From ad824783fb23bbc8295cffb6214b3b82d25f7d4a Mon Sep 17 00:00:00 2001 From: Alexandre Courbot Date: Tue, 3 Dec 2013 12:20:11 +0900 Subject: [PATCH] gpio: better lookup method for platform GPIOs Change the format of the platform GPIO lookup tables to make them less confusing and improve lookup efficiency. The previous format was a single linked-list that required to compare the device name and function ID of every single GPIO defined for each lookup. Switch that to a list of per-device tables, so that the lookup can be done in two steps, omitting the GPIOs that are not relevant for a particular device. The matching rules are now defined as follows: - The device name must match *exactly*, and can be NULL for GPIOs not assigned to a particular device, - If the function ID in the lookup table is NULL, the con_id argument of gpiod_get() will not be used for lookup. However, if it is defined, it must match exactly. - The index must always match. Signed-off-by: Alexandre Courbot Acked-by: Mika Westerberg Reviewed-by: Andy Shevchenko Signed-off-by: Linus Walleij --- Documentation/gpio/board.txt | 28 +++++---- drivers/gpio/gpiolib.c | 108 +++++++++++++++++++---------------- include/linux/gpio/driver.h | 21 ++++--- 3 files changed, 85 insertions(+), 72 deletions(-) diff --git a/Documentation/gpio/board.txt b/Documentation/gpio/board.txt index 0d03506f2cc5..ba169faad5c6 100644 --- a/Documentation/gpio/board.txt +++ b/Documentation/gpio/board.txt @@ -72,10 +72,11 @@ where - chip_label is the label of the gpiod_chip instance providing the GPIO - chip_hwnum is the hardware number of the GPIO within the chip - - dev_id is the identifier of the device that will make use of this GPIO. If - NULL, the GPIO will be available to all devices. + - dev_id is the identifier of the device that will make use of this GPIO. It + can be NULL, in which case it will be matched for calls to gpiod_get() + with a NULL device. - con_id is the name of the GPIO function from the device point of view. It - can be NULL. + can be NULL, in which case it will match any function. - idx is the index of the GPIO within the function. - flags is defined to specify the following properties: * GPIOF_ACTIVE_LOW - to configure the GPIO as active-low @@ -86,18 +87,23 @@ In the future, these flags might be extended to support more properties. Note that GPIO_LOOKUP() is just a shortcut to GPIO_LOOKUP_IDX() where idx = 0. -A lookup table can then be defined as follows: +A lookup table can then be defined as follows, with an empty entry defining its +end: - struct gpiod_lookup gpios_table[] = { - GPIO_LOOKUP_IDX("gpio.0", 15, "foo.0", "led", 0, GPIO_ACTIVE_HIGH), - GPIO_LOOKUP_IDX("gpio.0", 16, "foo.0", "led", 1, GPIO_ACTIVE_HIGH), - GPIO_LOOKUP_IDX("gpio.0", 17, "foo.0", "led", 2, GPIO_ACTIVE_HIGH), - GPIO_LOOKUP("gpio.0", 1, "foo.0", "power", GPIO_ACTIVE_LOW), - }; +struct gpiod_lookup_table gpios_table = { + .dev_id = "foo.0", + .table = { + GPIO_LOOKUP_IDX("gpio.0", 15, "led", 0, GPIO_ACTIVE_HIGH), + GPIO_LOOKUP_IDX("gpio.0", 16, "led", 1, GPIO_ACTIVE_HIGH), + GPIO_LOOKUP_IDX("gpio.0", 17, "led", 2, GPIO_ACTIVE_HIGH), + GPIO_LOOKUP("gpio.0", 1, "power", GPIO_ACTIVE_LOW), + { }, + }, +}; And the table can be added by the board code as follows: - gpiod_add_table(gpios_table, ARRAY_SIZE(gpios_table)); + gpiod_add_lookup_table(&gpios_table); The driver controlling "foo.0" will then be able to obtain its GPIOs as follows: diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 44a232701179..4eb262a31777 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -2260,18 +2260,14 @@ void gpiod_set_value_cansleep(struct gpio_desc *desc, int value) EXPORT_SYMBOL_GPL(gpiod_set_value_cansleep); /** - * gpiod_add_table() - register GPIO device consumers - * @table: array of consumers to register - * @num: number of consumers in table + * gpiod_add_lookup_table() - register GPIO device consumers + * @table: table of consumers to register */ -void gpiod_add_table(struct gpiod_lookup *table, size_t size) +void gpiod_add_lookup_table(struct gpiod_lookup_table *table) { mutex_lock(&gpio_lookup_lock); - while (size--) { - list_add_tail(&table->list, &gpio_lookup_list); - table++; - } + list_add_tail(&table->list, &gpio_lookup_list); mutex_unlock(&gpio_lookup_lock); } @@ -2327,72 +2323,84 @@ static struct gpio_desc *acpi_find_gpio(struct device *dev, const char *con_id, return desc; } -static struct gpio_desc *gpiod_find(struct device *dev, const char *con_id, - unsigned int idx, - enum gpio_lookup_flags *flags) +static struct gpiod_lookup_table *gpiod_find_lookup_table(struct device *dev) { const char *dev_id = dev ? dev_name(dev) : NULL; - struct gpio_desc *desc = ERR_PTR(-ENODEV); - unsigned int match, best = 0; - struct gpiod_lookup *p; + struct gpiod_lookup_table *table; mutex_lock(&gpio_lookup_lock); - list_for_each_entry(p, &gpio_lookup_list, list) { - match = 0; + list_for_each_entry(table, &gpio_lookup_list, list) { + if (table->dev_id && dev_id) { + /* + * Valid strings on both ends, must be identical to have + * a match + */ + if (!strcmp(table->dev_id, dev_id)) + goto found; + } else { + /* + * One of the pointers is NULL, so both must be to have + * a match + */ + if (dev_id == table->dev_id) + goto found; + } + } + table = NULL; - if (p->dev_id) { - if (!dev_id || strcmp(p->dev_id, dev_id)) - continue; +found: + mutex_unlock(&gpio_lookup_lock); + return table; +} - match += 2; - } +static struct gpio_desc *gpiod_find(struct device *dev, const char *con_id, + unsigned int idx, + enum gpio_lookup_flags *flags) +{ + struct gpio_desc *desc = ERR_PTR(-ENODEV); + struct gpiod_lookup_table *table; + struct gpiod_lookup *p; - if (p->con_id) { - if (!con_id || strcmp(p->con_id, con_id)) - continue; + table = gpiod_find_lookup_table(dev); + if (!table) + return desc; - match += 1; - } + for (p = &table->table[0]; p->chip_label; p++) { + struct gpio_chip *chip; + /* idx must always match exactly */ if (p->idx != idx) continue; - if (match > best) { - struct gpio_chip *chip; - - chip = find_chip_by_name(p->chip_label); - - if (!chip) { - dev_warn(dev, "cannot find GPIO chip %s\n", - p->chip_label); - continue; - } + /* If the lookup entry has a con_id, require exact match */ + if (p->con_id && (!con_id || strcmp(p->con_id, con_id))) + continue; - if (chip->ngpio <= p->chip_hwnum) { - dev_warn(dev, "GPIO chip %s has %d GPIOs\n", - chip->label, chip->ngpio); - continue; - } + chip = find_chip_by_name(p->chip_label); - desc = gpio_to_desc(chip->base + p->chip_hwnum); - *flags = p->flags; + if (!chip) { + dev_warn(dev, "cannot find GPIO chip %s\n", + p->chip_label); + continue; + } - if (match != 3) - best = match; - else - break; + if (chip->ngpio <= p->chip_hwnum) { + dev_warn(dev, "GPIO chip %s has %d GPIOs\n", + chip->label, chip->ngpio); + continue; } - } - mutex_unlock(&gpio_lookup_lock); + desc = gpiochip_offset_to_desc(chip, p->chip_hwnum); + *flags = p->flags; + } return desc; } /** * gpio_get - obtain a GPIO for a given GPIO function - * @dev: GPIO consumer + * @dev: GPIO consumer, can be NULL for system-global GPIOs * @con_id: function within the GPIO consumer * * Return the GPIO descriptor corresponding to the function con_id of device diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h index c849676c6787..44c66b29a2d9 100644 --- a/include/linux/gpio/driver.h +++ b/include/linux/gpio/driver.h @@ -141,7 +141,6 @@ enum gpio_lookup_flags { * platform data. */ struct gpiod_lookup { - struct list_head list; /* * name of the chip the GPIO belongs to */ @@ -150,10 +149,6 @@ struct gpiod_lookup { * hardware number (i.e. relative to the chip) of the GPIO */ u16 chip_hwnum; - /* - * name of device that can claim this GPIO - */ - const char *dev_id; /* * name of the GPIO from the device's point of view */ @@ -168,28 +163,32 @@ struct gpiod_lookup { enum gpio_lookup_flags flags; }; +struct gpiod_lookup_table { + struct list_head list; + const char *dev_id; + struct gpiod_lookup table[]; +}; + /* * Simple definition of a single GPIO under a con_id */ -#define GPIO_LOOKUP(_chip_label, _chip_hwnum, _dev_id, _con_id, _flags) \ - GPIO_LOOKUP_IDX(_chip_label, _chip_hwnum, _dev_id, _con_id, 0, _flags) +#define GPIO_LOOKUP(_chip_label, _chip_hwnum, _con_id, _flags) \ + GPIO_LOOKUP_IDX(_chip_label, _chip_hwnum, _con_id, 0, _flags) /* * Use this macro if you need to have several GPIOs under the same con_id. * Each GPIO needs to use a different index and can be accessed using * gpiod_get_index() */ -#define GPIO_LOOKUP_IDX(_chip_label, _chip_hwnum, _dev_id, _con_id, _idx, \ - _flags) \ +#define GPIO_LOOKUP_IDX(_chip_label, _chip_hwnum, _con_id, _idx, _flags) \ { \ .chip_label = _chip_label, \ .chip_hwnum = _chip_hwnum, \ - .dev_id = _dev_id, \ .con_id = _con_id, \ .idx = _idx, \ .flags = _flags, \ } -void gpiod_add_table(struct gpiod_lookup *table, size_t size); +void gpiod_add_lookup_table(struct gpiod_lookup_table *table); #endif -- 2.20.1