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linux
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drivers
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gpio
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gpio-74x164.c
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drivers
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gpio
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gpio-74x164.c
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/* * 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/of_gpio.h> #include <linux/slab.h> #include <linux/module.h> #define GEN_74X164_NUMBER_GPIOS 8 struct gen_74x164_chip { struct spi_device *spi; 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_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(chip->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 __devinit gen_74x164_probe(struct spi_device *spi) { struct gen_74x164_chip *chip; struct gen_74x164_chip_platform_data *pdata; int ret; if (!spi->dev.of_node) { dev_err(&spi->dev, "No device tree data available.\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 = devm_kzalloc(&spi->dev, sizeof(*chip), GFP_KERNEL); if (!chip) return -ENOMEM; pdata = spi->dev.platform_data; if (pdata && pdata->base) chip->gpio_chip.base = pdata->base; else chip->gpio_chip.base = -1; 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; 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"); ret = -EINVAL; goto exit_destroy; } chip->gpio_chip.ngpio = GEN_74X164_NUMBER_GPIOS * chip->registers; chip->buffer = devm_kzalloc(&spi->dev, chip->gpio_chip.ngpio, GFP_KERNEL); if (!chip->buffer) { ret = -ENOMEM; goto exit_destroy; } 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); 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); else dev_err(&spi->dev, "Failed to remove the GPIO controller: %d\n", ret); return ret; } 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 = of_match_ptr(gen_74x164_dt_ids), }, .probe = gen_74x164_probe, .remove = __devexit_p(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");
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