[PATCH RFC 2/2] clk: meson: g12a: add suspend-resume hooks

[Neil Armstrong]

Add suspend and resume hooks used to refresh the CPU clock tree
when resuming from suspend, in the case where the PSCI firmware
alters the clock tree.

In the Amlogic G12A suspend/resume case, the PSCI firmware will
alter the Fixed PLL dyn tree when entering with the CPU clock from
this same tree, but using a different path to achieve the same rate.

Signed-off-by: Neil Armstrong <narmstrong@xxxxxxxxxxxx>
---
 drivers/clk/meson/g12a.c | 71 +++++++++++++++++++++++++++++++++++-----
 1 file changed, 63 insertions(+), 8 deletions(-)

diff --git a/drivers/clk/meson/g12a.c b/drivers/clk/meson/g12a.c
index b3af61cc6fb9..9f6f634225b7 100644
--- a/drivers/clk/meson/g12a.c
+++ b/drivers/clk/meson/g12a.c
@@ -4992,6 +4992,19 @@ static int meson_g12b_dvfs_setup(struct platform_device *pdev)
 	return 0;
 }
 
+static int meson_g12b_resume(struct device *dev)
+{
+	u32 ret;
+
+	ret = clk_invalidate_rate(
+			__clk_lookup(clk_hw_get_name(&g12b_cpu_clk.hw)));
+	if (ret)
+		return ret;
+
+	return clk_invalidate_rate(
+			__clk_lookup(clk_hw_get_name(&g12b_cpub_clk.hw)));
+}
+
 static int meson_g12a_dvfs_setup(struct platform_device *pdev)
 {
 	struct clk_hw **hws = g12a_hw_onecell_data.hws;
@@ -5024,34 +5037,68 @@ static int meson_g12a_dvfs_setup(struct platform_device *pdev)
 	return 0;
 }
 
+static int meson_g12a_resume(struct device *dev)
+{
+	return clk_invalidate_rate(
+			__clk_lookup(clk_hw_get_name(&g12a_cpu_clk.hw)));
+}
+
 struct meson_g12a_data {
 	const struct meson_eeclkc_data eeclkc_data;
 	int (*dvfs_setup)(struct platform_device *pdev);
+	int (*resume)(struct device *dev);
 };
 
+static const struct
+meson_g12a_data *meson_g12a_get_data(struct device *dev)
+{
+	const struct meson_eeclkc_data *eeclkc_data =
+			of_device_get_match_data(dev);
+
+	if (!eeclkc_data)
+		return ERR_PTR(-EINVAL);
+
+	return container_of(eeclkc_data, struct meson_g12a_data,
+			    eeclkc_data);
+}
+
 static int meson_g12a_probe(struct platform_device *pdev)
 {
-	const struct meson_eeclkc_data *eeclkc_data;
-	const struct meson_g12a_data *g12a_data;
 	int ret;
+	const struct meson_g12a_data *g12a_data =
+			meson_g12a_get_data(&pdev->dev);
 
-	eeclkc_data = of_device_get_match_data(&pdev->dev);
-	if (!eeclkc_data)
-		return -EINVAL;
+	if (IS_ERR(g12a_data))
+		return PTR_ERR(g12a_data);
 
 	ret = meson_eeclkc_probe(pdev);
 	if (ret)
 		return ret;
 
-	g12a_data = container_of(eeclkc_data, struct meson_g12a_data,
-				 eeclkc_data);
-
 	if (g12a_data->dvfs_setup)
 		return g12a_data->dvfs_setup(pdev);
 
 	return 0;
 }
 
+static int __maybe_unused g12a_clkc_suspend(struct device *dev)
+{
+	return 0;
+}
+
+static int __maybe_unused g12a_clkc_resume(struct device *dev)
+{
+	const struct meson_g12a_data *g12a_data = meson_g12a_get_data(dev);
+
+	if (IS_ERR(g12a_data))
+		return PTR_ERR(g12a_data);
+
+	if (g12a_data->resume)
+		return g12a_data->resume(dev);
+
+	return 0;
+}
+
 static const struct meson_g12a_data g12a_clkc_data = {
 	.eeclkc_data = {
 		.regmap_clks = g12a_clk_regmaps,
@@ -5061,6 +5108,7 @@ static const struct meson_g12a_data g12a_clkc_data = {
 		.init_count = ARRAY_SIZE(g12a_init_regs),
 	},
 	.dvfs_setup = meson_g12a_dvfs_setup,
+	.resume = meson_g12a_resume,
 };
 
 static const struct meson_g12a_data g12b_clkc_data = {
@@ -5070,6 +5118,7 @@ static const struct meson_g12a_data g12b_clkc_data = {
 		.hw_onecell_data = &g12b_hw_onecell_data,
 	},
 	.dvfs_setup = meson_g12b_dvfs_setup,
+	.resume = meson_g12b_resume,
 };
 
 static const struct meson_g12a_data sm1_clkc_data = {
@@ -5079,6 +5128,11 @@ static const struct meson_g12a_data sm1_clkc_data = {
 		.hw_onecell_data = &sm1_hw_onecell_data,
 	},
 	.dvfs_setup = meson_g12a_dvfs_setup,
+	.resume = meson_g12a_resume,
+};
+
+static const struct dev_pm_ops g12a_clkc_dev_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(g12a_clkc_suspend, g12a_clkc_resume)
 };
 
 static const struct of_device_id clkc_match_table[] = {
@@ -5102,6 +5156,7 @@ static struct platform_driver g12a_driver = {
 	.driver		= {
 		.name	= "g12a-clkc",
 		.of_match_table = clkc_match_table,
+		.pm	= &g12a_clkc_dev_pm_ops,
 	},
 };
 
-- 
2.22.0