diff options
Diffstat (limited to 'drivers/gpio/gpio-gw-pld.c')
| -rw-r--r-- | drivers/gpio/gpio-gw-pld.c | 134 |
1 files changed, 134 insertions, 0 deletions
diff --git a/drivers/gpio/gpio-gw-pld.c b/drivers/gpio/gpio-gw-pld.c new file mode 100644 index 0000000000..899335da93 --- /dev/null +++ b/drivers/gpio/gpio-gw-pld.c @@ -0,0 +1,134 @@ +// 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_LICENSE("GPL"); +MODULE_AUTHOR("Linus Walleij <linus.walleij@linaro.org>"); |