register write may trigger a power irq, ensure
> +		 * all previous register writes are complete by this point.
> +		 */
> +		mb();
> +	}
> +	return req_type;
> +}
> +
> +/* This function may sleep*/
> +static void sdhci_msm_writew(struct sdhci_host *host, u16 val, int reg)
> +{
> +	u32 req_type = 0;
> +
> +	req_type = __sdhci_msm_check_write(host, val, reg);
> +	writew_relaxed(val, host->ioaddr + reg);
> +
> +	if (req_type)
> +		sdhci_msm_check_power_status(host, req_type);
> +}
> +
> +/* This function may sleep*/
> +static void sdhci_msm_writeb(struct sdhci_host *host, u8 val, int reg)
> +{
> +	u32 req_type = 0;
> +
> +	req_type = __sdhci_msm_check_write(host, val, reg);
> +
> +	writeb_relaxed(val, host->ioaddr + reg);
> +
> +	if (req_type)
> +		sdhci_msm_check_power_status(host, req_type);
> +}
> +#endif
>  static const struct of_device_id sdhci_msm_dt_match[] = {
>  	{ .compatible = "qcom,sdhci-msm-v4" },
>  	{},
> @@ -1264,6 +1327,10 @@ static void sdhci_msm_set_clock(struct sdhci_host *host, unsigned int clock)
>  	.get_max_clock = sdhci_msm_get_max_clock,
>  	.set_bus_width = sdhci_set_bus_width,
>  	.set_uhs_signaling = sdhci_msm_set_uhs_signaling,
> +#ifdef CONFIG_MMC_SDHCI_IO_ACCESSORS
> +	.write_w = sdhci_msm_writew,
> +	.write_b = sdhci_msm_writeb,
> +#endif
>  };
>  
>  static const struct sdhci_pltfm_data sdhci_msm_pdata = {
>