[PATCH v3 3/7] gpiolib: Add support for GPIO line table lookup

[Geert Uytterhoeven]

Currently GPIOs can only be referred to by GPIO controller and offset in
GPIO lookup tables.

Add support for looking them up by line name.

Signed-off-by: Geert Uytterhoeven <address@hidden>
---
If this is rejected, the GPIO Aggregator documentation and code must be
updated.

v3:
  - New.
---
 drivers/gpio/gpiolib.c       | 12 ++++++++++++
 include/linux/gpio/machine.h |  2 +-
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index d24a3d79dcfe69ad..cb608512ad6bbded 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -4475,6 +4475,18 @@ static struct gpio_desc *gpiod_find(struct device *dev, 
const char *con_id,
                if (p->con_id && (!con_id || strcmp(p->con_id, con_id)))
                        continue;
 
+               if (p->chip_hwnum == (u16)-1) {
+                       desc = gpio_name_to_desc(p->chip_label);
+                       if (desc) {
+                               *flags = p->flags;
+                               return desc;
+                       }
+
+                       dev_warn(dev, "cannot find GPIO line %s, deferring\n",
+                                p->chip_label);
+                       return ERR_PTR(-EPROBE_DEFER);
+               }
+
                chip = find_chip_by_name(p->chip_label);
 
                if (!chip) {
diff --git a/include/linux/gpio/machine.h b/include/linux/gpio/machine.h
index 1ebe5be05d5f81fa..84c1c097e55eefaf 100644
--- a/include/linux/gpio/machine.h
+++ b/include/linux/gpio/machine.h
@@ -31,7 +31,7 @@ enum gpio_lookup_flags {
  */
 struct gpiod_lookup {
        const char *chip_label;
-       u16 chip_hwnum;
+       u16 chip_hwnum;                 /* if -1, chip_label is named line */
        const char *con_id;
        unsigned int idx;
        unsigned long flags;
-- 
2.17.1