From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001 From: André Fabian Silva Delgado Date: Wed, 5 Aug 2015 17:04:01 -0300 Subject: Initial import --- drivers/gpio/gpio-74x164.c | 197 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 197 insertions(+) create mode 100644 drivers/gpio/gpio-74x164.c (limited to 'drivers/gpio/gpio-74x164.c') diff --git a/drivers/gpio/gpio-74x164.c b/drivers/gpio/gpio-74x164.c new file mode 100644 index 000000000..e3d968f75 --- /dev/null +++ b/drivers/gpio/gpio-74x164.c @@ -0,0 +1,197 @@ +/* + * 74Hx164 - Generic serial-in/parallel-out 8-bits shift register GPIO driver + * + * Copyright (C) 2010 Gabor Juhos + * Copyright (C) 2010 Miguel Gaio + * + * 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 +#include +#include +#include +#include +#include +#include + +#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; + + 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 "); +MODULE_AUTHOR("Miguel Gaio "); +MODULE_DESCRIPTION("GPIO expander driver for 74X164 8-bits shift register"); +MODULE_LICENSE("GPL v2"); -- cgit v1.2.3-54-g00ecf