mmc: pwrseq_simple: Parse DTS for the power-off-delay-us property

If the optional power-off-delay-us property is found, insert the
corresponding delay after asserting the GPIO during power off. This enables
a graceful shutdown sequence for some devices.

Cc: linux-mmc@vger.kernel.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>

diff --git a/drivers/mmc/core/pwrseq_simple.c b/drivers/mmc/core/pwrseq_simple.c
index 1304160..13ef162 100644 (file)
--- a/drivers/mmc/core/pwrseq_simple.c
+++ b/drivers/mmc/core/pwrseq_simple.c
@@ -27,6 +27,7 @@ struct mmc_pwrseq_simple {
        struct mmc_pwrseq pwrseq;
        bool clk_enabled;
        u32 post_power_on_delay_ms;
+       u32 power_off_delay_us;
        struct clk *ext_clk;
        struct gpio_descs *reset_gpios;
 };
@@ -78,6 +79,10 @@ static void mmc_pwrseq_simple_power_off(struct mmc_host *host)
 
        mmc_pwrseq_simple_set_gpios_value(pwrseq, 1);
 
+       if (pwrseq->power_off_delay_us)
+               usleep_range(pwrseq->power_off_delay_us,
+                       2 * pwrseq->power_off_delay_us);
+
        if (!IS_ERR(pwrseq->ext_clk) && pwrseq->clk_enabled) {
                clk_disable_unprepare(pwrseq->ext_clk);
                pwrseq->clk_enabled = false;
@@ -119,6 +124,8 @@ static int mmc_pwrseq_simple_probe(struct platform_device *pdev)
 
        device_property_read_u32(dev, "post-power-on-delay-ms",
                                 &pwrseq->post_power_on_delay_ms);
+       device_property_read_u32(dev, "power-off-delay-us",
+                                &pwrseq->power_off_delay_us);
 
        pwrseq->pwrseq.dev = dev;
        pwrseq->pwrseq.ops = &mmc_pwrseq_simple_ops;