mmc: add ability to save power by powering off cards

Power can be saved by powering off cards that are not in use.  This is
similar to suspend / resume except it is under the control of the driver,
and does not require any power management support.  It can only be used
when the driver can monitor whether the card is removed, otherwise it is
unsafe.  This is possible because, unlike suspend, the driver still
receives card detect and / or cover switch interrupts.

Signed-off-by: Adrian Hunter <adrian.hunter@nokia.com>
Acked-by: Matt Fleming <matt@console-pimps.org>
Cc: Ian Molton <ian@mnementh.co.uk>
Cc: "Roberto A. Foglietta" <roberto.foglietta@gmail.com>
Cc: Jarkko Lavinen <jarkko.lavinen@nokia.com>
Cc: Denis Karpov <ext-denis.2.karpov@nokia.com>
Cc: Pierre Ossman <pierre@ossman.eu>
Cc: Philip Langdale <philipl@overt.org>
Cc: "Madhusudhan" <madhu.cr@ti.com>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 02f2b1871a384c4c3c7bcd7672b683750d0d9d39..be1fc013fbe98e2e29cd206fe26e5ddc4970ad51 100644 (file)
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -1151,6 +1151,40 @@ void mmc_stop_host(struct mmc_host *host)
        mmc_power_off(host);
 }
 
+void mmc_power_save_host(struct mmc_host *host)
+{
+       mmc_bus_get(host);
+
+       if (!host->bus_ops || host->bus_dead || !host->bus_ops->power_restore) {
+               mmc_bus_put(host);
+               return;
+       }
+
+       if (host->bus_ops->power_save)
+               host->bus_ops->power_save(host);
+
+       mmc_bus_put(host);
+
+       mmc_power_off(host);
+}
+EXPORT_SYMBOL(mmc_power_save_host);
+
+void mmc_power_restore_host(struct mmc_host *host)
+{
+       mmc_bus_get(host);
+
+       if (!host->bus_ops || host->bus_dead || !host->bus_ops->power_restore) {
+               mmc_bus_put(host);
+               return;
+       }
+
+       mmc_power_up(host);
+       host->bus_ops->power_restore(host);
+
+       mmc_bus_put(host);
+}
+EXPORT_SYMBOL(mmc_power_restore_host);
+
 #ifdef CONFIG_PM
 
 /**

diff --git a/drivers/mmc/core/core.h b/drivers/mmc/core/core.h
index c819effa1032c5ccebf896dff58d78f6e7ca13d5..f7eb4c4ca0149d87232b170bb3b65f159f924aec 100644 (file)
--- a/drivers/mmc/core/core.h
+++ b/drivers/mmc/core/core.h
@@ -20,6 +20,8 @@ struct mmc_bus_ops {
        void (*detect)(struct mmc_host *);
        void (*suspend)(struct mmc_host *);
        void (*resume)(struct mmc_host *);
+       void (*power_save)(struct mmc_host *);
+       void (*power_restore)(struct mmc_host *);
 };
 
 void mmc_attach_bus(struct mmc_host *host, const struct mmc_bus_ops *ops);

diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index 995db1853a81419435c8039d91736a5ac7414c8e..27e842df6a6f623989cd035b5f3adb0447dac1e4 100644 (file)
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -549,6 +549,14 @@ static void mmc_resume(struct mmc_host *host)
 
 }
 
+static void mmc_power_restore(struct mmc_host *host)
+{
+       host->card->state &= ~MMC_STATE_HIGHSPEED;
+       mmc_claim_host(host);
+       mmc_init_card(host, host->ocr, host->card);
+       mmc_release_host(host);
+}
+
 #ifdef CONFIG_MMC_UNSAFE_RESUME
 
 static const struct mmc_bus_ops mmc_ops = {
@@ -556,6 +564,7 @@ static const struct mmc_bus_ops mmc_ops = {
        .detect = mmc_detect,
        .suspend = mmc_suspend,
        .resume = mmc_resume,
+       .power_restore = mmc_power_restore,
 };
 
 static void mmc_attach_bus_ops(struct mmc_host *host)
@@ -570,6 +579,7 @@ static const struct mmc_bus_ops mmc_ops = {
        .detect = mmc_detect,
        .suspend = NULL,
        .resume = NULL,
+       .power_restore = mmc_power_restore,
 };
 
 static const struct mmc_bus_ops mmc_ops_unsafe = {
@@ -577,6 +587,7 @@ static const struct mmc_bus_ops mmc_ops_unsafe = {
        .detect = mmc_detect,
        .suspend = mmc_suspend,
        .resume = mmc_resume,
+       .power_restore = mmc_power_restore,
 };
 
 static void mmc_attach_bus_ops(struct mmc_host *host)

diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
index 92fa9dceca7962d784dd66bf0baa3beefea3f221..222a60928cdbfe3d9da0670a760fe55574f61610 100644 (file)
--- a/drivers/mmc/core/sd.c
+++ b/drivers/mmc/core/sd.c
@@ -603,6 +603,14 @@ static void mmc_sd_resume(struct mmc_host *host)
 
 }
 
+static void mmc_sd_power_restore(struct mmc_host *host)
+{
+       host->card->state &= ~MMC_STATE_HIGHSPEED;
+       mmc_claim_host(host);
+       mmc_sd_init_card(host, host->ocr, host->card);
+       mmc_release_host(host);
+}
+
 #ifdef CONFIG_MMC_UNSAFE_RESUME
 
 static const struct mmc_bus_ops mmc_sd_ops = {
@@ -610,6 +618,7 @@ static const struct mmc_bus_ops mmc_sd_ops = {
        .detect = mmc_sd_detect,
        .suspend = mmc_sd_suspend,
        .resume = mmc_sd_resume,
+       .power_restore = mmc_sd_power_restore,
 };
 
 static void mmc_sd_attach_bus_ops(struct mmc_host *host)
@@ -624,6 +633,7 @@ static const struct mmc_bus_ops mmc_sd_ops = {
        .detect = mmc_sd_detect,
        .suspend = NULL,
        .resume = NULL,
+       .power_restore = mmc_sd_power_restore,
 };
 
 static const struct mmc_bus_ops mmc_sd_ops_unsafe = {
@@ -631,6 +641,7 @@ static const struct mmc_bus_ops mmc_sd_ops_unsafe = {
        .detect = mmc_sd_detect,
        .suspend = mmc_sd_suspend,
        .resume = mmc_sd_resume,
+       .power_restore = mmc_sd_power_restore,
 };
 
 static void mmc_sd_attach_bus_ops(struct mmc_host *host)

diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index bb867d2c26bdc5ad1c651b4a85a89f1a2890f54a..c1cbe598d470930a389a16b73eb897d1f4f444a3 100644 (file)
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -223,6 +223,9 @@ static inline void *mmc_priv(struct mmc_host *host)
 extern int mmc_suspend_host(struct mmc_host *, pm_message_t);
 extern int mmc_resume_host(struct mmc_host *);
 
+extern void mmc_power_save_host(struct mmc_host *host);
+extern void mmc_power_restore_host(struct mmc_host *host);
+
 extern void mmc_detect_change(struct mmc_host *, unsigned long delay);
 extern void mmc_request_done(struct mmc_host *, struct mmc_request *);