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, ®); 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, ®); 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"); 189