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>

1 files changed, 34 insertions, 0 deletions

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 02f2b18..be1fc01 100644
--- 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
 
 /**