[U-Boot] [RFC 1/2] mmc: introduce mmc_power_init and pwrup hook function

[Peng Fan]

In device tree, there is vmmc-supply property for SD/MMC.
Introduce mmc_power_init function and pwrup hook function to let
the specific drivers handle vmmc-supply.

mmc_power_init will first invoke board_mmc_power_init to
avoid break boards which already implement board_mmc_power_init.

Then if pwrup hook functions have been implemented for different
mmc drivers, pwrup will be invoked.

Signed-off-by: Peng Fan <van.freenix at gmail.com>
Cc: Pantelis Antoniou <panto at antoniou-consulting.com>
Cc: Andrew Gabbasov <andrew_gabbasov at mentor.com>
Cc: Simon Glass <sjg at chromium.org>
Cc: Stephen Warren <swarren at nvidia.com>
Cc: Clemens Gruber <clemens.gruber at pqgruber.com>
Cc: Eric Nelson <eric at nelint.com>
Cc: Stefano Babic <sbabic at denx.de>
Cc: Fabio Estevam <fabio.estevam at nxp.com>
---
 drivers/mmc/mmc.c | 15 ++++++++++++++-
 include/mmc.h     |  1 +
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c
index ede5d6e..f6d5c6f 100644
--- a/drivers/mmc/mmc.c
+++ b/drivers/mmc/mmc.c
@@ -1594,6 +1594,16 @@ __weak void board_mmc_power_init(void)
 {
 }
 
+__weak int mmc_power_init(struct mmc *mmc)
+{
+	board_mmc_power_init();
+
+	if (mmc->cfg->ops->pwrup)
+		return mmc->cfg->ops->pwrup(mmc);
+
+	return 0;
+}
+
 int mmc_start_init(struct mmc *mmc)
 {
 	int err;
@@ -1613,7 +1623,10 @@ int mmc_start_init(struct mmc *mmc)
 #ifdef CONFIG_FSL_ESDHC_ADAPTER_IDENT
 	mmc_adapter_card_type_ident();
 #endif
-	board_mmc_power_init();
+
+	err = mmc_power_init(mmc);
+	if (err)
+		return err;
 
 	/* made sure it's not NULL earlier */
 	err = mmc->cfg->ops->init(mmc);
diff --git a/include/mmc.h b/include/mmc.h
index d652c14..111ff75 100644
--- a/include/mmc.h
+++ b/include/mmc.h
@@ -329,6 +329,7 @@ struct mmc_ops {
 	int (*init)(struct mmc *mmc);
 	int (*getcd)(struct mmc *mmc);
 	int (*getwp)(struct mmc *mmc);
+	int (*pwrup)(struct mmc *mmc);
 };
 
 struct mmc_config {
-- 
2.6.2