drivers/gpio/gpio-ts4900.c

   1 /*
   2  * Digital I/O driver for Technologic Systems I2C FPGA Core
   3  *
   4  * Copyright (C) 2015 Technologic Systems
   5  * Copyright (C) 2016 Savoir-Faire Linux
   6  *
   7  * This program is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  *
  11  * This program is distributed "as is" WITHOUT ANY WARRANTY of any
  12  * kind, whether expressed or implied; without even the implied warranty
  13  * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License version 2 for more details.
  15  */
  16
  17 #include <linux/gpio/driver.h>
  18 #include <linux/i2c.h>
  19 #include <linux/of_device.h>
  20 #include <linux/module.h>
  21 #include <linux/regmap.h>
  22
  23 #define DEFAULT_PIN_NUMBER      32
  24 /*
  25  * Register bits used by the GPIO device
  26  * Some boards, such as TS-7970 do not have a separate input bit
  27  */
  28 #define TS4900_GPIO_OE          0x01
  29 #define TS4900_GPIO_OUT         0x02
  30 #define TS4900_GPIO_IN          0x04
  31 #define TS7970_GPIO_IN          0x02
  32
  33 struct ts4900_gpio_priv {
  34         struct regmap *regmap;
  35         struct gpio_chip gpio_chip;
  36         unsigned int input_bit;
  37 };
  38
  39 static int ts4900_gpio_get_direction(struct gpio_chip *chip,
  40                                      unsigned int offset)
  41 {
  42         struct ts4900_gpio_priv *priv = gpiochip_get_data(chip);
  43         unsigned int reg;
  44
  45         regmap_read(priv->regmap, offset, &reg);
  46
  47         return !(reg & TS4900_GPIO_OE);
  48 }
  49
  50 static int ts4900_gpio_direction_input(struct gpio_chip *chip,
  51                                        unsigned int offset)
  52 {
  53         struct ts4900_gpio_priv *priv = gpiochip_get_data(chip);
  54
  55         /*
  56          * This will clear the output enable bit, the other bits are
  57          * dontcare when this is cleared
  58          */
  59         return regmap_write(priv->regmap, offset, 0);
  60 }
  61
  62 static int ts4900_gpio_direction_output(struct gpio_chip *chip,
  63                                         unsigned int offset, int value)
  64 {
  65         struct ts4900_gpio_priv *priv = gpiochip_get_data(chip);
  66         int ret;
  67
  68         if (value)
  69                 ret = regmap_write(priv->regmap, offset, TS4900_GPIO_OE |
  70                                                          TS4900_GPIO_OUT);
  71         else
  72                 ret = regmap_write(priv->regmap, offset, TS4900_GPIO_OE);
  73
  74         return ret;
  75 }
  76
  77 static int ts4900_gpio_get(struct gpio_chip *chip, unsigned int offset)
  78 {
  79         struct ts4900_gpio_priv *priv = gpiochip_get_data(chip);
  80         unsigned int reg;
  81
  82         regmap_read(priv->regmap, offset, &reg);
  83
  84         return !!(reg & priv->input_bit);
  85 }
  86
  87 static void ts4900_gpio_set(struct gpio_chip *chip, unsigned int offset,
  88                             int value)
  89 {
  90         struct ts4900_gpio_priv *priv = gpiochip_get_data(chip);
  91
  92         if (value)
  93                 regmap_update_bits(priv->regmap, offset, TS4900_GPIO_OUT,
  94                                    TS4900_GPIO_OUT);
  95         else
  96                 regmap_update_bits(priv->regmap, offset, TS4900_GPIO_OUT, 0);
  97 }
  98
  99 static const struct regmap_config ts4900_regmap_config = {
 100         .reg_bits = 16,
 101         .val_bits = 8,
 102 };
 103
 104 static const struct gpio_chip template_chip = {
 105         .label                  = "ts4900-gpio",
 106         .owner                  = THIS_MODULE,
 107         .get_direction          = ts4900_gpio_get_direction,
 108         .direction_input        = ts4900_gpio_direction_input,
 109         .direction_output       = ts4900_gpio_direction_output,
 110         .get                    = ts4900_gpio_get,
 111         .set                    = ts4900_gpio_set,
 112         .base                   = -1,
 113         .can_sleep              = true,
 114 };
 115
 116 static const struct of_device_id ts4900_gpio_of_match_table[] = {
 117         {
 118                 .compatible = "technologic,ts4900-gpio",
 119                 .data = (void *)TS4900_GPIO_IN,
 120         }, {
 121                 .compatible = "technologic,ts7970-gpio",
 122                 .data = (void *)TS7970_GPIO_IN,
 123         },
 124         { /* sentinel */ },
 125 };
 126 MODULE_DEVICE_TABLE(of, ts4900_gpio_of_match_table);
 127
 128 static int ts4900_gpio_probe(struct i2c_client *client,
 129                         const struct i2c_device_id *id)
 130 {
 131         struct ts4900_gpio_priv *priv;
 132         u32 ngpio;
 133         int ret;
 134
 135         if (of_property_read_u32(client->dev.of_node, "ngpios", &ngpio))
 136                 ngpio = DEFAULT_PIN_NUMBER;
 137
 138         priv = devm_kzalloc(&client->dev, sizeof(*priv), GFP_KERNEL);
 139         if (!priv)
 140                 return -ENOMEM;
 141
 142         priv->gpio_chip = template_chip;
 143         priv->gpio_chip.label = "ts4900-gpio";
 144         priv->gpio_chip.ngpio = ngpio;
 145         priv->gpio_chip.parent = &client->dev;
 146         priv->input_bit = (uintptr_t)of_device_get_match_data(&client->dev);
 147
 148         priv->regmap = devm_regmap_init_i2c(client, &ts4900_regmap_config);
 149         if (IS_ERR(priv->regmap)) {
 150                 ret = PTR_ERR(priv->regmap);
 151                 dev_err(&client->dev, "Failed to allocate register map: %d\n",
 152                         ret);
 153                 return ret;
 154         }
 155
 156         ret = devm_gpiochip_add_data(&client->dev, &priv->gpio_chip, priv);
 157         if (ret < 0) {
 158                 dev_err(&client->dev, "Unable to register gpiochip\n");
 159                 return ret;
 160         }
 161
 162         i2c_set_clientdata(client, priv);
 163
 164         return 0;
 165 }
 166
 167 static const struct i2c_device_id ts4900_gpio_id_table[] = {
 168         { "ts4900-gpio", },
 169         { /* sentinel */ }
 170 };
 171 MODULE_DEVICE_TABLE(i2c, ts4900_gpio_id_table);
 172
 173 static struct i2c_driver ts4900_gpio_driver = {
 174         .driver = {
 175                 .name = "ts4900-gpio",
 176                 .of_match_table = ts4900_gpio_of_match_table,
 177         },
 178         .probe = ts4900_gpio_probe,
 179         .id_table = ts4900_gpio_id_table,
 180 };
 181 module_i2c_driver(ts4900_gpio_driver);
 182
 183 MODULE_AUTHOR("Technologic Systems");
 184 MODULE_DESCRIPTION("GPIO interface for Technologic Systems I2C-FPGA core");
 185 MODULE_LICENSE("GPL");