[PATCH 2/2] mmc: dw_mmc: Handle wp-gpios from device tree

Doug Anderson
2012-11-22T19:11:46Z

On some SoCs (like exynos5250) you need to use an external GPIO for
write protect. Add support for wp-gpios to the core dw_mmc driver
since it could be useful across multiple SoCs.

With this change I am able to make use of the write protect for the
external SD slot on exynos5250-snow.

Signed-off-by: Doug Anderson <dianders@chromium.org>
---
drivers/mmc/host/dw_mmc.c | 35 +++++++++++++++++++++++++++++++++++
1 files changed, 35 insertions(+), 0 deletions(-)

diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
index 5b41348..9c79870 100644
--- a/drivers/mmc/host/dw_mmc.c
+++ b/drivers/mmc/host/dw_mmc.c
@@ -34,6 +34,7 @@
#include <linux/regulator/consumer.h>
#include <linux/workqueue.h>
#include <linux/of.h>
+#include <linux/of_gpio.h>

#include "dw_mmc.h"

@@ -74,6 +75,7 @@ struct idmac_desc {
* struct dw_mci_slot - MMC slot state
* @mmc: The mmc_host representing this slot.
* @host: The MMC controller this slot is using.
+ * @wp_gpio: If gpio_is_valid() we'll use this to read write protect.
* @ctype: Card type for this slot.
* @mrq: mmc_request currently being processed or waiting to be
* processed, or NULL when the slot is idle.
@@ -88,6 +90,8 @@ struct dw_mci_slot {
struct mmc_host *mmc;
struct dw_mci *host;

+ int wp_gpio;
+
u32 ctype;

struct mmc_request *mrq;
@@ -832,6 +836,8 @@ static int dw_mci_get_ro(struct mmc_host *mmc)
read_only = 0;
else if (brd->get_ro)
read_only = brd->get_ro(slot->id);
+ else if (gpio_is_valid(slot->wp_gpio))
+ read_only = gpio_get_value(slot->wp_gpio);
else
read_only =
mci_readl(slot->host, WRTPRT) & (1 << slot->id) ? 1 : 0;
@@ -1802,6 +1808,29 @@ static u32 dw_mci_of_get_bus_wd(struct device *dev, u8 slot)
" as 1\n");
return bus_wd;
}
+
+/* find the write protect gpio for a given slot; or -1 if none specified */
+static u32 dw_mci_of_get_wp_gpio(struct device *dev, u8 slot)
+{
+ struct device_node *np = dw_mci_of_find_slot_node(dev, slot);
+ int gpio;
+
+ if (!np)
+ return -1;
+
+ gpio = of_get_named_gpio(np, "wp-gpios", 0);
+
+ /* Having a missing entry is valid; return silently */
+ if (!gpio_is_valid(gpio))
+ return -1;
+
+ if (devm_gpio_request(dev, gpio, "dw-mci-wp")) {
+ dev_warn(dev, "gpio [%d] request failed\n", gpio);
+ return -1;
+ }
+
+ return gpio;
+}
#else /* CONFIG_OF */
static u32 dw_mci_of_get_bus_wd(struct device *dev, u8 slot)
{
@@ -1811,6 +1840,10 @@ static struct device_node *dw_mci_of_find_slot_node(struct device *dev, u8 slot)
{
return NULL;
}
+static u32 dw_mci_of_get_wp_gpio(struct device *dev, u8 slot)
+{
+ return -1;
+}
#endif /* CONFIG_OF */

static int dw_mci_init_slot(struct dw_mci *host, unsigned int id)
@@ -1923,6 +1956,8 @@ static int dw_mci_init_slot(struct dw_mci *host, unsigned int id)
else
clear_bit(DW_MMC_CARD_PRESENT, &slot->flags);

+ slot->wp_gpio = dw_mci_of_get_wp_gpio(host->dev, slot->id);
+
mmc_add_host(mmc);

#if defined(CONFIG_DEBUG_FS)
--
1.7.7.3