linux-kernel - [PATCH 21/23] gpio: mockup: provide a way to delete dummy chips

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Message-Id: <20200904154547.3836-22-brgl@bgdev.pl>
Date:   Fri,  4 Sep 2020 17:45:45 +0200
From:   Bartosz Golaszewski <brgl@...ev.pl>
To:     Linus Walleij <linus.walleij@...aro.org>,
        Jonathan Corbet <corbet@....net>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Kent Gibson <warthog618@...il.com>
Cc:     linux-gpio@...r.kernel.org, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
        Bartosz Golaszewski <bgolaszewski@...libre.com>
Subject: [PATCH 21/23] gpio: mockup: provide a way to delete dummy chips

From: Bartosz Golaszewski <bgolaszewski@...libre.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@...libre.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);
+		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