add new system file

hc

2024-02-20 102a0743326a03cd1a1202ceda21e175b7d3575c

 kernel/drivers/mailbox/mailbox-test.c
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@@ -1,12 +1,8 @@
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+// SPDX-License-Identifier: GPL-2.0-or-later
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 /*
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  * Copyright (C) 2015 ST Microelectronics
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  *
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  * Author: Lee Jones <lee.jones@linaro.org>
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- *
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- * This program is free software; you can redistribute it and/or modify
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- * it under the terms of the GNU General Public License as published by
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- * the Free Software Foundation; either version 2 of the License, or
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- * (at your option) any later version.
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  */
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 #include <linux/debugfs.h>
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@@ -16,6 +12,7 @@
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 #include <linux/kernel.h>
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 #include <linux/mailbox_client.h>
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 #include <linux/module.h>
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+#include <linux/mutex.h>
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 #include <linux/of.h>
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 #include <linux/platform_device.h>
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 #include <linux/poll.h>
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@@ -31,7 +28,6 @@
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 				 (MBOX_MAX_MSG_LEN / MBOX_BYTES_PER_LINE))
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 static bool mbox_data_ready;
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-static struct dentry *root_debugfs_dir;
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 struct mbox_test_device {
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 	struct device		*dev;
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@@ -43,8 +39,10 @@
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 	char			*signal;
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 	char			*message;
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 	spinlock_t		lock;
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+	struct mutex		mutex;
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 	wait_queue_head_t	waitq;
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 	struct fasync_struct	*async_queue;
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+	struct dentry		*root_debugfs_dir;
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 };
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 static ssize_t mbox_test_signal_write(struct file *filp,
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@@ -99,6 +97,7 @@
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 				       size_t count, loff_t *ppos)
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 {
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 	struct mbox_test_device *tdev = filp->private_data;
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+	char *message;
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 	void *data;
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 	int ret;
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@@ -114,10 +113,13 @@
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 		return -EINVAL;
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 	}
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-	tdev->message = kzalloc(MBOX_MAX_MSG_LEN, GFP_KERNEL);
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-	if (!tdev->message)
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+	message = kzalloc(MBOX_MAX_MSG_LEN, GFP_KERNEL);
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+	if (!message)
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 		return -ENOMEM;
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+	mutex_lock(&tdev->mutex);
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+
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+	tdev->message = message;
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 	ret = copy_from_user(tdev->message, userbuf, count);
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 	if (ret) {
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 		ret = -EFAULT;
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@@ -147,6 +149,8 @@
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 	kfree(tdev->signal);
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 	kfree(tdev->message);
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 	tdev->signal = NULL;
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+
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+	mutex_unlock(&tdev->mutex);
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 	return ret < 0 ? ret : count;
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 }
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@@ -262,16 +266,16 @@
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 	if (!debugfs_initialized())
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 		return 0;
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-	root_debugfs_dir = debugfs_create_dir("mailbox", NULL);
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-	if (!root_debugfs_dir) {
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+	tdev->root_debugfs_dir = debugfs_create_dir(dev_name(&pdev->dev), NULL);
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+	if (!tdev->root_debugfs_dir) {
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 		dev_err(&pdev->dev, "Failed to create Mailbox debugfs\n");
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 		return -EINVAL;
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 	}
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-	debugfs_create_file("message", 0600, root_debugfs_dir,
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+	debugfs_create_file("message", 0600, tdev->root_debugfs_dir,
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 			    tdev, &mbox_test_message_ops);
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-	debugfs_create_file("signal", 0200, root_debugfs_dir,
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+	debugfs_create_file("signal", 0200, tdev->root_debugfs_dir,
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 			    tdev, &mbox_test_signal_ops);
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 	return 0;
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@@ -396,6 +400,7 @@
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 	platform_set_drvdata(pdev, tdev);
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 	spin_lock_init(&tdev->lock);
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+	mutex_init(&tdev->mutex);
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 	if (tdev->rx_channel) {
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 		tdev->rx_buffer = devm_kzalloc(&pdev->dev,
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@@ -418,7 +423,7 @@
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 {
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 	struct mbox_test_device *tdev = platform_get_drvdata(pdev);
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-	debugfs_remove_recursive(root_debugfs_dir);
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+	debugfs_remove_recursive(tdev->root_debugfs_dir);
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 	if (tdev->tx_channel)
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 		mbox_free_channel(tdev->tx_channel);