gpio: omap: fix clk_prepare/unprepare usage

As per CCF documentation (clk.txt) the clk_prepare/unprepare APIs
are not allowed in atomic context. But now OMAP GPIO driver
uses them while applying debounce settings and as part
of PM runtime irqsafe operations:

- omap_gpio_debounce() is holding the lock with IRQs off.
  + omap2_set_gpio_debounce()
   + clk_prepare_enable()
    + clk_prepare() this one might sleep.

- pm_runtime_get_sync() is holding the lock with IRQs off
  + omap_gpio_runtime_suspend()
    + raw_spin_lock_irqsave()
    + omap_gpio_dbck_disable()
      + clk_disable_unprepare()

Hence, fix it by moeving dbclk prepare/unprepare in OMAP GPIO
omap_gpio_probe/omap_gpio_remove. Also, while here, ensure that
debounce functionality is disabled if clk_get() failed,
because otherwise kernel will carsh in omap2_set_gpio_debounce().

Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Santosh Shilimkar <ssantosh@kernel.org>
Tested-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

diff --git a/drivers/gpio/gpio-omap.c b/drivers/gpio/gpio-omap.c
index 1f02acd577e3429a5c2cf1dd01173ee29f28e576..2ae0d47e955443f7f1aec2f51c522466aa54ce30 100644 (file)
--- a/drivers/gpio/gpio-omap.c
+++ b/drivers/gpio/gpio-omap.c
@@ -176,7 +176,7 @@ static inline void omap_gpio_rmw(void __iomem *base, u32 reg, u32 mask, bool set
 static inline void omap_gpio_dbck_enable(struct gpio_bank *bank)
 {
        if (bank->dbck_enable_mask && !bank->dbck_enabled) {
-               clk_prepare_enable(bank->dbck);
+               clk_enable(bank->dbck);
                bank->dbck_enabled = true;
 
                writel_relaxed(bank->dbck_enable_mask,
@@ -194,7 +194,7 @@ static inline void omap_gpio_dbck_disable(struct gpio_bank *bank)
                 */
                writel_relaxed(0, bank->base + bank->regs->debounce_en);
 
-               clk_disable_unprepare(bank->dbck);
+               clk_disable(bank->dbck);
                bank->dbck_enabled = false;
        }
 }
@@ -227,7 +227,7 @@ static void omap2_set_gpio_debounce(struct gpio_bank *bank, unsigned offset,
 
        l = BIT(offset);
 
-       clk_prepare_enable(bank->dbck);
+       clk_enable(bank->dbck);
        reg = bank->base + bank->regs->debounce;
        writel_relaxed(debounce, reg);
 
@@ -241,7 +241,7 @@ static void omap2_set_gpio_debounce(struct gpio_bank *bank, unsigned offset,
        bank->dbck_enable_mask = val;
 
        writel_relaxed(val, reg);
-       clk_disable_unprepare(bank->dbck);
+       clk_disable(bank->dbck);
        /*
         * Enable debounce clock per module.
         * This call is mandatory because in omap_gpio_request() when
@@ -286,7 +286,7 @@ static void omap_clear_gpio_debounce(struct gpio_bank *bank, unsigned offset)
                bank->context.debounce = 0;
                writel_relaxed(bank->context.debounce, bank->base +
                             bank->regs->debounce);
-               clk_disable_unprepare(bank->dbck);
+               clk_disable(bank->dbck);
                bank->dbck_enabled = false;
        }
 }
@@ -1070,10 +1070,6 @@ static void omap_gpio_mod_init(struct gpio_bank *bank)
         /* Initialize interface clk ungated, module enabled */
        if (bank->regs->ctrl)
                writel_relaxed(0, base + bank->regs->ctrl);
-
-       bank->dbck = clk_get(bank->dev, "dbclk");
-       if (IS_ERR(bank->dbck))
-               dev_err(bank->dev, "Could not get gpio dbck\n");
 }
 
 static int omap_gpio_chip_init(struct gpio_bank *bank, struct irq_chip *irqc)
@@ -1234,6 +1230,17 @@ static int omap_gpio_probe(struct platform_device *pdev)
                return PTR_ERR(bank->base);
        }
 
+       if (bank->dbck_flag) {
+               bank->dbck = devm_clk_get(bank->dev, "dbclk");
+               if (IS_ERR(bank->dbck)) {
+                       dev_err(bank->dev,
+                               "Could not get gpio dbck. Disable debounce\n");
+                       bank->dbck_flag = false;
+               } else {
+                       clk_prepare(bank->dbck);
+               }
+       }
+
        platform_set_drvdata(pdev, bank);
 
        pm_runtime_enable(bank->dev);
@@ -1265,6 +1272,8 @@ static int omap_gpio_remove(struct platform_device *pdev)
        list_del(&bank->node);
        gpiochip_remove(&bank->chip);
        pm_runtime_disable(bank->dev);
+       if (bank->dbck_flag)
+               clk_unprepare(bank->dbck);
 
        return 0;
 }