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197 lines
4.8 KiB
197 lines
4.8 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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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 <[email protected]> |
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* Copyright (C) 2010 Miguel Gaio <[email protected]> |
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*/ |
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#include <linux/bitops.h> |
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#include <linux/gpio/consumer.h> |
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#include <linux/gpio/driver.h> |
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#include <linux/module.h> |
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#include <linux/mutex.h> |
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#include <linux/property.h> |
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#include <linux/slab.h> |
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#include <linux/spi/spi.h> |
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#define GEN_74X164_NUMBER_GPIOS 8 |
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struct gen_74x164_chip { |
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struct gpio_chip gpio_chip; |
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struct mutex lock; |
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struct gpio_desc *gpiod_oe; |
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u32 registers; |
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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 sent 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, store the bytes in reverse order. |
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*/ |
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u8 buffer[]; |
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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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return spi_write(to_spi_device(chip->gpio_chip.parent), chip->buffer, |
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chip->registers); |
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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 = gpiochip_get_data(gc); |
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u8 bank = chip->registers - 1 - 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 = gpiochip_get_data(gc); |
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u8 bank = chip->registers - 1 - 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 void gen_74x164_set_multiple(struct gpio_chip *gc, unsigned long *mask, |
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unsigned long *bits) |
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{ |
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struct gen_74x164_chip *chip = gpiochip_get_data(gc); |
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unsigned long offset; |
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unsigned long bankmask; |
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size_t bank; |
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unsigned long bitmask; |
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mutex_lock(&chip->lock); |
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for_each_set_clump8(offset, bankmask, mask, chip->registers * 8) { |
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bank = chip->registers - 1 - offset / 8; |
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bitmask = bitmap_get_value8(bits, offset) & bankmask; |
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chip->buffer[bank] &= ~bankmask; |
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chip->buffer[bank] |= bitmask; |
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} |
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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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u32 nregs; |
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int ret; |
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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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ret = device_property_read_u32(&spi->dev, "registers-number", &nregs); |
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if (ret) { |
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dev_err(&spi->dev, "Missing 'registers-number' property.\n"); |
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return -EINVAL; |
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} |
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chip = devm_kzalloc(&spi->dev, sizeof(*chip) + nregs, GFP_KERNEL); |
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if (!chip) |
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return -ENOMEM; |
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chip->gpiod_oe = devm_gpiod_get_optional(&spi->dev, "enable", |
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GPIOD_OUT_LOW); |
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if (IS_ERR(chip->gpiod_oe)) |
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return PTR_ERR(chip->gpiod_oe); |
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gpiod_set_value_cansleep(chip->gpiod_oe, 1); |
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spi_set_drvdata(spi, chip); |
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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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chip->gpio_chip.set_multiple = gen_74x164_set_multiple; |
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chip->gpio_chip.base = -1; |
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chip->registers = nregs; |
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chip->gpio_chip.ngpio = GEN_74X164_NUMBER_GPIOS * chip->registers; |
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chip->gpio_chip.can_sleep = true; |
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chip->gpio_chip.parent = &spi->dev; |
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chip->gpio_chip.owner = THIS_MODULE; |
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mutex_init(&chip->lock); |
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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_data(&chip->gpio_chip, chip); |
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if (!ret) |
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return 0; |
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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 = spi_get_drvdata(spi); |
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gpiod_set_value_cansleep(chip->gpiod_oe, 0); |
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gpiochip_remove(&chip->gpio_chip); |
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mutex_destroy(&chip->lock); |
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return 0; |
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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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{ .compatible = "nxp,74lvc594" }, |
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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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.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 <[email protected]>"); |
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MODULE_AUTHOR("Miguel Gaio <[email protected]>"); |
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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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