gpio: omap: use raw locks for locking

This patch converts gpio_bank.lock from a spin_lock into a
raw_spin_lock. The call path is to access this lock is always under a
raw_spin_lock, for instance
- __setup_irq() holds &desc->lock with irq off
  + __irq_set_trigger()
   + omap_gpio_irq_type()

- handle_level_irq() (runs with irqs off therefore raw locks)
  + mask_ack_irq()
   + omap_gpio_mask_irq()

This fixes the obvious backtrace on -RT. However the locking vs context
is not and this is not limited to -RT:
- omap_gpio_irq_type() is called with IRQ off and has an conditional
  call to pm_runtime_get_sync() which may sleep. Either it may happen or
  it may not happen but pm_runtime_get_sync() should not be called with
  irqs off.

- omap_gpio_debounce() is holding the lock with IRQs off.
  + omap2_set_gpio_debounce()
   + clk_prepare_enable()
    + clk_prepare() this one might sleep.
  The number of users of gpiod_set_debounce() / gpio_set_debounce()
  looks low but still this is not good.

Acked-by: Javier Martinez Canillas <javier@dowhile0.org>
Acked-by: Santosh Shilimkar <ssantosh@kernel.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

diff --git a/drivers/gpio/gpio-omap.c b/drivers/gpio/gpio-omap.c
index 04ea23b..a2ff0ee 100644 (file)
--- a/drivers/gpio/gpio-omap.c
+++ b/drivers/gpio/gpio-omap.c
@@ -57,7 +57,7 @@ struct gpio_bank {
        u32 saved_datain;
        u32 level_mask;
        u32 toggle_mask;
-       spinlock_t lock;
+       raw_spinlock_t lock;
        struct gpio_chip chip;
        struct clk *dbck;
        u32 mod_usage;
@@ -498,17 +498,17 @@ static int omap_gpio_irq_type(struct irq_data *d, unsigned type)
        if (!BANK_USED(bank))
                pm_runtime_get_sync(bank->dev);
 
-       spin_lock_irqsave(&bank->lock, flags);
+       raw_spin_lock_irqsave(&bank->lock, flags);
        retval = omap_set_gpio_triggering(bank, offset, type);
        if (retval)
                goto error;
        omap_gpio_init_irq(bank, offset);
        if (!omap_gpio_is_input(bank, offset)) {
-               spin_unlock_irqrestore(&bank->lock, flags);
+               raw_spin_unlock_irqrestore(&bank->lock, flags);
                retval = -EINVAL;
                goto error;
        }
-       spin_unlock_irqrestore(&bank->lock, flags);
+       raw_spin_unlock_irqrestore(&bank->lock, flags);
 
        if (type & (IRQ_TYPE_LEVEL_LOW | IRQ_TYPE_LEVEL_HIGH))
                irq_set_handler_locked(d, handle_level_irq);
@@ -634,14 +634,14 @@ static int omap_set_gpio_wakeup(struct gpio_bank *bank, unsigned offset,
                return -EINVAL;
        }
 
-       spin_lock_irqsave(&bank->lock, flags);
+       raw_spin_lock_irqsave(&bank->lock, flags);
        if (enable)
                bank->context.wake_en |= gpio_bit;
        else
                bank->context.wake_en &= ~gpio_bit;
 
        writel_relaxed(bank->context.wake_en, bank->base + bank->regs->wkup_en);
-       spin_unlock_irqrestore(&bank->lock, flags);
+       raw_spin_unlock_irqrestore(&bank->lock, flags);
 
        return 0;
 }
@@ -667,10 +667,10 @@ static int omap_gpio_request(struct gpio_chip *chip, unsigned offset)
        if (!BANK_USED(bank))
                pm_runtime_get_sync(bank->dev);
 
-       spin_lock_irqsave(&bank->lock, flags);
+       raw_spin_lock_irqsave(&bank->lock, flags);
        omap_enable_gpio_module(bank, offset);
        bank->mod_usage |= BIT(offset);
-       spin_unlock_irqrestore(&bank->lock, flags);
+       raw_spin_unlock_irqrestore(&bank->lock, flags);
 
        return 0;
 }
@@ -680,14 +680,14 @@ static void omap_gpio_free(struct gpio_chip *chip, unsigned offset)
        struct gpio_bank *bank = container_of(chip, struct gpio_bank, chip);
        unsigned long flags;
 
-       spin_lock_irqsave(&bank->lock, flags);
+       raw_spin_lock_irqsave(&bank->lock, flags);
        bank->mod_usage &= ~(BIT(offset));
        if (!LINE_USED(bank->irq_usage, offset)) {
                omap_set_gpio_direction(bank, offset, 1);
                omap_clear_gpio_debounce(bank, offset);
        }
        omap_disable_gpio_module(bank, offset);
-       spin_unlock_irqrestore(&bank->lock, flags);
+       raw_spin_unlock_irqrestore(&bank->lock, flags);
 
        /*
         * If this is the last gpio to be freed in the bank,
@@ -789,7 +789,7 @@ static unsigned int omap_gpio_irq_startup(struct irq_data *d)
        if (!BANK_USED(bank))
                pm_runtime_get_sync(bank->dev);
 
-       spin_lock_irqsave(&bank->lock, flags);
+       raw_spin_lock_irqsave(&bank->lock, flags);
 
        if (!LINE_USED(bank->mod_usage, offset))
                omap_set_gpio_direction(bank, offset, 1);
@@ -798,12 +798,12 @@ static unsigned int omap_gpio_irq_startup(struct irq_data *d)
        omap_enable_gpio_module(bank, offset);
        bank->irq_usage |= BIT(offset);
 
-       spin_unlock_irqrestore(&bank->lock, flags);
+       raw_spin_unlock_irqrestore(&bank->lock, flags);
        omap_gpio_unmask_irq(d);
 
        return 0;
 err:
-       spin_unlock_irqrestore(&bank->lock, flags);
+       raw_spin_unlock_irqrestore(&bank->lock, flags);
        if (!BANK_USED(bank))
                pm_runtime_put(bank->dev);
        return -EINVAL;
@@ -815,7 +815,7 @@ static void omap_gpio_irq_shutdown(struct irq_data *d)
        unsigned long flags;
        unsigned offset = d->hwirq;
 
-       spin_lock_irqsave(&bank->lock, flags);
+       raw_spin_lock_irqsave(&bank->lock, flags);
        bank->irq_usage &= ~(BIT(offset));
        omap_set_gpio_irqenable(bank, offset, 0);
        omap_clear_gpio_irqstatus(bank, offset);
@@ -823,7 +823,7 @@ static void omap_gpio_irq_shutdown(struct irq_data *d)
        if (!LINE_USED(bank->mod_usage, offset))
                omap_clear_gpio_debounce(bank, offset);
        omap_disable_gpio_module(bank, offset);
-       spin_unlock_irqrestore(&bank->lock, flags);
+       raw_spin_unlock_irqrestore(&bank->lock, flags);
 
        /*
         * If this is the last IRQ to be freed in the bank,
@@ -847,10 +847,10 @@ static void omap_gpio_mask_irq(struct irq_data *d)
        unsigned offset = d->hwirq;
        unsigned long flags;
 
-       spin_lock_irqsave(&bank->lock, flags);
+       raw_spin_lock_irqsave(&bank->lock, flags);
        omap_set_gpio_irqenable(bank, offset, 0);
        omap_set_gpio_triggering(bank, offset, IRQ_TYPE_NONE);
-       spin_unlock_irqrestore(&bank->lock, flags);
+       raw_spin_unlock_irqrestore(&bank->lock, flags);
 }
 
 static void omap_gpio_unmask_irq(struct irq_data *d)
@@ -860,7 +860,7 @@ static void omap_gpio_unmask_irq(struct irq_data *d)
        u32 trigger = irqd_get_trigger_type(d);
        unsigned long flags;
 
-       spin_lock_irqsave(&bank->lock, flags);
+       raw_spin_lock_irqsave(&bank->lock, flags);
        if (trigger)
                omap_set_gpio_triggering(bank, offset, trigger);
 
@@ -872,7 +872,7 @@ static void omap_gpio_unmask_irq(struct irq_data *d)
        }
 
        omap_set_gpio_irqenable(bank, offset, 1);
-       spin_unlock_irqrestore(&bank->lock, flags);
+       raw_spin_unlock_irqrestore(&bank->lock, flags);
 }
 
 /*---------------------------------------------------------------------*/
@@ -885,9 +885,9 @@ static int omap_mpuio_suspend_noirq(struct device *dev)
                                        OMAP_MPUIO_GPIO_MASKIT / bank->stride;
        unsigned long           flags;
 
-       spin_lock_irqsave(&bank->lock, flags);
+       raw_spin_lock_irqsave(&bank->lock, flags);
        writel_relaxed(0xffff & ~bank->context.wake_en, mask_reg);
-       spin_unlock_irqrestore(&bank->lock, flags);
+       raw_spin_unlock_irqrestore(&bank->lock, flags);
 
        return 0;
 }
@@ -900,9 +900,9 @@ static int omap_mpuio_resume_noirq(struct device *dev)
                                        OMAP_MPUIO_GPIO_MASKIT / bank->stride;
        unsigned long           flags;
 
-       spin_lock_irqsave(&bank->lock, flags);
+       raw_spin_lock_irqsave(&bank->lock, flags);
        writel_relaxed(bank->context.wake_en, mask_reg);
-       spin_unlock_irqrestore(&bank->lock, flags);
+       raw_spin_unlock_irqrestore(&bank->lock, flags);
 
        return 0;
 }
@@ -948,9 +948,9 @@ static int omap_gpio_get_direction(struct gpio_chip *chip, unsigned offset)
 
        bank = container_of(chip, struct gpio_bank, chip);
        reg = bank->base + bank->regs->direction;
-       spin_lock_irqsave(&bank->lock, flags);
+       raw_spin_lock_irqsave(&bank->lock, flags);
        dir = !!(readl_relaxed(reg) & BIT(offset));
-       spin_unlock_irqrestore(&bank->lock, flags);
+       raw_spin_unlock_irqrestore(&bank->lock, flags);
        return dir;
 }
 
@@ -960,9 +960,9 @@ static int omap_gpio_input(struct gpio_chip *chip, unsigned offset)
        unsigned long flags;
 
        bank = container_of(chip, struct gpio_bank, chip);
-       spin_lock_irqsave(&bank->lock, flags);
+       raw_spin_lock_irqsave(&bank->lock, flags);
        omap_set_gpio_direction(bank, offset, 1);
-       spin_unlock_irqrestore(&bank->lock, flags);
+       raw_spin_unlock_irqrestore(&bank->lock, flags);
        return 0;
 }
 
@@ -984,10 +984,10 @@ static int omap_gpio_output(struct gpio_chip *chip, unsigned offset, int value)
        unsigned long flags;
 
        bank = container_of(chip, struct gpio_bank, chip);
-       spin_lock_irqsave(&bank->lock, flags);
+       raw_spin_lock_irqsave(&bank->lock, flags);
        bank->set_dataout(bank, offset, value);
        omap_set_gpio_direction(bank, offset, 0);
-       spin_unlock_irqrestore(&bank->lock, flags);
+       raw_spin_unlock_irqrestore(&bank->lock, flags);
        return 0;
 }
 
@@ -999,9 +999,9 @@ static int omap_gpio_debounce(struct gpio_chip *chip, unsigned offset,
 
        bank = container_of(chip, struct gpio_bank, chip);
 
-       spin_lock_irqsave(&bank->lock, flags);
+       raw_spin_lock_irqsave(&bank->lock, flags);
        omap2_set_gpio_debounce(bank, offset, debounce);
-       spin_unlock_irqrestore(&bank->lock, flags);
+       raw_spin_unlock_irqrestore(&bank->lock, flags);
 
        return 0;
 }
@@ -1012,9 +1012,9 @@ static void omap_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
        unsigned long flags;
 
        bank = container_of(chip, struct gpio_bank, chip);
-       spin_lock_irqsave(&bank->lock, flags);
+       raw_spin_lock_irqsave(&bank->lock, flags);
        bank->set_dataout(bank, offset, value);
-       spin_unlock_irqrestore(&bank->lock, flags);
+       raw_spin_unlock_irqrestore(&bank->lock, flags);
 }
 
 /*---------------------------------------------------------------------*/
@@ -1210,7 +1210,7 @@ static int omap_gpio_probe(struct platform_device *pdev)
        else
                bank->set_dataout = omap_set_gpio_dataout_mask;
 
-       spin_lock_init(&bank->lock);
+       raw_spin_lock_init(&bank->lock);
 
        /* Static mapping, never released */
        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
@@ -1268,7 +1268,7 @@ static int omap_gpio_runtime_suspend(struct device *dev)
        unsigned long flags;
        u32 wake_low, wake_hi;
 
-       spin_lock_irqsave(&bank->lock, flags);
+       raw_spin_lock_irqsave(&bank->lock, flags);
 
        /*
         * Only edges can generate a wakeup event to the PRCM.
@@ -1321,7 +1321,7 @@ update_gpio_context_count:
                                bank->get_context_loss_count(bank->dev);
 
        omap_gpio_dbck_disable(bank);
-       spin_unlock_irqrestore(&bank->lock, flags);
+       raw_spin_unlock_irqrestore(&bank->lock, flags);
 
        return 0;
 }
@@ -1336,7 +1336,7 @@ static int omap_gpio_runtime_resume(struct device *dev)
        unsigned long flags;
        int c;
 
-       spin_lock_irqsave(&bank->lock, flags);
+       raw_spin_lock_irqsave(&bank->lock, flags);
 
        /*
         * On the first resume during the probe, the context has not
@@ -1372,14 +1372,14 @@ static int omap_gpio_runtime_resume(struct device *dev)
                        if (c != bank->context_loss_count) {
                                omap_gpio_restore_context(bank);
                        } else {
-                               spin_unlock_irqrestore(&bank->lock, flags);
+                               raw_spin_unlock_irqrestore(&bank->lock, flags);
                                return 0;
                        }
                }
        }
 
        if (!bank->workaround_enabled) {
-               spin_unlock_irqrestore(&bank->lock, flags);
+               raw_spin_unlock_irqrestore(&bank->lock, flags);
                return 0;
        }
 
@@ -1434,7 +1434,7 @@ static int omap_gpio_runtime_resume(struct device *dev)
        }
 
        bank->workaround_enabled = false;
-       spin_unlock_irqrestore(&bank->lock, flags);
+       raw_spin_unlock_irqrestore(&bank->lock, flags);
 
        return 0;
 }