@@ -11,8 +11,13 @@ for several SOC designs.
Required properties:
- compatible : contains "mmc,pwrseq-simple".
+Optional properties:
+- reset-gpios : contains a list of GPIO specifiers, though currently only one
+ specifier is supported.
+
Example:
sdhci0_pwrseq {
compatible = "mmc,pwrseq-simple";
+ reset-gpios = <&gpio1 12 0>;
}
@@ -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_power_up(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_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 = {
+ .power_up = mmc_pwrseq_simple_power_up,
+ .power_on = mmc_pwrseq_simple_power_on,
+ .power_off = mmc_pwrseq_simple_power_up,
.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;
}
The need for a reset GPIO has several times been pointed out from earlier posted patchsets. Especially some WLAN chips which are attached to an SDIO interface may use a GPIO reset. In this first version, one reset pin is supported. We may want to extend the support to cover more pins, but let's leave that as a future change. The added DT binding for the reset GPIO can easily be extended to manage several pins. The reset GPIO is asserted at initialization and prior we start the power up procedure. It will then be de-asserted right after the power has been provided for the external chip/card, from the ->power_on() callback. Note, the reset GPIO is optional. Thus we don't return an error even if we can't find a GPIO pin for the consumer. Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org> --- .../devicetree/bindings/mmc/mmc,pwrseq-simple.txt | 5 +++ drivers/mmc/core/pwrseq_simple.c | 38 ++++++++++++++++++++++ 2 files changed, 43 insertions(+)