1 /*
2  * intel_scu_ipc.c: Driver for the Intel SCU IPC mechanism
3  *
4  * (C) Copyright 2008-2010 Intel Corporation
5  * Author: Sreedhara DS (sreedhara.ds@intel.com)
6  *
7  * This program is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU General Public License
9  * as published by the Free Software Foundation; version 2
10  * of the License.
11  *
12  * This driver provides ioctl interfaces to call intel scu ipc driver api
13  */
14 
15 #include <linux/module.h>
16 #include <linux/kernel.h>
17 #include <linux/errno.h>
18 #include <linux/types.h>
19 #include <linux/fs.h>
20 #include <linux/fcntl.h>
21 #include <linux/sched.h>
22 #include <linux/uaccess.h>
23 #include <linux/slab.h>
24 #include <linux/init.h>
25 #include <asm/intel_scu_ipc.h>
26 
27 static int major;
28 
29 /* ioctl commnds */
30 #define	INTE_SCU_IPC_REGISTER_READ	0
31 #define INTE_SCU_IPC_REGISTER_WRITE	1
32 #define INTE_SCU_IPC_REGISTER_UPDATE	2
33 
34 struct scu_ipc_data {
35 	u32     count;  /* No. of registers */
36 	u16     addr[5]; /* Register addresses */
37 	u8      data[5]; /* Register data */
38 	u8      mask; /* Valid for read-modify-write */
39 };
40 
41 /**
42  *	scu_reg_access		-	implement register access ioctls
43  *	@cmd: command we are doing (read/write/update)
44  *	@data: kernel copy of ioctl data
45  *
46  *	Allow the user to perform register accesses on the SCU via the
47  *	kernel interface
48  */
49 
50 static int scu_reg_access(u32 cmd, struct scu_ipc_data  *data)
51 {
52 	unsigned int count = data->count;
53 
54 	if (count == 0 || count == 3 || count > 4)
55 		return -EINVAL;
56 
57 	switch (cmd) {
58 	case INTE_SCU_IPC_REGISTER_READ:
59 		return intel_scu_ipc_readv(data->addr, data->data, count);
60 	case INTE_SCU_IPC_REGISTER_WRITE:
61 		return intel_scu_ipc_writev(data->addr, data->data, count);
62 	case INTE_SCU_IPC_REGISTER_UPDATE:
63 		return intel_scu_ipc_update_register(data->addr[0],
64 						    data->data[0], data->mask);
65 	default:
66 		return -ENOTTY;
67 	}
68 }
69 
70 /**
71  *	scu_ipc_ioctl		-	control ioctls for the SCU
72  *	@fp: file handle of the SCU device
73  *	@cmd: ioctl coce
74  *	@arg: pointer to user passed structure
75  *
76  *	Support the I/O and firmware flashing interfaces of the SCU
77  */
78 static long scu_ipc_ioctl(struct file *fp, unsigned int cmd,
79 							unsigned long arg)
80 {
81 	int ret;
82 	struct scu_ipc_data  data;
83 	void __user *argp = (void __user *)arg;
84 
85 	if (!capable(CAP_SYS_RAWIO))
86 		return -EPERM;
87 
88 	if (copy_from_user(&data, argp, sizeof(struct scu_ipc_data)))
89 		return -EFAULT;
90 	ret = scu_reg_access(cmd, &data);
91 	if (ret < 0)
92 		return ret;
93 	if (copy_to_user(argp, &data, sizeof(struct scu_ipc_data)))
94 		return -EFAULT;
95 	return 0;
96 }
97 
98 static const struct file_operations scu_ipc_fops = {
99 	.unlocked_ioctl = scu_ipc_ioctl,
100 };
101 
102 static int __init ipc_module_init(void)
103 {
104 	major = register_chrdev(0, "intel_mid_scu", &scu_ipc_fops);
105 	if (major < 0)
106 		return major;
107 
108 	return 0;
109 }
110 
111 static void __exit ipc_module_exit(void)
112 {
113 	unregister_chrdev(major, "intel_mid_scu");
114 }
115 
116 module_init(ipc_module_init);
117 module_exit(ipc_module_exit);
118 
119 MODULE_LICENSE("GPL v2");
120 MODULE_DESCRIPTION("Utility driver for intel scu ipc");
121 MODULE_AUTHOR("Sreedhara <sreedhara.ds@intel.com>");
122