[PATCH v4 2/3] clk: samsung: Extract parent clock enabling to common function

[Sam Protsenko <semen.protsenko@xxxxxxxxxx>]

Extract parent clock enabling from exynos_arm64_register_cmu() to
dedicated function.

Tested-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
Signed-off-by: Sam Protsenko <semen.protsenko@xxxxxxxxxx>
---
Changes in v4:
  - Rebased on top of krzk/linux.git/for-next tree
  - Reworked exynos_arm64_enable_bus_clk() user code to only print an
    error message if that function fails

Changes in v3:
  - Rebased on top of latest soc/for-next tree
  - Added Marek's Acked-by tag

Changes in v2:
  - Rebased on top of latest soc/for-next tree
  - Improved English in kernel doc comment
  - Added clk_prepare_enable() return value check
  - Added exynos_arm64_enable_bus_clk() check in
    exynos_arm64_register_cmu()
  - Changed the commit message to reflect code changes

 drivers/clk/samsung/clk-exynos-arm64.c | 57 ++++++++++++++++++--------
 1 file changed, 41 insertions(+), 16 deletions(-)

diff --git a/drivers/clk/samsung/clk-exynos-arm64.c b/drivers/clk/samsung/clk-exynos-arm64.c
index b921b9a1134a..60fd820c14aa 100644
--- a/drivers/clk/samsung/clk-exynos-arm64.c
+++ b/drivers/clk/samsung/clk-exynos-arm64.c
@@ -56,6 +56,37 @@ static void __init exynos_arm64_init_clocks(struct device_node *np,
 	iounmap(reg_base);
 }
 
+/**
+ * exynos_arm64_enable_bus_clk - Enable parent clock of specified CMU
+ *
+ * @dev:	Device object; may be NULL if this function is not being
+ *		called from platform driver probe function
+ * @np:		CMU device tree node
+ * @cmu:	CMU data
+ *
+ * Keep CMU parent clock running (needed for CMU registers access).
+ *
+ * Return: 0 on success or a negative error code on failure.
+ */
+static int __init exynos_arm64_enable_bus_clk(struct device *dev,
+		struct device_node *np, const struct samsung_cmu_info *cmu)
+{
+	struct clk *parent_clk;
+
+	if (!cmu->clk_name)
+		return 0;
+
+	if (dev)
+		parent_clk = clk_get(dev, cmu->clk_name);
+	else
+		parent_clk = of_clk_get_by_name(np, cmu->clk_name);
+
+	if (IS_ERR(parent_clk))
+		return PTR_ERR(parent_clk);
+
+	return clk_prepare_enable(parent_clk);
+}
+
 /**
  * exynos_arm64_register_cmu - Register specified Exynos CMU domain
  * @dev:	Device object; may be NULL if this function is not being
@@ -72,22 +103,16 @@ static void __init exynos_arm64_init_clocks(struct device_node *np,
 void __init exynos_arm64_register_cmu(struct device *dev,
 		struct device_node *np, const struct samsung_cmu_info *cmu)
 {
-	/* Keep CMU parent clock running (needed for CMU registers access) */
-	if (cmu->clk_name) {
-		struct clk *parent_clk;
-
-		if (dev)
-			parent_clk = clk_get(dev, cmu->clk_name);
-		else
-			parent_clk = of_clk_get_by_name(np, cmu->clk_name);
-
-		if (IS_ERR(parent_clk)) {
-			pr_err("%s: could not find bus clock %s; err = %ld\n",
-			       __func__, cmu->clk_name, PTR_ERR(parent_clk));
-		} else {
-			clk_prepare_enable(parent_clk);
-		}
-	}
+	int err;
+
+	/*
+	 * Try to boot even if the parent clock enablement fails, as it might be
+	 * already enabled by bootloader.
+	 */
+	err = exynos_arm64_enable_bus_clk(dev, np, cmu);
+	if (err)
+		pr_err("%s: could not enable bus clock %s; err = %d\n",
+		       __func__, cmu->clk_name, err);
 
 	exynos_arm64_init_clocks(np, cmu->clk_regs, cmu->nr_clk_regs);
 	samsung_cmu_register_one(np, cmu);
-- 
2.39.2