pcf8575_gpio.c
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/*
* PCF8575 I2C GPIO EXPANDER DRIVER
*
* Copyright (C) 2016 Texas Instruments Incorporated - http://www.ti.com/
*
* Vignesh R <vigneshr@ti.com>
*
* SPDX-License-Identifier: GPL-2.0
*
*
* Driver for TI PCF-8575 16-bit I2C gpio expander. Based on
* gpio-pcf857x Linux Kernel(v4.7) driver.
*
* Copyright (C) 2007 David Brownell
*
*/
/*
* NOTE: The driver and devicetree bindings are borrowed from Linux
* Kernel, but driver does not support all PCF857x devices. It currently
* supports PCF8575 16-bit expander by TI and NXP.
*
* TODO(vigneshr@ti.com):
* Support 8 bit PCF857x compatible expanders.
*/
#include <common.h>
#include <dm.h>
#include <i2c.h>
#include <asm-generic/gpio.h>
DECLARE_GLOBAL_DATA_PTR;
struct pcf8575_chip {
int gpio_count; /* No. GPIOs supported by the chip */
/* 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 "out" 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.
*/
unsigned int out; /* software latch */
const char *bank_name; /* Name of the expander bank */
};
/* Read/Write to 16-bit I/O expander */
static int pcf8575_i2c_write_le16(struct udevice *dev, unsigned int word)
{
struct dm_i2c_chip *chip = dev_get_parent_platdata(dev);
u8 buf[2] = { word & 0xff, word >> 8, };
int ret;
ret = dm_i2c_write(dev, 0, buf, 2);
if (ret)
printf("%s i2c write failed to addr %x\n", __func__,
chip->chip_addr);
return ret;
}
static int pcf8575_i2c_read_le16(struct udevice *dev)
{
struct dm_i2c_chip *chip = dev_get_parent_platdata(dev);
u8 buf[2];
int ret;
ret = dm_i2c_read(dev, 0, buf, 2);
if (ret) {
printf("%s i2c read failed from addr %x\n", __func__,
chip->chip_addr);
return ret;
}
return (buf[1] << 8) | buf[0];
}
static int pcf8575_direction_input(struct udevice *dev, unsigned offset)
{
struct pcf8575_chip *plat = dev_get_platdata(dev);
int status;
plat->out |= BIT(offset);
status = pcf8575_i2c_write_le16(dev, plat->out);
return status;
}
static int pcf8575_direction_output(struct udevice *dev,
unsigned int offset, int value)
{
struct pcf8575_chip *plat = dev_get_platdata(dev);
int ret;
if (value)
plat->out |= BIT(offset);
else
plat->out &= ~BIT(offset);
ret = pcf8575_i2c_write_le16(dev, plat->out);
return ret;
}
static int pcf8575_get_value(struct udevice *dev, unsigned int offset)
{
int value;
value = pcf8575_i2c_read_le16(dev);
return (value < 0) ? value : ((value & BIT(offset)) >> offset);
}
static int pcf8575_set_value(struct udevice *dev, unsigned int offset,
int value)
{
return pcf8575_direction_output(dev, offset, value);
}
static int pcf8575_ofdata_platdata(struct udevice *dev)
{
struct pcf8575_chip *plat = dev_get_platdata(dev);
struct gpio_dev_priv *uc_priv = dev_get_uclass_priv(dev);
int n_latch;
uc_priv->gpio_count = fdtdec_get_int(gd->fdt_blob, dev_of_offset(dev),
"gpio-count", 16);
uc_priv->bank_name = fdt_getprop(gd->fdt_blob, dev_of_offset(dev),
"gpio-bank-name", NULL);
if (!uc_priv->bank_name)
uc_priv->bank_name = fdt_get_name(gd->fdt_blob,
dev_of_offset(dev), NULL);
n_latch = fdtdec_get_uint(gd->fdt_blob, dev_of_offset(dev),
"lines-initial-states", 0);
plat->out = ~n_latch;
return 0;
}
static int pcf8575_gpio_probe(struct udevice *dev)
{
struct gpio_dev_priv *uc_priv = dev_get_uclass_priv(dev);
debug("%s GPIO controller with %d gpios probed\n",
uc_priv->bank_name, uc_priv->gpio_count);
return 0;
}
static const struct dm_gpio_ops pcf8575_gpio_ops = {
.direction_input = pcf8575_direction_input,
.direction_output = pcf8575_direction_output,
.get_value = pcf8575_get_value,
.set_value = pcf8575_set_value,
};
static const struct udevice_id pcf8575_gpio_ids[] = {
{ .compatible = "nxp,pcf8575" },
{ .compatible = "ti,pcf8575" },
{ }
};
U_BOOT_DRIVER(gpio_pcf8575) = {
.name = "gpio_pcf8575",
.id = UCLASS_GPIO,
.ops = &pcf8575_gpio_ops,
.of_match = pcf8575_gpio_ids,
.ofdata_to_platdata = pcf8575_ofdata_platdata,
.probe = pcf8575_gpio_probe,
.platdata_auto_alloc_size = sizeof(struct pcf8575_chip),
};