[PATCH v2 15/21] serial_lpuart: add clock enable if CONFIG_CLK is defined

[Giulio Benetti]

This driver assumes that lpuart clock is already enabled before probing
but using DM only lpuart won't be automatically enabled so add
clk_enable() when probing if CONFIG_CLK is defined. If clock is not
found, because DM is not used, let's emit a warning and proceed, because
serial clock could also be already enabled by non DM code. If clock is
found but cna't be enabled then return with error.

Signed-off-by: Giulio Benetti <giulio.benetti at benettiengineering.com>
---
V1->V2:
* moved error as warning if clk not found
---
 drivers/serial/serial_lpuart.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/serial/serial_lpuart.c b/drivers/serial/serial_lpuart.c
index 4b0a964d1b..b2ec56172e 100644
--- a/drivers/serial/serial_lpuart.c
+++ b/drivers/serial/serial_lpuart.c
@@ -483,6 +483,22 @@ static int lpuart_serial_pending(struct udevice *dev, bool input)
 
 static int lpuart_serial_probe(struct udevice *dev)
 {
+#if CONFIG_IS_ENABLED(CLK)
+	struct clk per_clk;
+	int ret;
+
+	ret = clk_get_by_name(dev, "per", &per_clk);
+	if (!ret) {
+		ret = clk_enable(&per_clk);
+		if (ret) {
+			dev_err(dev, "Failed to get per clk: %d\n", ret);
+			return ret;
+		}
+	} else {
+		dev_warn(dev, "Failed to get per clk: %d\n",  ret);
+	}
+#endif
+
 	if (is_lpuart32(dev))
 		return _lpuart32_serial_init(dev);
 	else
-- 
2.20.1