i2c: tegra: Move clk_prepare/clk_set_rate to probe

Currently the i2c-tegra bus driver prepares, enables
and set_rates its clocks separately for each transfer.
This causes locking problems when doing I2C transfers
from clock notifiers; see
http://lists.infradead.org/pipermail/linux-arm-kernel/2014-July/268653.html

This patch moves clk_prepare/unprepare and clk_set_rate calls to
the probe function, leaving only clk_enable/disable to be
done on each transfer. This solves the locking issue.

Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
Reviewed-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
index 87d0371..efba1eb 100644 (file)
--- a/drivers/i2c/busses/i2c-tegra.c
+++ b/drivers/i2c/busses/i2c-tegra.c
@@ -380,34 +380,33 @@ static inline int tegra_i2c_clock_enable(struct tegra_i2c_dev *i2c_dev)
 {
        int ret;
        if (!i2c_dev->hw->has_single_clk_source) {
-               ret = clk_prepare_enable(i2c_dev->fast_clk);
+               ret = clk_enable(i2c_dev->fast_clk);
                if (ret < 0) {
                        dev_err(i2c_dev->dev,
                                "Enabling fast clk failed, err %d\n", ret);
                        return ret;
                }
        }
-       ret = clk_prepare_enable(i2c_dev->div_clk);
+       ret = clk_enable(i2c_dev->div_clk);
        if (ret < 0) {
                dev_err(i2c_dev->dev,
                        "Enabling div clk failed, err %d\n", ret);
-               clk_disable_unprepare(i2c_dev->fast_clk);
+               clk_disable(i2c_dev->fast_clk);
        }
        return ret;
 }
 
 static inline void tegra_i2c_clock_disable(struct tegra_i2c_dev *i2c_dev)
 {
-       clk_disable_unprepare(i2c_dev->div_clk);
+       clk_disable(i2c_dev->div_clk);
        if (!i2c_dev->hw->has_single_clk_source)
-               clk_disable_unprepare(i2c_dev->fast_clk);
+               clk_disable(i2c_dev->fast_clk);
 }
 
 static int tegra_i2c_init(struct tegra_i2c_dev *i2c_dev)
 {
        u32 val;
        int err = 0;
-       int clk_multiplier = I2C_CLK_MULTIPLIER_STD_FAST_MODE;
        u32 clk_divisor;
 
        err = tegra_i2c_clock_enable(i2c_dev);
@@ -428,9 +427,6 @@ static int tegra_i2c_init(struct tegra_i2c_dev *i2c_dev)
        i2c_writel(i2c_dev, val, I2C_CNFG);
        i2c_writel(i2c_dev, 0, I2C_INT_MASK);
 
-       clk_multiplier *= (i2c_dev->hw->clk_divisor_std_fast_mode + 1);
-       clk_set_rate(i2c_dev->div_clk, i2c_dev->bus_clk_rate * clk_multiplier);
-
        /* Make sure clock divisor programmed correctly */
        clk_divisor = i2c_dev->hw->clk_divisor_hs_mode;
        clk_divisor |= i2c_dev->hw->clk_divisor_std_fast_mode <<
@@ -712,6 +708,7 @@ static int tegra_i2c_probe(struct platform_device *pdev)
        void __iomem *base;
        int irq;
        int ret = 0;
+       int clk_multiplier = I2C_CLK_MULTIPLIER_STD_FAST_MODE;
 
        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        base = devm_ioremap_resource(&pdev->dev, res);
@@ -777,17 +774,39 @@ static int tegra_i2c_probe(struct platform_device *pdev)
 
        platform_set_drvdata(pdev, i2c_dev);
 
+       if (!i2c_dev->hw->has_single_clk_source) {
+               ret = clk_prepare(i2c_dev->fast_clk);
+               if (ret < 0) {
+                       dev_err(i2c_dev->dev, "Clock prepare failed %d\n", ret);
+                       return ret;
+               }
+       }
+
+       clk_multiplier *= (i2c_dev->hw->clk_divisor_std_fast_mode + 1);
+       ret = clk_set_rate(i2c_dev->div_clk,
+                          i2c_dev->bus_clk_rate * clk_multiplier);
+       if (ret) {
+               dev_err(i2c_dev->dev, "Clock rate change failed %d\n", ret);
+               goto unprepare_fast_clk;
+       }
+
+       ret = clk_prepare(i2c_dev->div_clk);
+       if (ret < 0) {
+               dev_err(i2c_dev->dev, "Clock prepare failed %d\n", ret);
+               goto unprepare_fast_clk;
+       }
+
        ret = tegra_i2c_init(i2c_dev);
        if (ret) {
                dev_err(&pdev->dev, "Failed to initialize i2c controller");
-               return ret;
+               goto unprepare_div_clk;
        }
 
        ret = devm_request_irq(&pdev->dev, i2c_dev->irq,
                        tegra_i2c_isr, 0, dev_name(&pdev->dev), i2c_dev);
        if (ret) {
                dev_err(&pdev->dev, "Failed to request irq %i\n", i2c_dev->irq);
-               return ret;
+               goto unprepare_div_clk;
        }
 
        i2c_set_adapdata(&i2c_dev->adapter, i2c_dev);
@@ -803,16 +822,30 @@ static int tegra_i2c_probe(struct platform_device *pdev)
        ret = i2c_add_numbered_adapter(&i2c_dev->adapter);
        if (ret) {
                dev_err(&pdev->dev, "Failed to add I2C adapter\n");
-               return ret;
+               goto unprepare_div_clk;
        }
 
        return 0;
+
+unprepare_div_clk:
+       clk_unprepare(i2c_dev->div_clk);
+
+unprepare_fast_clk:
+       if (!i2c_dev->hw->has_single_clk_source)
+               clk_unprepare(i2c_dev->fast_clk);
+
+       return ret;
 }
 
 static int tegra_i2c_remove(struct platform_device *pdev)
 {
        struct tegra_i2c_dev *i2c_dev = platform_get_drvdata(pdev);
        i2c_del_adapter(&i2c_dev->adapter);
+
+       clk_unprepare(i2c_dev->div_clk);
+       if (!i2c_dev->hw->has_single_clk_source)
+               clk_unprepare(i2c_dev->fast_clk);
+
        return 0;
 }