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