// SPDX-License-Identifier: GPL-2.0-or-later
/*
* GPIO Testing Device Driver
*
* Copyright (C) 2014 Kamlakant Patel <[email protected]>
* Copyright (C) 2015-2016 Bamvor Jian Zhang <[email protected]>
* Copyright (C) 2017 Bartosz Golaszewski <[email protected]>
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/cleanup.h>
#include <linux/debugfs.h>
#include <linux/device.h>
#include <linux/gpio/driver.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/irq_sim.h>
#include <linux/irqdomain.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/string_helpers.h>
#include <linux/uaccess.h>
#define GPIO_MOCKUP_MAX_GC 10
/*
* We're storing two values per chip: the GPIO base and the number
* of GPIO lines.
*/
#define GPIO_MOCKUP_MAX_RANGES (GPIO_MOCKUP_MAX_GC * 2)
/* Maximum of four properties + the sentinel. */
#define GPIO_MOCKUP_MAX_PROP 5
/*
* struct gpio_pin_status - structure describing a GPIO status
* @dir: Configures direction of gpio as "in" or "out"
* @value: Configures status of the gpio as 0(low) or 1(high)
* @pull: Configures the current pull of the GPIO as 0 (pull-down) or
* 1 (pull-up)
* @requested: Request status of this GPIO
*/
struct gpio_mockup_line_status {
int dir;
int value;
int pull;
bool requested;
};
struct gpio_mockup_chip {
struct gpio_chip gc;
struct gpio_mockup_line_status *lines;
struct irq_domain *irq_sim_domain;
struct dentry *dbg_dir;
struct mutex lock;
};
struct gpio_mockup_dbgfs_private {
struct gpio_mockup_chip *chip;
unsigned int offset;
};
static int gpio_mockup_ranges[GPIO_MOCKUP_MAX_RANGES];
static int gpio_mockup_num_ranges;
module_param_array(gpio_mockup_ranges, int, &gpio_mockup_num_ranges, 0400);
static bool gpio_mockup_named_lines;
module_param_named(gpio_mockup_named_lines,
gpio_mockup_named_lines, bool, 0400);
static struct dentry *gpio_mockup_dbg_dir;
static int gpio_mockup_range_base(unsigned int index)
{
return gpio_mockup_ranges[index * 2];
}
static int gpio_mockup_range_ngpio(unsigned int index)
{
return gpio_mockup_ranges[index * 2 + 1];
}
static int __gpio_mockup_get(struct gpio_mockup_chip *chip,
unsigned int offset)
{
return chip->lines[offset].value;
}
static int gpio_mockup_get(struct gpio_chip *gc, unsigned int offset)
{
struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
int val;
scoped_guard(mutex, &chip->lock)
val = __gpio_mockup_get(chip, offset);
return val;
}
static int gpio_mockup_get_multiple(struct gpio_chip *gc,
unsigned long *mask, unsigned long *bits)
{
struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
unsigned int bit, val;
scoped_guard(mutex, &chip->lock) {
for_each_set_bit(bit, mask, gc->ngpio) {
val = __gpio_mockup_get(chip, bit);
__assign_bit(bit, bits, val);
}
}
return 0;
}
static void __gpio_mockup_set(struct gpio_mockup_chip *chip,
unsigned int offset, int value)
{
chip->lines[offset].value = !!value;
}
static void gpio_mockup_set(struct gpio_chip *gc,
unsigned int offset, int value)
{
struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
guard(mutex)(&chip->lock);
__gpio_mockup_set(chip, offset, value);
}
static void gpio_mockup_set_multiple(struct gpio_chip *gc,
unsigned long *mask, unsigned long *bits)
{
struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
unsigned int bit;
guard(mutex)(&chip->lock);
for_each_set_bit(bit, mask, gc->ngpio)
__gpio_mockup_set(chip, bit, test_bit(bit, bits));
}
static int gpio_mockup_apply_pull(struct gpio_mockup_chip *chip,
unsigned int offset, int value)
{
struct gpio_mockup_line_status *line = &chip->lines[offset];
int curr, irq, irq_type, ret = 0;
guard(mutex)(&chip->lock);
if (line->requested && line->dir == GPIO_LINE_DIRECTION_IN) {
curr = __gpio_mockup_get(chip, offset);
if (curr == value)
goto out;
irq = irq_find_mapping(chip->irq_sim_domain, offset);
if (!irq)
/*
* This is fine - it just means, nobody is listening
* for interrupts on this line, otherwise
* irq_create_mapping() would have been called from
* the to_irq() callback.
*/
goto set_value;
irq_type = irq_get_trigger_type(irq);
if ((value == 1 && (irq_type & IRQ_TYPE_EDGE_RISING)) ||
(value == 0 && (irq_type & IRQ_TYPE_EDGE_FALLING))) {
ret = irq_set_irqchip_state(irq, IRQCHIP_STATE_PENDING,
true);
if (ret)
goto out;
}
}
set_value:
/* Change the value unless we're actively driving the line. */
if (!line->requested || line->dir == GPIO_LINE_DIRECTION_IN)
__gpio_mockup_set(chip, offset, value);
out:
chip->lines[offset].pull = value;
return ret;
}
static int gpio_mockup_set_config(struct gpio_chip *gc,
unsigned int offset, unsigned long config)
{
struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
switch (pinconf_to_config_param(config)) {
case PIN_CONFIG_BIAS_PULL_UP:
return gpio_mockup_apply_pull(chip, offset, 1);
case PIN_CONFIG_BIAS_PULL_DOWN:
return gpio_mockup_apply_pull(chip, offset, 0);
default:
break;
}
return -ENOTSUPP;
}
static int gpio_mockup_dirout(struct gpio_chip *gc,
unsigned int offset, int value)
{
struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
scoped_guard(mutex, &chip->lock) {
chip->lines[offset].dir = GPIO_LINE_DIRECTION_OUT;
__gpio_mockup_set(chip, offset, value);
}
return 0;
}
static int gpio_mockup_dirin(struct gpio_chip *gc, unsigned int offset)
{
struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
scoped_guard(mutex, &chip->lock)
chip->lines[offset].dir = GPIO_LINE_DIRECTION_IN;
return 0;
}
static int gpio_mockup_get_direction(struct gpio_chip *gc, unsigned int offset)
{
struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
int direction;
scoped_guard(mutex, &chip->lock)
direction = chip->lines[offset].dir;
return direction;
}
static int gpio_mockup_to_irq(struct gpio_chip *gc, unsigned int offset)
{
struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
return irq_create_mapping(chip->irq_sim_domain, offset);
}
static int gpio_mockup_request(struct gpio_chip *gc, unsigned int offset)
{
struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
scoped_guard(mutex, &chip->lock)
chip->lines[offset].requested = true;
return 0;
}
static void gpio_mockup_free(struct gpio_chip *gc, unsigned int offset)
{
struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
guard(mutex)(&chip->lock);
chip->lines[offset].requested = false;
__gpio_mockup_set(chip, offset, chip->lines[offset].pull);
}
static ssize_t gpio_mockup_debugfs_read(struct file *file,
char __user *usr_buf,
size_t size, loff_t *ppos)
{
struct gpio_mockup_dbgfs_private *priv;
struct gpio_mockup_chip *chip;
struct seq_file *sfile;
struct gpio_chip *gc;
int val, cnt;
char buf[3];
if (*ppos != 0)
return 0;
sfile = file->private_data;
priv = sfile->private;
chip = priv->chip;
gc = &chip->gc;
val = gpio_mockup_get(gc, priv->offset);
cnt = snprintf(buf, sizeof(buf), "%d\n", val);
return simple_read_from_buffer(usr_buf, size, ppos, buf, cnt);
}
static ssize_t gpio_mockup_debugfs_write(struct file *file,
const char __user *usr_buf,
size_t size, loff_t *ppos)
{
struct gpio_mockup_dbgfs_private *priv;
int rv, val;
struct seq_file *sfile;
if (*ppos != 0)
return -EINVAL;
rv = kstrtoint_from_user(usr_buf, size, 0, &val);
if (rv)
return rv;
if (val != 0 && val != 1)
return -EINVAL;
sfile = file->private_data;
priv = sfile->private;
rv = gpio_mockup_apply_pull(priv->chip, priv->offset, val);
if (rv)
return rv;
return size;
}
static int gpio_mockup_debugfs_open(struct inode *inode, struct file *file)
{
return single_open(file, NULL, inode->i_private);
}
/*
* Each mockup chip is represented by a directory named after the chip's device
* name under /sys/kernel/debug/gpio-mockup/. Each line is represented by
* a file using the line's offset as the name under the chip's directory.
*
* Reading from the line's file yields the current *value*, writing to the
* line's file changes the current *pull*. Default pull for mockup lines is
* down.
*
* Examples:
* - when a line pulled down is requested in output mode and driven high, its
* value will return to 0 once it's released
* - when the line is requested in output mode and driven high, writing 0 to
* the corresponding debugfs file will change the pull to down but the
* reported value will still be 1 until the line is released
* - line requested in input mode always reports the same value as its pull
* configuration
* - when the line is requested in input mode and monitored for events, writing
* the same value to the debugfs file will be a noop, while writing the
* opposite value will generate a dummy interrupt with an appropriate edge
*/
static const struct file_operations gpio_mockup_debugfs_ops = {
.owner = THIS_MODULE,
.open = gpio_mockup_debugfs_open,
.read = gpio_mockup_debugfs_read,
.write = gpio_mockup_debugfs_write,
.release = single_release,
};
static void gpio_mockup_debugfs_setup(struct device *dev,
struct gpio_mockup_chip *chip)
{
struct gpio_mockup_dbgfs_private *priv;
struct gpio_chip *gc;
const char *devname;
char *name;
int i;
gc = &chip->gc;
/*
* There can only be a single GPIO device per platform device in
* gpio-mockup so using device_find_any_child() is OK.
*/
struct device *child __free(put_device) = device_find_any_child(dev);
if (!child)
return;
devname = dev_name(child);
chip->dbg_dir = debugfs_create_dir(devname, gpio_mockup_dbg_dir);
for (i = 0; i < gc->ngpio; i++) {
name = devm_kasprintf(dev, GFP_KERNEL, "%d", i);
if (!name)
return;
priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
if (!priv)
return;
priv->chip = chip;
priv->offset = i;
debugfs_create_file(name, 0600, chip->dbg_dir, priv,
&gpio_mockup_debugfs_ops);
}
}
static void gpio_mockup_debugfs_cleanup(void *data)
{
struct gpio_mockup_chip *chip = data;
debugfs_remove_recursive(chip->dbg_dir);
}
static void gpio_mockup_dispose_mappings(void *data)
{
struct gpio_mockup_chip *chip = data;
struct gpio_chip *gc = &chip->gc;
int i, irq;
for (i = 0; i < gc->ngpio; i++) {
irq = irq_find_mapping(chip->irq_sim_domain, i);
if (irq)
irq_dispose_mapping(irq);
}
}
static int gpio_mockup_probe(struct platform_device *pdev)
{
struct gpio_mockup_chip *chip;
struct gpio_chip *gc;
struct device *dev;
const char *name;
int rv, base, i;
u16 ngpio;
dev = &pdev->dev;
rv = device_property_read_u32(dev, "gpio-base", &base);
if (rv)
base = -1;
rv = device_property_read_u16(dev, "nr-gpios", &ngpio);
if (rv)
return rv;
rv = device_property_read_string(dev, "chip-label", &name);
if (rv)
name = dev_name(dev);
chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
if (!chip)
return -ENOMEM;
mutex_init(&chip->lock);
gc = &chip->gc;
gc->base = base;
gc->ngpio = ngpio;
gc->label = name;
gc->owner = THIS_MODULE;
gc->parent = dev;
gc->get = gpio_mockup_get;
gc->set = gpio_mockup_set;
gc->get_multiple = gpio_mockup_get_multiple;
gc->set_multiple = gpio_mockup_set_multiple;
gc->direction_output = gpio_mockup_dirout;
gc->direction_input = gpio_mockup_dirin;
gc->get_direction = gpio_mockup_get_direction;
gc->set_config = gpio_mockup_set_config;
gc->to_irq = gpio_mockup_to_irq;
gc->request = gpio_mockup_request;
gc->free = gpio_mockup_free;
chip->lines = devm_kcalloc(dev, gc->ngpio,
sizeof(*chip->lines), GFP_KERNEL);
if (!chip->lines)
return -ENOMEM;
for (i = 0; i < gc->ngpio; i++)
chip->lines[i].dir = GPIO_LINE_DIRECTION_IN;
chip->irq_sim_domain = devm_irq_domain_create_sim(dev, NULL,
gc->ngpio);
if (IS_ERR(chip->irq_sim_domain))
return PTR_ERR(chip->irq_sim_domain);
rv = devm_add_action_or_reset(dev, gpio_mockup_dispose_mappings, chip);
if (rv)
return rv;
rv = devm_gpiochip_add_data(dev, &chip->gc, chip);
if (rv)
return rv;
gpio_mockup_debugfs_setup(dev, chip);
return devm_add_action_or_reset(dev, gpio_mockup_debugfs_cleanup, chip);
}
static const struct of_device_id gpio_mockup_of_match[] = {
{ .compatible = "gpio-mockup", },
{},
};
MODULE_DEVICE_TABLE(of, gpio_mockup_of_match);
static struct platform_driver gpio_mockup_driver = {
.driver = {
.name = "gpio-mockup",
.of_match_table = gpio_mockup_of_match,
},
.probe = gpio_mockup_probe,
};
static struct platform_device *gpio_mockup_pdevs[GPIO_MOCKUP_MAX_GC];
static void gpio_mockup_unregister_pdevs(void)
{
struct platform_device *pdev;
struct fwnode_handle *fwnode;
int i;
for (i = 0; i < GPIO_MOCKUP_MAX_GC; i++) {
pdev = gpio_mockup_pdevs[i];
if (!pdev)
continue;
fwnode = dev_fwnode(&pdev->dev);
platform_device_unregister(pdev);
fwnode_remove_software_node(fwnode);
}
}
static int __init gpio_mockup_register_chip(int idx)
{
struct property_entry properties[GPIO_MOCKUP_MAX_PROP];
struct platform_device_info pdevinfo;
struct platform_device *pdev;
struct fwnode_handle *fwnode;
char **line_names = NULL;
char chip_label[32];
int prop = 0, base;
u16 ngpio;
memset(properties, 0, sizeof(properties));
memset(&pdevinfo, 0, sizeof(pdevinfo));
snprintf(chip_label, sizeof(chip_label), "gpio-mockup-%c", idx + 'A');
properties[prop++] = PROPERTY_ENTRY_STRING("chip-label", chip_label);
base = gpio_mockup_range_base(idx);
if (base >= 0)
properties[prop++] = PROPERTY_ENTRY_U32("gpio-base", base);
ngpio = base < 0 ? gpio_mockup_range_ngpio(idx)
: gpio_mockup_range_ngpio(idx) - base;
properties[prop++] = PROPERTY_ENTRY_U16("nr-gpios", ngpio);
if (gpio_mockup_named_lines) {
line_names = kasprintf_strarray(GFP_KERNEL, chip_label, ngpio);
if (!line_names)
return -ENOMEM;
properties[prop++] = PROPERTY_ENTRY_STRING_ARRAY_LEN(
"gpio-line-names", line_names, ngpio);
}
fwnode = fwnode_create_software_node(properties, NULL);
if (IS_ERR(fwnode)) {
kfree_strarray(line_names, ngpio);
return PTR_ERR(fwnode);
}
pdevinfo.name = "gpio-mockup";
pdevinfo.id = idx;
pdevinfo.fwnode = fwnode;
pdev = platform_device_register_full(&pdevinfo);
kfree_strarray(line_names, ngpio);
if (IS_ERR(pdev)) {
fwnode_remove_software_node(fwnode);
pr_err("error registering device");
return PTR_ERR(pdev);
}
gpio_mockup_pdevs[idx] = pdev;
return 0;
}
static int __init gpio_mockup_init(void)
{
int i, num_chips, err;
if ((gpio_mockup_num_ranges % 2) ||
(gpio_mockup_num_ranges > GPIO_MOCKUP_MAX_RANGES))
return -EINVAL;
/* Each chip is described by two values. */
num_chips = gpio_mockup_num_ranges / 2;
/*
* The second value in the <base GPIO - number of GPIOS> pair must
* always be greater than 0.
*/
for (i = 0; i < num_chips; i++) {
if (gpio_mockup_range_ngpio(i) < 0)
return -EINVAL;
}
gpio_mockup_dbg_dir = debugfs_create_dir("gpio-mockup", NULL);
err = platform_driver_register(&gpio_mockup_driver);
if (err) {
pr_err("error registering platform driver\n");
debugfs_remove_recursive(gpio_mockup_dbg_dir);
return err;
}
for (i = 0; i < num_chips; i++) {
err = gpio_mockup_register_chip(i);
if (err) {
platform_driver_unregister(&gpio_mockup_driver);
gpio_mockup_unregister_pdevs();
debugfs_remove_recursive(gpio_mockup_dbg_dir);
return err;
}
}
return 0;
}
static void __exit gpio_mockup_exit(void)
{
gpio_mockup_unregister_pdevs();
debugfs_remove_recursive(gpio_mockup_dbg_dir);
platform_driver_unregister(&gpio_mockup_driver);
}
module_init(gpio_mockup_init);
module_exit(gpio_mockup_exit);
MODULE_AUTHOR("Kamlakant Patel <[email protected]>");
MODULE_AUTHOR("Bamvor Jian Zhang <[email protected]>");
MODULE_AUTHOR("Bartosz Golaszewski <[email protected]>");
MODULE_DESCRIPTION("GPIO Testing driver");
MODULE_LICENSE("GPL v2");
Codebase Browser
linux