linux-kernel - Re: [RFC 3/3] mmc: sdhci-pxav3: Add ->voltage

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Date:	Wed, 2 Sep 2015 21:51:49 +0800
From:	Shawn Lin <shawn.lin@...k-chips.com>
To:	Vaibhav Hiremath <vaibhav.hiremath@...aro.org>,
	linux-mmc@...r.kernel.org
Cc:	shawn.lin@...k-chips.com, ulf.hansson@...aro.org,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [RFC 3/3] mmc: sdhci-pxav3: Add ->voltage_switch callback support

On 2015/9/2 3:32, Vaibhav Hiremath wrote:
> In case PXA1928 family of devices, there is device/controller specific
> configuration to control voltage/power on the IO pins.
>
> This patch implements and enables the sdhci_ops->voltage_switch()
> callback api.
> Note that IO pad register addresses are fetched as a memory resource.
>
> For example, in case of PXA1928 and family of devices, the DT property
> would look something like,
>
> sdh1: sdh@...80000 {
> 	compatible = "mrvl,pxav3-mmc";
> 	reg-names = "sdhci", "io-pwr", "io-pwr-lock-unlock";
> 	reg = <0xd4280000 0x120>,
> 		<0xd401e81c 4>,
> 		<0xd4015068 8>;
> 	...
> };
>
> Signed-off-by: Vaibhav Hiremath <vaibhav.hiremath@...aro.org>
> ---
>   drivers/mmc/host/sdhci-pxav3.c | 59 ++++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 59 insertions(+)
>
> diff --git a/drivers/mmc/host/sdhci-pxav3.c b/drivers/mmc/host/sdhci-pxav3.c
> index 5d26fe0..cebb2f9 100644
> --- a/drivers/mmc/host/sdhci-pxav3.c
> +++ b/drivers/mmc/host/sdhci-pxav3.c
> @@ -63,11 +63,18 @@
>   #define IO_PWR_AKEY_ASSAR		0xeb10
>   #define IO_PWR_MMC1_PAD_1V8		BIT(2)
>
> +/* IO Power control */
> +#define IO_PWR_AKEY_ASFAR		0xbaba
> +#define IO_PWR_AKEY_ASSAR		0xeb10
> +#define IO_PWR_MMC1_PAD_1V8		BIT(2)
> +
>   struct sdhci_pxa {
>   	struct clk *clk_core;
>   	struct clk *clk_io;
>   	u8	power_mode;
>   	void __iomem *sdio3_conf_reg;
> +	void __iomem *io_pwr_reg;
> +	void __iomem *io_pwr_lock_reg;
>   };
>
>   /*
> @@ -307,6 +314,38 @@ static void pxav3_set_uhs_signaling(struct sdhci_host *host, unsigned int uhs)
>   		__func__, uhs, ctrl_2);
>   }
>
> +static void pxav3_voltage_switch(struct sdhci_host *host,
> +						u8 signal_voltage)
> +{
> +	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> +	struct sdhci_pxa *pxa = pltfm_host->priv;
> +	unsigned int val;
> +
> +	if (!pxa->io_pwr_reg || !pxa->io_pwr_lock_reg)
> +		return;
> +
> +	/* Lock register is 64 bit: First & Second access register */
> +	writel(IO_PWR_AKEY_ASFAR, pxa->io_pwr_lock_reg);
> +	writel(IO_PWR_AKEY_ASSAR, pxa->io_pwr_lock_reg + 4);
> +	val = readl(pxa->io_pwr_reg);
> +
> +	switch (signal_voltage) {
> +	case MMC_SIGNAL_VOLTAGE_180:
> +	case MMC_SIGNAL_VOLTAGE_120:
> +		val |= IO_PWR_MMC1_PAD_1V8;
> +		break;
> +	case MMC_SIGNAL_VOLTAGE_330:
> +	default:
> +		val &= ~IO_PWR_MMC1_PAD_1V8;
> +		break;
> +	}
> +
> +	writel(IO_PWR_AKEY_ASFAR, pxa->io_pwr_lock_reg);
> +	writel(IO_PWR_AKEY_ASSAR, pxa->io_pwr_lock_reg + 4);
> +
> +	writel(val, pxa->io_pwr_reg);
> +}
> +
>   static const struct sdhci_ops pxav3_sdhci_ops = {
>   	.set_clock			= sdhci_set_clock,
>   	.platform_send_init_74_clocks	= pxav3_gen_init_74_clocks,
> @@ -314,6 +353,7 @@ static const struct sdhci_ops pxav3_sdhci_ops = {
>   	.set_bus_width			= sdhci_set_bus_width,
>   	.reset				= pxav3_reset,
>   	.set_uhs_signaling		= pxav3_set_uhs_signaling,
> +	.voltage_switch			= pxav3_voltage_switch,
>   };
>
>   static struct sdhci_pltfm_data sdhci_pxav3_pdata = {
> @@ -368,6 +408,7 @@ static int sdhci_pxav3_probe(struct platform_device *pdev)
>   	struct sdhci_host *host = NULL;
>   	struct sdhci_pxa *pxa = NULL;
>   	const struct of_device_id *match;
> +	struct resource *res;
>   	int ret;
>
>   	pxa = devm_kzalloc(&pdev->dev, sizeof(struct sdhci_pxa), GFP_KERNEL);
> @@ -408,6 +449,24 @@ static int sdhci_pxav3_probe(struct platform_device *pdev)
>   			goto err_mbus_win;
>   	}
>
> +	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "io-pwr-conf");
> +	if (res) {
> +		pxa->io_pwr_reg = devm_ioremap_resource(&pdev->dev, res);
> +		if (IS_ERR(pxa->io_pwr_reg)) {
> +			ret = PTR_ERR(pxa->io_pwr_reg);
> +			goto err_mbus_win;
> +		}
> +	}

Hi Vaibhav,

Why not get it from syscon and use regmap API to deal with it.
IMO, that's okay, you can find examples from
drivers/mmc/host/dw_mmc-k3.c: dw_mci_hi6220_switch_voltage


> +
> +	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "io-pwr-lock-unlock");
> +	if (res) {
> +		pxa->io_pwr_lock_reg = devm_ioremap_resource(&pdev->dev, res);
> +		if (IS_ERR(pxa->io_pwr_lock_reg)) {
> +			ret = PTR_ERR(pxa->io_pwr_lock_reg);
> +			goto err_mbus_win;
> +		}
> +	}
> +
>   	match = of_match_device(of_match_ptr(sdhci_pxav3_of_match), &pdev->dev);
>   	if (match) {
>   		ret = mmc_of_parse(host->mmc);
>


-- 
Best Regards
Shawn Lin

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