clk: zynq: Add dummy clock enable function

A lot of Xilinx drivers are checking -ENOSYS which means that clock driver
doesn't have enable function. Remove this checking from drivers and create
dummy enable function as was done for clk_fixed_rate driver by
commit 6bf6d81c11 ("clk: fixed_rate: add dummy enable() function").

Signed-off-by: Michal Simek <michal.simek@xilinx.com>

drivers/clk/clk_zynq.c

@@ -444,11 +444,21 @@ static ulong zynq_clk_get_rate(struct clk *clk)
 }
 #endif
 
+static int dummy_enable(struct clk *clk)
+{
+	/*
+	 * Add implementation but by default all clocks are enabled
+	 * after power up which is only one supported case now.
+	 */
+	return 0;
+}
+
 static struct clk_ops zynq_clk_ops = {
 	.get_rate = zynq_clk_get_rate,
 #ifndef CONFIG_SPL_BUILD
 	.set_rate = zynq_clk_set_rate,
 #endif
+	.enable = dummy_enable,
 };
 
 static int zynq_clk_probe(struct udevice *dev)

drivers/mmc/zynq_sdhci.c

@@ -577,7 +577,7 @@ static int arasan_sdhci_probe(struct udevice *dev)
 	debug("%s: CLK %ld\n", __func__, clock);
 
 	ret = clk_enable(&clk);
-	if (ret && ret != -ENOSYS) {
+	if (ret) {
 		dev_err(dev, "failed to enable clock\n");
 		return ret;
 	}

drivers/net/zynq_gem.c

@@ -477,13 +477,13 @@ static int zynq_gem_init(struct udevice *dev)
 	}
 
 	ret = clk_set_rate(&priv->clk, clk_rate);
-	if (IS_ERR_VALUE(ret) && ret != (unsigned long)-ENOSYS) {
+	if (IS_ERR_VALUE(ret)) {
 		dev_err(dev, "failed to set tx clock rate\n");
 		return ret;
 	}
 
 	ret = clk_enable(&priv->clk);
-	if (ret && ret != -ENOSYS) {
+	if (ret) {
 		dev_err(dev, "failed to enable tx clock\n");
 		return ret;
 	}

drivers/serial/serial_zynq.c

@@ -127,7 +127,7 @@ static int zynq_serial_setbrg(struct udevice *dev, int baudrate)
 	debug("%s: CLK %ld\n", __func__, clock);
 
 	ret = clk_enable(&clk);
-	if (ret && ret != -ENOSYS) {
+	if (ret) {
 		dev_err(dev, "failed to enable clock\n");
 		return ret;
 	}

drivers/spi/zynq_qspi.c

@@ -193,7 +193,7 @@ static int zynq_qspi_probe(struct udevice *bus)
 	}
 
 	ret = clk_enable(&clk);
-	if (ret && ret != -ENOSYS) {
+	if (ret) {
 		dev_err(bus, "failed to enable clock\n");
 		return ret;
 	}

drivers/spi/zynq_spi.c

@@ -143,7 +143,7 @@ static int zynq_spi_probe(struct udevice *bus)
 	}
 
 	ret = clk_enable(&clk);
-	if (ret && ret != -ENOSYS) {
+	if (ret) {
 		dev_err(bus, "failed to enable clock\n");
 		return ret;
 	}

drivers/spi/zynqmp_gqspi.c

@@ -373,7 +373,7 @@ static int zynqmp_qspi_probe(struct udevice *bus)
 	debug("%s: CLK %ld\n", __func__, clock);
 
 	ret = clk_enable(&clk);
-	if (ret && ret != -ENOSYS) {
+	if (ret) {
 		dev_err(bus, "failed to enable clock\n");
 		return ret;
 	}

drivers/watchdog/xilinx_wwdt.c

@@ -90,9 +90,8 @@ static int xlnx_wwdt_start(struct udevice *dev, u64 timeout, ulong flags)
 	/* Calculate timeout count */
 	count = timeout * clock_f;
 
-	/* clk_enable will return -ENOSYS when it is not implemented */
 	ret = clk_enable(&wdt->clk);
-	if (ret && ret != -ENOSYS) {
+	if (ret) {
 		dev_err(dev, "failed to enable clock\n");
 		return ret;
 	}