Hi Michael
On Sat, May 18, 2019 at 01:36:06AM +0200, Michael Grzeschik wrote:
> This driver was derived from the kernel driver gpio-pcf857x.c by removing
> locking and interrupt support.
>
> Signed-off-by: Michael Grzeschik <m.grzeschik@xxxxxxxxxxxxxx>
> ---
> drivers/gpio/Kconfig | 24 +++
> drivers/gpio/Makefile | 1 +
> drivers/gpio/gpio-pcf857x.c | 274 ++++++++++++++++++++++++++++++++
> include/platform_data/pcf857x.h | 48 ++++++
> 4 files changed, 347 insertions(+)
> create mode 100644 drivers/gpio/gpio-pcf857x.c
> create mode 100644 include/platform_data/pcf857x.h
>
> diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
> index c535904ed0..b3719cd92b 100644
> --- a/drivers/gpio/Kconfig
> +++ b/drivers/gpio/Kconfig
> @@ -98,6 +98,30 @@ 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
> + 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
> +
> + Your board setup code will need to declare the expanders in
> + use, and assign numbers to the GPIOs they expose. Those GPIOs
> + can then be used from drivers and other kernel code, just like
> + other GPIOs, but only accessible from task contexts.
The way I read the above code this driver requires platform_data
but I reqd the code as we can also configure this only usinf OF.
Likely a stale kernel help comment that you just copied over which is
fine.
> +
> + This driver provides an in-kernel interface to those GPIOs using
> + platform-neutral GPIO calls.
This last sentence does not makes too much sense in barebox.
> +
> 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..02ca39e45b
> --- /dev/null
> +++ b/drivers/gpio/gpio-pcf857x.c
> @@ -0,0 +1,274 @@
> +/*
> + * 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>
> +#include <platform_data/pcf857x.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 pcf857x_platform_data *pdata = dev->platform_data;
> + struct device_node *np = dev->device_node;
> + struct pcf857x *gpio;
> + unsigned long driver_data;
> + unsigned int n_latch = 0;
> + int ret;
> +
> + if (IS_ENABLED(CONFIG_OF) && np)
> + of_property_read_u32(np, "lines-initial-states", &n_latch);
> + else if (pdata)
> + n_latch = pdata->n_latch;
> +
> + /* Allocate, initialize, and register this gpio_chip. */
> + gpio = xzalloc(sizeof(*gpio));
> + if (!gpio)
> + return -ENOMEM;
> +
> + ret = dev_get_drvdata(dev, (const void **)&driver_data);
> + if (ret)
> + return ret;
> +
> + gpio->chip.base = pdata ? pdata->gpio_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. The setup() method can do that, but it
> + * may cause transient glitching since it can't know the last value
> + * written (some pins may need to be driven low).
> + *
> + * 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;
> +
> + /* Let platform code set up the GPIOs and their users.
> + * Now is the first time anyone could use them.
> + */
> + if (pdata && pdata->setup) {
> + ret = pdata->setup(client,
> + gpio->chip.base, gpio->chip.ngpio,
> + pdata->context);
> + if (ret < 0)
> + dev_warn(&client->dev, "setup failed, %d\n", 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);
> diff --git a/include/platform_data/pcf857x.h b/include/platform_data/pcf857x.h
> new file mode 100644
> index 0000000000..4a4a830d05
> --- /dev/null
> +++ b/include/platform_data/pcf857x.h
> @@ -0,0 +1,48 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef __LINUX_PCF857X_H
> +#define __LINUX_PCF857X_H
> +
> +#include <linux/types.h>
> +#include <i2c/i2c.h>
> +
> +/**
> + * struct pcf857x_platform_data - data to set up pcf857x driver
> + * @gpio_base: number of the chip's first GPIO
> + * @n_latch: optional bit-inverse of initial register value; if
> + * you leave this initialized to zero the driver will act
> + * like the chip was just reset
> + * @setup: optional callback issued once the GPIOs are valid
> + * @teardown: optional callback issued before the GPIOs are invalidated
> + * @context: optional parameter passed to setup() and teardown()
> + *
> + * In addition to the I2C_BOARD_INFO() state appropriate to each chip,
> + * the i2c_board_info used with the pcf875x driver must provide its
> + * platform_data (pointer to one of these structures) with at least
> + * the gpio_base value initialized.
> + *
> + * The @setup callback may be used with the kind of board-specific glue
> + * which hands the (now-valid) GPIOs to other drivers, or which puts
> + * devices in their initial states using these GPIOs.
> + *
> + * These GPIO chips are only "quasi-bidirectional"; read the chip specs
> + * to understand the behavior. They don't have separate registers to
> + * record which pins are used for input or output, record which output
> + * values are driven, or provide access to input values. That must be
> + * inferred by reading the chip's value and knowing the last value written
> + * to it. If you leave n_latch initialized to zero, that last written
> + * value is presumed to be all ones (as if the chip were just reset).
> + */
> +struct pcf857x_platform_data {
> + unsigned gpio_base;
> + unsigned n_latch;
> +
> + int (*setup)(struct i2c_client *client,
> + int gpio, unsigned ngpio,
> + void *context);
> + int (*teardown)(struct i2c_client *client,
> + int gpio, unsigned ngpio,
> + void *context);
teardown is never used in barebox, but I assume this is left to keep diff
towards the original kernel version minimal.
> + void *context;
> +};
> +
> +#endif /* __LINUX_PCF857X_H */
Sam
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