Hi,
On Wed, Jan 14, 2015 at 01:02:10PM +0000, Ulf Hansson wrote:
> 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 to the external chip/card, from the ->post_power_on()
> callback.
This needs to be specified a little more explicitly in the binding
document below, as it forms part of the contract of the binding.
>
> 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.hans...@linaro.org>
> ---
>
> Changes in v2:
> - Adopted to the changed names of the pwrseq callbacks.
>
> ---
> .../devicetree/bindings/mmc/mmc,pwrseq-simple.txt | 5 +++
> drivers/mmc/core/pwrseq_simple.c | 38
> ++++++++++++++++++++++
> 2 files changed, 43 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/mmc/mmc,pwrseq-simple.txt
> b/Documentation/devicetree/bindings/mmc/mmc,pwrseq-simple.txt
> index e1b7f9c..6fe0cd6 100644
> --- a/Documentation/devicetree/bindings/mmc/mmc,pwrseq-simple.txt
> +++ b/Documentation/devicetree/bindings/mmc/mmc,pwrseq-simple.txt
> @@ -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.
The support is a Linux issue. If the binding is meant to describe a
list, mention that, and what the expected semantics are.
Is it that difficult to have the driver iterate over the list now?
Thanks,
Mark.
> +
> Example:
>
> sdhci0_pwrseq {
> compatible = "mmc,pwrseq-simple";
> + reset-gpios = <&gpio1 12 0>;
> }
> 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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