mmc: sdhci-esdhc: calculate sdclk divider from controller clock

The SDCLK is divided down from the host controller clock. Host
controller clock may be different from the maximum SDCLK, so
get it from the platform, instead of just using the max SDCLK.
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Acked-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Chris Ball <cjb@laptop.org>

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

@@ -391,6 +391,14 @@ static unsigned int esdhc_pltfm_get_min_clock(struct sdhci_host *host)
 	return clk_get_rate(pltfm_host->clk) / 256 / 16;
 }
 
+static inline void esdhc_pltfm_set_clock(struct sdhci_host *host,
+					 unsigned int clock)
+{
+	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
+
+	esdhc_set_clock(host, clock, clk_get_rate(pltfm_host->clk));
+}
+
 static unsigned int esdhc_pltfm_get_ro(struct sdhci_host *host)
 {
 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
@@ -438,7 +446,7 @@ static const struct sdhci_ops sdhci_esdhc_ops = {
 	.write_l = esdhc_writel_le,
 	.write_w = esdhc_writew_le,
 	.write_b = esdhc_writeb_le,
-	.set_clock = esdhc_set_clock,
+	.set_clock = esdhc_pltfm_set_clock,
 	.get_max_clock = sdhci_pltfm_clk_get_max_clock,
 	.get_min_clock = esdhc_pltfm_get_min_clock,
 	.get_ro = esdhc_pltfm_get_ro,

drivers/mmc/host/sdhci-esdhc.h

@@ -42,7 +42,8 @@
 
 #define ESDHC_HOST_CONTROL_RES	0x05
 
-static inline void esdhc_set_clock(struct sdhci_host *host, unsigned int clock)
+static inline void esdhc_set_clock(struct sdhci_host *host, unsigned int clock,
+				   unsigned int host_clock)
 {
 	int pre_div = 2;
 	int div = 1;
@@ -56,14 +57,14 @@ static inline void esdhc_set_clock(struct sdhci_host *host, unsigned int clock)
 		| ESDHC_CLOCK_MASK);
 	sdhci_writel(host, temp, ESDHC_SYSTEM_CONTROL);
 
-	while (host->max_clk / pre_div / 16 > clock && pre_div < 256)
+	while (host_clock / pre_div / 16 > clock && pre_div < 256)
 		pre_div *= 2;
 
-	while (host->max_clk / pre_div / div > clock && div < 16)
+	while (host_clock / pre_div / div > clock && div < 16)
 		div++;
 
 	dev_dbg(mmc_dev(host->mmc), "desired SD clock: %d, actual: %d\n",
-		clock, host->max_clk / pre_div / div);
+		clock, host_clock / pre_div / div);
 
 	pre_div >>= 1;
 	div--;

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

@@ -200,7 +200,7 @@ static void esdhc_of_set_clock(struct sdhci_host *host, unsigned int clock)
 	}
 
 	/* Set the clock */
-	esdhc_set_clock(host, clock);
+	esdhc_set_clock(host, clock, host->max_clk);
 }
 
 #ifdef CONFIG_PM