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 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, ®); 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"); 186