[PATCH v4] gpio: add driver for PCF857x, PCA{85, 96}7x, and MAX732[89] I2C GPIO expanders

Sascha Hauer s.hauer at pengutronix.de
Mon Jun 3 23:44:10 PDT 2019


On Tue, May 28, 2019 at 11:00:43AM +0200, Michael Grzeschik wrote:
> Reviewed-by: Sam Ravnborg <sam at ravnborg.org>
> Signed-off-by: Michael Grzeschik <m.grzeschik at pengutronix.de>
> ---
> v1 -> v2:
> 
> - removed unnecessary chapter in kconfig helptext
> - removed platform data setup and teardown callbacks
> - removed error path for xzalloc
> 
> v2 -> v3:
> 
> - removed include/platform_data/pcf857x.h
> - removed useage and comments of platform_data
> 
> v3 -> v4:
> 
> - added depends on CONFIG_OF

Applied, thanks

Sascha

> 
>  drivers/gpio/Kconfig        |  17 +++
>  drivers/gpio/Makefile       |   1 +
>  drivers/gpio/gpio-pcf857x.c | 256 ++++++++++++++++++++++++++++++++++++
>  3 files changed, 274 insertions(+)
>  create mode 100644 drivers/gpio/gpio-pcf857x.c
> 
> diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
> index c535904ed0..6a4de7fbc8 100644
> --- a/drivers/gpio/Kconfig
> +++ b/drivers/gpio/Kconfig
> @@ -98,6 +98,23 @@ config GPIO_PCA953X
>  
>  	  40 bits: pca9505, pca9698
>  
> +config GPIO_PCF857X
> +	tristate "PCF857x, PCA{85,96}7x, and MAX732[89] I2C GPIO expanders"
> +	depends on I2C
> +	depends on CONFIG_OF
> +	help
> +	  Say yes here to provide access to most "quasi-bidirectional" I2C
> +	  GPIO expanders used for additional digital outputs or inputs.
> +	  Most of these parts are from NXP, though TI is a second source for
> +	  some of them.  Compatible models include:
> +
> +	  8 bits:   pcf8574, pcf8574a, pca8574, pca8574a,
> +	            pca9670, pca9672, pca9674, pca9674a,
> +	  	    max7328, max7329
> +
> +	  16 bits:  pcf8575, pcf8575c, pca8575,
> +	            pca9671, pca9673, pca9675
> +
>  config GPIO_PL061
>  	bool "PrimeCell PL061 GPIO support"
>  	depends on ARM_AMBA
> diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
> index 52280f0bb4..990df01788 100644
> --- a/drivers/gpio/Makefile
> +++ b/drivers/gpio/Makefile
> @@ -14,6 +14,7 @@ obj-$(CONFIG_GPIO_MALTA_FPGA_I2C) += gpio-malta-fpga-i2c.o
>  obj-$(CONFIG_GPIO_ORION)	+= gpio-orion.o
>  obj-$(CONFIG_GPIO_OMAP)		+= gpio-omap.o
>  obj-$(CONFIG_GPIO_PCA953X)	+= gpio-pca953x.o
> +obj-$(CONFIG_GPIO_PCF857X)	+= gpio-pcf857x.o
>  obj-$(CONFIG_GPIO_PL061)	+= gpio-pl061.o
>  obj-$(CONFIG_GPIO_STMPE)	+= gpio-stmpe.o
>  obj-$(CONFIG_GPIO_TEGRA)	+= gpio-tegra.o
> diff --git a/drivers/gpio/gpio-pcf857x.c b/drivers/gpio/gpio-pcf857x.c
> new file mode 100644
> index 0000000000..6c1c0ac352
> --- /dev/null
> +++ b/drivers/gpio/gpio-pcf857x.c
> @@ -0,0 +1,256 @@
> +/*
> + * 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 <common.h>
> +#include <malloc.h>
> +#include <driver.h>
> +#include <xfuncs.h>
> +#include <errno.h>
> +#include <i2c/i2c.h>
> +#include <gpio.h>
> +
> +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);
> -- 
> 2.20.1
> 
> 
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