mmc: add power cyle support in mmc core

mmc/sd specification requires vdd to be disabled for 1 ms
and then enabled again during power cycle. Add a
function in mmc core to perform power cycle and set
the io signal to it's initial state.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>

diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c
index 1875b31ad1fbe302a7de5a0a728d8bf44a71daea..0ffe7bf417c8621e056509cdc2d512ebc0074baf 100644 (file)
--- a/drivers/mmc/mmc.c
+++ b/drivers/mmc/mmc.c
@@ -31,6 +31,7 @@ static const unsigned int sd_au_size[] = {
 };
 
 static int mmc_set_signal_voltage(struct mmc *mmc, uint signal_voltage);
+static int mmc_power_cycle(struct mmc *mmc);
 
 #if CONFIG_IS_ENABLED(MMC_TINY)
 static struct mmc mmc_static;
@@ -1920,25 +1921,83 @@ static int mmc_power_init(struct mmc *mmc)
                                          &mmc->vqmmc_supply);
        if (ret)
                debug("%s: No vqmmc supply\n", mmc->dev->name);
+#endif
+#else /* !CONFIG_DM_MMC */
+       /*
+        * Driver model should use a regulator, as above, rather than calling
+        * out to board code.
+        */
+       board_mmc_power_init();
+#endif
+       return 0;
+}
+
+/*
+ * put the host in the initial state:
+ * - turn on Vdd (card power supply)
+ * - configure the bus width and clock to minimal values
+ */
+static void mmc_set_initial_state(struct mmc *mmc)
+{
+       int err;
+
+       /* First try to set 3.3V. If it fails set to 1.8V */
+       err = mmc_set_signal_voltage(mmc, MMC_SIGNAL_VOLTAGE_330);
+       if (err != 0)
+               err = mmc_set_signal_voltage(mmc, MMC_SIGNAL_VOLTAGE_180);
+       if (err != 0)
+               printf("mmc: failed to set signal voltage\n");
+
+       mmc_select_mode(mmc, MMC_LEGACY);
+       mmc_set_bus_width(mmc, 1);
+       mmc_set_clock(mmc, 0);
+}
 
+static int mmc_power_on(struct mmc *mmc)
+{
+#if CONFIG_IS_ENABLED(DM_MMC) && CONFIG_IS_ENABLED(DM_REGULATOR)
        if (mmc->vmmc_supply) {
-               ret = regulator_set_enable(mmc->vmmc_supply, true);
+               int ret = regulator_set_enable(mmc->vmmc_supply, true);
+
                if (ret) {
                        puts("Error enabling VMMC supply\n");
                        return ret;
                }
        }
 #endif
-#else /* !CONFIG_DM_MMC */
-       /*
-        * Driver model should use a regulator, as above, rather than calling
-        * out to board code.
-        */
-       board_mmc_power_init();
+       return 0;
+}
+
+static int mmc_power_off(struct mmc *mmc)
+{
+#if CONFIG_IS_ENABLED(DM_MMC) && CONFIG_IS_ENABLED(DM_REGULATOR)
+       if (mmc->vmmc_supply) {
+               int ret = regulator_set_enable(mmc->vmmc_supply, false);
+
+               if (ret) {
+                       puts("Error disabling VMMC supply\n");
+                       return ret;
+               }
+       }
 #endif
        return 0;
 }
 
+static int mmc_power_cycle(struct mmc *mmc)
+{
+       int ret;
+
+       ret = mmc_power_off(mmc);
+       if (ret)
+               return ret;
+       /*
+        * SD spec recommends at least 1ms of delay. Let's wait for 2ms
+        * to be on the safer side.
+        */
+       udelay(2000);
+       return mmc_power_on(mmc);
+}
+
 int mmc_start_init(struct mmc *mmc)
 {
        bool no_card;
@@ -1967,6 +2026,10 @@ int mmc_start_init(struct mmc *mmc)
        if (err)
                return err;
 
+       err = mmc_power_on(mmc);
+       if (err)
+               return err;
+
 #if CONFIG_IS_ENABLED(DM_MMC)
        /* The device has already been probed ready for use */
 #else
@@ -1977,16 +2040,7 @@ int mmc_start_init(struct mmc *mmc)
 #endif
        mmc->ddr_mode = 0;
 
-       /* First try to set 3.3V. If it fails set to 1.8V */
-       err = mmc_set_signal_voltage(mmc, MMC_SIGNAL_VOLTAGE_330);
-       if (err != 0)
-               err = mmc_set_signal_voltage(mmc, MMC_SIGNAL_VOLTAGE_180);
-       if (err != 0)
-               printf("failed to set signal voltage\n");
-
-       mmc_set_bus_width(mmc, 1);
-       mmc_set_clock(mmc, 1);
-
+       mmc_set_initial_state(mmc);
        mmc_send_init_stream(mmc);
 
        /* Reset the Card */