mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-24 23:34:40 +07:00
d8f388d8dc
This adds a simple sysfs interface for GPIOs.
/sys/class/gpio
/export ... asks the kernel to export a GPIO to userspace
/unexport ... to return a GPIO to the kernel
/gpioN ... for each exported GPIO #N
/value ... always readable, writes fail for input GPIOs
/direction ... r/w as: in, out (default low); write high, low
/gpiochipN ... for each gpiochip; #N is its first GPIO
/base ... (r/o) same as N
/label ... (r/o) descriptive, not necessarily unique
/ngpio ... (r/o) number of GPIOs; numbered N .. N+(ngpio - 1)
GPIOs claimed by kernel code may be exported by its owner using a new
gpio_export() call, which should be most useful for driver debugging.
Such exports may optionally be done without a "direction" attribute.
Userspace may ask to take over a GPIO by writing to a sysfs control file,
helping to cope with incomplete board support or other "one-off"
requirements that don't merit full kernel support:
echo 23 > /sys/class/gpio/export
... will gpio_request(23, "sysfs") and gpio_export(23);
use /sys/class/gpio/gpio-23/direction to (re)configure it,
when that GPIO can be used as both input and output.
echo 23 > /sys/class/gpio/unexport
... will gpio_free(23), when it was exported as above
The extra D-space footprint is a few hundred bytes, except for the sysfs
resources associated with each exported GPIO. The additional I-space
footprint is about two thirds of the current size of gpiolib (!). Since
no /dev node creation is involved, no "udev" support is needed.
Related changes:
* This adds a device pointer to "struct gpio_chip". When GPIO
providers initialize that, sysfs gpio class devices become children of
that device instead of being "virtual" devices.
* The (few) gpio_chip providers which have such a device node have
been updated.
* Some gpio_chip drivers also needed to update their module "owner"
field ... for which missing kerneldoc was added.
* Some gpio_chips don't support input GPIOs. Those GPIOs are now
flagged appropriately when the chip is registered.
Based on previous patches, and discussion both on and off LKML.
A Documentation/ABI/testing/sysfs-gpio update is ready to submit once this
merges to mainline.
[akpm@linux-foundation.org: a few maintenance build fixes]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Cc: Greg KH <greg@kroah.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
303 lines
6.6 KiB
C
303 lines
6.6 KiB
C
/*
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* pca953x.c - 4/8/16 bit I/O ports
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*
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* Copyright (C) 2005 Ben Gardner <bgardner@wabtec.com>
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* Copyright (C) 2007 Marvell International Ltd.
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*
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* Derived from drivers/i2c/chips/pca9539.c
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; version 2 of the License.
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*/
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/i2c.h>
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#include <linux/i2c/pca953x.h>
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#include <asm/gpio.h>
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#define PCA953X_INPUT 0
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#define PCA953X_OUTPUT 1
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#define PCA953X_INVERT 2
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#define PCA953X_DIRECTION 3
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static const struct i2c_device_id pca953x_id[] = {
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{ "pca9534", 8, },
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{ "pca9535", 16, },
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{ "pca9536", 4, },
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{ "pca9537", 4, },
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{ "pca9538", 8, },
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{ "pca9539", 16, },
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{ "pca9554", 8, },
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{ "pca9555", 16, },
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{ "pca9557", 8, },
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{ "max7310", 8, },
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{ }
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};
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MODULE_DEVICE_TABLE(i2c, pca953x_id);
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struct pca953x_chip {
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unsigned gpio_start;
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uint16_t reg_output;
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uint16_t reg_direction;
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struct i2c_client *client;
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struct gpio_chip gpio_chip;
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};
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/* NOTE: we can't currently rely on fault codes to come from SMBus
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* calls, so we map all errors to EIO here and return zero otherwise.
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*/
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static int pca953x_write_reg(struct pca953x_chip *chip, int reg, uint16_t val)
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{
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int ret;
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if (chip->gpio_chip.ngpio <= 8)
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ret = i2c_smbus_write_byte_data(chip->client, reg, val);
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else
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ret = i2c_smbus_write_word_data(chip->client, reg << 1, val);
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if (ret < 0) {
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dev_err(&chip->client->dev, "failed writing register\n");
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return -EIO;
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}
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return 0;
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}
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static int pca953x_read_reg(struct pca953x_chip *chip, int reg, uint16_t *val)
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{
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int ret;
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if (chip->gpio_chip.ngpio <= 8)
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ret = i2c_smbus_read_byte_data(chip->client, reg);
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else
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ret = i2c_smbus_read_word_data(chip->client, reg << 1);
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if (ret < 0) {
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dev_err(&chip->client->dev, "failed reading register\n");
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return -EIO;
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}
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*val = (uint16_t)ret;
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return 0;
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}
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static int pca953x_gpio_direction_input(struct gpio_chip *gc, unsigned off)
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{
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struct pca953x_chip *chip;
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uint16_t reg_val;
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int ret;
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chip = container_of(gc, struct pca953x_chip, gpio_chip);
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reg_val = chip->reg_direction | (1u << off);
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ret = pca953x_write_reg(chip, PCA953X_DIRECTION, reg_val);
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if (ret)
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return ret;
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chip->reg_direction = reg_val;
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return 0;
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}
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static int pca953x_gpio_direction_output(struct gpio_chip *gc,
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unsigned off, int val)
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{
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struct pca953x_chip *chip;
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uint16_t reg_val;
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int ret;
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chip = container_of(gc, struct pca953x_chip, gpio_chip);
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/* set output level */
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if (val)
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reg_val = chip->reg_output | (1u << off);
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else
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reg_val = chip->reg_output & ~(1u << off);
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ret = pca953x_write_reg(chip, PCA953X_OUTPUT, reg_val);
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if (ret)
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return ret;
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chip->reg_output = reg_val;
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/* then direction */
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reg_val = chip->reg_direction & ~(1u << off);
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ret = pca953x_write_reg(chip, PCA953X_DIRECTION, reg_val);
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if (ret)
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return ret;
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chip->reg_direction = reg_val;
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return 0;
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}
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static int pca953x_gpio_get_value(struct gpio_chip *gc, unsigned off)
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{
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struct pca953x_chip *chip;
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uint16_t reg_val;
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int ret;
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chip = container_of(gc, struct pca953x_chip, gpio_chip);
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ret = pca953x_read_reg(chip, PCA953X_INPUT, ®_val);
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if (ret < 0) {
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/* NOTE: diagnostic already emitted; that's all we should
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* do unless gpio_*_value_cansleep() calls become different
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* from their nonsleeping siblings (and report faults).
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*/
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return 0;
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}
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return (reg_val & (1u << off)) ? 1 : 0;
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}
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static void pca953x_gpio_set_value(struct gpio_chip *gc, unsigned off, int val)
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{
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struct pca953x_chip *chip;
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uint16_t reg_val;
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int ret;
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chip = container_of(gc, struct pca953x_chip, gpio_chip);
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if (val)
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reg_val = chip->reg_output | (1u << off);
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else
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reg_val = chip->reg_output & ~(1u << off);
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ret = pca953x_write_reg(chip, PCA953X_OUTPUT, reg_val);
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if (ret)
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return;
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chip->reg_output = reg_val;
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}
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static void pca953x_setup_gpio(struct pca953x_chip *chip, int gpios)
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{
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struct gpio_chip *gc;
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gc = &chip->gpio_chip;
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gc->direction_input = pca953x_gpio_direction_input;
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gc->direction_output = pca953x_gpio_direction_output;
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gc->get = pca953x_gpio_get_value;
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gc->set = pca953x_gpio_set_value;
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gc->can_sleep = 1;
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gc->base = chip->gpio_start;
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gc->ngpio = gpios;
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gc->label = chip->client->name;
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gc->dev = &chip->client->dev;
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gc->owner = THIS_MODULE;
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}
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static int __devinit pca953x_probe(struct i2c_client *client,
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const struct i2c_device_id *id)
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{
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struct pca953x_platform_data *pdata;
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struct pca953x_chip *chip;
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int ret;
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pdata = client->dev.platform_data;
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if (pdata == NULL)
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return -ENODEV;
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chip = kzalloc(sizeof(struct pca953x_chip), GFP_KERNEL);
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if (chip == NULL)
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return -ENOMEM;
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chip->client = client;
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chip->gpio_start = pdata->gpio_base;
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/* initialize cached registers from their original values.
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* we can't share this chip with another i2c master.
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*/
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pca953x_setup_gpio(chip, id->driver_data);
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ret = pca953x_read_reg(chip, PCA953X_OUTPUT, &chip->reg_output);
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if (ret)
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goto out_failed;
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ret = pca953x_read_reg(chip, PCA953X_DIRECTION, &chip->reg_direction);
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if (ret)
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goto out_failed;
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/* set platform specific polarity inversion */
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ret = pca953x_write_reg(chip, PCA953X_INVERT, pdata->invert);
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if (ret)
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goto out_failed;
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ret = gpiochip_add(&chip->gpio_chip);
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if (ret)
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goto out_failed;
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if (pdata->setup) {
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ret = pdata->setup(client, chip->gpio_chip.base,
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chip->gpio_chip.ngpio, pdata->context);
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if (ret < 0)
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dev_warn(&client->dev, "setup failed, %d\n", ret);
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}
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i2c_set_clientdata(client, chip);
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return 0;
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out_failed:
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kfree(chip);
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return ret;
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}
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static int pca953x_remove(struct i2c_client *client)
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{
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struct pca953x_platform_data *pdata = client->dev.platform_data;
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struct pca953x_chip *chip = i2c_get_clientdata(client);
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int ret = 0;
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if (pdata->teardown) {
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ret = pdata->teardown(client, chip->gpio_chip.base,
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chip->gpio_chip.ngpio, pdata->context);
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if (ret < 0) {
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dev_err(&client->dev, "%s failed, %d\n",
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"teardown", ret);
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return ret;
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}
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}
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ret = gpiochip_remove(&chip->gpio_chip);
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if (ret) {
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dev_err(&client->dev, "%s failed, %d\n",
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"gpiochip_remove()", ret);
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return ret;
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}
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kfree(chip);
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return 0;
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}
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static struct i2c_driver pca953x_driver = {
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.driver = {
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.name = "pca953x",
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},
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.probe = pca953x_probe,
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.remove = pca953x_remove,
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.id_table = pca953x_id,
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};
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static int __init pca953x_init(void)
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{
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return i2c_add_driver(&pca953x_driver);
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}
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module_init(pca953x_init);
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static void __exit pca953x_exit(void)
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{
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i2c_del_driver(&pca953x_driver);
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}
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module_exit(pca953x_exit);
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MODULE_AUTHOR("eric miao <eric.miao@marvell.com>");
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MODULE_DESCRIPTION("GPIO expander driver for PCA953x");
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MODULE_LICENSE("GPL");
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