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         if (reg & TS4900_GPIO_OE)
  48                 return GPIO_LINE_DIRECTION_OUT;
  49
  50         return GPIO_LINE_DIRECTION_IN;
  51 }
  52
  53 static int ts4900_gpio_direction_input(struct gpio_chip *chip,
  54                                        unsigned int offset)
  55 {
  56         struct ts4900_gpio_priv *priv = gpiochip_get_data(chip);
  57
  58         /*
  59          * This will clear the output enable bit, the other bits are
  60          * dontcare when this is cleared
  61          */
  62         return regmap_write(priv->regmap, offset, 0);
  63 }
  64
  65 static int ts4900_gpio_direction_output(struct gpio_chip *chip,
  66                                         unsigned int offset, int value)
  67 {
  68         struct ts4900_gpio_priv *priv = gpiochip_get_data(chip);
  69         int ret;
  70
  71         if (value)
  72                 ret = regmap_write(priv->regmap, offset, TS4900_GPIO_OE |
  73                                                          TS4900_GPIO_OUT);
  74         else
  75                 ret = regmap_write(priv->regmap, offset, TS4900_GPIO_OE);
  76
  77         return ret;
  78 }
  79
  80 static int ts4900_gpio_get(struct gpio_chip *chip, unsigned int offset)
  81 {
  82         struct ts4900_gpio_priv *priv = gpiochip_get_data(chip);
  83         unsigned int reg;
  84
  85         regmap_read(priv->regmap, offset, &reg);
  86
  87         return !!(reg & priv->input_bit);
  88 }
  89
  90 static void ts4900_gpio_set(struct gpio_chip *chip, unsigned int offset,
  91                             int value)
  92 {
  93         struct ts4900_gpio_priv *priv = gpiochip_get_data(chip);
  94
  95         if (value)
  96                 regmap_update_bits(priv->regmap, offset, TS4900_GPIO_OUT,
  97                                    TS4900_GPIO_OUT);
  98         else
  99                 regmap_update_bits(priv->regmap, offset, TS4900_GPIO_OUT, 0);
 100 }
 101
 102 static const struct regmap_config ts4900_regmap_config = {
 103         .reg_bits = 16,
 104         .val_bits = 8,
 105 };
 106
 107 static const struct gpio_chip template_chip = {
 108         .label                  = "ts4900-gpio",
 109         .owner                  = THIS_MODULE,
 110         .get_direction          = ts4900_gpio_get_direction,
 111         .direction_input        = ts4900_gpio_direction_input,
 112         .direction_output       = ts4900_gpio_direction_output,
 113         .get                    = ts4900_gpio_get,
 114         .set                    = ts4900_gpio_set,
 115         .base                   = -1,
 116         .can_sleep              = true,
 117 };
 118
 119 static const struct of_device_id ts4900_gpio_of_match_table[] = {
 120         {
 121                 .compatible = "technologic,ts4900-gpio",
 122                 .data = (void *)TS4900_GPIO_IN,
 123         }, {
 124                 .compatible = "technologic,ts7970-gpio",
 125                 .data = (void *)TS7970_GPIO_IN,
 126         },
 127         { /* sentinel */ },
 128 };
 129 MODULE_DEVICE_TABLE(of, ts4900_gpio_of_match_table);
 130
 131 static int ts4900_gpio_probe(struct i2c_client *client,
 132                         const struct i2c_device_id *id)
 133 {
 134         struct ts4900_gpio_priv *priv;
 135         u32 ngpio;
 136         int ret;
 137
 138         if (of_property_read_u32(client->dev.of_node, "ngpios", &ngpio))
 139                 ngpio = DEFAULT_PIN_NUMBER;
 140
 141         priv = devm_kzalloc(&client->dev, sizeof(*priv), GFP_KERNEL);
 142         if (!priv)
 143                 return -ENOMEM;
 144
 145         priv->gpio_chip = template_chip;
 146         priv->gpio_chip.label = "ts4900-gpio";
 147         priv->gpio_chip.ngpio = ngpio;
 148         priv->gpio_chip.parent = &client->dev;
 149         priv->input_bit = (uintptr_t)of_device_get_match_data(&client->dev);
 150
 151         priv->regmap = devm_regmap_init_i2c(client, &ts4900_regmap_config);
 152         if (IS_ERR(priv->regmap)) {
 153                 ret = PTR_ERR(priv->regmap);
 154                 dev_err(&client->dev, "Failed to allocate register map: %d\n",
 155                         ret);
 156                 return ret;
 157         }
 158
 159         ret = devm_gpiochip_add_data(&client->dev, &priv->gpio_chip, priv);
 160         if (ret < 0) {
 161                 dev_err(&client->dev, "Unable to register gpiochip\n");
 162                 return ret;
 163         }
 164
 165         i2c_set_clientdata(client, priv);
 166
 167         return 0;
 168 }
 169
 170 static const struct i2c_device_id ts4900_gpio_id_table[] = {
 171         { "ts4900-gpio", },
 172         { /* sentinel */ }
 173 };
 174 MODULE_DEVICE_TABLE(i2c, ts4900_gpio_id_table);
 175
 176 static struct i2c_driver ts4900_gpio_driver = {
 177         .driver = {
 178                 .name = "ts4900-gpio",
 179                 .of_match_table = ts4900_gpio_of_match_table,
 180         },
 181         .probe = ts4900_gpio_probe,
 182         .id_table = ts4900_gpio_id_table,
 183 };
 184 module_i2c_driver(ts4900_gpio_driver);
 185
 186 MODULE_AUTHOR("Technologic Systems");
 187 MODULE_DESCRIPTION("GPIO interface for Technologic Systems I2C-FPGA core");
 188 MODULE_LICENSE("GPL");