gpio.h

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#ifndef _IPXE_GPIO_H
#define _IPXE_GPIO_H

/** @file
 *
 * General purpose I/O
 *
 */

FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );

#include <stdint.h>
#include <ipxe/list.h>
#include <ipxe/refcnt.h>
#include <ipxe/device.h>

/** A GPIO pin */
struct gpio {
        /** GPIO controller */
        struct gpios *gpios;
        /** Pin index */
        unsigned int index;
        /** Configuration */
        unsigned int config;
};

/** GPIO is active low
 *
 * This bit is chosen to match the devicetree standard usage.
 */
#define GPIO_CFG_ACTIVE_LOW 0x01

/** GPIO is an output */
#define GPIO_CFG_OUTPUT 0x0100

/** A GPIO controller */
struct gpios {
        /** Reference count */
        struct refcnt refcnt;
        /** List of GPIO controllers */
        struct list_head list;
        /** Generic device */
        struct device *dev;
        /** Number of GPIOs */
        unsigned int count;

        /** Individual GPIOs */
        struct gpio *gpio;
        /** GPIO operations */
        struct gpio_operations *op;

        /** Driver-private data */
        void *priv;
};

/** GPIO operations */
struct gpio_operations {
        /**
         * Get current GPIO input value
         *
         * @v gpios             GPIO controller
         * @v gpio              GPIO pin
         * @ret active          Pin is in the active state
         */
        int ( * in ) ( struct gpios *gpios, struct gpio *gpio );
        /**
         * Set current GPIO output value
         *
         * @v gpios             GPIO controller
         * @v gpio              GPIO pin
         * @v active            Set pin to active state
         */
        void ( * out ) ( struct gpios *gpios, struct gpio *gpio, int active );
        /**
         * Configure GPIO pin
         *
         * @v gpios             GPIO controller
         * @v gpio              GPIO pin
         * @v config            Configuration
         * @ret rc              Return status code
         */
        int ( * config ) ( struct gpios *gpios, struct gpio *gpio,
                           unsigned int config );
};

extern struct gpio_operations null_gpio_operations;

/**
 * Get reference to GPIO controller
 *
 * @v gpios             GPIO controller
 * @ret gpios           GPIO controller
 */
static inline __attribute__ (( always_inline )) struct gpios *
gpios_get ( struct gpios *gpios ) {
        ref_get ( &gpios->refcnt );
        return gpios;
}

/**
 * Drop reference to GPIO controller
 *
 * @v gpios             GPIO controller
 */
static inline __attribute__ (( always_inline )) void
gpios_put ( struct gpios *gpios ) {
        ref_put ( &gpios->refcnt );
}

/**
 * Get reference to GPIO pin
 *
 * @v gpio              GPIO pin
 * @ret gpio            GPIO pin
 */
static inline __attribute__ (( always_inline )) struct gpio *
gpio_get ( struct gpio *gpio ) {
        gpios_get ( gpio->gpios );
        return gpio;
}

/**
 * Drop reference to GPIO ping
 *
 * @v gpio              GPIO pin
 */
static inline __attribute__ (( always_inline )) void
gpio_put ( struct gpio *gpio ) {
        gpios_put ( gpio->gpios );
}

/**
 * Initialise a GPIO controller
 *
 * @v gpios             GPIO controller
 * @v op                GPIO operations
 */
static inline __attribute__ (( always_inline )) void
gpios_init ( struct gpios *gpios, struct gpio_operations *op ) {
        gpios->op = op;
}

/**
 * Stop using a GPIO controller
 *
 * @v gpios             GPIO controller
 *
 * Drivers should call this method immediately before the final call
 * to gpios_put().
 */
static inline __attribute__ (( always_inline )) void
gpios_nullify ( struct gpios *gpios ) {
        gpios->op = &null_gpio_operations;
}

/**
 * Get current GPIO input value
 *
 * @v gpio              GPIO pin
 * @ret active          Pin is in the active state
 */
static inline int gpio_in ( struct gpio *gpio ) {
        struct gpios *gpios = gpio->gpios;

        return gpios->op->in ( gpios, gpio );
}

/**
 * Set current GPIO output value
 *
 * @v gpio              GPIO pin
 * @v active            Set pin to active state
 */
static inline void gpio_out ( struct gpio *gpio, int active ) {
        struct gpios *gpios = gpio->gpios;

        gpios->op->out ( gpios, gpio, active );
}

/**
 * Configure GPIO pin
 *
 * @v gpio              GPIO pin
 * @v config            Configuration
 * @ret rc              Return status code
 */
static inline int gpio_config ( struct gpio *gpio, unsigned int config ) {
        struct gpios *gpios = gpio->gpios;

        return gpios->op->config ( gpios, gpio, config );
}

extern struct gpios * alloc_gpios ( unsigned int count, size_t priv_len );
extern int gpios_register ( struct gpios *gpios );
extern void gpios_unregister ( struct gpios *gpios );
extern struct gpios * gpios_find ( unsigned int bus_type,
                                   unsigned int location );

#endif /* _IPXE_GPIO_H */