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eghidoliBartosz Golaszewski
eghidoli
authored and
Bartosz Golaszewski
committed
gpio: fxl6408: add I2C GPIO expander driver
Add minimal driver for Fairchild FXL6408 8-bit I2C-controlled GPIO expander using the generic regmap based GPIO driver (GPIO_REGMAP). The driver implements setting the GPIO direction, reading inputs and writing outputs. In addition to that the FXL6408 has the following functionalities: - allows to monitor input ports for data transitions with an interrupt pin - all inputs can be configured with pull-up or pull-down resistors Datasheet: https://www.onsemi.com/download/data-sheet/pdf/fxl6408-d.pdf Signed-off-by: Emanuele Ghidoli <emanuele.ghidoli@toradex.com> Co-developed-by: Francesco Dolcini <francesco.dolcini@toradex.com> Signed-off-by: Francesco Dolcini <francesco.dolcini@toradex.com> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com> [Bartosz: order includes alphabetically] Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
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‎drivers/gpio/Kconfig‎

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@@ -1007,6 +1007,16 @@ config GPIO_ADNP
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enough to represent all pins, but the driver will assume a
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register layout for 64 pins (8 registers).
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config GPIO_FXL6408
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tristate "FXL6408 I2C GPIO expander"
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select GPIO_REGMAP
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select REGMAP_I2C
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help
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GPIO driver for Fairchild Semiconductor FXL6408 GPIO expander.
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To compile this driver as a module, choose M here: the module will
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be called gpio-fxl6408.
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config GPIO_GW_PLD
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tristate "Gateworks PLD GPIO Expander"
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depends on OF_GPIO

‎drivers/gpio/Makefile‎

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@@ -60,6 +60,7 @@ obj-$(CONFIG_GPIO_EP93XX) += gpio-ep93xx.o
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obj-$(CONFIG_GPIO_EXAR) += gpio-exar.o
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obj-$(CONFIG_GPIO_F7188X) += gpio-f7188x.o
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obj-$(CONFIG_GPIO_FTGPIO010) += gpio-ftgpio010.o
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obj-$(CONFIG_GPIO_FXL6408) += gpio-fxl6408.o
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obj-$(CONFIG_GPIO_GE_FPGA) += gpio-ge.o
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obj-$(CONFIG_GPIO_GPIO_MM) += gpio-gpio-mm.o
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obj-$(CONFIG_GPIO_GRGPIO) += gpio-grgpio.o

‎drivers/gpio/gpio-fxl6408.c‎

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// SPDX-License-Identifier: GPL-2.0-only
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/*
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* FXL6408 GPIO driver
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*
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* Copyright 2023 Toradex
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*
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* Author: Emanuele Ghidoli <emanuele.ghidoli@toradex.com>
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*/
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#include <linux/err.h>
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#include <linux/gpio/regmap.h>
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#include <linux/i2c.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/regmap.h>
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#define FXL6408_REG_DEVICE_ID 0x01
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#define FXL6408_MF_FAIRCHILD 0b101
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#define FXL6408_MF_SHIFT 5
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/* Bits set here indicate that the GPIO is an output. */
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#define FXL6408_REG_IO_DIR 0x03
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/*
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* Bits set here, when the corresponding bit of IO_DIR is set, drive
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* the output high instead of low.
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*/
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#define FXL6408_REG_OUTPUT 0x05
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/* Bits here make the output High-Z, instead of the OUTPUT value. */
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#define FXL6408_REG_OUTPUT_HIGH_Z 0x07
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/* Returns the current status (1 = HIGH) of the input pins. */
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#define FXL6408_REG_INPUT_STATUS 0x0f
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/*
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* Return the current interrupt status
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* This bit is HIGH if input GPIO != default state (register 09h).
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* The flag is cleared after being read (bit returns to 0).
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* The input must go back to default state and change again before this flag is raised again.
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*/
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#define FXL6408_REG_INT_STS 0x13
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#define FXL6408_NGPIO 8
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static const struct regmap_range rd_range[] = {
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{ FXL6408_REG_DEVICE_ID, FXL6408_REG_DEVICE_ID },
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{ FXL6408_REG_IO_DIR, FXL6408_REG_OUTPUT },
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{ FXL6408_REG_INPUT_STATUS, FXL6408_REG_INPUT_STATUS },
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};
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static const struct regmap_range wr_range[] = {
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{ FXL6408_REG_DEVICE_ID, FXL6408_REG_DEVICE_ID },
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{ FXL6408_REG_IO_DIR, FXL6408_REG_OUTPUT },
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{ FXL6408_REG_OUTPUT_HIGH_Z, FXL6408_REG_OUTPUT_HIGH_Z },
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};
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static const struct regmap_range volatile_range[] = {
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{ FXL6408_REG_DEVICE_ID, FXL6408_REG_DEVICE_ID },
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{ FXL6408_REG_INPUT_STATUS, FXL6408_REG_INPUT_STATUS },
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};
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static const struct regmap_access_table rd_table = {
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.yes_ranges = rd_range,
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.n_yes_ranges = ARRAY_SIZE(rd_range),
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};
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static const struct regmap_access_table wr_table = {
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.yes_ranges = wr_range,
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.n_yes_ranges = ARRAY_SIZE(wr_range),
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};
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static const struct regmap_access_table volatile_table = {
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.yes_ranges = volatile_range,
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.n_yes_ranges = ARRAY_SIZE(volatile_range),
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};
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static const struct regmap_config regmap = {
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.reg_bits = 8,
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.val_bits = 8,
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.max_register = FXL6408_REG_INT_STS,
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.wr_table = &wr_table,
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.rd_table = &rd_table,
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.volatile_table = &volatile_table,
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.cache_type = REGCACHE_RBTREE,
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.num_reg_defaults_raw = FXL6408_REG_INT_STS + 1,
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};
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static int fxl6408_identify(struct device *dev, struct regmap *regmap)
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{
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int val, ret;
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ret = regmap_read(regmap, FXL6408_REG_DEVICE_ID, &val);
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if (ret)
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return dev_err_probe(dev, ret, "error reading DEVICE_ID\n");
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if (val >> FXL6408_MF_SHIFT != FXL6408_MF_FAIRCHILD)
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return dev_err_probe(dev, -ENODEV, "invalid device id 0x%02x\n", val);
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return 0;
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}
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static int fxl6408_probe(struct i2c_client *client)
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{
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struct device *dev = &client->dev;
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int ret;
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struct gpio_regmap_config gpio_config = {
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.parent = dev,
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.ngpio = FXL6408_NGPIO,
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.reg_dat_base = GPIO_REGMAP_ADDR(FXL6408_REG_INPUT_STATUS),
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.reg_set_base = GPIO_REGMAP_ADDR(FXL6408_REG_OUTPUT),
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.reg_dir_out_base = GPIO_REGMAP_ADDR(FXL6408_REG_IO_DIR),
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.ngpio_per_reg = FXL6408_NGPIO,
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};
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gpio_config.regmap = devm_regmap_init_i2c(client, &regmap);
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if (IS_ERR(gpio_config.regmap))
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return dev_err_probe(dev, PTR_ERR(gpio_config.regmap),
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"failed to allocate register map\n");
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ret = fxl6408_identify(dev, gpio_config.regmap);
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if (ret)
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return ret;
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/* Disable High-Z of outputs, so that our OUTPUT updates actually take effect. */
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ret = regmap_write(gpio_config.regmap, FXL6408_REG_OUTPUT_HIGH_Z, 0);
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if (ret)
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return dev_err_probe(dev, ret, "failed to write 'output high Z' register\n");
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return PTR_ERR_OR_ZERO(devm_gpio_regmap_register(dev, &gpio_config));
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}
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static const __maybe_unused struct of_device_id fxl6408_dt_ids[] = {
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{ .compatible = "fcs,fxl6408" },
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{ }
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};
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MODULE_DEVICE_TABLE(of, fxl6408_dt_ids);
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static const struct i2c_device_id fxl6408_id[] = {
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{ "fxl6408", 0 },
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{ }
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};
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MODULE_DEVICE_TABLE(i2c, fxl6408_id);
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static struct i2c_driver fxl6408_driver = {
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.driver = {
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.name = "fxl6408",
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.of_match_table = fxl6408_dt_ids,
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},
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.probe_new = fxl6408_probe,
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.id_table = fxl6408_id,
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};
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module_i2c_driver(fxl6408_driver);
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MODULE_AUTHOR("Emanuele Ghidoli <emanuele.ghidoli@toradex.com>");
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MODULE_DESCRIPTION("FXL6408 GPIO driver");
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MODULE_LICENSE("GPL");

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