| /* |
| * 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 { |
| struct gpio_chip gpio_chip; |
| struct mutex lock; |
| u32 registers; |
| /* |
| * 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 sent will end up in the last |
| * register at the end of the transfer. So, to have a logical |
| * numbering, store the bytes in reverse order. |
| */ |
| u8 buffer[0]; |
| }; |
| |
| static int __gen_74x164_write_config(struct gen_74x164_chip *chip) |
| { |
| return spi_write(to_spi_device(chip->gpio_chip.parent), chip->buffer, |
| chip->registers); |
| } |
| |
| static int gen_74x164_get_value(struct gpio_chip *gc, unsigned offset) |
| { |
| struct gen_74x164_chip *chip = gpiochip_get_data(gc); |
| u8 bank = chip->registers - 1 - 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 = gpiochip_get_data(gc); |
| u8 bank = chip->registers - 1 - 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 void gen_74x164_set_multiple(struct gpio_chip *gc, unsigned long *mask, |
| unsigned long *bits) |
| { |
| struct gen_74x164_chip *chip = gpiochip_get_data(gc); |
| unsigned int i, idx, shift; |
| u8 bank, bankmask; |
| |
| mutex_lock(&chip->lock); |
| for (i = 0, bank = chip->registers - 1; i < chip->registers; |
| i++, bank--) { |
| idx = i / sizeof(*mask); |
| shift = i % sizeof(*mask) * BITS_PER_BYTE; |
| bankmask = mask[idx] >> shift; |
| if (!bankmask) |
| continue; |
| |
| chip->buffer[bank] &= ~bankmask; |
| chip->buffer[bank] |= bankmask & (bits[idx] >> shift); |
| } |
| __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; |
| u32 nregs; |
| 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; |
| |
| if (of_property_read_u32(spi->dev.of_node, "registers-number", |
| &nregs)) { |
| dev_err(&spi->dev, |
| "Missing registers-number property in the DT.\n"); |
| return -EINVAL; |
| } |
| |
| chip = devm_kzalloc(&spi->dev, sizeof(*chip) + nregs, 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.set_multiple = gen_74x164_set_multiple; |
| chip->gpio_chip.base = -1; |
| |
| chip->registers = nregs; |
| chip->gpio_chip.ngpio = GEN_74X164_NUMBER_GPIOS * chip->registers; |
| |
| of_property_read_u8_array(spi->dev.of_node, "registers-default", |
| chip->buffer, chip->registers); |
| |
| chip->gpio_chip.can_sleep = true; |
| chip->gpio_chip.parent = &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_data(&chip->gpio_chip, 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" }, |
| { .compatible = "nxp,74lvc594" }, |
| {}, |
| }; |
| MODULE_DEVICE_TABLE(of, gen_74x164_dt_ids); |
| |
| static struct spi_driver gen_74x164_driver = { |
| .driver = { |
| .name = "74x164", |
| .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"); |