diff options
Diffstat (limited to 'drivers/gpio/gpio-74x164.c')
| -rw-r--r-- | drivers/gpio/gpio-74x164.c | 202 |
1 files changed, 202 insertions, 0 deletions
diff --git a/drivers/gpio/gpio-74x164.c b/drivers/gpio/gpio-74x164.c new file mode 100644 index 000000000..fb7b62076 --- /dev/null +++ b/drivers/gpio/gpio-74x164.c @@ -0,0 +1,202 @@ +/* + * 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/driver.h> +#include <linux/gpio/consumer.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; + struct gpio_desc *gpiod_oe; + 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[]; +}; + +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; + + chip->gpiod_oe = devm_gpiod_get_optional(&spi->dev, "enable", + GPIOD_OUT_LOW); + if (IS_ERR(chip->gpiod_oe)) + return PTR_ERR(chip->gpiod_oe); + + gpiod_set_value_cansleep(chip->gpiod_oe, 1); + + 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; + + 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); + + gpiod_set_value_cansleep(chip->gpiod_oe, 0); + 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"); |