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authorUlf Hansson <ulf.hansson@linaro.org>2014-12-15 16:07:11 +0100
committerUlf Hansson <ulf.hansson@linaro.org>2015-01-28 12:32:13 +0100
commit862b5dcf9f2055ce6d1c9b0f6553079b7ee61b20 (patch)
treeb2603d3457928dcdc2d3c6384c6655c60126d4ad /drivers/mmc
parent8c96f89c62ecc8334d06820bff62ecf81be97c2b (diff)
downloadkernel-862b5dcf9f2055ce6d1c9b0f6553079b7ee61b20.tar.gz
mmc: pwrseq_simple: Add support for a reset GPIO pin
The need for reset GPIOs has several times been pointed out from erlier posted patchsets. Especially some WLAN chips which are attached to an SDIO interface may use a GPIO reset. The reset GPIO is asserted at initialization and prior we start the power up procedure. The GPIO will be de-asserted right after the power has been provided to the card, from the ->post_power_on() callback. Note, the reset GPIO is optional. Thus we don't return an error even if we can't find a GPIO for the consumer. Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org> Tested-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk> Reviewed-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Diffstat (limited to 'drivers/mmc')
-rw-r--r--drivers/mmc/core/pwrseq_simple.c38
1 files changed, 38 insertions, 0 deletions
diff --git a/drivers/mmc/core/pwrseq_simple.c b/drivers/mmc/core/pwrseq_simple.c
index 61c991e4009d..0958c696137f 100644
--- a/drivers/mmc/core/pwrseq_simple.c
+++ b/drivers/mmc/core/pwrseq_simple.c
@@ -11,6 +11,7 @@
#include <linux/slab.h>
#include <linux/device.h>
#include <linux/err.h>
+#include <linux/gpio/consumer.h>
#include <linux/mmc/host.h>
@@ -18,31 +19,68 @@
struct mmc_pwrseq_simple {
struct mmc_pwrseq pwrseq;
+ struct gpio_desc *reset_gpio;
};
+static void mmc_pwrseq_simple_pre_power_on(struct mmc_host *host)
+{
+ struct mmc_pwrseq_simple *pwrseq = container_of(host->pwrseq,
+ struct mmc_pwrseq_simple, pwrseq);
+
+ if (!IS_ERR(pwrseq->reset_gpio))
+ gpiod_set_value_cansleep(pwrseq->reset_gpio, 1);
+}
+
+static void mmc_pwrseq_simple_post_power_on(struct mmc_host *host)
+{
+ struct mmc_pwrseq_simple *pwrseq = container_of(host->pwrseq,
+ struct mmc_pwrseq_simple, pwrseq);
+
+ if (!IS_ERR(pwrseq->reset_gpio))
+ gpiod_set_value_cansleep(pwrseq->reset_gpio, 0);
+}
+
static void mmc_pwrseq_simple_free(struct mmc_host *host)
{
struct mmc_pwrseq_simple *pwrseq = container_of(host->pwrseq,
struct mmc_pwrseq_simple, pwrseq);
+ if (!IS_ERR(pwrseq->reset_gpio))
+ gpiod_put(pwrseq->reset_gpio);
+
kfree(pwrseq);
host->pwrseq = NULL;
}
static struct mmc_pwrseq_ops mmc_pwrseq_simple_ops = {
+ .pre_power_on = mmc_pwrseq_simple_pre_power_on,
+ .post_power_on = mmc_pwrseq_simple_post_power_on,
+ .power_off = mmc_pwrseq_simple_pre_power_on,
.free = mmc_pwrseq_simple_free,
};
int mmc_pwrseq_simple_alloc(struct mmc_host *host, struct device *dev)
{
struct mmc_pwrseq_simple *pwrseq;
+ int ret = 0;
pwrseq = kzalloc(sizeof(struct mmc_pwrseq_simple), GFP_KERNEL);
if (!pwrseq)
return -ENOMEM;
+ pwrseq->reset_gpio = gpiod_get_index(dev, "reset", 0, GPIOD_OUT_HIGH);
+ if (IS_ERR(pwrseq->reset_gpio) &&
+ PTR_ERR(pwrseq->reset_gpio) != -ENOENT &&
+ PTR_ERR(pwrseq->reset_gpio) != -ENOSYS) {
+ ret = PTR_ERR(pwrseq->reset_gpio);
+ goto free;
+ }
+
pwrseq->pwrseq.ops = &mmc_pwrseq_simple_ops;
host->pwrseq = &pwrseq->pwrseq;
return 0;
+free:
+ kfree(pwrseq);
+ return ret;
}