gpiolib: let gpiochip_add_pin_range() specify offset

Like with commit 3c739ad0df5eb41cd7adad879eda6aa09879eb76
it is not always enough to specify all the pins of a gpio_chip
from offset zero to be added to a pin map range, since the
mapping from GPIO to pin controller may not be linear at all,
but need to be broken into a few consecutive sub-ranges or
1-pin entries for complicated cases. The ranges may also be
sparse.

This alters the signature of the function to accept offsets
into both the GPIO-chip local pinspace and the pin controller
local pinspace.

Reviewed-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

1 files changed, 12 insertions, 0 deletions

diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c
index a40cd84c5c10..d542a141811a 100644
--- a/drivers/gpio/gpiolib-of.c
+++ b/drivers/gpio/gpiolib-of.c
@@ -238,8 +238,20 @@ static void of_gpiochip_add_pin_range(struct gpio_chip *chip)
                 if (!pctldev)
                         break;
 
+                /*
+                 * This assumes that the n GPIO pins are consecutive in the
+                 * GPIO number space, and that the pins are also consecutive
+                 * in their local number space. Currently it is not possible
+                 * to add different ranges for one and the same GPIO chip,
+                 * as the code assumes that we have one consecutive range
+                 * on both, mapping 1-to-1.
+                 *
+                 * TODO: make the OF bindings handle multiple sparse ranges
+                 * on the same GPIO chip.
+                 */
                 ret = gpiochip_add_pin_range(chip,
                                              pinctrl_dev_get_name(pctldev),
+                                             0, /* offset in gpiochip */
                                              pinspec.args[0],
                                              pinspec.args[1]);