[RFC PATCH 4/4] pinctrl: rockchip: avoid hardirq-unsafe functions in irq_chip

[John Keeping <john@metanate.com>]

With real-time preemption, regmap functions cannot be used in the
implementation of irq_chip since they use spinlocks which may sleep.

Move the setting of the mux for IRQs to an irq_bus_sync_unlock handler
where we are allowed to sleep.

Signed-off-by: John Keeping <john@metanate.com>
---
 drivers/pinctrl/pinctrl-rockchip.c | 44 ++++++++++++++++++++++++++++++++++----
 1 file changed, 40 insertions(+), 4 deletions(-)

diff --git a/drivers/pinctrl/pinctrl-rockchip.c b/drivers/pinctrl/pinctrl-rockchip.c
index 52e70c4aef7c..80f7c23d12d4 100644
--- a/drivers/pinctrl/pinctrl-rockchip.c
+++ b/drivers/pinctrl/pinctrl-rockchip.c
@@ -143,6 +143,9 @@ struct rockchip_drv {
  * @gpio_chip: gpiolib chip
  * @grange: gpio range
  * @slock: spinlock for the gpio bank
+ * @irq_lock: bus lock for irq chip
+ * @new_irqs: newly configured irqs which must be muxed as GPIOs in
+ *	irq_bus_sync_unlock()
  */
 struct rockchip_pin_bank {
 	void __iomem			*reg_base;
@@ -165,6 +168,8 @@ struct rockchip_pin_bank {
 	struct pinctrl_gpio_range	grange;
 	raw_spinlock_t			slock;
 	u32				toggle_edge_mode;
+	struct mutex			irq_lock;
+	u32				new_irqs;
 };
 
 #define PIN_BANK(id, pins, label)			\
@@ -2045,11 +2050,12 @@ static int rockchip_irq_set_type(struct irq_data *d, unsigned int type)
 	int ret;
 
 	/* make sure the pin is configured as gpio input */
-	ret = rockchip_set_mux(bank, d->hwirq, RK_FUNC_GPIO);
+	ret = rockchip_verify_mux(bank, d->hwirq, RK_FUNC_GPIO);
 	if (ret < 0)
 		return ret;
 
-	clk_enable(bank->clk);
+	bank->new_irqs |= mask;
+
 	raw_spin_lock_irqsave(&bank->slock, flags);
 
 	data = readl_relaxed(bank->reg_base + GPIO_SWPORT_DDR);
@@ -2107,7 +2113,6 @@ static int rockchip_irq_set_type(struct irq_data *d, unsigned int type)
 	default:
 		irq_gc_unlock(gc);
 		raw_spin_unlock_irqrestore(&bank->slock, flags);
-		clk_disable(bank->clk);
 		return -EINVAL;
 	}
 
@@ -2116,7 +2121,6 @@ static int rockchip_irq_set_type(struct irq_data *d, unsigned int type)
 
 	irq_gc_unlock(gc);
 	raw_spin_unlock_irqrestore(&bank->slock, flags);
-	clk_disable(bank->clk);
 
 	return 0;
 }
@@ -2160,6 +2164,34 @@ static void rockchip_irq_gc_mask_set_bit(struct irq_data *d)
 	clk_disable(bank->clk);
 }
 
+static void rockchip_irq_bus_lock(struct irq_data *d)
+{
+	struct irq_chip_generic *gc = irq_data_get_irq_chip_data(d);
+	struct rockchip_pin_bank *bank = gc->private;
+
+	clk_enable(bank->clk);
+	mutex_lock(&bank->irq_lock);
+}
+
+static void rockchip_irq_bus_sync_unlock(struct irq_data *d)
+{
+	struct irq_chip_generic *gc = irq_data_get_irq_chip_data(d);
+	struct rockchip_pin_bank *bank = gc->private;
+
+	while (bank->new_irqs) {
+		unsigned int irq = __ffs(bank->new_irqs);
+		int ret;
+
+		ret = rockchip_set_mux(bank, irq, RK_FUNC_GPIO);
+		WARN_ON(ret < 0);
+
+		bank->new_irqs &= ~BIT(irq);
+	}
+
+	mutex_unlock(&bank->irq_lock);
+	clk_disable(bank->clk);
+}
+
 static int rockchip_interrupts_register(struct platform_device *pdev,
 						struct rockchip_pinctrl *info)
 {
@@ -2225,6 +2257,9 @@ static int rockchip_interrupts_register(struct platform_device *pdev,
 		gc->chip_types[0].chip.irq_suspend = rockchip_irq_suspend;
 		gc->chip_types[0].chip.irq_resume = rockchip_irq_resume;
 		gc->chip_types[0].chip.irq_set_type = rockchip_irq_set_type;
+		gc->chip_types[0].chip.irq_bus_lock = rockchip_irq_bus_lock;
+		gc->chip_types[0].chip.irq_bus_sync_unlock =
+						rockchip_irq_bus_sync_unlock;
 		gc->wake_enabled = IRQ_MSK(bank->nr_pins);
 
 		irq_set_chained_handler_and_data(bank->irq,
@@ -2398,6 +2433,7 @@ static struct rockchip_pin_ctrl *rockchip_pinctrl_get_soc_data(
 		int bank_pins = 0;
 
 		raw_spin_lock_init(&bank->slock);
+		mutex_init(&bank->irq_lock);
 		bank->drvdata = d;
 		bank->pin_base = ctrl->nr_pins;
 		ctrl->nr_pins += bank->nr_pins;
-- 
2.12.0.377.gf910686b23.dirty