In function gpiochip_find_base, base number of a GPIO controller is found in decreasing order. ARCH_NR_GPIOS is used to define from which number we begin to search for base number of a GPIO controller.
In fact, ARCH_NR_GPIOS brings us some multiplatform problems, like: http://www.spinics.net/lists/devicetree/msg60433.html This patch adds the support to find base number of a GPIO controller in increasing order. It will assign base number from 0. A new dts property called gpio-number-forward must be add to the related GPIO dts nodes if you want it works well. Signed-off-by: Zhou Wang <[email protected]> --- drivers/gpio/gpiolib.c | 63 +++++++++++++++++++++++++++++++++++++++++------- 1 file changed, 54 insertions(+), 9 deletions(-) diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index e8e98ca..d5e8e13 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -55,6 +55,15 @@ static DEFINE_MUTEX(gpio_lookup_lock); static LIST_HEAD(gpio_lookup_list); LIST_HEAD(gpio_chips); +/* check find_base_order to find if prior GPIO controller and current GPIO + * controller find base number in different orders. Backward is default. + */ +static enum { + gpio_number_backward, + gpio_number_forward, + gpio_order_different, +} find_base_order; + static inline void desc_set_label(struct gpio_desc *d, const char *label) { d->label = label; @@ -107,18 +116,54 @@ struct gpio_chip *gpiod_to_chip(const struct gpio_desc *desc) EXPORT_SYMBOL_GPL(gpiod_to_chip); /* dynamic allocation of GPIOs, e.g. on a hotplugged device */ -static int gpiochip_find_base(int ngpio) +static int gpiochip_find_base(struct gpio_chip *gpio_chip) { + int base; struct gpio_chip *chip; - int base = ARCH_NR_GPIOS - ngpio; + int ngpio = gpio_chip->ngpio; - list_for_each_entry_reverse(chip, &gpio_chips, list) { - /* found a free space? */ - if (chip->base + chip->ngpio <= base) - break; - else + if (find_base_order == gpio_order_different) { + pr_err("%s: stop adding gpio chip\n", __func__); + return -EINVAL; + } + + if (of_property_read_bool(gpio_chip->dev->of_node, + "gpio-number-forward")) { + /* find base in increasing order */ + base = 0; + + if (!list_empty(&gpio_chips)) { + if (find_base_order == gpio_number_backward) { + find_base_order = gpio_order_different; + pr_err("%s: find base in different order\n", + __func__); + return -EINVAL; + } + chip = list_last_entry(&gpio_chips, struct gpio_chip, + list); + base = chip->base + chip->ngpio; + } + + find_base_order = gpio_number_forward; + } else { + if (find_base_order == gpio_number_forward) { + find_base_order = gpio_order_different; + pr_err("%s: find base in different order\n", __func__); + return -EINVAL; + } + + base = ARCH_NR_GPIOS - ngpio; + + list_for_each_entry_reverse(chip, &gpio_chips, list) { + /* found a free space? */ + if (chip->base + chip->ngpio <= base) + break; + else /* nope, check the space right before the chip */ - base = chip->base - ngpio; + base = chip->base - ngpio; + } + + find_base_order = gpio_number_backward; } if (gpio_is_valid(base)) { @@ -236,7 +281,7 @@ int gpiochip_add(struct gpio_chip *chip) spin_lock_irqsave(&gpio_lock, flags); if (base < 0) { - base = gpiochip_find_base(chip->ngpio); + base = gpiochip_find_base(chip); if (base < 0) { status = base; goto unlock; -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
