![Sachin Kamat](/assets/img/avatar_default.png)
'gen_74x164_dt_ids' is always compiled in. Hence the macro is not necessary. Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
223 lines
5.1 KiB
C
223 lines
5.1 KiB
C
/*
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* 74Hx164 - Generic serial-in/parallel-out 8-bits shift register GPIO driver
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*
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* Copyright (C) 2010 Gabor Juhos <juhosg@openwrt.org>
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* Copyright (C) 2010 Miguel Gaio <miguel.gaio@efixo.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/init.h>
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#include <linux/mutex.h>
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#include <linux/spi/spi.h>
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#include <linux/spi/74x164.h>
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#include <linux/gpio.h>
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#include <linux/of_gpio.h>
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#include <linux/slab.h>
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#include <linux/module.h>
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#define GEN_74X164_NUMBER_GPIOS 8
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struct gen_74x164_chip {
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struct spi_device *spi;
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u8 *buffer;
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struct gpio_chip gpio_chip;
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struct mutex lock;
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u32 registers;
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};
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static struct gen_74x164_chip *gpio_to_74x164_chip(struct gpio_chip *gc)
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{
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return container_of(gc, struct gen_74x164_chip, gpio_chip);
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}
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static int __gen_74x164_write_config(struct gen_74x164_chip *chip)
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{
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struct spi_message message;
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struct spi_transfer *msg_buf;
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int i, ret = 0;
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msg_buf = kzalloc(chip->registers * sizeof(struct spi_transfer),
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GFP_KERNEL);
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if (!msg_buf)
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return -ENOMEM;
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spi_message_init(&message);
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/*
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* Since the registers are chained, every byte sent will make
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* the previous byte shift to the next register in the
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* chain. Thus, the first byte send will end up in the last
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* register at the end of the transfer. So, to have a logical
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* numbering, send the bytes in reverse order so that the last
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* byte of the buffer will end up in the last register.
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*/
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for (i = chip->registers - 1; i >= 0; i--) {
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msg_buf[i].tx_buf = chip->buffer +i;
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msg_buf[i].len = sizeof(u8);
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spi_message_add_tail(msg_buf + i, &message);
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}
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ret = spi_sync(chip->spi, &message);
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kfree(msg_buf);
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return ret;
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}
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static int gen_74x164_get_value(struct gpio_chip *gc, unsigned offset)
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{
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struct gen_74x164_chip *chip = gpio_to_74x164_chip(gc);
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u8 bank = offset / 8;
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u8 pin = offset % 8;
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int ret;
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mutex_lock(&chip->lock);
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ret = (chip->buffer[bank] >> pin) & 0x1;
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mutex_unlock(&chip->lock);
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return ret;
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}
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static void gen_74x164_set_value(struct gpio_chip *gc,
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unsigned offset, int val)
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{
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struct gen_74x164_chip *chip = gpio_to_74x164_chip(gc);
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u8 bank = offset / 8;
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u8 pin = offset % 8;
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mutex_lock(&chip->lock);
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if (val)
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chip->buffer[bank] |= (1 << pin);
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else
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chip->buffer[bank] &= ~(1 << pin);
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__gen_74x164_write_config(chip);
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mutex_unlock(&chip->lock);
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}
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static int gen_74x164_direction_output(struct gpio_chip *gc,
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unsigned offset, int val)
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{
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gen_74x164_set_value(gc, offset, val);
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return 0;
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}
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static int gen_74x164_probe(struct spi_device *spi)
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{
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struct gen_74x164_chip *chip;
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struct gen_74x164_chip_platform_data *pdata;
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int ret;
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if (!spi->dev.of_node) {
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dev_err(&spi->dev, "No device tree data available.\n");
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return -EINVAL;
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}
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/*
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* bits_per_word cannot be configured in platform data
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*/
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spi->bits_per_word = 8;
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ret = spi_setup(spi);
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if (ret < 0)
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return ret;
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chip = devm_kzalloc(&spi->dev, sizeof(*chip), GFP_KERNEL);
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if (!chip)
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return -ENOMEM;
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pdata = dev_get_platdata(&spi->dev);
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if (pdata && pdata->base)
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chip->gpio_chip.base = pdata->base;
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else
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chip->gpio_chip.base = -1;
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mutex_init(&chip->lock);
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spi_set_drvdata(spi, chip);
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chip->spi = spi;
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chip->gpio_chip.label = spi->modalias;
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chip->gpio_chip.direction_output = gen_74x164_direction_output;
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chip->gpio_chip.get = gen_74x164_get_value;
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chip->gpio_chip.set = gen_74x164_set_value;
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if (of_property_read_u32(spi->dev.of_node, "registers-number", &chip->registers)) {
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dev_err(&spi->dev, "Missing registers-number property in the DT.\n");
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ret = -EINVAL;
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goto exit_destroy;
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}
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chip->gpio_chip.ngpio = GEN_74X164_NUMBER_GPIOS * chip->registers;
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chip->buffer = devm_kzalloc(&spi->dev, chip->registers, GFP_KERNEL);
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if (!chip->buffer) {
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ret = -ENOMEM;
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goto exit_destroy;
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}
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chip->gpio_chip.can_sleep = 1;
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chip->gpio_chip.dev = &spi->dev;
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chip->gpio_chip.owner = THIS_MODULE;
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ret = __gen_74x164_write_config(chip);
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if (ret) {
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dev_err(&spi->dev, "Failed writing: %d\n", ret);
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goto exit_destroy;
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}
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ret = gpiochip_add(&chip->gpio_chip);
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if (ret)
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goto exit_destroy;
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return ret;
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exit_destroy:
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mutex_destroy(&chip->lock);
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return ret;
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}
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static int gen_74x164_remove(struct spi_device *spi)
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{
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struct gen_74x164_chip *chip;
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int ret;
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chip = spi_get_drvdata(spi);
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if (chip == NULL)
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return -ENODEV;
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ret = gpiochip_remove(&chip->gpio_chip);
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if (!ret)
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mutex_destroy(&chip->lock);
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else
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dev_err(&spi->dev, "Failed to remove the GPIO controller: %d\n",
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ret);
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return ret;
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}
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static const struct of_device_id gen_74x164_dt_ids[] = {
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{ .compatible = "fairchild,74hc595" },
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{},
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};
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MODULE_DEVICE_TABLE(of, gen_74x164_dt_ids);
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static struct spi_driver gen_74x164_driver = {
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.driver = {
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.name = "74x164",
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.owner = THIS_MODULE,
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.of_match_table = gen_74x164_dt_ids,
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},
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.probe = gen_74x164_probe,
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.remove = gen_74x164_remove,
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};
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module_spi_driver(gen_74x164_driver);
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MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
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MODULE_AUTHOR("Miguel Gaio <miguel.gaio@efixo.com>");
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MODULE_DESCRIPTION("GPIO expander driver for 74X164 8-bits shift register");
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MODULE_LICENSE("GPL v2");
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