mmc: meson-gx: implement voltage switch callback

Implement voltage switch callback (shamelessly copied from sunxi mmc
driver). This allow, with the appropriate tuning function, to use
SD ultra high speed modes.

Reviewed-by: Kevin Hilman <khilman@baylibre.com>
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

diff --git a/drivers/mmc/host/meson-gx-mmc.c b/drivers/mmc/host/meson-gx-mmc.c
index 2fa18fa..0cffc70 100644 (file)
--- a/drivers/mmc/host/meson-gx-mmc.c
+++ b/drivers/mmc/host/meson-gx-mmc.c
@@ -1049,6 +1049,27 @@ static int meson_mmc_card_busy(struct mmc_host *mmc)
        return !(FIELD_GET(STATUS_DATI, regval) & 0xf);
 }
 
+static int meson_mmc_voltage_switch(struct mmc_host *mmc, struct mmc_ios *ios)
+{
+       /* vqmmc regulator is available */
+       if (!IS_ERR(mmc->supply.vqmmc)) {
+               /*
+                * The usual amlogic setup uses a GPIO to switch from one
+                * regulator to the other. While the voltage ramp up is
+                * pretty fast, care must be taken when switching from 3.3v
+                * to 1.8v. Please make sure the regulator framework is aware
+                * of your own regulator constraints
+                */
+               return mmc_regulator_set_vqmmc(mmc, ios);
+       }
+
+       /* no vqmmc regulator, assume fixed regulator at 3/3.3V */
+       if (ios->signal_voltage == MMC_SIGNAL_VOLTAGE_330)
+               return 0;
+
+       return -EINVAL;
+}
+
 static const struct mmc_host_ops meson_mmc_ops = {
        .request        = meson_mmc_request,
        .set_ios        = meson_mmc_set_ios,
@@ -1057,6 +1078,7 @@ static const struct mmc_host_ops meson_mmc_ops = {
        .post_req       = meson_mmc_post_req,
        .execute_tuning = meson_mmc_execute_tuning,
        .card_busy      = meson_mmc_card_busy,
+       .start_signal_voltage_switch = meson_mmc_voltage_switch,
 };
 
 static int meson_mmc_probe(struct platform_device *pdev)