regmap: Add support for devices with no interrupt readback

Merge series from William Breathitt Gray <william.gray@linaro.org>:

There are devices which have interrupt support with mask and ack
registers but no status register.  Add a flag which lets us support
them, we just assume that all the interrupts fired.

2 files changed, 17 insertions, 7 deletions

diff --git a/drivers/base/regmap/regmap-irq.c b/drivers/base/regmap/regmap-irq.c
index 8c903b8c9714..f4d544ee7c30 100644
--- a/drivers/base/regmap/regmap-irq.c
+++ b/drivers/base/regmap/regmap-irq.c
@@ -433,7 +433,10 @@ static irqreturn_t regmap_irq_thread(int irq, void *d)
 	 * possible in order to reduce the I/O overheads.
 	 */
 
-	if (chip->num_main_regs) {
+	if (chip->no_status) {
+		/* no status register so default to all active */
+		memset32(data->status_buf, GENMASK(31, 0), chip->num_regs);
+	} else if (chip->num_main_regs) {
 		unsigned int max_main_bits;
 		unsigned long size;
 
@@ -949,12 +952,17 @@ int regmap_add_irq_chip_fwnode(struct fwnode_handle *fwnode,
 			continue;
 
 		/* Ack masked but set interrupts */
-		reg = d->get_irq_reg(d, d->chip->status_base, i);
-		ret = regmap_read(map, reg, &d->status_buf[i]);
-		if (ret != 0) {
-			dev_err(map->dev, "Failed to read IRQ status: %d\n",
-				ret);
-			goto err_alloc;
+		if (d->chip->no_status) {
+			/* no status register so default to all active */
+			d->status_buf[i] = GENMASK(31, 0);
+		} else {
+			reg = d->get_irq_reg(d, d->chip->status_base, i);
+			ret = regmap_read(map, reg, &d->status_buf[i]);
+			if (ret != 0) {
+				dev_err(map->dev, "Failed to read IRQ status: %d\n",
+					ret);
+				goto err_alloc;
+			}
 		}
 
 		if (chip->status_invert)
diff --git a/include/linux/regmap.h b/include/linux/regmap.h
index 1c777566fb7d..19d54f019cc4 100644
--- a/include/linux/regmap.h
+++ b/include/linux/regmap.h
@@ -1567,6 +1567,7 @@ struct regmap_irq_chip_data;
  *		      offsets to each peripheral. Deprecated; the same thing
  *		      can be accomplished with a @get_irq_reg callback, without
  *		      the need for a @sub_reg_offsets table.
+ * @no_status: No status register: all interrupts assumed generated by device.
  *
  * @num_regs:    Number of registers in each control bank.
  *
@@ -1634,6 +1635,7 @@ struct regmap_irq_chip {
 	unsigned int clear_on_unmask:1;
 	unsigned int runtime_pm:1;
 	unsigned int not_fixed_stride:1;
+	unsigned int no_status:1;
 
 	int num_regs;