![Grant Likely](/assets/img/avatar_default.png)
Currently the kernel uses the struct device_node.data pointer to resolve a struct gpio_chip pointer from a device tree node. However, the .data member doesn't provide any type checking and there aren't any rules enforced on what it should be used for. There's no guarantee that the data stored in it actually points to an gpio_chip pointer. Instead of relying on the .data pointer, this patch modifies the code to add a lookup function which scans through the registered gpio_chips and returns the gpio_chip that has a pointer to the specified device_node. Signed-off-by: Grant Likely <grant.likely@secretlab.ca> CC: Andrew Morton <akpm@linux-foundation.org> CC: Anton Vorontsov <avorontsov@ru.mvista.com> CC: Grant Likely <grant.likely@secretlab.ca> CC: David Brownell <dbrownell@users.sourceforge.net> CC: Bill Gatliff <bgat@billgatliff.com> CC: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com> CC: Benjamin Herrenschmidt <benh@kernel.crashing.org> CC: Jean Delvare <khali@linux-fr.org> CC: linux-kernel@vger.kernel.org CC: devicetree-discuss@lists.ozlabs.org
260 lines
7.8 KiB
C
260 lines
7.8 KiB
C
#ifndef _ASM_GENERIC_GPIO_H
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#define _ASM_GENERIC_GPIO_H
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#include <linux/kernel.h>
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#include <linux/types.h>
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#include <linux/errno.h>
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#ifdef CONFIG_GPIOLIB
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#include <linux/compiler.h>
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/* Platforms may implement their GPIO interface with library code,
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* at a small performance cost for non-inlined operations and some
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* extra memory (for code and for per-GPIO table entries).
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*
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* While the GPIO programming interface defines valid GPIO numbers
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* to be in the range 0..MAX_INT, this library restricts them to the
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* smaller range 0..ARCH_NR_GPIOS-1.
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*/
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#ifndef ARCH_NR_GPIOS
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#define ARCH_NR_GPIOS 256
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#endif
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static inline int gpio_is_valid(int number)
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{
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/* only some non-negative numbers are valid */
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return ((unsigned)number) < ARCH_NR_GPIOS;
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}
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struct device;
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struct seq_file;
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struct module;
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struct device_node;
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/**
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* struct gpio_chip - abstract a GPIO controller
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* @label: for diagnostics
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* @dev: optional device providing the GPIOs
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* @owner: helps prevent removal of modules exporting active GPIOs
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* @request: optional hook for chip-specific activation, such as
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* enabling module power and clock; may sleep
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* @free: optional hook for chip-specific deactivation, such as
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* disabling module power and clock; may sleep
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* @direction_input: configures signal "offset" as input, or returns error
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* @get: returns value for signal "offset"; for output signals this
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* returns either the value actually sensed, or zero
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* @direction_output: configures signal "offset" as output, or returns error
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* @set: assigns output value for signal "offset"
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* @to_irq: optional hook supporting non-static gpio_to_irq() mappings;
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* implementation may not sleep
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* @dbg_show: optional routine to show contents in debugfs; default code
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* will be used when this is omitted, but custom code can show extra
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* state (such as pullup/pulldown configuration).
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* @base: identifies the first GPIO number handled by this chip; or, if
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* negative during registration, requests dynamic ID allocation.
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* @ngpio: the number of GPIOs handled by this controller; the last GPIO
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* handled is (base + ngpio - 1).
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* @can_sleep: flag must be set iff get()/set() methods sleep, as they
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* must while accessing GPIO expander chips over I2C or SPI
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* @names: if set, must be an array of strings to use as alternative
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* names for the GPIOs in this chip. Any entry in the array
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* may be NULL if there is no alias for the GPIO, however the
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* array must be @ngpio entries long. A name can include a single printk
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* format specifier for an unsigned int. It is substituted by the actual
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* number of the gpio.
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*
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* A gpio_chip can help platforms abstract various sources of GPIOs so
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* they can all be accessed through a common programing interface.
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* Example sources would be SOC controllers, FPGAs, multifunction
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* chips, dedicated GPIO expanders, and so on.
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*
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* Each chip controls a number of signals, identified in method calls
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* by "offset" values in the range 0..(@ngpio - 1). When those signals
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* are referenced through calls like gpio_get_value(gpio), the offset
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* is calculated by subtracting @base from the gpio number.
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*/
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struct gpio_chip {
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const char *label;
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struct device *dev;
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struct module *owner;
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int (*request)(struct gpio_chip *chip,
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unsigned offset);
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void (*free)(struct gpio_chip *chip,
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unsigned offset);
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int (*direction_input)(struct gpio_chip *chip,
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unsigned offset);
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int (*get)(struct gpio_chip *chip,
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unsigned offset);
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int (*direction_output)(struct gpio_chip *chip,
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unsigned offset, int value);
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int (*set_debounce)(struct gpio_chip *chip,
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unsigned offset, unsigned debounce);
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void (*set)(struct gpio_chip *chip,
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unsigned offset, int value);
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int (*to_irq)(struct gpio_chip *chip,
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unsigned offset);
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void (*dbg_show)(struct seq_file *s,
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struct gpio_chip *chip);
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int base;
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u16 ngpio;
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const char *const *names;
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unsigned can_sleep:1;
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unsigned exported:1;
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#if defined(CONFIG_OF_GPIO)
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/*
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* If CONFIG_OF is enabled, then all GPIO controllers described in the
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* device tree automatically may have an OF translation
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*/
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struct device_node *of_node;
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int of_gpio_n_cells;
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int (*of_xlate)(struct gpio_chip *gc, struct device_node *np,
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const void *gpio_spec, u32 *flags);
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#endif
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};
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extern const char *gpiochip_is_requested(struct gpio_chip *chip,
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unsigned offset);
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extern int __must_check gpiochip_reserve(int start, int ngpio);
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/* add/remove chips */
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extern int gpiochip_add(struct gpio_chip *chip);
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extern int __must_check gpiochip_remove(struct gpio_chip *chip);
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extern struct gpio_chip *gpiochip_find(void *data,
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int (*match)(struct gpio_chip *chip,
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void *data));
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/* Always use the library code for GPIO management calls,
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* or when sleeping may be involved.
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*/
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extern int gpio_request(unsigned gpio, const char *label);
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extern void gpio_free(unsigned gpio);
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extern int gpio_direction_input(unsigned gpio);
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extern int gpio_direction_output(unsigned gpio, int value);
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extern int gpio_set_debounce(unsigned gpio, unsigned debounce);
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extern int gpio_get_value_cansleep(unsigned gpio);
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extern void gpio_set_value_cansleep(unsigned gpio, int value);
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/* A platform's <asm/gpio.h> code may want to inline the I/O calls when
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* the GPIO is constant and refers to some always-present controller,
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* giving direct access to chip registers and tight bitbanging loops.
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*/
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extern int __gpio_get_value(unsigned gpio);
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extern void __gpio_set_value(unsigned gpio, int value);
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extern int __gpio_cansleep(unsigned gpio);
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extern int __gpio_to_irq(unsigned gpio);
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#define GPIOF_DIR_OUT (0 << 0)
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#define GPIOF_DIR_IN (1 << 0)
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#define GPIOF_INIT_LOW (0 << 1)
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#define GPIOF_INIT_HIGH (1 << 1)
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#define GPIOF_IN (GPIOF_DIR_IN)
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#define GPIOF_OUT_INIT_LOW (GPIOF_DIR_OUT | GPIOF_INIT_LOW)
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#define GPIOF_OUT_INIT_HIGH (GPIOF_DIR_OUT | GPIOF_INIT_HIGH)
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/**
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* struct gpio - a structure describing a GPIO with configuration
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* @gpio: the GPIO number
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* @flags: GPIO configuration as specified by GPIOF_*
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* @label: a literal description string of this GPIO
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*/
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struct gpio {
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unsigned gpio;
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unsigned long flags;
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const char *label;
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};
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extern int gpio_request_one(unsigned gpio, unsigned long flags, const char *label);
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extern int gpio_request_array(struct gpio *array, size_t num);
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extern void gpio_free_array(struct gpio *array, size_t num);
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#ifdef CONFIG_GPIO_SYSFS
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/*
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* A sysfs interface can be exported by individual drivers if they want,
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* but more typically is configured entirely from userspace.
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*/
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extern int gpio_export(unsigned gpio, bool direction_may_change);
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extern int gpio_export_link(struct device *dev, const char *name,
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unsigned gpio);
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extern int gpio_sysfs_set_active_low(unsigned gpio, int value);
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extern void gpio_unexport(unsigned gpio);
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#endif /* CONFIG_GPIO_SYSFS */
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#else /* !CONFIG_HAVE_GPIO_LIB */
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static inline int gpio_is_valid(int number)
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{
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/* only non-negative numbers are valid */
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return number >= 0;
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}
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/* platforms that don't directly support access to GPIOs through I2C, SPI,
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* or other blocking infrastructure can use these wrappers.
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*/
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static inline int gpio_cansleep(unsigned gpio)
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{
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return 0;
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}
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static inline int gpio_get_value_cansleep(unsigned gpio)
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{
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might_sleep();
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return gpio_get_value(gpio);
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}
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static inline void gpio_set_value_cansleep(unsigned gpio, int value)
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{
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might_sleep();
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gpio_set_value(gpio, value);
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}
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#endif /* !CONFIG_HAVE_GPIO_LIB */
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#ifndef CONFIG_GPIO_SYSFS
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struct device;
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/* sysfs support is only available with gpiolib, where it's optional */
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static inline int gpio_export(unsigned gpio, bool direction_may_change)
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{
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return -ENOSYS;
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}
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static inline int gpio_export_link(struct device *dev, const char *name,
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unsigned gpio)
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{
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return -ENOSYS;
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}
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static inline int gpio_sysfs_set_active_low(unsigned gpio, int value)
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{
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return -ENOSYS;
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}
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static inline void gpio_unexport(unsigned gpio)
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{
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}
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#endif /* CONFIG_GPIO_SYSFS */
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#endif /* _ASM_GENERIC_GPIO_H */
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