| 1 | /* |
| 2 | * 74Hx164 - Generic serial-in/parallel-out 8-bits shift register GPIO driver |
| 3 | * |
| 4 | * Copyright (C) 2010 Gabor Juhos <juhosg@openwrt.org> |
| 5 | * Copyright (C) 2010 Miguel Gaio <miguel.gaio@efixo.com> |
| 6 | * |
| 7 | * This program is free software; you can redistribute it and/or modify |
| 8 | * it under the terms of the GNU General Public License version 2 as |
| 9 | * published by the Free Software Foundation. |
| 10 | */ |
| 11 | |
| 12 | #include <linux/gpio/consumer.h> |
| 13 | #include <linux/init.h> |
| 14 | #include <linux/mutex.h> |
| 15 | #include <linux/spi/spi.h> |
| 16 | #include <linux/gpio.h> |
| 17 | #include <linux/of_gpio.h> |
| 18 | #include <linux/slab.h> |
| 19 | #include <linux/module.h> |
| 20 | |
| 21 | #define GEN_74X164_NUMBER_GPIOS 8 |
| 22 | |
| 23 | struct gen_74x164_chip { |
| 24 | struct gpio_chip gpio_chip; |
| 25 | struct mutex lock; |
| 26 | u32 registers; |
| 27 | /* |
| 28 | * Since the registers are chained, every byte sent will make |
| 29 | * the previous byte shift to the next register in the |
| 30 | * chain. Thus, the first byte sent will end up in the last |
| 31 | * register at the end of the transfer. So, to have a logical |
| 32 | * numbering, store the bytes in reverse order. |
| 33 | */ |
| 34 | u8 buffer[0]; |
| 35 | struct gpio_desc *gpiod_oe; |
| 36 | }; |
| 37 | |
| 38 | static int __gen_74x164_write_config(struct gen_74x164_chip *chip) |
| 39 | { |
| 40 | return spi_write(to_spi_device(chip->gpio_chip.parent), chip->buffer, |
| 41 | chip->registers); |
| 42 | } |
| 43 | |
| 44 | static int gen_74x164_get_value(struct gpio_chip *gc, unsigned offset) |
| 45 | { |
| 46 | struct gen_74x164_chip *chip = gpiochip_get_data(gc); |
| 47 | u8 bank = chip->registers - 1 - offset / 8; |
| 48 | u8 pin = offset % 8; |
| 49 | int ret; |
| 50 | |
| 51 | mutex_lock(&chip->lock); |
| 52 | ret = (chip->buffer[bank] >> pin) & 0x1; |
| 53 | mutex_unlock(&chip->lock); |
| 54 | |
| 55 | return ret; |
| 56 | } |
| 57 | |
| 58 | static void gen_74x164_set_value(struct gpio_chip *gc, |
| 59 | unsigned offset, int val) |
| 60 | { |
| 61 | struct gen_74x164_chip *chip = gpiochip_get_data(gc); |
| 62 | u8 bank = chip->registers - 1 - offset / 8; |
| 63 | u8 pin = offset % 8; |
| 64 | |
| 65 | mutex_lock(&chip->lock); |
| 66 | if (val) |
| 67 | chip->buffer[bank] |= (1 << pin); |
| 68 | else |
| 69 | chip->buffer[bank] &= ~(1 << pin); |
| 70 | |
| 71 | __gen_74x164_write_config(chip); |
| 72 | mutex_unlock(&chip->lock); |
| 73 | } |
| 74 | |
| 75 | static void gen_74x164_set_multiple(struct gpio_chip *gc, unsigned long *mask, |
| 76 | unsigned long *bits) |
| 77 | { |
| 78 | struct gen_74x164_chip *chip = gpiochip_get_data(gc); |
| 79 | unsigned int i, idx, shift; |
| 80 | u8 bank, bankmask; |
| 81 | |
| 82 | mutex_lock(&chip->lock); |
| 83 | for (i = 0, bank = chip->registers - 1; i < chip->registers; |
| 84 | i++, bank--) { |
| 85 | idx = i / sizeof(*mask); |
| 86 | shift = i % sizeof(*mask) * BITS_PER_BYTE; |
| 87 | bankmask = mask[idx] >> shift; |
| 88 | if (!bankmask) |
| 89 | continue; |
| 90 | |
| 91 | chip->buffer[bank] &= ~bankmask; |
| 92 | chip->buffer[bank] |= bankmask & (bits[idx] >> shift); |
| 93 | } |
| 94 | __gen_74x164_write_config(chip); |
| 95 | mutex_unlock(&chip->lock); |
| 96 | } |
| 97 | |
| 98 | static int gen_74x164_direction_output(struct gpio_chip *gc, |
| 99 | unsigned offset, int val) |
| 100 | { |
| 101 | gen_74x164_set_value(gc, offset, val); |
| 102 | return 0; |
| 103 | } |
| 104 | |
| 105 | static int gen_74x164_probe(struct spi_device *spi) |
| 106 | { |
| 107 | struct gen_74x164_chip *chip; |
| 108 | u32 nregs; |
| 109 | int ret; |
| 110 | |
| 111 | /* |
| 112 | * bits_per_word cannot be configured in platform data |
| 113 | */ |
| 114 | spi->bits_per_word = 8; |
| 115 | |
| 116 | ret = spi_setup(spi); |
| 117 | if (ret < 0) |
| 118 | return ret; |
| 119 | |
| 120 | if (of_property_read_u32(spi->dev.of_node, "registers-number", |
| 121 | &nregs)) { |
| 122 | dev_err(&spi->dev, |
| 123 | "Missing registers-number property in the DT.\n"); |
| 124 | return -EINVAL; |
| 125 | } |
| 126 | |
| 127 | chip = devm_kzalloc(&spi->dev, sizeof(*chip) + nregs, GFP_KERNEL); |
| 128 | if (!chip) |
| 129 | return -ENOMEM; |
| 130 | |
| 131 | chip->gpiod_oe = devm_gpiod_get_optional(&spi->dev, "enable", |
| 132 | GPIOD_OUT_LOW); |
| 133 | if (IS_ERR(chip->gpiod_oe)) |
| 134 | return PTR_ERR(chip->gpiod_oe); |
| 135 | |
| 136 | gpiod_set_value_cansleep(chip->gpiod_oe, 1); |
| 137 | |
| 138 | spi_set_drvdata(spi, chip); |
| 139 | |
| 140 | chip->gpio_chip.label = spi->modalias; |
| 141 | chip->gpio_chip.direction_output = gen_74x164_direction_output; |
| 142 | chip->gpio_chip.get = gen_74x164_get_value; |
| 143 | chip->gpio_chip.set = gen_74x164_set_value; |
| 144 | chip->gpio_chip.set_multiple = gen_74x164_set_multiple; |
| 145 | chip->gpio_chip.base = -1; |
| 146 | |
| 147 | chip->registers = nregs; |
| 148 | chip->gpio_chip.ngpio = GEN_74X164_NUMBER_GPIOS * chip->registers; |
| 149 | |
| 150 | chip->gpio_chip.can_sleep = true; |
| 151 | chip->gpio_chip.parent = &spi->dev; |
| 152 | chip->gpio_chip.owner = THIS_MODULE; |
| 153 | |
| 154 | mutex_init(&chip->lock); |
| 155 | |
| 156 | ret = __gen_74x164_write_config(chip); |
| 157 | if (ret) { |
| 158 | dev_err(&spi->dev, "Failed writing: %d\n", ret); |
| 159 | goto exit_destroy; |
| 160 | } |
| 161 | |
| 162 | ret = gpiochip_add_data(&chip->gpio_chip, chip); |
| 163 | if (!ret) |
| 164 | return 0; |
| 165 | |
| 166 | exit_destroy: |
| 167 | mutex_destroy(&chip->lock); |
| 168 | |
| 169 | return ret; |
| 170 | } |
| 171 | |
| 172 | static int gen_74x164_remove(struct spi_device *spi) |
| 173 | { |
| 174 | struct gen_74x164_chip *chip = spi_get_drvdata(spi); |
| 175 | |
| 176 | gpiod_set_value_cansleep(chip->gpiod_oe, 0); |
| 177 | gpiochip_remove(&chip->gpio_chip); |
| 178 | mutex_destroy(&chip->lock); |
| 179 | |
| 180 | return 0; |
| 181 | } |
| 182 | |
| 183 | static const struct of_device_id gen_74x164_dt_ids[] = { |
| 184 | { .compatible = "fairchild,74hc595" }, |
| 185 | { .compatible = "nxp,74lvc594" }, |
| 186 | {}, |
| 187 | }; |
| 188 | MODULE_DEVICE_TABLE(of, gen_74x164_dt_ids); |
| 189 | |
| 190 | static struct spi_driver gen_74x164_driver = { |
| 191 | .driver = { |
| 192 | .name = "74x164", |
| 193 | .of_match_table = gen_74x164_dt_ids, |
| 194 | }, |
| 195 | .probe = gen_74x164_probe, |
| 196 | .remove = gen_74x164_remove, |
| 197 | }; |
| 198 | module_spi_driver(gen_74x164_driver); |
| 199 | |
| 200 | MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>"); |
| 201 | MODULE_AUTHOR("Miguel Gaio <miguel.gaio@efixo.com>"); |
| 202 | MODULE_DESCRIPTION("GPIO expander driver for 74X164 8-bits shift register"); |
| 203 | MODULE_LICENSE("GPL v2"); |