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SubjectRe: [PATCH 21/23] gpio: mockup: provide a way to delete dummy chips
On Fri, Sep 04, 2020 at 05:45:45PM +0200, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bgolaszewski@baylibre.com>
>
> Add a new debugfs attribute 'delete_device' to which the chip label can
> be written to dynamically remove the associated dummy device.
>
> Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
> ---
> drivers/gpio/gpio-mockup.c | 70 +++++++++++++++++++++++++++++++++++++-
> 1 file changed, 69 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpio/gpio-mockup.c b/drivers/gpio/gpio-mockup.c
> index 1353239dc315..9d2de78a45c2 100644
> --- a/drivers/gpio/gpio-mockup.c
> +++ b/drivers/gpio/gpio-mockup.c
> @@ -19,6 +19,7 @@
> #include <linux/platform_device.h>
> #include <linux/property.h>
> #include <linux/slab.h>
> +#include <linux/string.h>
> #include <linux/string_helpers.h>
> #include <linux/uaccess.h>
>
> @@ -668,14 +669,81 @@ static int __init gpio_mockup_register_chips_from_params(void)
> return 0;
> }
>
> -static int __init gpio_mockup_init(void)
> +static ssize_t gpio_mockup_debugfs_delete_device_write(struct file *file,
> + const char __user *usr_buf,
> + size_t size, loff_t *ppos)
> {
> + struct gpio_mockup_device *mockup_dev;
> + char label[GPIO_MOCKUP_LABEL_SIZE];
> + struct list_head *curr;
> + struct device *dev;
> + const char *prop;
> int ret;
>
> + if (*ppos != 0)
> + return -EINVAL;
> +
> + ret = getline_from_user(label, sizeof(label), usr_buf, size);
> + if (ret < 0)
> + return ret;
> +
> + mutex_lock(&gpio_mockup_devices_lock);
> +
> + list_for_each(curr, &gpio_mockup_devices) {
> + mockup_dev = list_entry(curr, struct gpio_mockup_device, list);

Why not list_for_each_entry()?

> + dev = &mockup_dev->pdev->dev;
> +
> + ret = device_property_read_string(dev, "chip-label", &prop);
> + if (ret) {
> + mutex_unlock(&gpio_mockup_devices_lock);
> + return ret;
> + }
> +
> + if (sysfs_streq(label, prop)) {
> + gpio_mockup_unregister_one_device(mockup_dev);
> + mutex_unlock(&gpio_mockup_devices_lock);
> + return size;
> + }
> + }
> +
> + mutex_unlock(&gpio_mockup_devices_lock);
> + return -ENODEV;
> +}
> +
> +static const struct file_operations gpio_mockup_debugfs_delete_device_ops = {
> + .owner = THIS_MODULE,
> + .open = gpio_mockup_debugfs_open,
> + .write = gpio_mockup_debugfs_delete_device_write,
> + .llseek = no_llseek,
> + .release = single_release,
> +};
> +
> +static int __init gpio_mockup_debugfs_init(void)
> +{
> + struct dentry *entry;
> +
> gpio_mockup_dbg_dir = debugfs_create_dir("gpio-mockup", NULL);
> if (IS_ERR(gpio_mockup_dbg_dir))
> return PTR_ERR(gpio_mockup_dbg_dir);
>
> + entry = debugfs_create_file("delete_device", 0200, gpio_mockup_dbg_dir,
> + NULL, &gpio_mockup_debugfs_delete_device_ops);
> + if (IS_ERR(entry)) {
> + debugfs_remove_recursive(gpio_mockup_dbg_dir);
> + return PTR_ERR(entry);
> + }
> +
> + return 0;
> +}
> +
> +static int __init gpio_mockup_init(void)
> +{
> + int ret;
> +
> + ret = gpio_mockup_debugfs_init();
> + if (ret)
> + return ret;
> +
> ret = platform_driver_register(&gpio_mockup_driver);
> if (ret) {
> pr_err("error registering platform driver\n");
> --
> 2.26.1
>

--
With Best Regards,
Andy Shevchenko


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