clk: mvebu: armada-37xx-periph: add suspend/resume support

Add suspend/resume hooks in Armada 37xx peripheral clocks driver to
handle S2RAM operations.

One can think that these hooks are useless by comparing the register
values before and after a suspend/resume cycle: they will look the same
anyway. This is because of some scripts executed by the Cortex-M3 core
during ATF operations to init both the clocks and the DDR. These values
could be modified by the BL33 stage or by Linux itself and should be
preserved.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

1 files changed, 43 insertions, 0 deletions

diff --git a/drivers/clk/mvebu/armada-37xx-periph.c b/drivers/clk/mvebu/armada-37xx-periph.c
index 78048c2e3774..1f1cff428d78 100644
--- a/drivers/clk/mvebu/armada-37xx-periph.c
+++ b/drivers/clk/mvebu/armada-37xx-periph.c
@@ -57,6 +57,14 @@ struct clk_periph_driver_data {
         struct clk_hw_onecell_data *hw_data;
         spinlock_t lock;
         void __iomem *reg;
+
+        /* Storage registers for suspend/resume operations */
+        u32 tbg_sel;
+        u32 div_sel0;
+        u32 div_sel1;
+        u32 div_sel2;
+        u32 clk_sel;
+        u32 clk_dis;
 };
 
 struct clk_double_div {
@@ -673,6 +681,40 @@ static int armada_3700_add_composite_clk(const struct clk_periph_data *data,
         return PTR_ERR_OR_ZERO(*hw);
 }
 
+static int __maybe_unused armada_3700_periph_clock_suspend(struct device *dev)
+{
+        struct clk_periph_driver_data *data = dev_get_drvdata(dev);
+
+        data->tbg_sel = readl(data->reg + TBG_SEL);
+        data->div_sel0 = readl(data->reg + DIV_SEL0);
+        data->div_sel1 = readl(data->reg + DIV_SEL1);
+        data->div_sel2 = readl(data->reg + DIV_SEL2);
+        data->clk_sel = readl(data->reg + CLK_SEL);
+        data->clk_dis = readl(data->reg + CLK_DIS);
+
+        return 0;
+}
+
+static int __maybe_unused armada_3700_periph_clock_resume(struct device *dev)
+{
+        struct clk_periph_driver_data *data = dev_get_drvdata(dev);
+
+        /* Follow the same order than what the Cortex-M3 does (ATF code) */
+        writel(data->clk_dis, data->reg + CLK_DIS);
+        writel(data->div_sel0, data->reg + DIV_SEL0);
+        writel(data->div_sel1, data->reg + DIV_SEL1);
+        writel(data->div_sel2, data->reg + DIV_SEL2);
+        writel(data->tbg_sel, data->reg + TBG_SEL);
+        writel(data->clk_sel, data->reg + CLK_SEL);
+
+        return 0;
+}
+
+static const struct dev_pm_ops armada_3700_periph_clock_pm_ops = {
+        SET_SYSTEM_SLEEP_PM_OPS(armada_3700_periph_clock_suspend,
+                                armada_3700_periph_clock_resume)
+};
+
 static int armada_3700_periph_clock_probe(struct platform_device *pdev)
 {
         struct clk_periph_driver_data *driver_data;
@@ -748,6 +790,7 @@ static struct platform_driver armada_3700_periph_clock_driver = {
         .driver         = {
                 .name   = "marvell-armada-3700-periph-clock",
                 .of_match_table = armada_3700_periph_clock_of_match,
+                .pm     = &armada_3700_periph_clock_pm_ops,
         },
 };