1 /* 2 * Digital I/O driver for Technologic Systems I2C FPGA Core 3 * 4 * Copyright (C) 2015, 2018 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 /* Only clear the OE bit here, requires a RMW. Prevents potential issue 59 * with OE and data getting to the physical pin at different times. 60 */ 61 return regmap_update_bits(priv->regmap, offset, TS4900_GPIO_OE, 0); 62 } 63 64 static int ts4900_gpio_direction_output(struct gpio_chip *chip, 65 unsigned int offset, int value) 66 { 67 struct ts4900_gpio_priv *priv = gpiochip_get_data(chip); 68 unsigned int reg; 69 int ret; 70 71 /* If changing from an input to an output, we need to first set the 72 * proper data bit to what is requested and then set OE bit. This 73 * prevents a glitch that can occur on the IO line 74 */ 75 regmap_read(priv->regmap, offset, ®); 76 if (!(reg & TS4900_GPIO_OE)) { 77 if (value) 78 reg = TS4900_GPIO_OUT; 79 else 80 reg &= ~TS4900_GPIO_OUT; 81 82 regmap_write(priv->regmap, offset, reg); 83 } 84 85 if (value) 86 ret = regmap_write(priv->regmap, offset, TS4900_GPIO_OE | 87 TS4900_GPIO_OUT); 88 else 89 ret = regmap_write(priv->regmap, offset, TS4900_GPIO_OE); 90 91 return ret; 92 } 93 94 static int ts4900_gpio_get(struct gpio_chip *chip, unsigned int offset) 95 { 96 struct ts4900_gpio_priv *priv = gpiochip_get_data(chip); 97 unsigned int reg; 98 99 regmap_read(priv->regmap, offset, ®); 100 101 return !!(reg & priv->input_bit); 102 } 103 104 static void ts4900_gpio_set(struct gpio_chip *chip, unsigned int offset, 105 int value) 106 { 107 struct ts4900_gpio_priv *priv = gpiochip_get_data(chip); 108 109 if (value) 110 regmap_update_bits(priv->regmap, offset, TS4900_GPIO_OUT, 111 TS4900_GPIO_OUT); 112 else 113 regmap_update_bits(priv->regmap, offset, TS4900_GPIO_OUT, 0); 114 } 115 116 static const struct regmap_config ts4900_regmap_config = { 117 .reg_bits = 16, 118 .val_bits = 8, 119 }; 120 121 static const struct gpio_chip template_chip = { 122 .label = "ts4900-gpio", 123 .owner = THIS_MODULE, 124 .get_direction = ts4900_gpio_get_direction, 125 .direction_input = ts4900_gpio_direction_input, 126 .direction_output = ts4900_gpio_direction_output, 127 .get = ts4900_gpio_get, 128 .set = ts4900_gpio_set, 129 .base = -1, 130 .can_sleep = true, 131 }; 132 133 static const struct of_device_id ts4900_gpio_of_match_table[] = { 134 { 135 .compatible = "technologic,ts4900-gpio", 136 .data = (void *)TS4900_GPIO_IN, 137 }, { 138 .compatible = "technologic,ts7970-gpio", 139 .data = (void *)TS7970_GPIO_IN, 140 }, 141 { /* sentinel */ }, 142 }; 143 MODULE_DEVICE_TABLE(of, ts4900_gpio_of_match_table); 144 145 static int ts4900_gpio_probe(struct i2c_client *client, 146 const struct i2c_device_id *id) 147 { 148 struct ts4900_gpio_priv *priv; 149 u32 ngpio; 150 int ret; 151 152 if (of_property_read_u32(client->dev.of_node, "ngpios", &ngpio)) 153 ngpio = DEFAULT_PIN_NUMBER; 154 155 priv = devm_kzalloc(&client->dev, sizeof(*priv), GFP_KERNEL); 156 if (!priv) 157 return -ENOMEM; 158 159 priv->gpio_chip = template_chip; 160 priv->gpio_chip.label = "ts4900-gpio"; 161 priv->gpio_chip.ngpio = ngpio; 162 priv->gpio_chip.parent = &client->dev; 163 priv->input_bit = (uintptr_t)of_device_get_match_data(&client->dev); 164 165 priv->regmap = devm_regmap_init_i2c(client, &ts4900_regmap_config); 166 if (IS_ERR(priv->regmap)) { 167 ret = PTR_ERR(priv->regmap); 168 dev_err(&client->dev, "Failed to allocate register map: %d\n", 169 ret); 170 return ret; 171 } 172 173 ret = devm_gpiochip_add_data(&client->dev, &priv->gpio_chip, priv); 174 if (ret < 0) { 175 dev_err(&client->dev, "Unable to register gpiochip\n"); 176 return ret; 177 } 178 179 i2c_set_clientdata(client, priv); 180 181 return 0; 182 } 183 184 static const struct i2c_device_id ts4900_gpio_id_table[] = { 185 { "ts4900-gpio", }, 186 { /* sentinel */ } 187 }; 188 MODULE_DEVICE_TABLE(i2c, ts4900_gpio_id_table); 189 190 static struct i2c_driver ts4900_gpio_driver = { 191 .driver = { 192 .name = "ts4900-gpio", 193 .of_match_table = ts4900_gpio_of_match_table, 194 }, 195 .probe = ts4900_gpio_probe, 196 .id_table = ts4900_gpio_id_table, 197 }; 198 module_i2c_driver(ts4900_gpio_driver); 199 200 MODULE_AUTHOR("Technologic Systems"); 201 MODULE_DESCRIPTION("GPIO interface for Technologic Systems I2C-FPGA core"); 202 MODULE_LICENSE("GPL"); 203