drivers/gpio/gpio-74x164.c

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