mfd: max77620: Mask/unmask interrupt before/after servicing it

The programming guidelines of the MAX77620 for servicing interrupt is:
1. When interrupt occurs from PMIC, mask the PMIC interrupt by
   setting GLBLM.
2. Read IRQTOP and service the interrupt.
3. Once all interrupts has been checked and serviced, the interrupt
   service routine un-masks the hardware interrupt line by clearing
   GLBLM.

Add the pre and post interrupt service handler for mask and unmask the
global interrupt mask bit (for step 1 and 3) as callback from regmap-irq.

Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/max77620.c

@@ -111,15 +111,6 @@ static const struct mfd_cell max20024_children[] = {
 	},
 };
 
-static struct regmap_irq_chip max77620_top_irq_chip = {
-	.name = "max77620-top",
-	.irqs = max77620_top_irqs,
-	.num_irqs = ARRAY_SIZE(max77620_top_irqs),
-	.num_regs = 2,
-	.status_base = MAX77620_REG_IRQTOP,
-	.mask_base = MAX77620_REG_IRQTOPM,
-};
-
 static const struct regmap_range max77620_readable_ranges[] = {
 	regmap_reg_range(MAX77620_REG_CNFGGLBL1, MAX77620_REG_DVSSD4),
 };
@@ -180,6 +171,51 @@ static const struct regmap_config max20024_regmap_config = {
 	.volatile_table = &max77620_volatile_table,
 };
 
+/*
+ * MAX77620 and MAX20024 has the following steps of the interrupt handling
+ * for TOP interrupts:
+ * 1. When interrupt occurs from PMIC, mask the PMIC interrupt by setting GLBLM.
+ * 2. Read IRQTOP and service the interrupt.
+ * 3. Once all interrupts has been checked and serviced, the interrupt service
+ *    routine un-masks the hardware interrupt line by clearing GLBLM.
+ */
+static int max77620_irq_global_mask(void *irq_drv_data)
+{
+	struct max77620_chip *chip = irq_drv_data;
+	int ret;
+
+	ret = regmap_update_bits(chip->rmap, MAX77620_REG_INTENLBT,
+				 MAX77620_GLBLM_MASK, MAX77620_GLBLM_MASK);
+	if (ret < 0)
+		dev_err(chip->dev, "Failed to set GLBLM: %d\n", ret);
+
+	return ret;
+}
+
+static int max77620_irq_global_unmask(void *irq_drv_data)
+{
+	struct max77620_chip *chip = irq_drv_data;
+	int ret;
+
+	ret = regmap_update_bits(chip->rmap, MAX77620_REG_INTENLBT,
+				 MAX77620_GLBLM_MASK, 0);
+	if (ret < 0)
+		dev_err(chip->dev, "Failed to reset GLBLM: %d\n", ret);
+
+	return ret;
+}
+
+static struct regmap_irq_chip max77620_top_irq_chip = {
+	.name = "max77620-top",
+	.irqs = max77620_top_irqs,
+	.num_irqs = ARRAY_SIZE(max77620_top_irqs),
+	.num_regs = 2,
+	.status_base = MAX77620_REG_IRQTOP,
+	.mask_base = MAX77620_REG_IRQTOPM,
+	.handle_pre_irq = max77620_irq_global_mask,
+	.handle_post_irq = max77620_irq_global_unmask,
+};
+
 /* max77620_get_fps_period_reg_value:  Get FPS bit field value from
  *				       requested periods.
  * MAX77620 supports the FPS period of 40, 80, 160, 320, 540, 1280, 2560
@@ -431,6 +467,7 @@ static int max77620_probe(struct i2c_client *client,
 	if (ret < 0)
 		return ret;
 
+	max77620_top_irq_chip.irq_drv_data = chip;
 	ret = devm_regmap_add_irq_chip(chip->dev, chip->rmap, client->irq,
 				       IRQF_ONESHOT | IRQF_SHARED,
 				       chip->irq_base, &max77620_top_irq_chip,