mmc: esdhc: Implement power management for ESDHC

For FSL ESDHC controllers, when entering sleep the controller will power off,
therefore the registers will lose their values, and the driver should save
the value of registers during suspend and write them back during resume.
Signed-off-by: Jerry Huang <Chang-Ming.Huang@freescale.com>
Signed-off-by: Jiang Yutang <b14898@freescale.com>
Acked-by: Anton Vorontsov <cbouatmailru@gmail.com>
Signed-off-by: Chris Ball <cjb@laptop.org>

drivers/mmc/host/sdhci-of-esdhc.c

@@ -114,6 +114,20 @@ static unsigned int esdhc_of_get_min_clock(struct sdhci_host *host)
 	return pltfm_host->clock / 256 / 16;
 }
 
+#ifdef CONFIG_PM
+static u32 esdhc_proctl;
+static void esdhc_of_suspend(struct sdhci_host *host)
+{
+	esdhc_proctl = sdhci_be32bs_readl(host, SDHCI_HOST_CONTROL);
+}
+
+static void esdhc_of_resume(struct sdhci_host *host)
+{
+	esdhc_of_enable_dma(host);
+	sdhci_be32bs_writel(host, esdhc_proctl, SDHCI_HOST_CONTROL);
+}
+#endif
+
 static struct sdhci_ops sdhci_esdhc_ops = {
 	.read_l = sdhci_be32bs_readl,
 	.read_w = esdhc_readw,
@@ -125,6 +139,10 @@ static struct sdhci_ops sdhci_esdhc_ops = {
 	.enable_dma = esdhc_of_enable_dma,
 	.get_max_clock = esdhc_of_get_max_clock,
 	.get_min_clock = esdhc_of_get_min_clock,
+#ifdef CONFIG_PM
+	.platform_suspend = esdhc_of_suspend,
+	.platform_resume = esdhc_of_resume,
+#endif
 };
 
 static struct sdhci_pltfm_data sdhci_esdhc_pdata = {