[PATCH v7 07/11] clk: imx: scu: add suspend/resume support

[Dong Aisheng]

Clock state will be lost when its power domain is completely off
during system suspend/resume. So we save and restore the state
accordingly in suspend/resume callback.

Cc: Shawn Guo <shawnguo at kernel.org>
Cc: Sascha Hauer <kernel at pengutronix.de>
Cc: Michael Turquette <mturquette at baylibre.com>
Reviewed-by: Stephen Boyd <sboyd at kernel.org>
Signed-off-by: Dong Aisheng <aisheng.dong at nxp.com>
---
ChangeLog:
v6->v7:
 * no changes
v5:
 * make suspend/resume function static
v4: no changes
v3: new patch
---
 drivers/clk/imx/clk-scu.c | 49 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)

diff --git a/drivers/clk/imx/clk-scu.c b/drivers/clk/imx/clk-scu.c
index f5dc6731a217..229a290ca5b6 100644
--- a/drivers/clk/imx/clk-scu.c
+++ b/drivers/clk/imx/clk-scu.c
@@ -45,6 +45,10 @@ struct clk_scu {
 	struct clk_hw hw;
 	u16 rsrc_id;
 	u8 clk_type;
+
+	/* for state save&restore */
+	bool is_enabled;
+	u32 rate;
 };
 
 /*
@@ -430,6 +434,9 @@ struct clk_hw *__imx_clk_scu(struct device *dev, const char *name,
 		hw = ERR_PTR(ret);
 	}
 
+	if (dev)
+		dev_set_drvdata(dev, clk);
+
 	return hw;
 }
 
@@ -486,10 +493,52 @@ static int imx_clk_scu_probe(struct platform_device *pdev)
 	return 0;
 }
 
+static int __maybe_unused imx_clk_scu_suspend(struct device *dev)
+{
+	struct clk_scu *clk = dev_get_drvdata(dev);
+
+	clk->rate = clk_hw_get_rate(&clk->hw);
+	clk->is_enabled = clk_hw_is_enabled(&clk->hw);
+
+	if (clk->rate)
+		dev_dbg(dev, "save rate %d\n", clk->rate);
+
+	if (clk->is_enabled)
+		dev_dbg(dev, "save enabled state\n");
+
+	return 0;
+}
+
+static int __maybe_unused imx_clk_scu_resume(struct device *dev)
+{
+	struct clk_scu *clk = dev_get_drvdata(dev);
+	int ret = 0;
+
+	if (clk->rate) {
+		ret = clk_scu_set_rate(&clk->hw, clk->rate, 0);
+		dev_dbg(dev, "restore rate %d %s\n", clk->rate,
+			!ret ? "success" : "failed");
+	}
+
+	if (clk->is_enabled) {
+		ret = clk_scu_prepare(&clk->hw);
+		dev_dbg(dev, "restore enabled state %s\n",
+			!ret ? "success" : "failed");
+	}
+
+	return ret;
+}
+
+static const struct dev_pm_ops imx_clk_scu_pm_ops = {
+	SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(imx_clk_scu_suspend,
+				      imx_clk_scu_resume)
+};
+
 static struct platform_driver imx_clk_scu_driver = {
 	.driver = {
 		.name = "imx-scu-clk",
 		.suppress_bind_attrs = true,
+		.pm = &imx_clk_scu_pm_ops,
 	},
 	.probe = imx_clk_scu_probe,
 };
-- 
2.23.0