diff options
Diffstat (limited to 'drivers/gpio/gpio-ts4900.c')
| -rw-r--r-- | drivers/gpio/gpio-ts4900.c | 199 |
1 files changed, 199 insertions, 0 deletions
diff --git a/drivers/gpio/gpio-ts4900.c b/drivers/gpio/gpio-ts4900.c new file mode 100644 index 000000000..410452306 --- /dev/null +++ b/drivers/gpio/gpio-ts4900.c @@ -0,0 +1,199 @@ +/* + * Digital I/O driver for Technologic Systems I2C FPGA Core + * + * Copyright (C) 2015, 2018 Technologic Systems + * Copyright (C) 2016 Savoir-Faire Linux + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * This program is distributed "as is" WITHOUT ANY WARRANTY of any + * kind, whether expressed or implied; without even the implied warranty + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License version 2 for more details. + */ + +#include <linux/gpio/driver.h> +#include <linux/i2c.h> +#include <linux/of_device.h> +#include <linux/module.h> +#include <linux/regmap.h> + +#define DEFAULT_PIN_NUMBER 32 +/* + * Register bits used by the GPIO device + * Some boards, such as TS-7970 do not have a separate input bit + */ +#define TS4900_GPIO_OE 0x01 +#define TS4900_GPIO_OUT 0x02 +#define TS4900_GPIO_IN 0x04 +#define TS7970_GPIO_IN 0x02 + +struct ts4900_gpio_priv { + struct regmap *regmap; + struct gpio_chip gpio_chip; + unsigned int input_bit; +}; + +static int ts4900_gpio_get_direction(struct gpio_chip *chip, + unsigned int offset) +{ + struct ts4900_gpio_priv *priv = gpiochip_get_data(chip); + unsigned int reg; + + regmap_read(priv->regmap, offset, ®); + + return !(reg & TS4900_GPIO_OE); +} + +static int ts4900_gpio_direction_input(struct gpio_chip *chip, + unsigned int offset) +{ + struct ts4900_gpio_priv *priv = gpiochip_get_data(chip); + + /* Only clear the OE bit here, requires a RMW. Prevents potential issue + * with OE and data getting to the physical pin at different times. + */ + return regmap_update_bits(priv->regmap, offset, TS4900_GPIO_OE, 0); +} + +static int ts4900_gpio_direction_output(struct gpio_chip *chip, + unsigned int offset, int value) +{ + struct ts4900_gpio_priv *priv = gpiochip_get_data(chip); + unsigned int reg; + int ret; + + /* If changing from an input to an output, we need to first set the + * proper data bit to what is requested and then set OE bit. This + * prevents a glitch that can occur on the IO line + */ + regmap_read(priv->regmap, offset, ®); + if (!(reg & TS4900_GPIO_OE)) { + if (value) + reg = TS4900_GPIO_OUT; + else + reg &= ~TS4900_GPIO_OUT; + + regmap_write(priv->regmap, offset, reg); + } + + if (value) + ret = regmap_write(priv->regmap, offset, TS4900_GPIO_OE | + TS4900_GPIO_OUT); + else + ret = regmap_write(priv->regmap, offset, TS4900_GPIO_OE); + + return ret; +} + +static int ts4900_gpio_get(struct gpio_chip *chip, unsigned int offset) +{ + struct ts4900_gpio_priv *priv = gpiochip_get_data(chip); + unsigned int reg; + + regmap_read(priv->regmap, offset, ®); + + return !!(reg & priv->input_bit); +} + +static void ts4900_gpio_set(struct gpio_chip *chip, unsigned int offset, + int value) +{ + struct ts4900_gpio_priv *priv = gpiochip_get_data(chip); + + if (value) + regmap_update_bits(priv->regmap, offset, TS4900_GPIO_OUT, + TS4900_GPIO_OUT); + else + regmap_update_bits(priv->regmap, offset, TS4900_GPIO_OUT, 0); +} + +static const struct regmap_config ts4900_regmap_config = { + .reg_bits = 16, + .val_bits = 8, +}; + +static const struct gpio_chip template_chip = { + .label = "ts4900-gpio", + .owner = THIS_MODULE, + .get_direction = ts4900_gpio_get_direction, + .direction_input = ts4900_gpio_direction_input, + .direction_output = ts4900_gpio_direction_output, + .get = ts4900_gpio_get, + .set = ts4900_gpio_set, + .base = -1, + .can_sleep = true, +}; + +static const struct of_device_id ts4900_gpio_of_match_table[] = { + { + .compatible = "technologic,ts4900-gpio", + .data = (void *)TS4900_GPIO_IN, + }, { + .compatible = "technologic,ts7970-gpio", + .data = (void *)TS7970_GPIO_IN, + }, + { /* sentinel */ }, +}; +MODULE_DEVICE_TABLE(of, ts4900_gpio_of_match_table); + +static int ts4900_gpio_probe(struct i2c_client *client, + const struct i2c_device_id *id) +{ + struct ts4900_gpio_priv *priv; + u32 ngpio; + int ret; + + if (of_property_read_u32(client->dev.of_node, "ngpios", &ngpio)) + ngpio = DEFAULT_PIN_NUMBER; + + priv = devm_kzalloc(&client->dev, sizeof(*priv), GFP_KERNEL); + if (!priv) + return -ENOMEM; + + priv->gpio_chip = template_chip; + priv->gpio_chip.label = "ts4900-gpio"; + priv->gpio_chip.ngpio = ngpio; + priv->gpio_chip.parent = &client->dev; + priv->input_bit = (uintptr_t)of_device_get_match_data(&client->dev); + + priv->regmap = devm_regmap_init_i2c(client, &ts4900_regmap_config); + if (IS_ERR(priv->regmap)) { + ret = PTR_ERR(priv->regmap); + dev_err(&client->dev, "Failed to allocate register map: %d\n", + ret); + return ret; + } + + ret = devm_gpiochip_add_data(&client->dev, &priv->gpio_chip, priv); + if (ret < 0) { + dev_err(&client->dev, "Unable to register gpiochip\n"); + return ret; + } + + i2c_set_clientdata(client, priv); + + return 0; +} + +static const struct i2c_device_id ts4900_gpio_id_table[] = { + { "ts4900-gpio", }, + { /* sentinel */ } +}; +MODULE_DEVICE_TABLE(i2c, ts4900_gpio_id_table); + +static struct i2c_driver ts4900_gpio_driver = { + .driver = { + .name = "ts4900-gpio", + .of_match_table = ts4900_gpio_of_match_table, + }, + .probe = ts4900_gpio_probe, + .id_table = ts4900_gpio_id_table, +}; +module_i2c_driver(ts4900_gpio_driver); + +MODULE_AUTHOR("Technologic Systems"); +MODULE_DESCRIPTION("GPIO interface for Technologic Systems I2C-FPGA core"); +MODULE_LICENSE("GPL"); |