drivers/gpio/gpio-ts4900.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Digital I/O driver for Technologic Systems I2C FPGA Core
   4  *
   5  * Copyright (C) 2015, 2018 Technologic Systems
   6  * Copyright (C) 2016 Savoir-Faire Linux
   7  */
   8
   9 #include <linux/gpio/driver.h>
  10 #include <linux/i2c.h>
  11 #include <linux/module.h>
  12 #include <linux/property.h>
  13 #include <linux/regmap.h>
  14
  15 #define DEFAULT_PIN_NUMBER      32
  16 /*
  17  * Register bits used by the GPIO device
  18  * Some boards, such as TS-7970 do not have a separate input bit
  19  */
  20 #define TS4900_GPIO_OE          0x01
  21 #define TS4900_GPIO_OUT         0x02
  22 #define TS4900_GPIO_IN          0x04
  23 #define TS7970_GPIO_IN          0x02
  24
  25 struct ts4900_gpio_priv {
  26         struct regmap *regmap;
  27         struct gpio_chip gpio_chip;
  28         unsigned int input_bit;
  29 };
  30
  31 static int ts4900_gpio_get_direction(struct gpio_chip *chip,
  32                                      unsigned int offset)
  33 {
  34         struct ts4900_gpio_priv *priv = gpiochip_get_data(chip);
  35         unsigned int reg;
  36
  37         regmap_read(priv->regmap, offset, &reg);
  38
  39         if (reg & TS4900_GPIO_OE)
  40                 return GPIO_LINE_DIRECTION_OUT;
  41
  42         return GPIO_LINE_DIRECTION_IN;
  43 }
  44
  45 static int ts4900_gpio_direction_input(struct gpio_chip *chip,
  46                                        unsigned int offset)
  47 {
  48         struct ts4900_gpio_priv *priv = gpiochip_get_data(chip);
  49
  50         /*
  51          * Only clear the OE bit here, requires a RMW. Prevents a potential issue
  52          * with OE and DAT getting to the physical pin at different times.
  53          */
  54         return regmap_update_bits(priv->regmap, offset, TS4900_GPIO_OE, 0);
  55 }
  56
  57 static int ts4900_gpio_direction_output(struct gpio_chip *chip,
  58                                         unsigned int offset, int value)
  59 {
  60         struct ts4900_gpio_priv *priv = gpiochip_get_data(chip);
  61         unsigned int reg;
  62         int ret;
  63
  64         /*
  65          * If changing from an input to an output, we need to first set the
  66          * GPIO's DAT bit to what is requested and then set the OE bit. This
  67          * prevents a glitch that can occur on the IO line.
  68          */
  69         regmap_read(priv->regmap, offset, &reg);
  70         if (!(reg & TS4900_GPIO_OE)) {
  71                 if (value)
  72                         reg = TS4900_GPIO_OUT;
  73                 else
  74                         reg &= ~TS4900_GPIO_OUT;
  75
  76                 regmap_write(priv->regmap, offset, reg);
  77         }
  78
  79         if (value)
  80                 ret = regmap_write(priv->regmap, offset, TS4900_GPIO_OE |
  81                                                          TS4900_GPIO_OUT);
  82         else
  83                 ret = regmap_write(priv->regmap, offset, TS4900_GPIO_OE);
  84
  85         return ret;
  86 }
  87
  88 static int ts4900_gpio_get(struct gpio_chip *chip, unsigned int offset)
  89 {
  90         struct ts4900_gpio_priv *priv = gpiochip_get_data(chip);
  91         unsigned int reg;
  92
  93         regmap_read(priv->regmap, offset, &reg);
  94
  95         return !!(reg & priv->input_bit);
  96 }
  97
  98 static void ts4900_gpio_set(struct gpio_chip *chip, unsigned int offset,
  99                             int value)
 100 {
 101         struct ts4900_gpio_priv *priv = gpiochip_get_data(chip);
 102
 103         if (value)
 104                 regmap_update_bits(priv->regmap, offset, TS4900_GPIO_OUT,
 105                                    TS4900_GPIO_OUT);
 106         else
 107                 regmap_update_bits(priv->regmap, offset, TS4900_GPIO_OUT, 0);
 108 }
 109
 110 static const struct regmap_config ts4900_regmap_config = {
 111         .reg_bits = 16,
 112         .val_bits = 8,
 113 };
 114
 115 static const struct gpio_chip template_chip = {
 116         .label                  = "ts4900-gpio",
 117         .owner                  = THIS_MODULE,
 118         .get_direction          = ts4900_gpio_get_direction,
 119         .direction_input        = ts4900_gpio_direction_input,
 120         .direction_output       = ts4900_gpio_direction_output,
 121         .get                    = ts4900_gpio_get,
 122         .set                    = ts4900_gpio_set,
 123         .base                   = -1,
 124         .can_sleep              = true,
 125 };
 126
 127 static const struct of_device_id ts4900_gpio_of_match_table[] = {
 128         {
 129                 .compatible = "technologic,ts4900-gpio",
 130                 .data = (void *)TS4900_GPIO_IN,
 131         }, {
 132                 .compatible = "technologic,ts7970-gpio",
 133                 .data = (void *)TS7970_GPIO_IN,
 134         },
 135         { /* sentinel */ },
 136 };
 137 MODULE_DEVICE_TABLE(of, ts4900_gpio_of_match_table);
 138
 139 static int ts4900_gpio_probe(struct i2c_client *client)
 140 {
 141         struct ts4900_gpio_priv *priv;
 142         u32 ngpio;
 143         int ret;
 144
 145         if (device_property_read_u32(&client->dev, "ngpios", &ngpio))
 146                 ngpio = DEFAULT_PIN_NUMBER;
 147
 148         priv = devm_kzalloc(&client->dev, sizeof(*priv), GFP_KERNEL);
 149         if (!priv)
 150                 return -ENOMEM;
 151
 152         priv->gpio_chip = template_chip;
 153         priv->gpio_chip.label = "ts4900-gpio";
 154         priv->gpio_chip.ngpio = ngpio;
 155         priv->gpio_chip.parent = &client->dev;
 156         priv->input_bit = (uintptr_t)device_get_match_data(&client->dev);
 157
 158         priv->regmap = devm_regmap_init_i2c(client, &ts4900_regmap_config);
 159         if (IS_ERR(priv->regmap)) {
 160                 ret = PTR_ERR(priv->regmap);
 161                 dev_err(&client->dev, "Failed to allocate register map: %d\n",
 162                         ret);
 163                 return ret;
 164         }
 165
 166         ret = devm_gpiochip_add_data(&client->dev, &priv->gpio_chip, priv);
 167         if (ret < 0) {
 168                 dev_err(&client->dev, "Unable to register gpiochip\n");
 169                 return ret;
 170         }
 171
 172         i2c_set_clientdata(client, priv);
 173
 174         return 0;
 175 }
 176
 177 static const struct i2c_device_id ts4900_gpio_id_table[] = {
 178         { "ts4900-gpio", },
 179         { /* sentinel */ }
 180 };
 181 MODULE_DEVICE_TABLE(i2c, ts4900_gpio_id_table);
 182
 183 static struct i2c_driver ts4900_gpio_driver = {
 184         .driver = {
 185                 .name = "ts4900-gpio",
 186                 .of_match_table = ts4900_gpio_of_match_table,
 187         },
 188         .probe = ts4900_gpio_probe,
 189         .id_table = ts4900_gpio_id_table,
 190 };
 191 module_i2c_driver(ts4900_gpio_driver);
 192
 193 MODULE_AUTHOR("Technologic Systems");
 194 MODULE_DESCRIPTION("GPIO interface for Technologic Systems I2C-FPGA core");
 195 MODULE_LICENSE("GPL");