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linux/drivers/gpio/gpio-max730x.c
Uwe Kleine-König 06de2cd788 gpio: max730x: Make __max730x_remove() return void
An spi or i2c remove callback is only called for devices that probed
successfully. In this case this implies that __max730x_probe() set a
non-NULL driver data. So the check ts == NULL is never true. With this
check dropped, __max730x_remove() returns zero unconditionally. Make it
return void instead which makes it easier to see in the callers that
there is no error to handle.

Also the return value of i2c and spi remove callbacks is ignored anyway.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
2021-10-13 19:52:26 +02:00

237 lines
5.6 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/**
* Copyright (C) 2006 Juergen Beisert, Pengutronix
* Copyright (C) 2008 Guennadi Liakhovetski, Pengutronix
* Copyright (C) 2009 Wolfram Sang, Pengutronix
*
* The Maxim MAX7300/1 device is an I2C/SPI driven GPIO expander. There are
* 28 GPIOs. 8 of them can trigger an interrupt. See datasheet for more
* details
* Note:
* - DIN must be stable at the rising edge of clock.
* - when writing:
* - always clock in 16 clocks at once
* - at DIN: D15 first, D0 last
* - D0..D7 = databyte, D8..D14 = commandbyte
* - D15 = low -> write command
* - when reading
* - always clock in 16 clocks at once
* - at DIN: D15 first, D0 last
* - D0..D7 = dummy, D8..D14 = register address
* - D15 = high -> read command
* - raise CS and assert it again
* - always clock in 16 clocks at once
* - at DOUT: D15 first, D0 last
* - D0..D7 contains the data from the first cycle
*
* The driver exports a standard gpiochip interface
*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/mutex.h>
#include <linux/spi/max7301.h>
#include <linux/gpio/driver.h>
#include <linux/slab.h>
/*
* Pin configurations, see MAX7301 datasheet page 6
*/
#define PIN_CONFIG_MASK 0x03
#define PIN_CONFIG_IN_PULLUP 0x03
#define PIN_CONFIG_IN_WO_PULLUP 0x02
#define PIN_CONFIG_OUT 0x01
#define PIN_NUMBER 28
static int max7301_direction_input(struct gpio_chip *chip, unsigned offset)
{
struct max7301 *ts = container_of(chip, struct max7301, chip);
u8 *config;
u8 offset_bits, pin_config;
int ret;
/* First 4 pins are unused in the controller */
offset += 4;
offset_bits = (offset & 3) << 1;
config = &ts->port_config[offset >> 2];
if (ts->input_pullup_active & BIT(offset))
pin_config = PIN_CONFIG_IN_PULLUP;
else
pin_config = PIN_CONFIG_IN_WO_PULLUP;
mutex_lock(&ts->lock);
*config = (*config & ~(PIN_CONFIG_MASK << offset_bits))
| (pin_config << offset_bits);
ret = ts->write(ts->dev, 0x08 + (offset >> 2), *config);
mutex_unlock(&ts->lock);
return ret;
}
static int __max7301_set(struct max7301 *ts, unsigned offset, int value)
{
if (value) {
ts->out_level |= 1 << offset;
return ts->write(ts->dev, 0x20 + offset, 0x01);
} else {
ts->out_level &= ~(1 << offset);
return ts->write(ts->dev, 0x20 + offset, 0x00);
}
}
static int max7301_direction_output(struct gpio_chip *chip, unsigned offset,
int value)
{
struct max7301 *ts = container_of(chip, struct max7301, chip);
u8 *config;
u8 offset_bits;
int ret;
/* First 4 pins are unused in the controller */
offset += 4;
offset_bits = (offset & 3) << 1;
config = &ts->port_config[offset >> 2];
mutex_lock(&ts->lock);
*config = (*config & ~(PIN_CONFIG_MASK << offset_bits))
| (PIN_CONFIG_OUT << offset_bits);
ret = __max7301_set(ts, offset, value);
if (!ret)
ret = ts->write(ts->dev, 0x08 + (offset >> 2), *config);
mutex_unlock(&ts->lock);
return ret;
}
static int max7301_get(struct gpio_chip *chip, unsigned offset)
{
struct max7301 *ts = gpiochip_get_data(chip);
int config, level = -EINVAL;
/* First 4 pins are unused in the controller */
offset += 4;
mutex_lock(&ts->lock);
config = (ts->port_config[offset >> 2] >> ((offset & 3) << 1))
& PIN_CONFIG_MASK;
switch (config) {
case PIN_CONFIG_OUT:
/* Output: return cached level */
level = !!(ts->out_level & (1 << offset));
break;
case PIN_CONFIG_IN_WO_PULLUP:
case PIN_CONFIG_IN_PULLUP:
/* Input: read out */
level = ts->read(ts->dev, 0x20 + offset) & 0x01;
}
mutex_unlock(&ts->lock);
return level;
}
static void max7301_set(struct gpio_chip *chip, unsigned offset, int value)
{
struct max7301 *ts = gpiochip_get_data(chip);
/* First 4 pins are unused in the controller */
offset += 4;
mutex_lock(&ts->lock);
__max7301_set(ts, offset, value);
mutex_unlock(&ts->lock);
}
int __max730x_probe(struct max7301 *ts)
{
struct device *dev = ts->dev;
struct max7301_platform_data *pdata;
int i, ret;
pdata = dev_get_platdata(dev);
mutex_init(&ts->lock);
dev_set_drvdata(dev, ts);
/* Power up the chip and disable IRQ output */
ts->write(dev, 0x04, 0x01);
if (pdata) {
ts->input_pullup_active = pdata->input_pullup_active;
ts->chip.base = pdata->base;
} else {
ts->chip.base = -1;
}
ts->chip.label = dev->driver->name;
ts->chip.direction_input = max7301_direction_input;
ts->chip.get = max7301_get;
ts->chip.direction_output = max7301_direction_output;
ts->chip.set = max7301_set;
ts->chip.ngpio = PIN_NUMBER;
ts->chip.can_sleep = true;
ts->chip.parent = dev;
ts->chip.owner = THIS_MODULE;
/*
* initialize pullups according to platform data and cache the
* register values for later use.
*/
for (i = 1; i < 8; i++) {
int j;
/*
* initialize port_config with "0xAA", which means
* input with internal pullup disabled. This is needed
* to avoid writing zeros (in the inner for loop),
* which is not allowed according to the datasheet.
*/
ts->port_config[i] = 0xAA;
for (j = 0; j < 4; j++) {
int offset = (i - 1) * 4 + j;
ret = max7301_direction_input(&ts->chip, offset);
if (ret)
goto exit_destroy;
}
}
ret = gpiochip_add_data(&ts->chip, ts);
if (!ret)
return ret;
exit_destroy:
mutex_destroy(&ts->lock);
return ret;
}
EXPORT_SYMBOL_GPL(__max730x_probe);
void __max730x_remove(struct device *dev)
{
struct max7301 *ts = dev_get_drvdata(dev);
/* Power down the chip and disable IRQ output */
ts->write(dev, 0x04, 0x00);
gpiochip_remove(&ts->chip);
mutex_destroy(&ts->lock);
}
EXPORT_SYMBOL_GPL(__max730x_remove);
MODULE_AUTHOR("Juergen Beisert, Wolfram Sang");
MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("MAX730x GPIO-Expanders, generic parts");