drivers/gpio/gpio-74x164.c

   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 of_device_id gen_74x164_dt_ids[] = {
 178         { .compatible = "fairchild,74hc595" },
 179         { .compatible = "nxp,74lvc594" },
 180         {},
 181 };
 182 MODULE_DEVICE_TABLE(of, gen_74x164_dt_ids);
 183
 184 static struct spi_driver gen_74x164_driver = {
 185         .driver = {
 186                 .name           = "74x164",
 187                 .of_match_table = gen_74x164_dt_ids,
 188         },
 189         .probe          = gen_74x164_probe,
 190         .remove         = gen_74x164_remove,
 191 };
 192 module_spi_driver(gen_74x164_driver);
 193
 194 MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
 195 MODULE_AUTHOR("Miguel Gaio <miguel.gaio@efixo.com>");
 196 MODULE_DESCRIPTION("GPIO expander driver for 74X164 8-bits shift register");
 197 MODULE_LICENSE("GPL v2");