mmc: sdhci-pxav2: add optional pinctrl for SDIO IRQ workaround

The PXA168 errata recommends that the CMD signal should be detached from
the SD bus while performing the dummy CMD0 to restart the clock.
Implement this using pinctrl states.
Signed-off-by: Doug Brown <doug@schmorgal.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Link: https://lore.kernel.org/r/20230116194401.20372-8-doug@schmorgal.comSigned-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/sdhci-pxav2.c

@@ -22,6 +22,7 @@
 #include <linux/of_device.h>
 #include <linux/mmc/sdio.h>
 #include <linux/mmc/mmc.h>
+#include <linux/pinctrl/consumer.h>
 
 #include "sdhci.h"
 #include "sdhci-pltfm.h"
@@ -45,6 +46,9 @@
 
 struct sdhci_pxav2_host {
 	struct mmc_request *sdio_mrq;
+	struct pinctrl *pinctrl;
+	struct pinctrl_state *pins_default;
+	struct pinctrl_state *pins_cmd_gpio;
 };
 
 static void pxav2_reset(struct sdhci_host *host, u8 mask)
@@ -104,6 +108,11 @@ static u32 pxav1_irq(struct sdhci_host *host, u32 intmask)
 		/* The dummy CMD0 for the SDIO workaround just completed */
 		sdhci_writel(host, intmask & SDHCI_INT_CMD_MASK, SDHCI_INT_STATUS);
 		intmask &= ~SDHCI_INT_CMD_MASK;
+
+		/* Restore MMC function to CMD pin */
+		if (pxav2_host->pinctrl && pxav2_host->pins_default)
+			pinctrl_select_state(pxav2_host->pinctrl, pxav2_host->pins_default);
+
 		sdio_mrq = pxav2_host->sdio_mrq;
 		pxav2_host->sdio_mrq = NULL;
 		mmc_request_done(host->mmc, sdio_mrq);
@@ -129,6 +138,11 @@ static void pxav1_request_done(struct sdhci_host *host, struct mmc_request *mrq)
 		/* Clock is now stopped, so restart it by sending a dummy CMD0 */
 		pxav2_host = sdhci_pltfm_priv(sdhci_priv(host));
 		pxav2_host->sdio_mrq = mrq;
+
+		/* Set CMD as high output rather than MMC function while we do CMD0 */
+		if (pxav2_host->pinctrl && pxav2_host->pins_cmd_gpio)
+			pinctrl_select_state(pxav2_host->pinctrl, pxav2_host->pins_cmd_gpio);
+
 		sdhci_writel(host, 0, SDHCI_ARGUMENT);
 		sdhci_writew(host, 0, SDHCI_TRANSFER_MODE);
 		sdhci_writew(host, SDHCI_MAKE_CMD(MMC_GO_IDLE_STATE, SDHCI_CMD_RESP_NONE),
@@ -240,6 +254,7 @@ static int sdhci_pxav2_probe(struct platform_device *pdev)
 {
 	struct sdhci_pltfm_host *pltfm_host;
 	struct sdhci_pxa_platdata *pdata = pdev->dev.platform_data;
+	struct sdhci_pxav2_host *pxav2_host;
 	struct device *dev = &pdev->dev;
 	struct sdhci_host *host = NULL;
 	const struct sdhci_pxa_variant *variant;
@@ -247,11 +262,12 @@ static int sdhci_pxav2_probe(struct platform_device *pdev)
 	int ret;
 	struct clk *clk, *clk_core;
 
-	host = sdhci_pltfm_init(pdev, NULL, sizeof(struct sdhci_pxav2_host));
+	host = sdhci_pltfm_init(pdev, NULL, sizeof(*pxav2_host));
 	if (IS_ERR(host))
 		return PTR_ERR(host);
 
 	pltfm_host = sdhci_priv(host);
+	pxav2_host = sdhci_pltfm_priv(pltfm_host);
 
 	clk = devm_clk_get(dev, "io");
 	if (IS_ERR(clk) && PTR_ERR(clk) != -EPROBE_DEFER)
@@ -307,6 +323,21 @@ static int sdhci_pxav2_probe(struct platform_device *pdev)
 	host->quirks |= variant->extra_quirks;
 	host->ops = variant->ops;
 
+	/* Set up optional pinctrl for PXA168 SDIO IRQ fix */
+	pxav2_host->pinctrl = devm_pinctrl_get(dev);
+	if (!IS_ERR(pxav2_host->pinctrl)) {
+		pxav2_host->pins_cmd_gpio = pinctrl_lookup_state(pxav2_host->pinctrl,
+								 "state_cmd_gpio");
+		if (IS_ERR(pxav2_host->pins_cmd_gpio))
+			pxav2_host->pins_cmd_gpio = NULL;
+		pxav2_host->pins_default = pinctrl_lookup_state(pxav2_host->pinctrl,
+								"default");
+		if (IS_ERR(pxav2_host->pins_default))
+			pxav2_host->pins_default = NULL;
+	} else {
+		pxav2_host->pinctrl = NULL;
+	}
+
 	ret = sdhci_add_host(host);
 	if (ret)
 		goto disable_clk;