regmap: irq: Allow using zero value for ack_base

In some cases, clear interrupt register may be at address 0.
This patch allows to use such configurations by adding additional
configuration bit to indicate this.

[With doc fix from Levente Kurusa <levex@linux.com> -- broonie]

Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Signed-off-by: Mark Brown <broonie@linaro.org>

2 files changed, 7 insertions, 4 deletions

diff --git a/drivers/base/regmap/regmap-irq.c b/drivers/base/regmap/regmap-irq.c
index 763c60d3d277..82692068d3cb 100644
--- a/drivers/base/regmap/regmap-irq.c
+++ b/drivers/base/regmap/regmap-irq.c
@@ -113,7 +113,7 @@ static void regmap_irq_sync_unlock(struct irq_data *data)
                  * OR if there is masked interrupt which hasn't been Acked,
                  * it'll be ignored in irq handler, then may introduce irq storm
                  */
-                if (d->mask_buf[i] && d->chip->ack_base) {
+                if (d->mask_buf[i] && (d->chip->ack_base || d->chip->use_ack)) {
                         reg = d->chip->ack_base +
                                 (i * map->reg_stride * d->irq_reg_stride);
                         ret = regmap_write(map, reg, d->mask_buf[i]);
@@ -271,7 +271,7 @@ static irqreturn_t regmap_irq_thread(int irq, void *d)
         for (i = 0; i < data->chip->num_regs; i++) {
                 data->status_buf[i] &= ~data->mask_buf[i];
 
-                if (data->status_buf[i] && chip->ack_base) {
+                if (data->status_buf[i] && (chip->ack_base || chip->use_ack)) {
                         reg = chip->ack_base +
                                 (i * map->reg_stride * data->irq_reg_stride);
                         ret = regmap_write(map, reg, data->status_buf[i]);
@@ -448,7 +448,7 @@ int regmap_add_irq_chip(struct regmap *map, int irq, int irq_flags,
                         goto err_alloc;
                 }
 
-                if (d->status_buf[i] && chip->ack_base) {
+                if (d->status_buf[i] && (chip->ack_base || chip->use_ack)) {
                         reg = chip->ack_base +
                                 (i * map->reg_stride * d->irq_reg_stride);
                         ret = regmap_write(map, reg,
diff --git a/include/linux/regmap.h b/include/linux/regmap.h
index e55907804d39..c9e5fb197eb6 100644
--- a/include/linux/regmap.h
+++ b/include/linux/regmap.h
@@ -497,11 +497,13 @@ struct regmap_irq {
  *
  * @status_base: Base status register address.
  * @mask_base:   Base mask register address.
- * @ack_base:    Base ack address.  If zero then the chip is clear on read.
+ * @ack_base:    Base ack address. If zero then the chip is clear on read.
+ *               Using zero value is possible with @use_ack bit.
  * @wake_base:   Base address for wake enables.  If zero unsupported.
  * @irq_reg_stride:  Stride to use for chips where registers are not contiguous.
  * @init_ack_masked: Ack all masked interrupts once during initalization.
  * @mask_invert: Inverted mask register: cleared bits are masked out.
+ * @use_ack:     Use @ack register even if it is zero.
  * @wake_invert: Inverted wake register: cleared bits are wake enabled.
  * @runtime_pm:  Hold a runtime PM lock on the device when accessing it.
  *
@@ -520,6 +522,7 @@ struct regmap_irq_chip {
         unsigned int irq_reg_stride;
         bool init_ack_masked:1;
         bool mask_invert:1;
+        bool use_ack:1;
         bool wake_invert:1;
         bool runtime_pm:1;