mmc: sh_mobile_sdhi: support modular mmc-core with non-standard hotplug

Currently if a platform wants to implement a non-standard card-detection
method, it would need to call tmio_mmc_cd_wakeup(), which is an inline
function, calling mmc_detect_change(). For this the platform would have
to link mmc_core statically into the kernel, losing the ability to build
it as a module. This patch adds a callback to the sh_mobile_sdhi driver,
which eliminates this dependency.
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Acked-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Chris Ball <cjb@laptop.org>

drivers/mmc/host/sh_mobile_sdhi.c

@@ -90,6 +90,15 @@ static int sh_mobile_sdhi_write16_hook(struct tmio_mmc_host *host, int addr)
 	return 0;
 }
 
+static void sh_mobile_sdhi_cd_wakeup(const struct platform_device *pdev)
+{
+	mmc_detect_change(dev_get_drvdata(&pdev->dev), msecs_to_jiffies(100));
+}
+
+static const struct sh_mobile_sdhi_ops sdhi_ops = {
+	.cd_wakeup = sh_mobile_sdhi_cd_wakeup,
+};
+
 static int __devinit sh_mobile_sdhi_probe(struct platform_device *pdev)
 {
 	struct sh_mobile_sdhi *priv;
@@ -110,7 +119,7 @@ static int __devinit sh_mobile_sdhi_probe(struct platform_device *pdev)
 	p->pdata = mmc_data;
 
 	if (p->init) {
-		ret = p->init(pdev);
+		ret = p->init(pdev, &sdhi_ops);
 		if (ret)
 			goto einit;
 	}

include/linux/mmc/sh_mobile_sdhi.h

@@ -10,6 +10,14 @@ struct tmio_mmc_data;
 #define SH_MOBILE_SDHI_IRQ_SDCARD	"sdcard"
 #define SH_MOBILE_SDHI_IRQ_SDIO		"sdio"
 
+/**
+ * struct sh_mobile_sdhi_ops - SDHI driver callbacks
+ * @cd_wakeup:		trigger a card-detection run
+ */
+struct sh_mobile_sdhi_ops {
+	void (*cd_wakeup)(const struct platform_device *pdev);
+};
+
 struct sh_mobile_sdhi_info {
 	int dma_slave_tx;
 	int dma_slave_rx;
@@ -22,7 +30,8 @@ struct sh_mobile_sdhi_info {
 	int (*get_cd)(struct platform_device *pdev);
 
 	/* callbacks for board specific setup code */
-	int (*init)(struct platform_device *pdev);
+	int (*init)(struct platform_device *pdev,
+		    const struct sh_mobile_sdhi_ops *ops);
 	void (*cleanup)(struct platform_device *pdev);
 };