1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * 74Hx164 - Generic serial-in/parallel-out 8-bits shift register GPIO driver 4 * 5 * Copyright (C) 2010 Gabor Juhos <juhosg@openwrt.org> 6 * Copyright (C) 2010 Miguel Gaio <miguel.gaio@efixo.com> 7 */ 8 9 #include <linux/bitops.h> 10 #include <linux/gpio/consumer.h> 11 #include <linux/gpio/driver.h> 12 #include <linux/module.h> 13 #include <linux/mutex.h> 14 #include <linux/property.h> 15 #include <linux/slab.h> 16 #include <linux/spi/spi.h> 17 18 #define GEN_74X164_NUMBER_GPIOS 8 19 20 struct gen_74x164_chip { 21 struct gpio_chip gpio_chip; 22 struct mutex lock; 23 struct gpio_desc *gpiod_oe; 24 u32 registers; 25 /* 26 * Since the registers are chained, every byte sent will make 27 * the previous byte shift to the next register in the 28 * chain. Thus, the first byte sent will end up in the last 29 * register at the end of the transfer. So, to have a logical 30 * numbering, store the bytes in reverse order. 31 */ 32 u8 buffer[]; 33 }; 34 35 static int __gen_74x164_write_config(struct gen_74x164_chip *chip) 36 { 37 return spi_write(to_spi_device(chip->gpio_chip.parent), chip->buffer, 38 chip->registers); 39 } 40 41 static int gen_74x164_get_value(struct gpio_chip *gc, unsigned offset) 42 { 43 struct gen_74x164_chip *chip = gpiochip_get_data(gc); 44 u8 bank = chip->registers - 1 - offset / 8; 45 u8 pin = offset % 8; 46 int ret; 47 48 mutex_lock(&chip->lock); 49 ret = (chip->buffer[bank] >> pin) & 0x1; 50 mutex_unlock(&chip->lock); 51 52 return ret; 53 } 54 55 static void gen_74x164_set_value(struct gpio_chip *gc, 56 unsigned offset, int val) 57 { 58 struct gen_74x164_chip *chip = gpiochip_get_data(gc); 59 u8 bank = chip->registers - 1 - offset / 8; 60 u8 pin = offset % 8; 61 62 mutex_lock(&chip->lock); 63 if (val) 64 chip->buffer[bank] |= (1 << pin); 65 else 66 chip->buffer[bank] &= ~(1 << pin); 67 68 __gen_74x164_write_config(chip); 69 mutex_unlock(&chip->lock); 70 } 71 72 static void gen_74x164_set_multiple(struct gpio_chip *gc, unsigned long *mask, 73 unsigned long *bits) 74 { 75 struct gen_74x164_chip *chip = gpiochip_get_data(gc); 76 unsigned long offset; 77 unsigned long bankmask; 78 size_t bank; 79 unsigned long bitmask; 80 81 mutex_lock(&chip->lock); 82 for_each_set_clump8(offset, bankmask, mask, chip->registers * 8) { 83 bank = chip->registers - 1 - offset / 8; 84 bitmask = bitmap_get_value8(bits, offset) & bankmask; 85 86 chip->buffer[bank] &= ~bankmask; 87 chip->buffer[bank] |= bitmask; 88 } 89 __gen_74x164_write_config(chip); 90 mutex_unlock(&chip->lock); 91 } 92 93 static int gen_74x164_direction_output(struct gpio_chip *gc, 94 unsigned offset, int val) 95 { 96 gen_74x164_set_value(gc, offset, val); 97 return 0; 98 } 99 100 static int gen_74x164_probe(struct spi_device *spi) 101 { 102 struct gen_74x164_chip *chip; 103 u32 nregs; 104 int ret; 105 106 /* 107 * bits_per_word cannot be configured in platform data 108 */ 109 spi->bits_per_word = 8; 110 111 ret = spi_setup(spi); 112 if (ret < 0) 113 return ret; 114 115 ret = device_property_read_u32(&spi->dev, "registers-number", &nregs); 116 if (ret) { 117 dev_err(&spi->dev, "Missing 'registers-number' property.\n"); 118 return -EINVAL; 119 } 120 121 chip = devm_kzalloc(&spi->dev, sizeof(*chip) + nregs, GFP_KERNEL); 122 if (!chip) 123 return -ENOMEM; 124 125 chip->gpiod_oe = devm_gpiod_get_optional(&spi->dev, "enable", 126 GPIOD_OUT_LOW); 127 if (IS_ERR(chip->gpiod_oe)) 128 return PTR_ERR(chip->gpiod_oe); 129 130 gpiod_set_value_cansleep(chip->gpiod_oe, 1); 131 132 spi_set_drvdata(spi, chip); 133 134 chip->gpio_chip.label = spi->modalias; 135 chip->gpio_chip.direction_output = gen_74x164_direction_output; 136 chip->gpio_chip.get = gen_74x164_get_value; 137 chip->gpio_chip.set = gen_74x164_set_value; 138 chip->gpio_chip.set_multiple = gen_74x164_set_multiple; 139 chip->gpio_chip.base = -1; 140 141 chip->registers = nregs; 142 chip->gpio_chip.ngpio = GEN_74X164_NUMBER_GPIOS * chip->registers; 143 144 chip->gpio_chip.can_sleep = true; 145 chip->gpio_chip.parent = &spi->dev; 146 chip->gpio_chip.owner = THIS_MODULE; 147 148 mutex_init(&chip->lock); 149 150 ret = __gen_74x164_write_config(chip); 151 if (ret) { 152 dev_err(&spi->dev, "Failed writing: %d\n", ret); 153 goto exit_destroy; 154 } 155 156 ret = gpiochip_add_data(&chip->gpio_chip, chip); 157 if (!ret) 158 return 0; 159 160 exit_destroy: 161 mutex_destroy(&chip->lock); 162 163 return ret; 164 } 165 166 static int gen_74x164_remove(struct spi_device *spi) 167 { 168 struct gen_74x164_chip *chip = spi_get_drvdata(spi); 169 170 gpiod_set_value_cansleep(chip->gpiod_oe, 0); 171 gpiochip_remove(&chip->gpio_chip); 172 mutex_destroy(&chip->lock); 173 174 return 0; 175 } 176 177 static const struct spi_device_id gen_74x164_spi_ids[] = { 178 { .name = "74hc595" }, 179 { .name = "74lvc594" }, 180 {}, 181 }; 182 MODULE_DEVICE_TABLE(spi, gen_74x164_spi_ids); 183 184 static const struct of_device_id gen_74x164_dt_ids[] = { 185 { .compatible = "fairchild,74hc595" }, 186 { .compatible = "nxp,74lvc594" }, 187 {}, 188 }; 189 MODULE_DEVICE_TABLE(of, gen_74x164_dt_ids); 190 191 static struct spi_driver gen_74x164_driver = { 192 .driver = { 193 .name = "74x164", 194 .of_match_table = gen_74x164_dt_ids, 195 }, 196 .probe = gen_74x164_probe, 197 .remove = gen_74x164_remove, 198 .id_table = gen_74x164_spi_ids, 199 }; 200 module_spi_driver(gen_74x164_driver); 201 202 MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>"); 203 MODULE_AUTHOR("Miguel Gaio <miguel.gaio@efixo.com>"); 204 MODULE_DESCRIPTION("GPIO expander driver for 74X164 8-bits shift register"); 205 MODULE_LICENSE("GPL v2"); 206