mmc: zynq: Determine base clock frequency via clock framework

The zynq_sdhci controller driver use CONFIG_ZYNQ_SDHCI_MAX_FREQ as base
clock frequency but this clock is not fixed and depends on the hardware
configuration. Additionally the value of CONFIG_ZYNQ_SDHCI_MAX_FREQ
doesn't match the real base clock frequency of SDIO_FREQ. Use the clock
framework to determine the frequency at run time.

Signed-off-by: Stefan Herbrechtsmeier <stefan.herbrechtsmeier@weidmueller.com>
Reviewed-by: Jaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>

drivers/mmc/zynq_sdhci.c

@@ -6,6 +6,7 @@
  * SPDX-License-Identifier:	GPL-2.0+
  */
 
+#include <clk.h>
 #include <common.h>
 #include <dm.h>
 #include <fdtdec.h>
@@ -27,8 +28,29 @@ static int arasan_sdhci_probe(struct udevice *dev)
 	struct arasan_sdhci_plat *plat = dev_get_platdata(dev);
 	struct mmc_uclass_priv *upriv = dev_get_uclass_priv(dev);
 	struct sdhci_host *host = dev_get_priv(dev);
+	struct clk clk;
+	unsigned long clock;
 	int ret;
 
+	ret = clk_get_by_index(dev, 0, &clk);
+	if (ret < 0) {
+		dev_err(dev, "failed to get clock\n");
+		return ret;
+	}
+
+	clock = clk_get_rate(&clk);
+	if (IS_ERR_VALUE(clock)) {
+		dev_err(dev, "failed to get rate\n");
+		return clock;
+	}
+	debug("%s: CLK %ld\n", __func__, clock);
+
+	ret = clk_enable(&clk);
+	if (ret && ret != -ENOSYS) {
+		dev_err(dev, "failed to enable clock\n");
+		return ret;
+	}
+
 	host->quirks = SDHCI_QUIRK_WAIT_SEND_CMD |
 		       SDHCI_QUIRK_BROKEN_R1B;
 
@@ -36,9 +58,9 @@ static int arasan_sdhci_probe(struct udevice *dev)
 	host->quirks |= SDHCI_QUIRK_NO_HISPD_BIT;
 #endif
 
-	host->max_clk = CONFIG_ZYNQ_SDHCI_MAX_FREQ;
+	host->max_clk = clock;
 
-	ret = sdhci_setup_cfg(&plat->cfg, host, 0,
+	ret = sdhci_setup_cfg(&plat->cfg, host, CONFIG_ZYNQ_SDHCI_MAX_FREQ,
 			      CONFIG_ZYNQ_SDHCI_MIN_FREQ);
 	host->mmc = &plat->mmc;
 	if (ret)