[COMMON] i2c: exynos5: Fix possible ABBA deadlock by keeping I2C clock prepared

This patch came from commit "3b566a5c38b7311a545ac536a3b43944153918d2"

---------------------------------------------------------------------
commit 10ff4c5239a137abfc896ec73ef3d15a0f86a16a upstream.

The exynos5 I2C controller driver always prepares and enables a clock
before using it and then disables unprepares it when the clock is not
used anymore.

But this can cause a possible ABBA deadlock in some scenarios since a
driver that uses regmap to access its I2C registers, will first grab
the regmap lock and then the I2C xfer function will grab the prepare
lock when preparing the I2C clock. But since the clock driver also
uses regmap for I2C accesses, preparing a clock will first grab the
prepare lock and then the regmap lock when using the regmap API.

An example of this happens on the Exynos5422 Odroid XU4 board where a
s2mps11 PMIC is used and both the s2mps11 regulators and clk drivers
share the same I2C regmap.

The possible deadlock is reported by the kernel lockdep:

   Possible unsafe locking scenario:

           CPU0                    CPU1
           ----                    ----
   lock(sec_core:428:(regmap)->lock);
                                   lock(prepare_lock);
                                   lock(sec_core:428:(regmap)->lock);
   lock(prepare_lock);

   *** DEADLOCK ***

Fix it by leaving the code prepared on probe and use {en,dis}able in
the I2C transfer function.

This patch is similar to commit 34e81ad5f0b6 ("i2c: s3c2410: fix ABBA
deadlock by keeping clock prepared") that fixes the same bug in other
driver for an I2C controller found in Samsung SoCs.
--------------------------------------------------------------------

This patch is similar to commit "3b566a5c38b7311a545ac536a3b43944153918d2"
to apply current exynos5 hsi2c driver.

Change-Id: Iefc7a31e2c2db1e3f539654aa609aa6a8ed4cbfe
Signed-off-by: Youngmin Nam <youngmin.nam@samsung.com>

diff --git a/drivers/i2c/busses/i2c-exynos5.c b/drivers/i2c/busses/i2c-exynos5.c
index 2b95bc1f05c6d8cfd2e31c22b8ffcb24f56a59db..4619a859103a70d36ff65a87b96272600325e26e 100644 (file)
--- a/drivers/i2c/busses/i2c-exynos5.c
+++ b/drivers/i2c/busses/i2c-exynos5.c
@@ -810,11 +810,19 @@ static int exynos5_i2c_xfer(struct i2c_adapter *adap,
        clk_ret = pm_runtime_get_sync(i2c->dev);
        if (clk_ret < 0) {
                exynos_update_ip_idle_status(i2c->idle_ip_index, 0);
-               clk_prepare_enable(i2c->clk);
+               ret = clk_enable(i2c->clk);
+               if (ret) {
+                       exynos_update_ip_idle_status(i2c->idle_ip_index, 1);
+                       return ret;
+               }
        }
 #else
        exynos_update_ip_idle_status(i2c->idle_ip_index, 0);
-       clk_prepare_enable(i2c->clk);
+       ret = clk_enable(i2c->clk);
+       if (ret) {
+               exynos_update_ip_idle_status(i2c->idle_ip_index, 1);
+               return ret;
+       }
 #endif
 
        /* If master is in arbitration lost state before transfer */
@@ -873,14 +881,14 @@ static int exynos5_i2c_xfer(struct i2c_adapter *adap,
  out:
 #ifdef CONFIG_PM
        if (clk_ret < 0) {
-               clk_disable_unprepare(i2c->clk);
+               clk_disable(i2c->clk);
                exynos_update_ip_idle_status(i2c->idle_ip_index, 1);
        } else {
                pm_runtime_mark_last_busy(i2c->dev);
                pm_runtime_put_autosuspend(i2c->dev);
        }
 #else
-       clk_disable_unprepare(i2c->clk);
+       clk_disable(i2c->clk);
        exynos_update_ip_idle_status(i2c->idle_ip_index, 1);
 #endif
 
@@ -995,6 +1003,12 @@ static int exynos5_i2c_probe(struct platform_device *pdev)
                return -ENOENT;
        }
 
+       ret = clk_prepare(i2c->clk);
+       if (ret) {
+               dev_err(&pdev->dev, "Clock prepare failed\n");
+                       return ret;
+       }
+
 #ifdef CONFIG_PM
        pm_runtime_use_autosuspend(&pdev->dev);
        pm_runtime_set_autosuspend_delay(&pdev->dev,
@@ -1007,7 +1021,7 @@ static int exynos5_i2c_probe(struct platform_device *pdev)
        if (i2c->regs == NULL) {
                dev_err(&pdev->dev, "cannot map HS-I2C IO\n");
                ret = PTR_ERR(i2c->regs);
-               goto err_clk;
+               goto err_clk1;
        }
 
        i2c->adap.dev.of_node = np;
@@ -1021,7 +1035,7 @@ static int exynos5_i2c_probe(struct platform_device *pdev)
                if (ret <= 0) {
                        dev_err(&pdev->dev, "cannot find HS-I2C IRQ\n");
                        ret = -EINVAL;
-                       goto err_clk;
+                       goto err_clk1;
                }
 
                ret = devm_request_irq(&pdev->dev, i2c->irq,
@@ -1031,7 +1045,7 @@ static int exynos5_i2c_probe(struct platform_device *pdev)
                if (ret != 0) {
                        dev_err(&pdev->dev, "cannot request HS-I2C IRQ %d\n",
                                        i2c->irq);
-                       goto err_clk;
+                       goto err_clk1;
                }
        }
        platform_set_drvdata(pdev, i2c);
@@ -1039,7 +1053,11 @@ static int exynos5_i2c_probe(struct platform_device *pdev)
        pm_runtime_get_sync(&pdev->dev);
 #else
        exynos_update_ip_idle_status(i2c->idle_ip_index, 0);
-       clk_prepare_enable(i2c->clk);
+       ret = clk_enable(i2c->clk);
+       if (ret) {
+               exynos_update_ip_idle_status(i2c->idle_ip_index, 1);
+               return ret;
+       }
 #endif
 
        /* Clear pending interrupts from u-boot or misc causes */
@@ -1049,7 +1067,7 @@ static int exynos5_i2c_probe(struct platform_device *pdev)
 
        ret = exynos5_hsi2c_clock_setup(i2c);
        if (ret)
-               goto err_clk;
+               goto err_clk2;
 
        i2c->bus_id = of_alias_get_id(i2c->adap.dev.of_node, "hsi2c");
 
@@ -1059,14 +1077,14 @@ static int exynos5_i2c_probe(struct platform_device *pdev)
        ret = i2c_add_numbered_adapter(&i2c->adap);
        if (ret < 0) {
                dev_err(&pdev->dev, "failed to add bus to i2c core\n");
-               goto err_clk;
+               goto err_clk2;
        }
 
 #ifdef CONFIG_PM
        pm_runtime_mark_last_busy(&pdev->dev);
        pm_runtime_put_autosuspend(&pdev->dev);
 #else
-       clk_disable_unprepare(i2c->clk);
+       clk_disable(i2c->clk);
        exynos_update_ip_idle_status(i2c->idle_ip_index, 1);
 #endif
 
@@ -1076,9 +1094,15 @@ static int exynos5_i2c_probe(struct platform_device *pdev)
 
        return 0;
 
- err_clk:
+ err_clk2:
+#ifdef CONFIG_PM
+       pm_runtime_mark_last_busy(&pdev->dev);
+       pm_runtime_put_autosuspend(&pdev->dev);
+#else
        clk_disable_unprepare(i2c->clk);
        exynos_update_ip_idle_status(i2c->idle_ip_index, 1);
+#endif
+ err_clk1:
        return ret;
 }
 
@@ -1088,6 +1112,8 @@ static int exynos5_i2c_remove(struct platform_device *pdev)
 
        i2c_del_adapter(&i2c->adap);
 
+       clk_unprepare(i2c->clk);
+
        return 0;
 }
 
@@ -1098,6 +1124,7 @@ static int exynos5_i2c_suspend_noirq(struct device *dev)
 
        i2c_lock_adapter(&i2c->adap);
        i2c->suspended = 1;
+       clk_unprepare(i2c->clk);
        i2c_unlock_adapter(&i2c->adap);
 
        return 0;
@@ -1107,12 +1134,17 @@ static int exynos5_i2c_resume_noirq(struct device *dev)
 {
        struct platform_device *pdev = to_platform_device(dev);
        struct exynos5_i2c *i2c = platform_get_drvdata(pdev);
+       int ret = 0;
 
        i2c_lock_adapter(&i2c->adap);
        exynos_update_ip_idle_status(i2c->idle_ip_index, 0);
-       clk_prepare_enable(i2c->clk);
+       ret = clk_prepare_enable(i2c->clk);
+       if (ret) {
+               exynos_update_ip_idle_status(i2c->idle_ip_index, 1);
+               return ret;
+       }
        exynos5_i2c_reset(i2c);
-       clk_disable_unprepare(i2c->clk);
+       clk_disable(i2c->clk);
        exynos_update_ip_idle_status(i2c->idle_ip_index, 1);
        i2c->suspended = 0;
        i2c_unlock_adapter(&i2c->adap);
@@ -1138,7 +1170,7 @@ static int exynos5_i2c_runtime_suspend(struct device *dev)
        struct platform_device *pdev = to_platform_device(dev);
        struct exynos5_i2c *i2c = platform_get_drvdata(pdev);
 
-       clk_disable_unprepare(i2c->clk);
+       clk_disable(i2c->clk);
        exynos_update_ip_idle_status(i2c->idle_ip_index, 1);
 
        return 0;
@@ -1148,9 +1180,14 @@ static int exynos5_i2c_runtime_resume(struct device *dev)
 {
        struct platform_device *pdev = to_platform_device(dev);
        struct exynos5_i2c *i2c = platform_get_drvdata(pdev);
+       int ret = 0;
 
        exynos_update_ip_idle_status(i2c->idle_ip_index, 0);
-       clk_prepare_enable(i2c->clk);
+       ret = clk_enable(i2c->clk);
+       if (ret) {
+               exynos_update_ip_idle_status(i2c->idle_ip_index, 1);
+               return ret;
+       }
 
        return 0;
 }