gpio: mockup: implement event injecting over debugfs

Create a debugfs directory for every mockup chip and a single file
for every line. Writing (0 or 1) to these files allows the user to
inject line events (falling or rising edge respectively).

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

diff --git a/drivers/gpio/gpio-mockup.c b/drivers/gpio/gpio-mockup.c
index 03beadb20dee0761be0ba45ec0bbf99090b69d96..06dac72cb69c0c1c6e9005c748a613985dea111b 100644 (file)
--- a/drivers/gpio/gpio-mockup.c
+++ b/drivers/gpio/gpio-mockup.c
@@ -14,11 +14,16 @@
 #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_work.h>
+#include <linux/debugfs.h>
+#include <linux/uaccess.h>
+
+#include "gpiolib.h"
 
 #define GPIO_MOCKUP_NAME       "gpio-mockup"
 #define        GPIO_MOCKUP_MAX_GC      10
@@ -47,6 +52,13 @@ struct gpio_mockup_chip {
        struct gpio_chip gc;
        struct gpio_mockup_line_status *lines;
        struct gpio_mockup_irq_context irq_ctx;
+       struct dentry *dbg_dir;
+};
+
+struct gpio_mockup_dbgfs_private {
+       struct gpio_mockup_chip *chip;
+       struct gpio_desc *desc;
+       int offset;
 };
 
 static int gpio_mockup_ranges[GPIO_MOCKUP_MAX_GC << 1];
@@ -58,6 +70,7 @@ module_param_named(gpio_mockup_named_lines,
                   gpio_mockup_named_lines, bool, 0400);
 
 static const char gpio_mockup_name_start = 'A';
+static struct dentry *gpio_mockup_dbg_dir;
 
 static int gpio_mockup_get(struct gpio_chip *gc, unsigned int offset)
 {
@@ -175,6 +188,94 @@ static int gpio_mockup_irqchip_setup(struct device *dev,
        return 0;
 }
 
+static ssize_t gpio_mockup_event_write(struct file *file,
+                                      const 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_desc *desc;
+       struct gpio_chip *gc;
+       int status, val;
+       char buf;
+
+       sfile = file->private_data;
+       priv = sfile->private;
+       desc = priv->desc;
+       chip = priv->chip;
+       gc = &chip->gc;
+
+       status = copy_from_user(&buf, usr_buf, 1);
+       if (status)
+               return status;
+
+       if (buf == '0')
+               val = 0;
+       else if (buf == '1')
+               val = 1;
+       else
+               return -EINVAL;
+
+       gpiod_set_value_cansleep(desc, val);
+       priv->chip->irq_ctx.irq = gc->irq_base + priv->offset;
+       irq_work_queue(&priv->chip->irq_ctx.work);
+
+       return size;
+}
+
+static int gpio_mockup_event_open(struct inode *inode, struct file *file)
+{
+       return single_open(file, NULL, inode->i_private);
+}
+
+static const struct file_operations gpio_mockup_event_ops = {
+       .owner = THIS_MODULE,
+       .open = gpio_mockup_event_open,
+       .write = gpio_mockup_event_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;
+       char *name;
+       int i;
+
+       gc = &chip->gc;
+
+       chip->dbg_dir = debugfs_create_dir(gc->label, gpio_mockup_dbg_dir);
+       if (!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_event_ops);
+               if (!evfile)
+                       goto err;
+       }
+
+       return;
+
+err:
+       dev_err(dev, "error creating debugfs directory\n");
+}
+
 static int gpio_mockup_add(struct device *dev,
                           struct gpio_mockup_chip *chip,
                           const char *name, int base, int ngpio)
@@ -209,7 +310,14 @@ static int gpio_mockup_add(struct device *dev,
        if (ret)
                return ret;
 
-       return devm_gpiochip_add_data(dev, &chip->gc, chip);
+       ret = devm_gpiochip_add_data(dev, &chip->gc, chip);
+       if (ret)
+               return ret;
+
+       if (gpio_mockup_dbg_dir)
+               gpio_mockup_debugfs_setup(dev, chip);
+
+       return 0;
 }
 
 static int gpio_mockup_probe(struct platform_device *pdev)
@@ -291,6 +399,11 @@ static int __init mock_device_init(void)
 {
        int err;
 
+       gpio_mockup_dbg_dir = debugfs_create_dir("gpio-mockup-event", NULL);
+       if (!gpio_mockup_dbg_dir)
+               pr_err("%s: error creating debugfs directory\n",
+                      GPIO_MOCKUP_NAME);
+
        pdev = platform_device_alloc(GPIO_MOCKUP_NAME, -1);
        if (!pdev)
                return -ENOMEM;
@@ -312,6 +425,7 @@ static int __init mock_device_init(void)
 
 static void __exit mock_device_exit(void)
 {
+       debugfs_remove_recursive(gpio_mockup_dbg_dir);
        platform_driver_unregister(&gpio_mockup_driver);
        platform_device_unregister(pdev);
 }