--- /dev/null
+/*
+ * Linear Technology LTC4306 and LTC4305 I2C multiplexer/switch
+ *
+ * Copyright (C) 2017 Analog Devices Inc.
+ *
+ * Licensed under the GPL-2.
+ *
+ * Based on: i2c-mux-pca954x.c
+ *
+ * Datasheet: http://cds.linear.com/docs/en/datasheet/4306.pdf
+ */
+
+#include <linux/gpio/consumer.h>
+#include <linux/gpio/driver.h>
+#include <linux/i2c-mux.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/property.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+
+#define LTC4305_MAX_NCHANS 2
+#define LTC4306_MAX_NCHANS 4
+
+#define LTC_REG_STATUS 0x0
+#define LTC_REG_CONFIG 0x1
+#define LTC_REG_MODE 0x2
+#define LTC_REG_SWITCH 0x3
+
+#define LTC_DOWNSTREAM_ACCL_EN BIT(6)
+#define LTC_UPSTREAM_ACCL_EN BIT(7)
+
+#define LTC_GPIO_ALL_INPUT 0xC0
+#define LTC_SWITCH_MASK 0xF0
+
+enum ltc_type {
+ ltc_4305,
+ ltc_4306,
+};
+
+struct chip_desc {
+ u8 nchans;
+ u8 num_gpios;
+};
+
+struct ltc4306 {
+ struct regmap *regmap;
+ struct gpio_chip gpiochip;
+ const struct chip_desc *chip;
+};
+
+static const struct chip_desc chips[] = {
+ [ltc_4305] = {
+ .nchans = LTC4305_MAX_NCHANS,
+ },
+ [ltc_4306] = {
+ .nchans = LTC4306_MAX_NCHANS,
+ .num_gpios = 2,
+ },
+};
+
+static bool ltc4306_is_volatile_reg(struct device *dev, unsigned int reg)
+{
+ return (reg == LTC_REG_CONFIG) ? true : false;
+}
+
+static const struct regmap_config ltc4306_regmap_config = {
+ .reg_bits = 8,
+ .val_bits = 8,
+ .max_register = LTC_REG_SWITCH,
+ .volatile_reg = ltc4306_is_volatile_reg,
+ .cache_type = REGCACHE_FLAT,
+};
+
+static int ltc4306_gpio_get(struct gpio_chip *chip, unsigned int offset)
+{
+ struct ltc4306 *data = gpiochip_get_data(chip);
+ unsigned int val;
+ int ret;
+
+ ret = regmap_read(data->regmap, LTC_REG_CONFIG, &val);
+ if (ret < 0)
+ return ret;
+
+ return !!(val & BIT(1 - offset));
+}
+
+static void ltc4306_gpio_set(struct gpio_chip *chip, unsigned int offset,
+ int value)
+{
+ struct ltc4306 *data = gpiochip_get_data(chip);
+
+ regmap_update_bits(data->regmap, LTC_REG_CONFIG, BIT(5 - offset),
+ value ? BIT(5 - offset) : 0);
+}
+
+static int ltc4306_gpio_get_direction(struct gpio_chip *chip,
+ unsigned int offset)
+{
+ struct ltc4306 *data = gpiochip_get_data(chip);
+ unsigned int val;
+ int ret;
+
+ ret = regmap_read(data->regmap, LTC_REG_MODE, &val);
+ if (ret < 0)
+ return ret;
+
+ return !!(val & BIT(7 - offset));
+}
+
+static int ltc4306_gpio_direction_input(struct gpio_chip *chip,
+ unsigned int offset)
+{
+ struct ltc4306 *data = gpiochip_get_data(chip);
+
+ return regmap_update_bits(data->regmap, LTC_REG_MODE,
+ BIT(7 - offset), BIT(7 - offset));
+}
+
+static int ltc4306_gpio_direction_output(struct gpio_chip *chip,
+ unsigned int offset, int value)
+{
+ struct ltc4306 *data = gpiochip_get_data(chip);
+
+ ltc4306_gpio_set(chip, offset, value);
+ return regmap_update_bits(data->regmap, LTC_REG_MODE,
+ BIT(7 - offset), 0);
+}
+
+static int ltc4306_gpio_set_config(struct gpio_chip *chip,
+ unsigned int offset, unsigned long config)
+{
+ struct ltc4306 *data = gpiochip_get_data(chip);
+ unsigned int val;
+
+ switch (pinconf_to_config_param(config)) {
+ case PIN_CONFIG_DRIVE_OPEN_DRAIN:
+ val = 0;
+ break;
+ case PIN_CONFIG_DRIVE_PUSH_PULL:
+ val = BIT(4 - offset);
+ break;
+ default:
+ return -ENOTSUPP;
+ }
+
+ return regmap_update_bits(data->regmap, LTC_REG_MODE,
+ BIT(4 - offset), val);
+}
+
+static int ltc4306_gpio_init(struct ltc4306 *data)
+{
+ struct device *dev = regmap_get_device(data->regmap);
+
+ if (!data->chip->num_gpios)
+ return 0;
+
+ data->gpiochip.label = dev_name(dev);
+ data->gpiochip.base = -1;
+ data->gpiochip.ngpio = data->chip->num_gpios;
+ data->gpiochip.parent = dev;
+ data->gpiochip.can_sleep = true;
+ data->gpiochip.get_direction = ltc4306_gpio_get_direction;
+ data->gpiochip.direction_input = ltc4306_gpio_direction_input;
+ data->gpiochip.direction_output = ltc4306_gpio_direction_output;
+ data->gpiochip.get = ltc4306_gpio_get;
+ data->gpiochip.set = ltc4306_gpio_set;
+ data->gpiochip.set_config = ltc4306_gpio_set_config;
+ data->gpiochip.owner = THIS_MODULE;
+
+ /* gpiolib assumes all GPIOs default input */
+ regmap_write(data->regmap, LTC_REG_MODE, LTC_GPIO_ALL_INPUT);
+
+ return devm_gpiochip_add_data(dev, &data->gpiochip, data);
+}
+
+static int ltc4306_select_mux(struct i2c_mux_core *muxc, u32 chan)
+{
+ struct ltc4306 *data = i2c_mux_priv(muxc);
+
+ return regmap_update_bits(data->regmap, LTC_REG_SWITCH,
+ LTC_SWITCH_MASK, BIT(7 - chan));
+}
+
+static int ltc4306_deselect_mux(struct i2c_mux_core *muxc, u32 chan)
+{
+ struct ltc4306 *data = i2c_mux_priv(muxc);
+
+ return regmap_update_bits(data->regmap, LTC_REG_SWITCH,
+ LTC_SWITCH_MASK, 0);
+}
+
+static const struct i2c_device_id ltc4306_id[] = {
+ { "ltc4305", ltc_4305 },
+ { "ltc4306", ltc_4306 },
+ { }
+};
+MODULE_DEVICE_TABLE(i2c, ltc4306_id);
+
+static const struct of_device_id ltc4306_of_match[] = {
+ { .compatible = "lltc,ltc4305", .data = &chips[ltc_4305] },
+ { .compatible = "lltc,ltc4306", .data = &chips[ltc_4306] },
+ { }
+};
+MODULE_DEVICE_TABLE(of, ltc4306_of_match);
+
+static int ltc4306_probe(struct i2c_client *client,
+ const struct i2c_device_id *id)
+{
+ struct i2c_adapter *adap = to_i2c_adapter(client->dev.parent);
+ const struct chip_desc *chip;
+ struct i2c_mux_core *muxc;
+ struct ltc4306 *data;
+ struct gpio_desc *gpio;
+ bool idle_disc;
+ unsigned int val = 0;
+ int num, ret;
+
+ chip = of_device_get_match_data(&client->dev);
+
+ if (!chip)
+ chip = &chips[id->driver_data];
+
+ idle_disc = device_property_read_bool(&client->dev,
+ "i2c-mux-idle-disconnect");
+
+ muxc = i2c_mux_alloc(adap, &client->dev,
+ chip->nchans, sizeof(*data),
+ I2C_MUX_LOCKED, ltc4306_select_mux,
+ idle_disc ? ltc4306_deselect_mux : NULL);
+ if (!muxc)
+ return -ENOMEM;
+ data = i2c_mux_priv(muxc);
+ data->chip = chip;
+
+ i2c_set_clientdata(client, muxc);
+
+ data->regmap = devm_regmap_init_i2c(client, <c4306_regmap_config);
+ if (IS_ERR(data->regmap)) {
+ ret = PTR_ERR(data->regmap);
+ dev_err(&client->dev, "Failed to allocate register map: %d\n",
+ ret);
+ return ret;
+ }
+
+ /* Reset and enable the mux if an enable GPIO is specified. */
+ gpio = devm_gpiod_get_optional(&client->dev, "enable", GPIOD_OUT_LOW);
+ if (IS_ERR(gpio))
+ return PTR_ERR(gpio);
+
+ if (gpio) {
+ udelay(1);
+ gpiod_set_value(gpio, 1);
+ }
+
+ /*
+ * Write the mux register at addr to verify
+ * that the mux is in fact present. This also
+ * initializes the mux to disconnected state.
+ */
+ if (regmap_write(data->regmap, LTC_REG_SWITCH, 0) < 0) {
+ dev_warn(&client->dev, "probe failed\n");
+ return -ENODEV;
+ }
+
+ if (device_property_read_bool(&client->dev,
+ "ltc,downstream-accelerators-enable"))
+ val |= LTC_DOWNSTREAM_ACCL_EN;
+
+ if (device_property_read_bool(&client->dev,
+ "ltc,upstream-accelerators-enable"))
+ val |= LTC_UPSTREAM_ACCL_EN;
+
+ if (regmap_write(data->regmap, LTC_REG_CONFIG, val) < 0)
+ return -ENODEV;
+
+ ret = ltc4306_gpio_init(data);
+ if (ret < 0)
+ return ret;
+
+ /* Now create an adapter for each channel */
+ for (num = 0; num < chip->nchans; num++) {
+ ret = i2c_mux_add_adapter(muxc, 0, num, 0);
+ if (ret) {
+ i2c_mux_del_adapters(muxc);
+ return ret;
+ }
+ }
+
+ dev_info(&client->dev,
+ "registered %d multiplexed busses for I2C switch %s\n",
+ num, client->name);
+
+ return 0;
+}
+
+static int ltc4306_remove(struct i2c_client *client)
+{
+ struct i2c_mux_core *muxc = i2c_get_clientdata(client);
+
+ i2c_mux_del_adapters(muxc);
+
+ return 0;
+}
+
+static struct i2c_driver ltc4306_driver = {
+ .driver = {
+ .name = "ltc4306",
+ .of_match_table = of_match_ptr(ltc4306_of_match),
+ },
+ .probe = ltc4306_probe,
+ .remove = ltc4306_remove,
+ .id_table = ltc4306_id,
+};
+
+module_i2c_driver(ltc4306_driver);
+
+MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
+MODULE_DESCRIPTION("Linear Technology LTC4306, LTC4305 I2C mux/switch driver");
+MODULE_LICENSE("GPL v2");
projects / kernel.git / commitdiff