[PATCH v2 1/2] i2c: uniphier: add suspend / resume support

[Masahiro Yamada]

When resuming, set up registers that have been lost in the sleep state.
Also, add clock handling in the resume / suspend hooks.

Signed-off-by: Masahiro Yamada <yamada.masah...@socionext.com>
---

Changes in v2:
  - Fix define but not used warning

 drivers/i2c/busses/i2c-uniphier.c | 40 ++++++++++++++++++++++++++++++++++-----
 1 file changed, 35 insertions(+), 5 deletions(-)

diff --git a/drivers/i2c/busses/i2c-uniphier.c 
b/drivers/i2c/busses/i2c-uniphier.c
index 777c0fe93653..bb181b088291 100644
--- a/drivers/i2c/busses/i2c-uniphier.c
+++ b/drivers/i2c/busses/i2c-uniphier.c
@@ -53,6 +53,7 @@ struct uniphier_i2c_priv {
        void __iomem *membase;
        struct clk *clk;
        unsigned int busy_cnt;
+       unsigned int clk_cycle;
 };
 
 static irqreturn_t uniphier_i2c_interrupt(int irq, void *dev_id)
@@ -316,13 +317,13 @@ static struct i2c_bus_recovery_info 
uniphier_i2c_bus_recovery_info = {
        .unprepare_recovery = uniphier_i2c_unprepare_recovery,
 };
 
-static void uniphier_i2c_hw_init(struct uniphier_i2c_priv *priv,
-                                u32 bus_speed, unsigned long clk_rate)
+static void uniphier_i2c_hw_init(struct uniphier_i2c_priv *priv)
 {
+       unsigned int cyc = priv->clk_cycle;
+
        uniphier_i2c_reset(priv, true);
 
-       writel((clk_rate / bus_speed / 2 << 16) | (clk_rate / bus_speed),
-              priv->membase + UNIPHIER_I2C_CLK);
+       writel((cyc / 2 << 16) | cyc, priv->membase + UNIPHIER_I2C_CLK);
 
        uniphier_i2c_reset(priv, false);
 }
@@ -376,6 +377,7 @@ static int uniphier_i2c_probe(struct platform_device *pdev)
                goto disable_clk;
        }
 
+       priv->clk_cycle = clk_rate / bus_speed;
        init_completion(&priv->comp);
        priv->adap.owner = THIS_MODULE;
        priv->adap.algo = &uniphier_i2c_algo;
@@ -386,7 +388,7 @@ static int uniphier_i2c_probe(struct platform_device *pdev)
        i2c_set_adapdata(&priv->adap, priv);
        platform_set_drvdata(pdev, priv);
 
-       uniphier_i2c_hw_init(priv, bus_speed, clk_rate);
+       uniphier_i2c_hw_init(priv);
 
        ret = devm_request_irq(dev, irq, uniphier_i2c_interrupt, 0, pdev->name,
                               priv);
@@ -413,6 +415,33 @@ static int uniphier_i2c_remove(struct platform_device 
*pdev)
        return 0;
 }
 
+static int __maybe_unused uniphier_i2c_suspend(struct device *dev)
+{
+       struct uniphier_i2c_priv *priv = dev_get_drvdata(dev);
+
+       clk_disable_unprepare(priv->clk);
+
+       return 0;
+}
+
+static int __maybe_unused uniphier_i2c_resume(struct device *dev)
+{
+       struct uniphier_i2c_priv *priv = dev_get_drvdata(dev);
+       int ret;
+
+       ret = clk_prepare_enable(priv->clk);
+       if (ret)
+               return ret;
+
+       uniphier_i2c_hw_init(priv);
+
+       return 0;
+}
+
+static const struct dev_pm_ops uniphier_i2c_pm_ops = {
+       SET_SYSTEM_SLEEP_PM_OPS(uniphier_i2c_suspend, uniphier_i2c_resume)
+};
+
 static const struct of_device_id uniphier_i2c_match[] = {
        { .compatible = "socionext,uniphier-i2c" },
        { /* sentinel */ }
@@ -425,6 +454,7 @@ static struct platform_driver uniphier_i2c_drv = {
        .driver = {
                .name  = "uniphier-i2c",
                .of_match_table = uniphier_i2c_match,
+               .pm = &uniphier_i2c_pm_ops,
        },
 };
 module_platform_driver(uniphier_i2c_drv);
-- 
2.7.4