[PATCH 1/3] serial: mxs-auart: rework clock handling in mxs_get_clks and probe

[Rosen Penev]

Use devm_clk_get_enabled for the AHB clock so its enable/disable
lifetime is managed by the driver model. Move the mod clock
(clk) prepare_enable out of mxs_get_clks and into probe so that
clk_set_rate is called while the clock is still disabled, avoiding
CLK_SET_RATE_GATE failures. Clean up the error labels accordingly.

Assisted-by: opencode:big-pickle
Signed-off-by: Rosen Penev <rosenp at gmail.com>
---
 drivers/tty/serial/mxs-auart.c | 47 ++++++++++++----------------------
 1 file changed, 17 insertions(+), 30 deletions(-)

diff --git a/drivers/tty/serial/mxs-auart.c b/drivers/tty/serial/mxs-auart.c
index 697318dbb146..1390fa000a5b 100644
--- a/drivers/tty/serial/mxs-auart.c
+++ b/drivers/tty/serial/mxs-auart.c
@@ -1470,34 +1470,22 @@ static int mxs_get_clks(struct mxs_auart_port *s,
 		return PTR_ERR(s->clk);
 	}
 
-	s->clk_ahb = devm_clk_get(s->dev, "ahb");
+	s->clk_ahb = devm_clk_get_enabled(s->dev, "ahb");
 	if (IS_ERR(s->clk_ahb)) {
 		dev_err(s->dev, "Failed to get \"ahb\" clk\n");
 		return PTR_ERR(s->clk_ahb);
 	}
 
-	err = clk_prepare_enable(s->clk_ahb);
-	if (err) {
-		dev_err(s->dev, "Failed to enable ahb_clk!\n");
-		return err;
-	}
-
+	/*
+	 * Set mod clock rate while it is still disabled so
+	 * CLK_SET_RATE_GATE does not cause clk_set_rate to fail.
+	 * The mod clock will be enabled in mxs_auart_startup()
+	 * and in probe after mxs_get_clks returns.
+	 */
 	err = clk_set_rate(s->clk, clk_get_rate(s->clk_ahb));
-	if (err) {
+	if (err)
 		dev_err(s->dev, "Failed to set rate!\n");
-		goto disable_clk_ahb;
-	}
 
-	err = clk_prepare_enable(s->clk);
-	if (err) {
-		dev_err(s->dev, "Failed to enable clk!\n");
-		goto disable_clk_ahb;
-	}
-
-	return 0;
-
-disable_clk_ahb:
-	clk_disable_unprepare(s->clk_ahb);
 	return err;
 }
 
@@ -1604,17 +1592,21 @@ static int mxs_auart_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
+	ret = clk_prepare_enable(s->clk);
+	if (ret)
+		return ret;
+
 	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	if (!r) {
 		ret = -ENXIO;
-		goto out_disable_clks;
+		goto out_disable_clk;
 	}
 
 	s->port.mapbase = r->start;
 	s->port.membase = ioremap(r->start, resource_size(r));
 	if (!s->port.membase) {
 		ret = -ENOMEM;
-		goto out_disable_clks;
+		goto out_disable_clk;
 	}
 	s->port.ops = &mxs_auart_ops;
 	s->port.iotype = UPIO_MEM;
@@ -1681,11 +1673,8 @@ static int mxs_auart_probe(struct platform_device *pdev)
 out_iounmap:
 	iounmap(s->port.membase);
 
-out_disable_clks:
-	if (is_asm9260_auart(s)) {
-		clk_disable_unprepare(s->clk);
-		clk_disable_unprepare(s->clk_ahb);
-	}
+out_disable_clk:
+	clk_disable_unprepare(s->clk);
 	return ret;
 }
 
@@ -1697,10 +1686,8 @@ static void mxs_auart_remove(struct platform_device *pdev)
 	auart_port[pdev->id] = NULL;
 	mxs_auart_free_gpio_irq(s);
 	iounmap(s->port.membase);
-	if (is_asm9260_auart(s)) {
+	if (is_asm9260_auart(s))
 		clk_disable_unprepare(s->clk);
-		clk_disable_unprepare(s->clk_ahb);
-	}
 }
 
 static struct platform_driver mxs_auart_driver = {
-- 
2.54.0