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    Subject[PATCH 14/14] mmc: meson-gx: implement voltage switch callback
    Date
    Implement voltage switch callback (shamelessly copied from sunxi mmc
    driver). This allow, with the appropriate tuning function, to use
    SD ultra high speed modes.

    Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
    ---
    drivers/mmc/host/meson-gx-mmc.c | 25 +++++++++++++++++++++++++
    1 file changed, 25 insertions(+)

    diff --git a/drivers/mmc/host/meson-gx-mmc.c b/drivers/mmc/host/meson-gx-mmc.c
    index e991c9e452ab..de2d7b8a9d97 100644
    --- a/drivers/mmc/host/meson-gx-mmc.c
    +++ b/drivers/mmc/host/meson-gx-mmc.c
    @@ -38,6 +38,8 @@
    #include <linux/interrupt.h>
    #include <linux/bitfield.h>

    +#include <linux/delay.h>
    +
    #define DRIVER_NAME "meson-gx-mmc"

    #define SD_EMMC_CLOCK 0x0
    @@ -1024,6 +1026,28 @@ 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,
    @@ -1032,6 +1056,7 @@ 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)
    --
    2.9.4
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