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 u32 major;
28 
29 #define MAX_FW_SIZE 264192
30 
31 /* ioctl commnds */
32 #define	INTE_SCU_IPC_REGISTER_READ	0
33 #define INTE_SCU_IPC_REGISTER_WRITE	1
34 #define INTE_SCU_IPC_REGISTER_UPDATE	2
35 #define INTE_SCU_IPC_FW_UPDATE		0xA2
36 
37 struct scu_ipc_data {
38 	u32     count;  /* No. of registers */
39 	u16     addr[5]; /* Register addresses */
40 	u8      data[5]; /* Register data */
41 	u8      mask; /* Valid for read-modify-write */
42 };
43 
44 /**
45  *	scu_reg_access		-	implement register access ioctls
46  *	@cmd: command we are doing (read/write/update)
47  *	@data: kernel copy of ioctl data
48  *
49  *	Allow the user to perform register accesses on the SCU via the
50  *	kernel interface
51  */
52 
53 static int scu_reg_access(u32 cmd, struct scu_ipc_data  *data)
54 {
55 	int count = data->count;
56 
57 	if (count == 0 || count == 3 || count > 4)
58 		return -EINVAL;
59 
60 	switch (cmd) {
61 	case INTE_SCU_IPC_REGISTER_READ:
62 		return intel_scu_ipc_readv(data->addr, data->data, count);
63 	case INTE_SCU_IPC_REGISTER_WRITE:
64 		return intel_scu_ipc_writev(data->addr, data->data, count);
65 	case INTE_SCU_IPC_REGISTER_UPDATE:
66 		return intel_scu_ipc_update_register(data->addr[0],
67 						    data->data[0], data->mask);
68 	default:
69 		return -ENOTTY;
70 	}
71 }
72 
73 /**
74  *	scu_ipc_ioctl		-	control ioctls for the SCU
75  *	@fp: file handle of the SCU device
76  *	@cmd: ioctl coce
77  *	@arg: pointer to user passed structure
78  *
79  *	Support the I/O and firmware flashing interfaces of the SCU
80  */
81 static long scu_ipc_ioctl(struct file *fp, unsigned int cmd,
82 							unsigned long arg)
83 {
84 	int ret;
85 	struct scu_ipc_data  data;
86 	void __user *argp = (void __user *)arg;
87 
88 	if (!capable(CAP_SYS_RAWIO))
89 		return -EPERM;
90 
91 	if (cmd == INTE_SCU_IPC_FW_UPDATE) {
92 			u8 *fwbuf = kmalloc(MAX_FW_SIZE, GFP_KERNEL);
93 			if (fwbuf == NULL)
94 				return -ENOMEM;
95 			if (copy_from_user(fwbuf, (u8 *)arg, MAX_FW_SIZE)) {
96 				kfree(fwbuf);
97 				return -EFAULT;
98 			}
99 			ret = intel_scu_ipc_fw_update(fwbuf, MAX_FW_SIZE);
100 			kfree(fwbuf);
101 			return ret;
102 	} else {
103 		if (copy_from_user(&data, argp, sizeof(struct scu_ipc_data)))
104 			return -EFAULT;
105 		ret = scu_reg_access(cmd, &data);
106 		if (ret < 0)
107 			return ret;
108 		if (copy_to_user(argp, &data, sizeof(struct scu_ipc_data)))
109 			return -EFAULT;
110 		return 0;
111 	}
112 }
113 
114 static const struct file_operations scu_ipc_fops = {
115 	.unlocked_ioctl = scu_ipc_ioctl,
116 };
117 
118 static int __init ipc_module_init(void)
119 {
120 	return register_chrdev(0, "intel_mid_scu", &scu_ipc_fops);
121 }
122 
123 static void __exit ipc_module_exit(void)
124 {
125 	unregister_chrdev(major, "intel_mid_scu");
126 }
127 
128 module_init(ipc_module_init);
129 module_exit(ipc_module_exit);
130 
131 MODULE_LICENSE("GPL v2");
132 MODULE_DESCRIPTION("Utility driver for intel scu ipc");
133 MODULE_AUTHOR("Sreedhara <sreedhara.ds@intel.com>");
134