linux/drivers/gpio/gpio-mockup.c
Bartosz Golaszewski 2a9e27408e gpio: mockup: rework debugfs interface
Modify the way the debugfs interface works in gpio-mockup. Introduce
the concept of dummy pull config which will keep the mockup lines in
known state. The pull values can be modified by writing to the debugfs
files corresponding to lines. Lines in input mode always report the
current pull value, lines in output mode change the line value but
it will revert back to the one specified by current pull when released.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
2019-02-19 17:42:29 +01:00

568 lines
14 KiB
C

// SPDX-License-Identifier: GPL-2.0+
/*
* GPIO Testing Device Driver
*
* Copyright (C) 2014 Kamlakant Patel <kamlakant.patel@broadcom.com>
* Copyright (C) 2015-2016 Bamvor Jian Zhang <bamv2005@gmail.com>
* Copyright (C) 2017 Bartosz Golaszewski <brgl@bgdev.pl>
*/
#include <linux/init.h>
#include <linux/module.h>
#include <linux/gpio/driver.h>
#include <linux/gpio/consumer.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/irq_sim.h>
#include <linux/debugfs.h>
#include <linux/uaccess.h>
#include <linux/property.h>
#include "gpiolib.h"
#define GPIO_MOCKUP_NAME "gpio-mockup"
#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 three properties + the sentinel. */
#define GPIO_MOCKUP_MAX_PROP 4
#define gpio_mockup_err(...) pr_err(GPIO_MOCKUP_NAME ": " __VA_ARGS__)
enum {
GPIO_MOCKUP_DIR_IN = 0,
GPIO_MOCKUP_DIR_OUT = 1,
};
/*
* struct gpio_pin_status - structure describing a GPIO status
* @dir: Configures direction of gpio as "in" or "out", 0=in, 1=out
* @value: Configures status of the gpio as 0(low) or 1(high)
*/
struct gpio_mockup_line_status {
int dir;
int value;
int pull;
};
struct gpio_mockup_chip {
struct gpio_chip gc;
struct gpio_mockup_line_status *lines;
struct irq_sim irqsim;
struct dentry *dbg_dir;
struct mutex lock;
};
struct gpio_mockup_dbgfs_private {
struct gpio_mockup_chip *chip;
struct gpio_desc *desc;
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;
mutex_lock(&chip->lock);
val = __gpio_mockup_get(chip, offset);
mutex_unlock(&chip->lock);
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;
mutex_lock(&chip->lock);
for_each_set_bit(bit, mask, gc->ngpio) {
val = __gpio_mockup_get(chip, bit);
__assign_bit(bit, bits, val);
}
mutex_unlock(&chip->lock);
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);
mutex_lock(&chip->lock);
__gpio_mockup_set(chip, offset, value);
mutex_unlock(&chip->lock);
}
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;
mutex_lock(&chip->lock);
for_each_set_bit(bit, mask, gc->ngpio)
__gpio_mockup_set(chip, bit, test_bit(bit, bits));
mutex_unlock(&chip->lock);
}
static int gpio_mockup_dirout(struct gpio_chip *gc,
unsigned int offset, int value)
{
struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
mutex_lock(&chip->lock);
chip->lines[offset].dir = GPIO_MOCKUP_DIR_OUT;
__gpio_mockup_set(chip, offset, value);
mutex_unlock(&chip->lock);
return 0;
}
static int gpio_mockup_dirin(struct gpio_chip *gc, unsigned int offset)
{
struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
mutex_lock(&chip->lock);
chip->lines[offset].dir = GPIO_MOCKUP_DIR_IN;
mutex_unlock(&chip->lock);
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;
mutex_lock(&chip->lock);
direction = !chip->lines[offset].dir;
mutex_unlock(&chip->lock);
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_sim_irqnum(&chip->irqsim, offset);
}
static void gpio_mockup_free(struct gpio_chip *gc, unsigned int offset)
{
struct gpio_mockup_chip *chip = gpiochip_get_data(gc);
__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;
char buf[3];
int val, rv;
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);
snprintf(buf, sizeof(buf), "%d\n", val);
rv = copy_to_user(usr_buf, buf, sizeof(buf));
if (rv)
return rv;
return sizeof(buf) - 1;
}
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, curr, irq, irq_type;
struct gpio_mockup_chip *chip;
struct seq_file *sfile;
struct gpio_desc *desc;
struct gpio_chip *gc;
struct irq_sim *sim;
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;
chip = priv->chip;
gc = &chip->gc;
desc = &gc->gpiodev->descs[priv->offset];
sim = &chip->irqsim;
mutex_lock(&chip->lock);
if (test_bit(FLAG_REQUESTED, &desc->flags) &&
!test_bit(FLAG_IS_OUT, &desc->flags)) {
curr = __gpio_mockup_get(chip, priv->offset);
if (curr == val)
goto out;
irq = irq_sim_irqnum(sim, priv->offset);
irq_type = irq_get_trigger_type(irq);
if ((val == 1 && (irq_type & IRQ_TYPE_EDGE_RISING)) ||
(val == 0 && (irq_type & IRQ_TYPE_EDGE_FALLING)))
irq_sim_fire(sim, priv->offset);
}
/* Change the value unless we're actively driving the line. */
if (!test_bit(FLAG_REQUESTED, &desc->flags) ||
!test_bit(FLAG_IS_OUT, &desc->flags))
__gpio_mockup_set(chip, priv->offset, val);
out:
chip->lines[priv->offset].pull = val;
mutex_unlock(&chip->lock);
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,
.llseek = no_llseek,
};
static void gpio_mockup_debugfs_setup(struct device *dev,
struct gpio_mockup_chip *chip)
{
struct gpio_mockup_dbgfs_private *priv;
struct dentry *evfile;
struct gpio_chip *gc;
const char *devname;
char *name;
int i;
gc = &chip->gc;
devname = dev_name(&gc->gpiodev->dev);
chip->dbg_dir = debugfs_create_dir(devname, gpio_mockup_dbg_dir);
if (IS_ERR_OR_NULL(chip->dbg_dir))
goto err;
for (i = 0; i < gc->ngpio; i++) {
name = devm_kasprintf(dev, GFP_KERNEL, "%d", i);
if (!name)
goto err;
priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
if (!priv)
goto err;
priv->chip = chip;
priv->offset = i;
priv->desc = &gc->gpiodev->descs[i];
evfile = debugfs_create_file(name, 0200, chip->dbg_dir, priv,
&gpio_mockup_debugfs_ops);
if (IS_ERR_OR_NULL(evfile))
goto err;
}
return;
err:
dev_err(dev, "error creating debugfs files\n");
}
static int gpio_mockup_name_lines(struct device *dev,
struct gpio_mockup_chip *chip)
{
struct gpio_chip *gc = &chip->gc;
char **names;
int i;
names = devm_kcalloc(dev, gc->ngpio, sizeof(char *), GFP_KERNEL);
if (!names)
return -ENOMEM;
for (i = 0; i < gc->ngpio; i++) {
names[i] = devm_kasprintf(dev, GFP_KERNEL,
"%s-%d", gc->label, i);
if (!names[i])
return -ENOMEM;
}
gc->names = (const char *const *)names;
return 0;
}
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;
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-name", &name);
if (rv)
name = NULL;
chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
if (!chip)
return -ENOMEM;
if (!name) {
name = devm_kasprintf(dev, GFP_KERNEL,
"%s-%c", pdev->name, pdev->id + 'A');
if (!name)
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->to_irq = gpio_mockup_to_irq;
gc->free = gpio_mockup_free;
chip->lines = devm_kcalloc(dev, gc->ngpio,
sizeof(*chip->lines), GFP_KERNEL);
if (!chip->lines)
return -ENOMEM;
if (device_property_read_bool(dev, "named-gpio-lines")) {
rv = gpio_mockup_name_lines(dev, chip);
if (rv)
return rv;
}
rv = devm_irq_sim_init(dev, &chip->irqsim, gc->ngpio);
if (rv < 0)
return rv;
rv = devm_gpiochip_add_data(dev, &chip->gc, chip);
if (rv)
return rv;
if (!IS_ERR_OR_NULL(gpio_mockup_dbg_dir))
gpio_mockup_debugfs_setup(dev, chip);
return 0;
}
static struct platform_driver gpio_mockup_driver = {
.driver = {
.name = GPIO_MOCKUP_NAME,
},
.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;
int i;
for (i = 0; i < GPIO_MOCKUP_MAX_GC; i++) {
pdev = gpio_mockup_pdevs[i];
if (pdev)
platform_device_unregister(pdev);
}
}
static int __init gpio_mockup_init(void)
{
struct property_entry properties[GPIO_MOCKUP_MAX_PROP];
int i, prop, num_chips, err = 0, base;
struct platform_device_info pdevinfo;
struct platform_device *pdev;
u16 ngpio;
if ((gpio_mockup_num_ranges < 2) ||
(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);
if (IS_ERR_OR_NULL(gpio_mockup_dbg_dir))
gpio_mockup_err("error creating debugfs directory\n");
err = platform_driver_register(&gpio_mockup_driver);
if (err) {
gpio_mockup_err("error registering platform driver\n");
return err;
}
for (i = 0; i < num_chips; i++) {
memset(properties, 0, sizeof(properties));
memset(&pdevinfo, 0, sizeof(pdevinfo));
prop = 0;
base = gpio_mockup_range_base(i);
if (base >= 0)
properties[prop++] = PROPERTY_ENTRY_U32("gpio-base",
base);
ngpio = base < 0 ? gpio_mockup_range_ngpio(i)
: gpio_mockup_range_ngpio(i) - base;
properties[prop++] = PROPERTY_ENTRY_U16("nr-gpios", ngpio);
if (gpio_mockup_named_lines)
properties[prop++] = PROPERTY_ENTRY_BOOL(
"named-gpio-lines");
pdevinfo.name = GPIO_MOCKUP_NAME;
pdevinfo.id = i;
pdevinfo.properties = properties;
pdev = platform_device_register_full(&pdevinfo);
if (IS_ERR(pdev)) {
gpio_mockup_err("error registering device");
platform_driver_unregister(&gpio_mockup_driver);
gpio_mockup_unregister_pdevs();
return PTR_ERR(pdev);
}
gpio_mockup_pdevs[i] = pdev;
}
return 0;
}
static void __exit gpio_mockup_exit(void)
{
debugfs_remove_recursive(gpio_mockup_dbg_dir);
platform_driver_unregister(&gpio_mockup_driver);
gpio_mockup_unregister_pdevs();
}
module_init(gpio_mockup_init);
module_exit(gpio_mockup_exit);
MODULE_AUTHOR("Kamlakant Patel <kamlakant.patel@broadcom.com>");
MODULE_AUTHOR("Bamvor Jian Zhang <bamv2005@gmail.com>");
MODULE_AUTHOR("Bartosz Golaszewski <brgl@bgdev.pl>");
MODULE_DESCRIPTION("GPIO Testing driver");
MODULE_LICENSE("GPL v2");