mmc: davinci: Add support for set_power callback

Some devices connected to the MMC bus are power controlled by external
means. For instance, an SDIO device may be powered down/up by an
external gpio line.

In order to avoid toggling power from within the MMC host driver, add a
set_power callback function, which will be called by set_ios upon
powering down/up.
Signed-off-by: NIdo Yariv <ido@wizery.com>
CC: Chris Ball <cjb@laptop.org>
Acked-by: NChris Ball <cjb@laptop.org>
Signed-off-by: NSekhar Nori <nsekhar@ti.com>

arch/arm/mach-davinci/include/mach/mmc.h

@@ -12,6 +12,9 @@ struct davinci_mmc_config {
 	/* get_cd()/get_wp() may sleep */
 	int	(*get_cd)(int module);
 	int	(*get_ro)(int module);
+
+	void	(*set_power)(int module, bool on);
+
 	/* wires == 0 is equivalent to wires == 4 (4-bit parallel) */
 	u8	wires;
 

drivers/mmc/host/davinci_mmc.c

@@ -807,12 +807,25 @@ static void calculate_clk_divider(struct mmc_host *mmc, struct mmc_ios *ios)
 static void mmc_davinci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
 {
 	struct mmc_davinci_host *host = mmc_priv(mmc);
+	struct platform_device *pdev = to_platform_device(mmc->parent);
+	struct davinci_mmc_config *config = pdev->dev.platform_data;
 
 	dev_dbg(mmc_dev(host->mmc),
 		"clock %dHz busmode %d powermode %d Vdd %04x\n",
 		ios->clock, ios->bus_mode, ios->power_mode,
 		ios->vdd);
 
+	switch (ios->power_mode) {
+	case MMC_POWER_OFF:
+		if (config && config->set_power)
+			config->set_power(pdev->id, false);
+		break;
+	case MMC_POWER_UP:
+		if (config && config->set_power)
+			config->set_power(pdev->id, true);
+		break;
+	}
+
 	switch (ios->bus_width) {
 	case MMC_BUS_WIDTH_8:
 		dev_dbg(mmc_dev(host->mmc), "Enabling 8 bit mode\n");