Eric Lee / smarc-fsl-linux-kernel

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drivers/acpi/custom_method.c 2.06 KB
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81f7e3824   Eric Lee   Initial Release, ... 
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  /*
   * custom_method.c - debugfs interface for customizing ACPI control method
   */
  
  #include <linux/init.h>
  #include <linux/module.h>
  #include <linux/kernel.h>
  #include <linux/uaccess.h>
  #include <linux/debugfs.h>
  #include <linux/acpi.h>
  
  #include "internal.h"
  
  #define _COMPONENT		ACPI_SYSTEM_COMPONENT
  ACPI_MODULE_NAME("custom_method");
  MODULE_LICENSE("GPL");
  
  static struct dentry *cm_dentry;
  
  /* /sys/kernel/debug/acpi/custom_method */
  
  static ssize_t cm_write(struct file *file, const char __user * user_buf,
  			size_t count, loff_t *ppos)
  {
  	static char *buf;
  	static u32 max_size;
  	static u32 uncopied_bytes;
  
  	struct acpi_table_header table;
  	acpi_status status;
  
  	if (!(*ppos)) {
  		/* parse the table header to get the table length */
  		if (count <= sizeof(struct acpi_table_header))
  			return -EINVAL;
  		if (copy_from_user(&table, user_buf,
  				   sizeof(struct acpi_table_header)))
  			return -EFAULT;
  		uncopied_bytes = max_size = table.length;
  		buf = kzalloc(max_size, GFP_KERNEL);
  		if (!buf)
  			return -ENOMEM;
  	}
  
  	if (buf == NULL)
  		return -EINVAL;
  
  	if ((*ppos > max_size) ||
  	    (*ppos + count > max_size) ||
  	    (*ppos + count < count) ||
  	    (count > uncopied_bytes))
  		return -EINVAL;
  
  	if (copy_from_user(buf + (*ppos), user_buf, count)) {
  		kfree(buf);
  		buf = NULL;
  		return -EFAULT;
  	}
  
  	uncopied_bytes -= count;
  	*ppos += count;
  
  	if (!uncopied_bytes) {
  		status = acpi_install_method(buf);
  		kfree(buf);
  		buf = NULL;
  		if (ACPI_FAILURE(status))
  			return -EINVAL;
  		add_taint(TAINT_OVERRIDDEN_ACPI_TABLE, LOCKDEP_NOW_UNRELIABLE);
  	}
  
  	return count;
  }
  
  static const struct file_operations cm_fops = {
  	.write = cm_write,
  	.llseek = default_llseek,
  };
  
  static int __init acpi_custom_method_init(void)
  {
  	if (acpi_debugfs_dir == NULL)
  		return -ENOENT;
  
  	cm_dentry = debugfs_create_file("custom_method", S_IWUSR,
  					acpi_debugfs_dir, NULL, &cm_fops);
  	if (cm_dentry == NULL)
  		return -ENODEV;
  
  	return 0;
  }
  
  static void __exit acpi_custom_method_exit(void)
  {
  	if (cm_dentry)
  		debugfs_remove(cm_dentry);
   }
  
  module_init(acpi_custom_method_init);
  module_exit(acpi_custom_method_exit);