pinctrl: samsung: use raw_spinlock for locking

This patch converts spin_[lock|unlock] functions of pin bank to
raw_spinlock to support preempt-rt. This can avoid BUG() assertion when
irqchip callbacks are triggerred. Spinlocks can be converted rt_mutex
which is preemptible when we apply preempt-rt patches.

According to "Documentation/driver-api/gpio/driver.rst",

"Realtime considerations: a realtime compliant GPIO driver should not
use spinlock_t or any sleepable APIs (like PM runtime) as part of its
irqchip implementation.

- spinlock_t should be replaced with raw_spinlock_t.[1]
"

Cc: Tomasz Figa <tomasz.figa@gmail.com>
Cc: Krzysztof Kozlowski <krzk@kernel.org>
Cc: Sylwester Nawrocki <s.nawrocki@samsung.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Chanho Park <chanho61.park@samsung.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Link: https://lore.kernel.org/r/20210121030009.25673-1-chanho61.park@samsung.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/samsung/pinctrl-exynos.c

@@ -58,13 +58,13 @@ static void exynos_irq_mask(struct irq_data *irqd)
 	unsigned long mask;
 	unsigned long flags;
 
-	spin_lock_irqsave(&bank->slock, flags);
+	raw_spin_lock_irqsave(&bank->slock, flags);
 
 	mask = readl(bank->eint_base + reg_mask);
 	mask |= 1 << irqd->hwirq;
 	writel(mask, bank->eint_base + reg_mask);
 
-	spin_unlock_irqrestore(&bank->slock, flags);
+	raw_spin_unlock_irqrestore(&bank->slock, flags);
 }
 
 static void exynos_irq_ack(struct irq_data *irqd)
@@ -97,13 +97,13 @@ static void exynos_irq_unmask(struct irq_data *irqd)
 	if (irqd_get_trigger_type(irqd) & IRQ_TYPE_LEVEL_MASK)
 		exynos_irq_ack(irqd);
 
-	spin_lock_irqsave(&bank->slock, flags);
+	raw_spin_lock_irqsave(&bank->slock, flags);
 
 	mask = readl(bank->eint_base + reg_mask);
 	mask &= ~(1 << irqd->hwirq);
 	writel(mask, bank->eint_base + reg_mask);
 
-	spin_unlock_irqrestore(&bank->slock, flags);
+	raw_spin_unlock_irqrestore(&bank->slock, flags);
 }
 
 static int exynos_irq_set_type(struct irq_data *irqd, unsigned int type)
@@ -169,14 +169,14 @@ static int exynos_irq_request_resources(struct irq_data *irqd)
 	shift = irqd->hwirq * bank_type->fld_width[PINCFG_TYPE_FUNC];
 	mask = (1 << bank_type->fld_width[PINCFG_TYPE_FUNC]) - 1;
 
-	spin_lock_irqsave(&bank->slock, flags);
+	raw_spin_lock_irqsave(&bank->slock, flags);
 
 	con = readl(bank->pctl_base + reg_con);
 	con &= ~(mask << shift);
 	con |= EXYNOS_PIN_FUNC_EINT << shift;
 	writel(con, bank->pctl_base + reg_con);
 
-	spin_unlock_irqrestore(&bank->slock, flags);
+	raw_spin_unlock_irqrestore(&bank->slock, flags);
 
 	return 0;
 }
@@ -192,14 +192,14 @@ static void exynos_irq_release_resources(struct irq_data *irqd)
 	shift = irqd->hwirq * bank_type->fld_width[PINCFG_TYPE_FUNC];
 	mask = (1 << bank_type->fld_width[PINCFG_TYPE_FUNC]) - 1;
 
-	spin_lock_irqsave(&bank->slock, flags);
+	raw_spin_lock_irqsave(&bank->slock, flags);
 
 	con = readl(bank->pctl_base + reg_con);
 	con &= ~(mask << shift);
 	con |= EXYNOS_PIN_FUNC_INPUT << shift;
 	writel(con, bank->pctl_base + reg_con);
 
-	spin_unlock_irqrestore(&bank->slock, flags);
+	raw_spin_unlock_irqrestore(&bank->slock, flags);
 
 	gpiochip_unlock_as_irq(&bank->gpio_chip, irqd->hwirq);
 }

drivers/pinctrl/samsung/pinctrl-s3c24xx.c

@@ -145,14 +145,14 @@ static void s3c24xx_eint_set_function(struct samsung_pinctrl_drv_data *d,
 	shift = pin * bank_type->fld_width[PINCFG_TYPE_FUNC];
 	mask = (1 << bank_type->fld_width[PINCFG_TYPE_FUNC]) - 1;
 
-	spin_lock_irqsave(&bank->slock, flags);
+	raw_spin_lock_irqsave(&bank->slock, flags);
 
 	val = readl(reg);
 	val &= ~(mask << shift);
 	val |= bank->eint_func << shift;
 	writel(val, reg);
 
-	spin_unlock_irqrestore(&bank->slock, flags);
+	raw_spin_unlock_irqrestore(&bank->slock, flags);
 }
 
 static int s3c24xx_eint_type(struct irq_data *data, unsigned int type)

drivers/pinctrl/samsung/pinctrl-samsung.c

@@ -400,14 +400,14 @@ static void samsung_pinmux_setup(struct pinctrl_dev *pctldev, unsigned selector,
 		reg += 4;
 	}
 
-	spin_lock_irqsave(&bank->slock, flags);
+	raw_spin_lock_irqsave(&bank->slock, flags);
 
 	data = readl(reg + type->reg_offset[PINCFG_TYPE_FUNC]);
 	data &= ~(mask << shift);
 	data |= func->val << shift;
 	writel(data, reg + type->reg_offset[PINCFG_TYPE_FUNC]);
 
-	spin_unlock_irqrestore(&bank->slock, flags);
+	raw_spin_unlock_irqrestore(&bank->slock, flags);
 }
 
 /* enable a specified pinmux by writing to registers */
@@ -451,7 +451,7 @@ static int samsung_pinconf_rw(struct pinctrl_dev *pctldev, unsigned int pin,
 	width = type->fld_width[cfg_type];
 	cfg_reg = type->reg_offset[cfg_type];
 
-	spin_lock_irqsave(&bank->slock, flags);
+	raw_spin_lock_irqsave(&bank->slock, flags);
 
 	mask = (1 << width) - 1;
 	shift = pin_offset * width;
@@ -468,7 +468,7 @@ static int samsung_pinconf_rw(struct pinctrl_dev *pctldev, unsigned int pin,
 		*config = PINCFG_PACK(cfg_type, data);
 	}
 
-	spin_unlock_irqrestore(&bank->slock, flags);
+	raw_spin_unlock_irqrestore(&bank->slock, flags);
 
 	return 0;
 }
@@ -561,9 +561,9 @@ static void samsung_gpio_set(struct gpio_chip *gc, unsigned offset, int value)
 	struct samsung_pin_bank *bank = gpiochip_get_data(gc);
 	unsigned long flags;
 
-	spin_lock_irqsave(&bank->slock, flags);
+	raw_spin_lock_irqsave(&bank->slock, flags);
 	samsung_gpio_set_value(gc, offset, value);
-	spin_unlock_irqrestore(&bank->slock, flags);
+	raw_spin_unlock_irqrestore(&bank->slock, flags);
 }
 
 /* gpiolib gpio_get callback function */
@@ -626,9 +626,9 @@ static int samsung_gpio_direction_input(struct gpio_chip *gc, unsigned offset)
 	unsigned long flags;
 	int ret;
 
-	spin_lock_irqsave(&bank->slock, flags);
+	raw_spin_lock_irqsave(&bank->slock, flags);
 	ret = samsung_gpio_set_direction(gc, offset, true);
-	spin_unlock_irqrestore(&bank->slock, flags);
+	raw_spin_unlock_irqrestore(&bank->slock, flags);
 	return ret;
 }
 
@@ -640,10 +640,10 @@ static int samsung_gpio_direction_output(struct gpio_chip *gc, unsigned offset,
 	unsigned long flags;
 	int ret;
 
-	spin_lock_irqsave(&bank->slock, flags);
+	raw_spin_lock_irqsave(&bank->slock, flags);
 	samsung_gpio_set_value(gc, offset, value);
 	ret = samsung_gpio_set_direction(gc, offset, false);
-	spin_unlock_irqrestore(&bank->slock, flags);
+	raw_spin_unlock_irqrestore(&bank->slock, flags);
 
 	return ret;
 }
@@ -1057,7 +1057,7 @@ samsung_pinctrl_get_soc_data(struct samsung_pinctrl_drv_data *d,
 		bank->eint_offset = bdata->eint_offset;
 		bank->name = bdata->name;
 
-		spin_lock_init(&bank->slock);
+		raw_spin_lock_init(&bank->slock);
 		bank->drvdata = d;
 		bank->pin_base = d->nr_pins;
 		d->nr_pins += bank->nr_pins;

drivers/pinctrl/samsung/pinctrl-samsung.h

@@ -171,7 +171,7 @@ struct samsung_pin_bank {
 	struct gpio_chip gpio_chip;
 	struct pinctrl_gpio_range grange;
 	struct exynos_irq_chip *irq_chip;
-	spinlock_t slock;
+	raw_spinlock_t slock;
 
 	u32 pm_save[PINCFG_TYPE_NUM + 1]; /* +1 to handle double CON registers*/
 };