diff options
Diffstat (limited to 'drivers/gpio/gpio-74x164.c')
| -rw-r--r-- | drivers/gpio/gpio-74x164.c | 177 |
1 files changed, 177 insertions, 0 deletions
diff --git a/drivers/gpio/gpio-74x164.c b/drivers/gpio/gpio-74x164.c new file mode 100644 index 0000000..7fb60b6 --- /dev/null +++ b/drivers/gpio/gpio-74x164.c @@ -0,0 +1,177 @@ +/* + * 74Hx164 - Generic serial-in/parallel-out 8-bits shift register GPIO driver + * + * Copyright (C) 2010 Gabor Juhos <juhosg@openwrt.org> + * Copyright (C) 2010 Miguel Gaio <miguel.gaio@efixo.com> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#include <linux/init.h> +#include <linux/mutex.h> +#include <linux/spi/spi.h> +#include <linux/spi/74x164.h> +#include <linux/gpio.h> +#include <linux/slab.h> + +struct gen_74x164_chip { + struct spi_device *spi; + struct gpio_chip gpio_chip; + struct mutex lock; + u8 port_config; +}; + +static struct gen_74x164_chip *gpio_to_chip(struct gpio_chip *gc) +{ + return container_of(gc, struct gen_74x164_chip, gpio_chip); +} + +static int __gen_74x164_write_config(struct gen_74x164_chip *chip) +{ + return spi_write(chip->spi, + &chip->port_config, sizeof(chip->port_config)); +} + +static int gen_74x164_get_value(struct gpio_chip *gc, unsigned offset) +{ + struct gen_74x164_chip *chip = gpio_to_chip(gc); + int ret; + + mutex_lock(&chip->lock); + ret = (chip->port_config >> offset) & 0x1; + mutex_unlock(&chip->lock); + + return ret; +} + +static void gen_74x164_set_value(struct gpio_chip *gc, + unsigned offset, int val) +{ + struct gen_74x164_chip *chip = gpio_to_chip(gc); + + mutex_lock(&chip->lock); + if (val) + chip->port_config |= (1 << offset); + else + chip->port_config &= ~(1 << offset); + + __gen_74x164_write_config(chip); + mutex_unlock(&chip->lock); +} + +static int gen_74x164_direction_output(struct gpio_chip *gc, + unsigned offset, int val) +{ + gen_74x164_set_value(gc, offset, val); + return 0; +} + +static int __devinit gen_74x164_probe(struct spi_device *spi) +{ + struct gen_74x164_chip *chip; + struct gen_74x164_chip_platform_data *pdata; + int ret; + + pdata = spi->dev.platform_data; + if (!pdata || !pdata->base) { + dev_dbg(&spi->dev, "incorrect or missing platform data\n"); + return -EINVAL; + } + + /* + * bits_per_word cannot be configured in platform data + */ + spi->bits_per_word = 8; + + ret = spi_setup(spi); + if (ret < 0) + return ret; + + chip = kzalloc(sizeof(*chip), GFP_KERNEL); + if (!chip) + return -ENOMEM; + + mutex_init(&chip->lock); + + dev_set_drvdata(&spi->dev, chip); + + chip->spi = spi; + + chip->gpio_chip.label = spi->modalias; + chip->gpio_chip.direction_output = gen_74x164_direction_output; + chip->gpio_chip.get = gen_74x164_get_value; + chip->gpio_chip.set = gen_74x164_set_value; + chip->gpio_chip.base = pdata->base; + chip->gpio_chip.ngpio = 8; + chip->gpio_chip.can_sleep = 1; + chip->gpio_chip.dev = &spi->dev; + chip->gpio_chip.owner = THIS_MODULE; + + ret = __gen_74x164_write_config(chip); + if (ret) { + dev_err(&spi->dev, "Failed writing: %d\n", ret); + goto exit_destroy; + } + + ret = gpiochip_add(&chip->gpio_chip); + if (ret) + goto exit_destroy; + + return ret; + +exit_destroy: + dev_set_drvdata(&spi->dev, NULL); + mutex_destroy(&chip->lock); + kfree(chip); + return ret; +} + +static int __devexit gen_74x164_remove(struct spi_device *spi) +{ + struct gen_74x164_chip *chip; + int ret; + + chip = dev_get_drvdata(&spi->dev); + if (chip == NULL) + return -ENODEV; + + dev_set_drvdata(&spi->dev, NULL); + + ret = gpiochip_remove(&chip->gpio_chip); + if (!ret) { + mutex_destroy(&chip->lock); + kfree(chip); + } else + dev_err(&spi->dev, "Failed to remove the GPIO controller: %d\n", + ret); + + return ret; +} + +static struct spi_driver gen_74x164_driver = { + .driver = { + .name = "74x164", + .owner = THIS_MODULE, + }, + .probe = gen_74x164_probe, + .remove = __devexit_p(gen_74x164_remove), +}; + +static int __init gen_74x164_init(void) +{ + return spi_register_driver(&gen_74x164_driver); +} +subsys_initcall(gen_74x164_init); + +static void __exit gen_74x164_exit(void) +{ + spi_unregister_driver(&gen_74x164_driver); +} +module_exit(gen_74x164_exit); + +MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>"); +MODULE_AUTHOR("Miguel Gaio <miguel.gaio@efixo.com>"); +MODULE_DESCRIPTION("GPIO expander driver for 74X164 8-bits shift register"); +MODULE_LICENSE("GPL v2"); |
