mmc: core: Add option to prevent eMMC sleep command

Host may now use MMC_CAP2_NO_SLEEP_CMD to disable the use
of eMMC sleep/awake command.

This option can be used when your platform has a buggy
kernel crash dump software, which is supposed to store
the dump on the eMMC, but is not able to wake up the eMMC
from sleep state.

In particular, failures have been seen with u-boot; even if
it is fixed there, platforms will be slow to update their
bootloader binaries.

Signed-off-by: Ulf Hansson <ulf.hansson@stericsson.com>
Reviewed-by: Hanumath Prasad <hanumath.prasad@stericsson.com>
Reviewed-by: Srinidhi Kasagar <srinidhi.kasagar@stericsson.com>
Acked-by: Subhash Jadavani <subhashj@codeaurora.org>
Signed-off-by: Chris Ball <cjb@laptop.org>

drivers/mmc/core/core.c

@@ -2246,6 +2246,9 @@ int mmc_card_awake(struct mmc_host *host)
 {
 	int err = -ENOSYS;
 
+	if (host->caps2 & MMC_CAP2_NO_SLEEP_CMD)
+		return 0;
+
 	mmc_bus_get(host);
 
 	if (host->bus_ops && !host->bus_dead && host->bus_ops->awake)
@@ -2261,6 +2264,9 @@ int mmc_card_sleep(struct mmc_host *host)
 {
 	int err = -ENOSYS;
 
+	if (host->caps2 & MMC_CAP2_NO_SLEEP_CMD)
+		return 0;
+
 	mmc_bus_get(host);
 
 	if (host->bus_ops && !host->bus_dead && host->bus_ops->sleep)

include/linux/mmc/host.h

@@ -247,6 +247,7 @@ struct mmc_host {
 #define MMC_CAP2_CACHE_CTRL	(1 << 1)	/* Allow cache control */
 #define MMC_CAP2_POWEROFF_NOTIFY (1 << 2)	/* Notify poweroff supported */
 #define MMC_CAP2_NO_MULTI_READ	(1 << 3)	/* Multiblock reads don't work */
+#define MMC_CAP2_NO_SLEEP_CMD	(1 << 4)	/* Don't allow sleep command */
 
 	mmc_pm_flag_t		pm_caps;	/* supported pm features */
 	unsigned int        power_notify_type;