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>

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 866431f..5050693 100644 (file)
--- 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++) {

diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h
index b562f95..bde6469 100644 (file)
--- a/include/asm-generic/gpio.h
+++ b/include/asm-generic/gpio.h
@@ -47,6 +47,7 @@ struct gpio;
 struct seq_file;
 struct module;
 struct device_node;
+struct gpio_desc;
 
 /**
  * struct gpio_chip - abstract a GPIO controller
@@ -76,6 +77,7 @@ struct device_node;
  *     negative during registration, requests dynamic ID allocation.
  * @ngpio: the number of GPIOs handled by this controller; the last GPIO
  *     handled is (base + ngpio - 1).
+ * @desc: array of ngpio descriptors. Private.
  * @can_sleep: flag must be set iff get()/set() methods sleep, as they
  *     must while accessing GPIO expander chips over I2C or SPI
  * @names: if set, must be an array of strings to use as alternative
@@ -126,6 +128,7 @@ struct gpio_chip {
                                                struct gpio_chip *chip);
        int                     base;
        u16                     ngpio;
+       struct gpio_desc        *desc;
        const char              *const *names;
        unsigned                can_sleep:1;
        unsigned                exported:1;