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.hans...@linaro.org>
---
Changes in v3:
- Updated commit message to make it clear that we support one reset
GPIO.
---
drivers/mmc/core/pwrseq_simple.c | 38 ++++++++++++++++++++++++++++++++++++++
1 file changed, 38 insertions(+)
diff --git a/drivers/mmc/core/pwrseq_simple.c b/drivers/mmc/core/pwrseq_simple.c
index 7f87bc1..42d9836 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;
}
--
1.9.1
--
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