mmc: add CD GPIO polling support to slot functions

A simple extension of mmc slot functions add support for CD GPIO polling
for cases where the GPIO cannot produce interrupts, or where this is not
desired for some reason.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Chris Ball <cjb@laptop.org>

diff --git a/drivers/mmc/core/slot-gpio.c b/drivers/mmc/core/slot-gpio.c
index 468e5a0..92cba02 100644 (file)
--- a/drivers/mmc/core/slot-gpio.c
+++ b/drivers/mmc/core/slot-gpio.c
@@ -18,7 +18,7 @@
 #include <linux/slab.h>
 
 struct mmc_gpio {
-       unsigned int cd_gpio;
+       int cd_gpio;
        char cd_label[0];
 };
 
@@ -29,6 +29,18 @@ static irqreturn_t mmc_gpio_cd_irqt(int irq, void *dev_id)
        return IRQ_HANDLED;
 }
 
+int mmc_gpio_get_cd(struct mmc_host *host)
+{
+       struct mmc_gpio *ctx = host->slot.handler_priv;
+
+       if (!ctx || !gpio_is_valid(ctx->cd_gpio))
+               return -ENOSYS;
+
+       return !gpio_get_value_cansleep(ctx->cd_gpio) ^
+               !!(host->caps2 & MMC_CAP2_CD_ACTIVE_HIGH);
+}
+EXPORT_SYMBOL(mmc_gpio_get_cd);
+
 int mmc_gpio_request_cd(struct mmc_host *host, unsigned int gpio)
 {
        size_t len = strlen(dev_name(host->parent)) + 4;
@@ -36,9 +48,6 @@ int mmc_gpio_request_cd(struct mmc_host *host, unsigned int gpio)
        int irq = gpio_to_irq(gpio);
        int ret;
 
-       if (irq < 0)
-               return irq;
-
        ctx = kmalloc(sizeof(*ctx) + len, GFP_KERNEL);
        if (!ctx)
                return -ENOMEM;
@@ -49,20 +58,32 @@ int mmc_gpio_request_cd(struct mmc_host *host, unsigned int gpio)
        if (ret < 0)
                goto egpioreq;
 
-       ret = request_threaded_irq(irq, NULL, mmc_gpio_cd_irqt,
+       /*
+        * Even if gpio_to_irq() returns a valid IRQ number, the platform might
+        * still prefer to poll, e.g., because that IRQ number is already used
+        * by another unit and cannot be shared.
+        */
+       if (irq >= 0 && host->caps & MMC_CAP_NEEDS_POLL)
+               irq = -EINVAL;
+
+       if (irq >= 0) {
+               ret = request_threaded_irq(irq, NULL, mmc_gpio_cd_irqt,
                        IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
                        ctx->cd_label, host);
-       if (ret < 0)
-               goto eirqreq;
+               if (ret < 0)
+                       irq = ret;
+       }
 
-       ctx->cd_gpio = gpio;
        host->slot.cd_irq = irq;
+
+       if (irq < 0)
+               host->caps |= MMC_CAP_NEEDS_POLL;
+
+       ctx->cd_gpio = gpio;
        host->slot.handler_priv = ctx;
 
        return 0;
 
-eirqreq:
-       gpio_free(gpio);
 egpioreq:
        kfree(ctx);
        return ret;
@@ -72,12 +93,21 @@ EXPORT_SYMBOL(mmc_gpio_request_cd);
 void mmc_gpio_free_cd(struct mmc_host *host)
 {
        struct mmc_gpio *ctx = host->slot.handler_priv;
+       int gpio;
 
-       if (!ctx)
+       if (!ctx || !gpio_is_valid(ctx->cd_gpio))
                return;
 
-       free_irq(host->slot.cd_irq, host);
-       gpio_free(ctx->cd_gpio);
+       if (host->slot.cd_irq >= 0) {
+               free_irq(host->slot.cd_irq, host);
+               host->slot.cd_irq = -EINVAL;
+       }
+
+       gpio = ctx->cd_gpio;
+       ctx->cd_gpio = -EINVAL;
+
+       gpio_free(gpio);
+       host->slot.handler_priv = NULL;
        kfree(ctx);
 }
 EXPORT_SYMBOL(mmc_gpio_free_cd);

diff --git a/include/linux/mmc/slot-gpio.h b/include/linux/mmc/slot-gpio.h
index edfaa32..1a977d7 100644 (file)
--- a/include/linux/mmc/slot-gpio.h
+++ b/include/linux/mmc/slot-gpio.h
@@ -12,6 +12,8 @@
 #define MMC_SLOT_GPIO_H
 
 struct mmc_host;
+
+int mmc_gpio_get_cd(struct mmc_host *host);
 int mmc_gpio_request_cd(struct mmc_host *host, unsigned int gpio);
 void mmc_gpio_free_cd(struct mmc_host *host);