mmc: core: Initial support for MMC power sequences

System on chip designs may specify a specific MMC power sequence. To
successfully detect an (e)MMC/SD/SDIO card, that power sequence must
be followed while initializing the card.

To be able to handle these SOC specific power sequences, let's add a
MMC power sequence interface. It provides the following functions to
help the mmc core to deal with these power sequences.

mmc_pwrseq_alloc() - Invoked from mmc_of_parse(), to initialize data.
mmc_pwrseq_pre_power_on()- Invoked in the beginning of mmc_power_up().
mmc_pwrseq_post_power_on()- Invoked at the end in mmc_power_up().
mmc_pwrseq_power_off()- Invoked from mmc_power_off().
mmc_pwrseq_free() - Invoked from mmc_free_host(), to free data.

Each MMC power sequence provider will be responsible to implement a set
of callbacks. These callbacks mirrors the functions above.

This patch adds the skeleton, following patches will extend the core of
the MMC power sequence and add support for a specific simple MMC power
sequence.

Do note, since the mmc_pwrseq_alloc() is invoked from mmc_of_parse(),
host drivers needs to make use of this API to enable the support for
MMC power sequences. Moreover the MMC power sequence support depends on
CONFIG_OF.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Tested-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Reviewed-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>

1 files changed, 40 insertions, 0 deletions

diff --git a/drivers/mmc/core/pwrseq.h b/drivers/mmc/core/pwrseq.h
new file mode 100644
index 000000000000..12aaf2b4745b
--- /dev/null
+++ b/drivers/mmc/core/pwrseq.h
@@ -0,0 +1,40 @@
+/*
+ * Copyright (C) 2014 Linaro Ltd
+ *
+ * Author: Ulf Hansson <ulf.hansson@linaro.org>
+ *
+ * License terms: GNU General Public License (GPL) version 2
+ */
+#ifndef _MMC_CORE_PWRSEQ_H
+#define _MMC_CORE_PWRSEQ_H
+
+struct mmc_pwrseq_ops {
+	void (*pre_power_on)(struct mmc_host *host);
+	void (*post_power_on)(struct mmc_host *host);
+	void (*power_off)(struct mmc_host *host);
+	void (*free)(struct mmc_host *host);
+};
+
+struct mmc_pwrseq {
+	struct mmc_pwrseq_ops *ops;
+};
+
+#ifdef CONFIG_OF
+
+int mmc_pwrseq_alloc(struct mmc_host *host);
+void mmc_pwrseq_pre_power_on(struct mmc_host *host);
+void mmc_pwrseq_post_power_on(struct mmc_host *host);
+void mmc_pwrseq_power_off(struct mmc_host *host);
+void mmc_pwrseq_free(struct mmc_host *host);
+
+#else
+
+static inline int mmc_pwrseq_alloc(struct mmc_host *host) { return 0; }
+static inline void mmc_pwrseq_pre_power_on(struct mmc_host *host) {}
+static inline void mmc_pwrseq_post_power_on(struct mmc_host *host) {}
+static inline void mmc_pwrseq_power_off(struct mmc_host *host) {}
+static inline void mmc_pwrseq_free(struct mmc_host *host) {}
+
+#endif
+
+#endif