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135 lines
3.1 KiB
135 lines
3.1 KiB
// 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 <[email protected]> |
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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 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.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 <[email protected]>");
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