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/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         struct gpio_desc        *gpiod_oe;
  27         u32                     registers;
  28         /*
  29          * Since the registers are chained, every byte sent will make
  30          * the previous byte shift to the next register in the
  31          * chain. Thus, the first byte sent will end up in the last
  32          * register at the end of the transfer. So, to have a logical
  33          * numbering, store the bytes in reverse order.
  34          */
  35         u8                      buffer[];
  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");