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>

1 files changed, 43 insertions, 13 deletions

diff --git a/drivers/mmc/core/slot-gpio.c b/drivers/mmc/core/slot-gpio.c
index 468e5a0e5126..92cba02c04be 100644
--- 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);