mmc: slot-gpio: add a helper to check capability of GPIO WP detection

Like mmc_can_gpio_cd(), mmc_can_gpio_ro() will also be useful for host
drivers to know whether GPIO write-protect detection is supported.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/core/slot-gpio.c

@@ -305,3 +305,11 @@ int mmc_gpiod_request_ro(struct mmc_host *host, const char *con_id,
 	return 0;
 }
 EXPORT_SYMBOL(mmc_gpiod_request_ro);
+
+bool mmc_can_gpio_ro(struct mmc_host *host)
+{
+	struct mmc_gpio *ctx = host->slot.handler_priv;
+
+	return ctx->ro_gpio ? true : false;
+}
+EXPORT_SYMBOL(mmc_can_gpio_ro);

include/linux/mmc/slot-gpio.h

@@ -33,5 +33,6 @@ void mmc_gpio_set_cd_isr(struct mmc_host *host,
 			 irqreturn_t (*isr)(int irq, void *dev_id));
 void mmc_gpiod_request_cd_irq(struct mmc_host *host);
 bool mmc_can_gpio_cd(struct mmc_host *host);
+bool mmc_can_gpio_ro(struct mmc_host *host);
 
 #endif