| /* |
| * 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/gpio.h> |
| #include <linux/of_gpio.h> |
| #include <linux/slab.h> |
| #include <linux/module.h> |
| |
| #define GEN_74X164_NUMBER_GPIOS 8 |
| |
| struct gen_74x164_chip { |
| u8 *buffer; |
| struct gpio_chip gpio_chip; |
| struct mutex lock; |
| u32 registers; |
| }; |
| |
| static struct gen_74x164_chip *gpio_to_74x164_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) |
| { |
| struct spi_device *spi = to_spi_device(chip->gpio_chip.dev); |
| struct spi_message message; |
| struct spi_transfer *msg_buf; |
| int i, ret = 0; |
| |
| msg_buf = kzalloc(chip->registers * sizeof(struct spi_transfer), |
| GFP_KERNEL); |
| if (!msg_buf) |
| return -ENOMEM; |
| |
| spi_message_init(&message); |
| |
| /* |
| * Since the registers are chained, every byte sent will make |
| * the previous byte shift to the next register in the |
| * chain. Thus, the first byte send will end up in the last |
| * register at the end of the transfer. So, to have a logical |
| * numbering, send the bytes in reverse order so that the last |
| * byte of the buffer will end up in the last register. |
| */ |
| for (i = chip->registers - 1; i >= 0; i--) { |
| msg_buf[i].tx_buf = chip->buffer + i; |
| msg_buf[i].len = sizeof(u8); |
| spi_message_add_tail(msg_buf + i, &message); |
| } |
| |
| ret = spi_sync(spi, &message); |
| |
| kfree(msg_buf); |
| |
| return ret; |
| } |
| |
| static int gen_74x164_get_value(struct gpio_chip *gc, unsigned offset) |
| { |
| struct gen_74x164_chip *chip = gpio_to_74x164_chip(gc); |
| u8 bank = offset / 8; |
| u8 pin = offset % 8; |
| int ret; |
| |
| mutex_lock(&chip->lock); |
| ret = (chip->buffer[bank] >> pin) & 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_74x164_chip(gc); |
| u8 bank = offset / 8; |
| u8 pin = offset % 8; |
| |
| mutex_lock(&chip->lock); |
| if (val) |
| chip->buffer[bank] |= (1 << pin); |
| else |
| chip->buffer[bank] &= ~(1 << pin); |
| |
| __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 gen_74x164_probe(struct spi_device *spi) |
| { |
| struct gen_74x164_chip *chip; |
| int ret; |
| |
| /* |
| * bits_per_word cannot be configured in platform data |
| */ |
| spi->bits_per_word = 8; |
| |
| ret = spi_setup(spi); |
| if (ret < 0) |
| return ret; |
| |
| chip = devm_kzalloc(&spi->dev, sizeof(*chip), GFP_KERNEL); |
| if (!chip) |
| return -ENOMEM; |
| |
| spi_set_drvdata(spi, chip); |
| |
| 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 = -1; |
| |
| if (of_property_read_u32(spi->dev.of_node, "registers-number", |
| &chip->registers)) { |
| dev_err(&spi->dev, |
| "Missing registers-number property in the DT.\n"); |
| return -EINVAL; |
| } |
| |
| chip->gpio_chip.ngpio = GEN_74X164_NUMBER_GPIOS * chip->registers; |
| chip->buffer = devm_kzalloc(&spi->dev, chip->registers, GFP_KERNEL); |
| if (!chip->buffer) |
| return -ENOMEM; |
| |
| of_property_read_u8_array(spi->dev.of_node, "registers-default", |
| chip->buffer, chip->registers); |
| |
| chip->gpio_chip.can_sleep = true; |
| chip->gpio_chip.dev = &spi->dev; |
| chip->gpio_chip.owner = THIS_MODULE; |
| |
| mutex_init(&chip->lock); |
| |
| 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) |
| return 0; |
| |
| exit_destroy: |
| mutex_destroy(&chip->lock); |
| |
| return ret; |
| } |
| |
| static int gen_74x164_remove(struct spi_device *spi) |
| { |
| struct gen_74x164_chip *chip = spi_get_drvdata(spi); |
| |
| gpiochip_remove(&chip->gpio_chip); |
| mutex_destroy(&chip->lock); |
| |
| return 0; |
| } |
| |
| static const struct of_device_id gen_74x164_dt_ids[] = { |
| { .compatible = "fairchild,74hc595" }, |
| {}, |
| }; |
| MODULE_DEVICE_TABLE(of, gen_74x164_dt_ids); |
| |
| static struct spi_driver gen_74x164_driver = { |
| .driver = { |
| .name = "74x164", |
| .owner = THIS_MODULE, |
| .of_match_table = gen_74x164_dt_ids, |
| }, |
| .probe = gen_74x164_probe, |
| .remove = gen_74x164_remove, |
| }; |
| module_spi_driver(gen_74x164_driver); |
| |
| 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"); |