gpiolib: let gpio_chip reference its descriptors

Add a pointer to the gpio_chip structure that references the array of
GPIO descriptors belonging to the chip, and update gpiolib code to use
this pointer instead of the global gpio_desc[] array. This is another
step towards the removal of the gpio_desc[] global array.

Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.orh>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

1 files changed, 23 insertions, 16 deletions

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 866431f674c3..5050693dcc35 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -72,6 +72,8 @@ struct gpio_desc {
 };
 static struct gpio_desc gpio_desc[ARCH_NR_GPIOS];
 
+#define GPIO_OFFSET_VALID(chip, offset) (offset >= 0 && offset < chip->ngpio)
+
 static LIST_HEAD(gpio_chips);
 
 #ifdef CONFIG_GPIO_SYSFS
@@ -112,7 +114,7 @@ static inline void desc_set_label(struct gpio_desc *d, const char *label)
  */
 static int gpio_chip_hwgpio(const struct gpio_desc *desc)
 {
-        return (desc - &gpio_desc[0]) - desc->chip->base;
+        return desc - &desc->chip->desc[0];
 }
 
 /**
@@ -133,7 +135,7 @@ static struct gpio_desc *gpio_to_desc(unsigned gpio)
  */
 static int desc_to_gpio(const struct gpio_desc *desc)
 {
-        return desc - &gpio_desc[0];
+        return desc->chip->base + gpio_chip_hwgpio(desc);
 }
 
 
@@ -1007,9 +1009,9 @@ static int gpiochip_export(struct gpio_chip *chip)
                 unsigned        gpio;
 
                 spin_lock_irqsave(&gpio_lock, flags);
-                gpio = chip->base;
-                while (gpio_desc[gpio].chip == chip)
-                        gpio_desc[gpio++].chip = NULL;
+                gpio = 0;
+                while (gpio < chip->ngpio)
+                        chip->desc[gpio++].chip = NULL;
                 spin_unlock_irqrestore(&gpio_lock, flags);
 
                 pr_debug("%s: chip %s status %d\n", __func__,
@@ -1186,8 +1188,11 @@ int gpiochip_add(struct gpio_chip *chip)
         status = gpiochip_add_to_list(chip);
 
         if (status == 0) {
-                for (id = base; id < base + chip->ngpio; id++) {
-                        gpio_desc[id].chip = chip;
+                chip->desc = &gpio_desc[chip->base];
+
+                for (id = 0; id < chip->ngpio; id++) {
+                        struct gpio_desc *desc = &chip->desc[id];
+                        desc->chip = chip;
 
                         /* REVISIT:  most hardware initializes GPIOs as
                          * inputs (often with pullups enabled) so power
@@ -1196,7 +1201,7 @@ int gpiochip_add(struct gpio_chip *chip)
                          * and in case chip->get_direction is not set,
                          * we may expose the wrong direction in sysfs.
                          */
-                        gpio_desc[id].flags = !chip->direction_input
+                        desc->flags = !chip->direction_input
                                 ? (1 << FLAG_IS_OUT)
                                 : 0;
                 }
@@ -1249,15 +1254,15 @@ int gpiochip_remove(struct gpio_chip *chip)
         gpiochip_remove_pin_ranges(chip);
         of_gpiochip_remove(chip);
 
-        for (id = chip->base; id < chip->base + chip->ngpio; id++) {
-                if (test_bit(FLAG_REQUESTED, &gpio_desc[id].flags)) {
+        for (id = 0; id < chip->ngpio; id++) {
+                if (test_bit(FLAG_REQUESTED, &chip->desc[id].flags)) {
                         status = -EBUSY;
                         break;
                 }
         }
         if (status == 0) {
-                for (id = chip->base; id < chip->base + chip->ngpio; id++)
-                        gpio_desc[id].chip = NULL;
+                for (id = 0; id < chip->ngpio; id++)
+                        chip->desc[id].chip = NULL;
 
                 list_del(&chip->list);
         }
@@ -1582,11 +1587,13 @@ EXPORT_SYMBOL_GPL(gpio_free_array);
  */
 const char *gpiochip_is_requested(struct gpio_chip *chip, unsigned offset)
 {
-        unsigned gpio = chip->base + offset;
-        struct gpio_desc *desc = &gpio_desc[gpio];
+        struct gpio_desc *desc;
 
-        if (!gpio_is_valid(gpio) || desc->chip != chip)
+        if (!GPIO_OFFSET_VALID(chip, offset))
                 return NULL;
+
+        desc = &chip->desc[offset];
+
         if (test_bit(FLAG_REQUESTED, &desc->flags) == 0)
                 return NULL;
 #ifdef CONFIG_DEBUG_FS
@@ -2025,7 +2032,7 @@ static void gpiolib_dbg_show(struct seq_file *s, struct gpio_chip *chip)
 {
         unsigned                i;
         unsigned                gpio = chip->base;
-        struct gpio_desc        *gdesc = &gpio_desc[gpio];
+        struct gpio_desc        *gdesc = &chip->desc[0];
         int                     is_out;
 
         for (i = 0; i < chip->ngpio; i++, gpio++, gdesc++) {