// SPDX-License-Identifier: GPL-2.0+ // // Gateworks I2C PLD GPIO expander // // Copyright (C) 2019 Linus Walleij <linus.walleij@linaro.org> // // Based on code and know-how from the OpenWrt driver: // Copyright (C) 2009 Gateworks Corporation // Authors: Chris Lang, Imre Kaloz #include <linux/bits.h> #include <linux/kernel.h> #include <linux/slab.h> #include <linux/gpio/driver.h> #include <linux/i2c.h> #include <linux/module.h> /** * struct gw_pld - State container for Gateworks PLD * @chip: GPIO chip instance * @client: I2C client * @out: shadow register for the output bute */ struct gw_pld { struct gpio_chip chip; struct i2c_client *client; u8 out; }; /* * The Gateworks I2C PLD chip only expose one read and one write register. * Writing a "one" bit (to match the reset state) lets that pin be used as an * input. It is an open-drain model. */ static int gw_pld_input8(struct gpio_chip *gc, unsigned offset) { struct gw_pld *gw = gpiochip_get_data(gc); gw->out |= BIT(offset); return i2c_smbus_write_byte(gw->client, gw->out); } static int gw_pld_get8(struct gpio_chip *gc, unsigned offset) { struct gw_pld *gw = gpiochip_get_data(gc); s32 val; val = i2c_smbus_read_byte(gw->client); return (val < 0) ? 0 : !!(val & BIT(offset)); } static int gw_pld_output8(struct gpio_chip *gc, unsigned offset, int value) { struct gw_pld *gw = gpiochip_get_data(gc); if (value) gw->out |= BIT(offset); else gw->out &= ~BIT(offset); return i2c_smbus_write_byte(gw->client, gw->out); } static void gw_pld_set8(struct gpio_chip *gc, unsigned offset, int value) { gw_pld_output8(gc, offset, value); } static int gw_pld_probe(struct i2c_client *client) { struct device *dev = &client->dev; struct gw_pld *gw; int ret; gw = devm_kzalloc(dev, sizeof(*gw), GFP_KERNEL); if (!gw) return -ENOMEM; gw->chip.base = -1; gw->chip.can_sleep = true; gw->chip.parent = dev; gw->chip.owner = THIS_MODULE; gw->chip.label = dev_name(dev); gw->chip.ngpio = 8; gw->chip.direction_input = gw_pld_input8; gw->chip.get = gw_pld_get8; gw->chip.direction_output = gw_pld_output8; gw->chip.set = gw_pld_set8; gw->client = client; /* * The Gateworks I2C PLD chip does not properly send the acknowledge * bit at all times, but we can still use the standard i2c_smbus * functions by simply ignoring this bit. */ client->flags |= I2C_M_IGNORE_NAK; gw->out = 0xFF; i2c_set_clientdata(client, gw); ret = devm_gpiochip_add_data(dev, &gw->chip, gw); if (ret) return ret; dev_info(dev, "registered Gateworks PLD GPIO device\n"); return 0; } static const struct i2c_device_id gw_pld_id[] = { { "gw-pld", }, { } }; MODULE_DEVICE_TABLE(i2c, gw_pld_id); static const struct of_device_id gw_pld_dt_ids[] = { { .compatible = "gateworks,pld-gpio", }, { }, }; MODULE_DEVICE_TABLE(of, gw_pld_dt_ids); static struct i2c_driver gw_pld_driver = { .driver = { .name = "gw_pld", .of_match_table = gw_pld_dt_ids, }, .probe = gw_pld_probe, .id_table = gw_pld_id, }; module_i2c_driver(gw_pld_driver); MODULE_DESCRIPTION("Gateworks I2C PLD GPIO expander"); MODULE_LICENSE("GPL"); MODULE_AUTHOR("Linus Walleij <linus.walleij@linaro.org>");