[PATCH 2/3] irqchip: stm32: protect configuration registers with hwspinlock

[Benjamin Gaignard <benjamin.gaignard@linaro.org>]

If a hwspinlock is defined in device tree use it to protect
configuration registers.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@st.com>
---
 drivers/irqchip/irq-stm32-exti.c | 36 ++++++++++++++++++++++++++++++------
 1 file changed, 30 insertions(+), 6 deletions(-)

diff --git a/drivers/irqchip/irq-stm32-exti.c b/drivers/irqchip/irq-stm32-exti.c
index 0a2088e12d96..a010a2eed078 100644
--- a/drivers/irqchip/irq-stm32-exti.c
+++ b/drivers/irqchip/irq-stm32-exti.c
@@ -6,6 +6,7 @@
  */
 
 #include <linux/bitops.h>
+#include <linux/hwspinlock.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/irq.h>
@@ -20,6 +21,8 @@
 
 #define IRQS_PER_BANK 32
 
+#define HWSPINLOCK_TIMEOUT	5 /* msec */
+
 struct stm32_exti_bank {
 	u32 imr_ofst;
 	u32 emr_ofst;
@@ -47,6 +50,7 @@ struct stm32_exti_drv_data {
 struct stm32_exti_chip_data {
 	struct stm32_exti_host_data *host_data;
 	const struct stm32_exti_bank *reg_bank;
+	struct hwspinlock *hwlock;
 	struct raw_spinlock rlock;
 	u32 wake_active;
 	u32 mask_cache;
@@ -275,25 +279,34 @@ static int stm32_irq_set_type(struct irq_data *d, unsigned int type)
 	struct stm32_exti_chip_data *chip_data = gc->private;
 	const struct stm32_exti_bank *stm32_bank = chip_data->reg_bank;
 	u32 rtsr, ftsr;
-	int err;
+	int err = 0;
 
 	irq_gc_lock(gc);
 
+	if (chip_data->hwlock)
+		err = hwspin_lock_timeout(chip_data->hwlock,
+					  HWSPINLOCK_TIMEOUT);
+
+	if (err)
+		goto unlock;
+
 	rtsr = irq_reg_readl(gc, stm32_bank->rtsr_ofst);
 	ftsr = irq_reg_readl(gc, stm32_bank->ftsr_ofst);
 
 	err = stm32_exti_set_type(d, type, &rtsr, &ftsr);
-	if (err) {
-		irq_gc_unlock(gc);
-		return err;
-	}
+	if (err)
+		goto unspinlock;
 
 	irq_reg_writel(gc, rtsr, stm32_bank->rtsr_ofst);
 	irq_reg_writel(gc, ftsr, stm32_bank->ftsr_ofst);
 
+unspinlock:
+	if (chip_data->hwlock)
+		hwspin_unlock(chip_data->hwlock);
+unlock:
 	irq_gc_unlock(gc);
 
-	return 0;
+	return err;
 }
 
 static void stm32_chip_suspend(struct stm32_exti_chip_data *chip_data,
@@ -670,6 +683,7 @@ static int __init stm32_exti_init(const struct stm32_exti_drv_data *drv_data,
 	int nr_irqs, ret, i;
 	struct irq_chip_generic *gc;
 	struct irq_domain *domain;
+	struct hwspinlock *hwlock = NULL;
 
 	host_data = stm32_exti_host_init(drv_data, node);
 	if (!host_data)
@@ -692,12 +706,22 @@ static int __init stm32_exti_init(const struct stm32_exti_drv_data *drv_data,
 		goto out_free_domain;
 	}
 
+	/* hwspinlock is optional */
+	ret = of_hwspin_lock_get_id(node, 0);
+	if (ret < 0) {
+		if (ret == -EPROBE_DEFER)
+			goto out_free_domain;
+	} else {
+		hwlock = hwspin_lock_request_specific(ret);
+	}
+
 	for (i = 0; i < drv_data->bank_nr; i++) {
 		const struct stm32_exti_bank *stm32_bank;
 		struct stm32_exti_chip_data *chip_data;
 
 		stm32_bank = drv_data->exti_banks[i];
 		chip_data = stm32_exti_chip_init(host_data, i, node);
+		chip_data->hwlock = hwlock;
 
 		gc = irq_get_domain_generic_chip(domain, i * IRQS_PER_BANK);
 
-- 
2.15.0