/* * Driver for pcf857x, pca857x, and pca967x I2C GPIO expanders * * This code was ported from linux-5.1 kernel by Michael Grzeschik. * * Copyright (C) 2007 David Brownell * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. */ #include #include #include #include #include #include #include static const struct platform_device_id pcf857x_id[] = { { "pcf8574", 8 }, { "pcf8574a", 8 }, { "pca8574", 8 }, { "pca9670", 8 }, { "pca9672", 8 }, { "pca9674", 8 }, { "pcf8575", 16 }, { "pca8575", 16 }, { "pca9671", 16 }, { "pca9673", 16 }, { "pca9675", 16 }, { "max7328", 8 }, { "max7329", 8 }, { } }; /* * The pcf857x, pca857x, and pca967x chips 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's not an open-drain model, but acts * a bit like one. This is described as "quasi-bidirectional"; read the * chip documentation for details. * * Many other I2C GPIO expander chips (like the pca953x models) have * more complex register models and more conventional circuitry using * push/pull drivers. They often use the same 0x20..0x27 addresses as * pcf857x parts, making the "legacy" I2C driver model problematic. */ struct pcf857x { struct gpio_chip chip; struct i2c_client *client; unsigned out; /* software latch */ int (*write)(struct i2c_client *client, unsigned data); int (*read)(struct i2c_client *client); }; static inline struct pcf857x *to_pcf(struct gpio_chip *gc) { return container_of(gc, struct pcf857x, chip); } /*-------------------------------------------------------------------------*/ /* Talk to 8-bit I/O expander */ static int i2c_write_le8(struct i2c_client *client, unsigned data) { return i2c_smbus_write_byte(client, data); } static int i2c_read_le8(struct i2c_client *client) { return (int)i2c_smbus_read_byte(client); } /* Talk to 16-bit I/O expander */ static int i2c_write_le16(struct i2c_client *client, unsigned word) { u8 buf[2] = { word & 0xff, word >> 8, }; int ret; ret = i2c_master_send(client, buf, 2); return (ret < 0) ? ret : 0; } static int i2c_read_le16(struct i2c_client *client) { u8 buf[2]; int ret; ret = i2c_master_recv(client, buf, 2); if (ret < 0) return ret; return (buf[1] << 8) | buf[0]; } /*-------------------------------------------------------------------------*/ static int pcf857x_input(struct gpio_chip *chip, unsigned offset) { struct pcf857x *gpio = to_pcf(chip); int ret; gpio->out |= (1 << offset); ret = gpio->write(gpio->client, gpio->out); return ret; } static int pcf857x_get(struct gpio_chip *chip, unsigned offset) { struct pcf857x *gpio = to_pcf(chip); int value; value = gpio->read(gpio->client); return (value < 0) ? value : !!(value & (1 << offset)); } static int pcf857x_output(struct gpio_chip *chip, unsigned offset, int value) { struct pcf857x *gpio = to_pcf(chip); unsigned bit = 1 << offset; int ret; if (value) gpio->out |= bit; else gpio->out &= ~bit; ret = gpio->write(gpio->client, gpio->out); return ret; } static void pcf857x_set(struct gpio_chip *chip, unsigned offset, int value) { pcf857x_output(chip, offset, value); } /*-------------------------------------------------------------------------*/ static struct gpio_ops pcf857x_gpio_ops = { .direction_input = pcf857x_input, .direction_output = pcf857x_output, .get = pcf857x_get, .set = pcf857x_set, }; static int pcf857x_probe(struct device_d *dev) { struct i2c_client *client = to_i2c_client(dev); struct device_node *np = dev->device_node; struct pcf857x *gpio; unsigned long driver_data; unsigned int n_latch = 0; int ret; if (!np) return -EINVAL; of_property_read_u32(np, "lines-initial-states", &n_latch); /* Allocate, initialize, and register this gpio_chip. */ gpio = xzalloc(sizeof(*gpio)); ret = dev_get_drvdata(dev, (const void **)&driver_data); if (ret) return ret; gpio->chip.base = -1; gpio->chip.ops = &pcf857x_gpio_ops; gpio->chip.ngpio = driver_data; gpio->chip.dev = &client->dev; /* NOTE: the OnSemi jlc1562b is also largely compatible with * these parts, notably for output. It has a low-resolution * DAC instead of pin change IRQs; and its inputs can be the * result of comparators. */ /* 8574 addresses are 0x20..0x27; 8574a uses 0x38..0x3f; * 9670, 9672, 9764, and 9764a use quite a variety. * * NOTE: we don't distinguish here between *4 and *4a parts. */ switch (gpio->chip.ngpio) { case 8: gpio->write = i2c_write_le8; gpio->read = i2c_read_le8; break; /* '75/'75c addresses are 0x20..0x27, just like the '74; * the '75c doesn't have a current source pulling high. * 9671, 9673, and 9765 use quite a variety of addresses. * * NOTE: we don't distinguish here between '75 and '75c parts. */ case 16: gpio->write = i2c_write_le16; gpio->read = i2c_read_le16; break; default: dev_warn(&client->dev, "unsupported number of gpios\n"); return -EINVAL; } gpio->client = client; /* NOTE: these chips have strange "quasi-bidirectional" I/O pins. * We can't actually know whether a pin is configured (a) as output * and driving the signal low, or (b) as input and reporting a low * value ... without knowing the last value written since the chip * came out of reset (if any). We can't read the latched output. * * In short, the only reliable solution for setting up pin direction * is to do it explicitly. * * Using n_latch avoids that trouble. When left initialized to zero, * our software copy of the "latch" then matches the chip's all-ones * reset state. Otherwise it flags pins to be driven low. */ gpio->out = ~n_latch; ret = gpiochip_add(&gpio->chip); if (ret) return ret; return ret; } static const struct of_device_id pcf857x_dt_ids[] = { { .compatible = "nxp,pcf8574", .data = (void *)8 }, { .compatible = "nxp,pcf8574a", .data = (void *)8 }, { .compatible = "nxp,pca8574", .data = (void *)8 }, { .compatible = "nxp,pca9670", .data = (void *)8 }, { .compatible = "nxp,pca9672", .data = (void *)8 }, { .compatible = "nxp,pca9674", .data = (void *)8 }, { .compatible = "nxp,pcf8575", .data = (void *)16 }, { .compatible = "nxp,pca8575", .data = (void *)16 }, { .compatible = "nxp,pca9671", .data = (void *)16 }, { .compatible = "nxp,pca9673", .data = (void *)16 }, { .compatible = "nxp,pca9675", .data = (void *)16 }, { .compatible = "maxim,max7328", .data = (void *)8 }, { .compatible = "maxim,max7329", .data = (void *)8 }, { } }; static struct driver_d pcf857x_driver = { .name = "pcf857x", .probe = pcf857x_probe, .of_compatible = DRV_OF_COMPAT(pcf857x_dt_ids), .id_table = pcf857x_id, }; device_i2c_driver(pcf857x_driver);