mmc: sdhci-dove: allow GPIOs to be used for card detection on Dove

This commit taken from Rabeeh's Cubox kernel and re-worked for DT;
Sebastian Hasselbrath is believed to be the original author.

Some Cuboxes require a GPIO for card detection; this implements the
optional GPIO support for card detection.  This GPIO is logic 0 for
card inserted.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Chris Ball <cjb@laptop.org>

drivers/mmc/host/sdhci-dove.c

@@ -19,20 +19,30 @@
  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  */
 
-#include <linux/err.h>
-#include <linux/io.h>
 #include <linux/clk.h>
 #include <linux/err.h>
-#include <linux/module.h>
+#include <linux/gpio.h>
+#include <linux/io.h>
 #include <linux/mmc/host.h>
+#include <linux/module.h>
 #include <linux/of.h>
+#include <linux/of_gpio.h>
 
 #include "sdhci-pltfm.h"
 
 struct sdhci_dove_priv {
 	struct clk *clk;
+	int gpio_cd;
 };
 
+static irqreturn_t sdhci_dove_carddetect_irq(int irq, void *data)
+{
+	struct sdhci_host *host = data;
+
+	tasklet_schedule(&host->card_tasklet);
+	return IRQ_HANDLED;
+}
+
 static u16 sdhci_dove_readw(struct sdhci_host *host, int reg)
 {
 	u16 ret;
@@ -50,16 +60,25 @@ static u16 sdhci_dove_readw(struct sdhci_host *host, int reg)
 
 static u32 sdhci_dove_readl(struct sdhci_host *host, int reg)
 {
+	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
+	struct sdhci_dove_priv *priv = pltfm_host->priv;
 	u32 ret;
 
+	ret = readl(host->ioaddr + reg);
+
 	switch (reg) {
 	case SDHCI_CAPABILITIES:
-		ret = readl(host->ioaddr + reg);
 		/* Mask the support for 3.0V */
 		ret &= ~SDHCI_CAN_VDD_300;
 		break;
-	default:
-		ret = readl(host->ioaddr + reg);
+	case SDHCI_PRESENT_STATE:
+		if (gpio_is_valid(priv->gpio_cd)) {
+			if (gpio_get_value(priv->gpio_cd) == 0)
+				ret |= SDHCI_CARD_PRESENT;
+			else
+				ret &= ~SDHCI_CARD_PRESENT;
+		}
+		break;
 	}
 	return ret;
 }
@@ -94,6 +113,23 @@ static int __devinit sdhci_dove_probe(struct platform_device *pdev)
 
 	priv->clk = devm_clk_get(&pdev->dev, NULL);
 
+	if (pdev->dev.of_node) {
+		priv->gpio_cd = of_get_named_gpio(pdev->dev.of_node,
+						  "cd-gpios", 0);
+	} else {
+		priv->gpio_cd = -EINVAL;
+	}
+
+	if (gpio_is_valid(priv->gpio_cd)) {
+		ret = gpio_request(priv->gpio_cd, "sdhci-cd");
+		if (ret) {
+			dev_err(&pdev->dev, "card detect gpio request failed: %d\n",
+				ret);
+			return ret;
+		}
+		gpio_direction_input(priv->gpio_cd);
+	}
+
 	host = sdhci_pltfm_init(pdev, &sdhci_dove_pdata);
 	if (IS_ERR(host)) {
 		ret = PTR_ERR(host);
@@ -112,13 +148,33 @@ static int __devinit sdhci_dove_probe(struct platform_device *pdev)
 	if (ret)
 		goto err_sdhci_add;
 
+	/*
+	 * We must request the IRQ after sdhci_add_host(), as the tasklet only
+	 * gets setup in sdhci_add_host() and we oops.
+	 */
+	if (gpio_is_valid(priv->gpio_cd)) {
+		ret = request_irq(gpio_to_irq(priv->gpio_cd),
+				  sdhci_dove_carddetect_irq,
+				  IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING,
+				  mmc_hostname(host->mmc), host);
+		if (ret) {
+			dev_err(&pdev->dev, "card detect irq request failed: %d\n",
+				ret);
+			goto err_request_irq;
+		}
+	}
+
 	return 0;
 
+err_request_irq:
+	sdhci_remove_host(host, 0);
 err_sdhci_add:
 	if (!IS_ERR(priv->clk))
 		clk_disable_unprepare(priv->clk);
 	sdhci_pltfm_free(pdev);
 err_sdhci_pltfm_init:
+	if (gpio_is_valid(priv->gpio_cd))
+		gpio_free(priv->gpio_cd);
 	return ret;
 }
 
@@ -130,6 +186,11 @@ static int __devexit sdhci_dove_remove(struct platform_device *pdev)
 
 	sdhci_pltfm_unregister(pdev);
 
+	if (gpio_is_valid(priv->gpio_cd)) {
+		free_irq(gpio_to_irq(priv->gpio_cd), host);
+		gpio_free(priv->gpio_cd);
+	}
+
 	if (!IS_ERR(priv->clk))
 		clk_disable_unprepare(priv->clk);