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linux/drivers/gpio/gpio-it87.c
Bartosz Golaszewski ef877a1590 gpio: it87: use new line value setter callbacks 
struct gpio_chip now has callbacks for setting line values that return
an integer, allowing to indicate failures. Convert the driver to using
them.

Reviewed-by: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20250423-gpiochip-set-rv-gpio-part2-v1-5-b22245cde81a@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2025-04-30 10:27:58 +02:00

415 lines
9 KiB
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// SPDX-License-Identifier: GPL-2.0-only
/*
* GPIO interface for IT87xx Super I/O chips
*
* Author: Diego Elio Pettenò <flameeyes@flameeyes.eu>
* Copyright (c) 2017 Google, Inc.
*
* Based on it87_wdt.c by Oliver Schuster
* gpio-it8761e.c by Denis Turischev
* gpio-stmpe.c by Rabin Vincent
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/io.h>
#include <linux/errno.h>
#include <linux/ioport.h>
#include <linux/slab.h>
#include <linux/gpio/driver.h>
/* Chip Id numbers */
#define NO_DEV_ID 0xffff
#define IT8613_ID 0x8613
#define IT8620_ID 0x8620
#define IT8628_ID 0x8628
#define IT8718_ID 0x8718
#define IT8728_ID 0x8728
#define IT8732_ID 0x8732
#define IT8761_ID 0x8761
#define IT8772_ID 0x8772
#define IT8786_ID 0x8786
/* IO Ports */
#define REG 0x2e
#define VAL 0x2f
/* Logical device Numbers LDN */
#define GPIO 0x07
/* Configuration Registers and Functions */
#define LDNREG 0x07
#define CHIPID 0x20
#define CHIPREV 0x22
/**
* struct it87_gpio - it87-specific GPIO chip
* @chip: the underlying gpio_chip structure
* @lock: a lock to avoid races between operations
* @io_base: base address for gpio ports
* @io_size: size of the port rage starting from io_base.
* @output_base: Super I/O register address for Output Enable register
* @simple_base: Super I/O 'Simple I/O' Enable register
* @simple_size: Super IO 'Simple I/O' Enable register size; this is
* required because IT87xx chips might only provide Simple I/O
* switches on a subset of lines, whereas the others keep the
* same status all time.
*/
struct it87_gpio {
struct gpio_chip chip;
spinlock_t lock;
u16 io_base;
u16 io_size;
u8 output_base;
u8 simple_base;
u8 simple_size;
};
static struct it87_gpio it87_gpio_chip = {
.lock = __SPIN_LOCK_UNLOCKED(it87_gpio_chip.lock),
};
/* Superio chip access functions; copied from wdt_it87 */
static inline int superio_enter(void)
{
/*
* Try to reserve REG and REG + 1 for exclusive access.
*/
if (!request_muxed_region(REG, 2, KBUILD_MODNAME))
return -EBUSY;
outb(0x87, REG);
outb(0x01, REG);
outb(0x55, REG);
outb(0x55, REG);
return 0;
}
static inline void superio_exit(void)
{
outb(0x02, REG);
outb(0x02, VAL);
release_region(REG, 2);
}
static inline void superio_select(int ldn)
{
outb(LDNREG, REG);
outb(ldn, VAL);
}
static inline int superio_inb(int reg)
{
outb(reg, REG);
return inb(VAL);
}
static inline void superio_outb(int val, int reg)
{
outb(reg, REG);
outb(val, VAL);
}
static inline int superio_inw(int reg)
{
int val;
outb(reg++, REG);
val = inb(VAL) << 8;
outb(reg, REG);
val |= inb(VAL);
return val;
}
static inline void superio_set_mask(int mask, int reg)
{
u8 curr_val = superio_inb(reg);
u8 new_val = curr_val | mask;
if (curr_val != new_val)
superio_outb(new_val, reg);
}
static inline void superio_clear_mask(int mask, int reg)
{
u8 curr_val = superio_inb(reg);
u8 new_val = curr_val & ~mask;
if (curr_val != new_val)
superio_outb(new_val, reg);
}
static int it87_gpio_request(struct gpio_chip *chip, unsigned gpio_num)
{
u8 mask, group;
int rc = 0;
struct it87_gpio *it87_gpio = gpiochip_get_data(chip);
mask = 1 << (gpio_num % 8);
group = (gpio_num / 8);
spin_lock(&it87_gpio->lock);
rc = superio_enter();
if (rc)
goto exit;
/* not all the IT87xx chips support Simple I/O and not all of
* them allow all the lines to be set/unset to Simple I/O.
*/
if (group < it87_gpio->simple_size)
superio_set_mask(mask, group + it87_gpio->simple_base);
/* clear output enable, setting the pin to input, as all the
* newly-exported GPIO interfaces are set to input.
*/
superio_clear_mask(mask, group + it87_gpio->output_base);
superio_exit();
exit:
spin_unlock(&it87_gpio->lock);
return rc;
}
static int it87_gpio_get(struct gpio_chip *chip, unsigned gpio_num)
{
u16 reg;
u8 mask;
struct it87_gpio *it87_gpio = gpiochip_get_data(chip);
mask = 1 << (gpio_num % 8);
reg = (gpio_num / 8) + it87_gpio->io_base;
return !!(inb(reg) & mask);
}
static int it87_gpio_direction_in(struct gpio_chip *chip, unsigned gpio_num)
{
u8 mask, group;
int rc = 0;
struct it87_gpio *it87_gpio = gpiochip_get_data(chip);
mask = 1 << (gpio_num % 8);
group = (gpio_num / 8);
spin_lock(&it87_gpio->lock);
rc = superio_enter();
if (rc)
goto exit;
/* clear the output enable bit */
superio_clear_mask(mask, group + it87_gpio->output_base);
superio_exit();
exit:
spin_unlock(&it87_gpio->lock);
return rc;
}
static int it87_gpio_set(struct gpio_chip *chip, unsigned int gpio_num, int val)
{
u8 mask, curr_vals;
u16 reg;
struct it87_gpio *it87_gpio = gpiochip_get_data(chip);
mask = 1 << (gpio_num % 8);
reg = (gpio_num / 8) + it87_gpio->io_base;
curr_vals = inb(reg);
if (val)
outb(curr_vals | mask, reg);
else
outb(curr_vals & ~mask, reg);
return 0;
}
static int it87_gpio_direction_out(struct gpio_chip *chip,
unsigned gpio_num, int val)
{
u8 mask, group;
int rc = 0;
struct it87_gpio *it87_gpio = gpiochip_get_data(chip);
mask = 1 << (gpio_num % 8);
group = (gpio_num / 8);
spin_lock(&it87_gpio->lock);
rc = superio_enter();
if (rc)
goto exit;
/* set the output enable bit */
superio_set_mask(mask, group + it87_gpio->output_base);
rc = it87_gpio_set(chip, gpio_num, val);
if (rc)
goto exit;
superio_exit();
exit:
spin_unlock(&it87_gpio->lock);
return rc;
}
static const struct gpio_chip it87_template_chip = {
.label = KBUILD_MODNAME,
.owner = THIS_MODULE,
.request = it87_gpio_request,
.get = it87_gpio_get,
.direction_input = it87_gpio_direction_in,
.set_rv = it87_gpio_set,
.direction_output = it87_gpio_direction_out,
.base = -1
};
static int __init it87_gpio_init(void)
{
int rc = 0, i;
u16 chip_type;
u8 chip_rev, gpio_ba_reg;
char *labels, **labels_table;
struct it87_gpio *it87_gpio = &it87_gpio_chip;
rc = superio_enter();
if (rc)
return rc;
chip_type = superio_inw(CHIPID);
chip_rev = superio_inb(CHIPREV) & 0x0f;
superio_exit();
it87_gpio->chip = it87_template_chip;
switch (chip_type) {
case IT8613_ID:
gpio_ba_reg = 0x62;
it87_gpio->io_size = 8; /* it8613 only needs 6, use 8 for alignment */
it87_gpio->output_base = 0xc8;
it87_gpio->simple_base = 0xc0;
it87_gpio->simple_size = 6;
it87_gpio->chip.ngpio = 64; /* has 48, use 64 for convenient calc */
break;
case IT8620_ID:
case IT8628_ID:
gpio_ba_reg = 0x62;
it87_gpio->io_size = 11;
it87_gpio->output_base = 0xc8;
it87_gpio->simple_size = 0;
it87_gpio->chip.ngpio = 64;
break;
case IT8718_ID:
case IT8728_ID:
case IT8732_ID:
case IT8772_ID:
case IT8786_ID:
gpio_ba_reg = 0x62;
it87_gpio->io_size = 8;
it87_gpio->output_base = 0xc8;
it87_gpio->simple_base = 0xc0;
it87_gpio->simple_size = 5;
it87_gpio->chip.ngpio = 64;
break;
case IT8761_ID:
gpio_ba_reg = 0x60;
it87_gpio->io_size = 4;
it87_gpio->output_base = 0xf0;
it87_gpio->simple_size = 0;
it87_gpio->chip.ngpio = 16;
break;
case NO_DEV_ID:
pr_err("no device\n");
return -ENODEV;
default:
pr_err("Unknown Chip found, Chip %04x Revision %x\n",
chip_type, chip_rev);
return -ENODEV;
}
rc = superio_enter();
if (rc)
return rc;
superio_select(GPIO);
/* fetch GPIO base address */
it87_gpio->io_base = superio_inw(gpio_ba_reg);
superio_exit();
pr_info("Found Chip IT%04x rev %x. %u GPIO lines starting at %04xh\n",
chip_type, chip_rev, it87_gpio->chip.ngpio,
it87_gpio->io_base);
if (!request_region(it87_gpio->io_base, it87_gpio->io_size,
KBUILD_MODNAME))
return -EBUSY;
/* Set up aliases for the GPIO connection.
*
* ITE documentation for recent chips such as the IT8728F
* refers to the GPIO lines as GPxy, with a coordinates system
* where x is the GPIO group (starting from 1) and y is the
* bit within the group.
*
* By creating these aliases, we make it easier to understand
* to which GPIO pin we're referring to.
*/
labels = kcalloc(it87_gpio->chip.ngpio, sizeof("it87_gpXY"),
GFP_KERNEL);
labels_table = kcalloc(it87_gpio->chip.ngpio, sizeof(const char *),
GFP_KERNEL);
if (!labels || !labels_table) {
rc = -ENOMEM;
goto labels_free;
}
for (i = 0; i < it87_gpio->chip.ngpio; i++) {
char *label = &labels[i * sizeof("it87_gpXY")];
sprintf(label, "it87_gp%u%u", 1+(i/8), i%8);
labels_table[i] = label;
}
it87_gpio->chip.names = (const char *const*)labels_table;
rc = gpiochip_add_data(&it87_gpio->chip, it87_gpio);
if (rc)
goto labels_free;
return 0;
labels_free:
kfree(labels_table);
kfree(labels);
release_region(it87_gpio->io_base, it87_gpio->io_size);
return rc;
}
static void __exit it87_gpio_exit(void)
{
struct it87_gpio *it87_gpio = &it87_gpio_chip;
gpiochip_remove(&it87_gpio->chip);
release_region(it87_gpio->io_base, it87_gpio->io_size);
kfree(it87_gpio->chip.names[0]);
kfree(it87_gpio->chip.names);
}
module_init(it87_gpio_init);
module_exit(it87_gpio_exit);
MODULE_AUTHOR("Diego Elio Pettenò <flameeyes@flameeyes.eu>");
MODULE_DESCRIPTION("GPIO interface for IT87xx Super I/O chips");
MODULE_LICENSE("GPL");
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