1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Driver for the Intel SCU IPC mechanism
4  *
5  * (C) Copyright 2008-2010 Intel Corporation
6  * Author: Sreedhara DS (sreedhara.ds@intel.com)
7  *
8  * This driver provides IOCTL interfaces to call Intel SCU IPC driver API.
9  */
10 
11 #include <linux/errno.h>
12 #include <linux/fcntl.h>
13 #include <linux/fs.h>
14 #include <linux/kernel.h>
15 #include <linux/module.h>
16 #include <linux/sched.h>
17 #include <linux/slab.h>
18 #include <linux/types.h>
19 #include <linux/uaccess.h>
20 
21 #include <asm/intel_scu_ipc.h>
22 
23 static int major;
24 
25 struct intel_scu_ipc_dev *scu;
26 static DEFINE_MUTEX(scu_lock);
27 
28 /* IOCTL commands */
29 #define	INTE_SCU_IPC_REGISTER_READ	0
30 #define INTE_SCU_IPC_REGISTER_WRITE	1
31 #define INTE_SCU_IPC_REGISTER_UPDATE	2
32 
33 struct scu_ipc_data {
34 	u32     count;  /* No. of registers */
35 	u16     addr[5]; /* Register addresses */
36 	u8      data[5]; /* Register data */
37 	u8      mask; /* Valid for read-modify-write */
38 };
39 
40 /**
41  *	scu_reg_access		-	implement register access ioctls
42  *	@cmd: command we are doing (read/write/update)
43  *	@data: kernel copy of ioctl data
44  *
45  *	Allow the user to perform register accesses on the SCU via the
46  *	kernel interface
47  */
48 
49 static int scu_reg_access(u32 cmd, struct scu_ipc_data  *data)
50 {
51 	unsigned int count = data->count;
52 
53 	if (count == 0 || count == 3 || count > 4)
54 		return -EINVAL;
55 
56 	switch (cmd) {
57 	case INTE_SCU_IPC_REGISTER_READ:
58 		return intel_scu_ipc_dev_readv(scu, data->addr, data->data, count);
59 	case INTE_SCU_IPC_REGISTER_WRITE:
60 		return intel_scu_ipc_dev_writev(scu, data->addr, data->data, count);
61 	case INTE_SCU_IPC_REGISTER_UPDATE:
62 		return intel_scu_ipc_dev_update(scu, data->addr[0], data->data[0],
63 						data->mask);
64 	default:
65 		return -ENOTTY;
66 	}
67 }
68 
69 /**
70  *	scu_ipc_ioctl		-	control ioctls for the SCU
71  *	@fp: file handle of the SCU device
72  *	@cmd: ioctl coce
73  *	@arg: pointer to user passed structure
74  *
75  *	Support the I/O and firmware flashing interfaces of the SCU
76  */
77 static long scu_ipc_ioctl(struct file *fp, unsigned int cmd,
78 							unsigned long arg)
79 {
80 	int ret;
81 	struct scu_ipc_data  data;
82 	void __user *argp = (void __user *)arg;
83 
84 	if (!capable(CAP_SYS_RAWIO))
85 		return -EPERM;
86 
87 	if (copy_from_user(&data, argp, sizeof(struct scu_ipc_data)))
88 		return -EFAULT;
89 	ret = scu_reg_access(cmd, &data);
90 	if (ret < 0)
91 		return ret;
92 	if (copy_to_user(argp, &data, sizeof(struct scu_ipc_data)))
93 		return -EFAULT;
94 	return 0;
95 }
96 
97 static int scu_ipc_open(struct inode *inode, struct file *file)
98 {
99 	int ret = 0;
100 
101 	/* Only single open at the time */
102 	mutex_lock(&scu_lock);
103 	if (scu) {
104 		ret = -EBUSY;
105 		goto unlock;
106 	}
107 
108 	scu = intel_scu_ipc_dev_get();
109 	if (!scu)
110 		ret = -ENODEV;
111 
112 unlock:
113 	mutex_unlock(&scu_lock);
114 	return ret;
115 }
116 
117 static int scu_ipc_release(struct inode *inode, struct file *file)
118 {
119 	mutex_lock(&scu_lock);
120 	intel_scu_ipc_dev_put(scu);
121 	scu = NULL;
122 	mutex_unlock(&scu_lock);
123 
124 	return 0;
125 }
126 
127 static const struct file_operations scu_ipc_fops = {
128 	.unlocked_ioctl = scu_ipc_ioctl,
129 	.open = scu_ipc_open,
130 	.release = scu_ipc_release,
131 };
132 
133 static int __init ipc_module_init(void)
134 {
135 	major = register_chrdev(0, "intel_mid_scu", &scu_ipc_fops);
136 	if (major < 0)
137 		return major;
138 
139 	return 0;
140 }
141 
142 static void __exit ipc_module_exit(void)
143 {
144 	unregister_chrdev(major, "intel_mid_scu");
145 }
146 
147 module_init(ipc_module_init);
148 module_exit(ipc_module_exit);
149 
150 MODULE_LICENSE("GPL v2");
151 MODULE_DESCRIPTION("Utility driver for intel scu ipc");
152 MODULE_AUTHOR("Sreedhara <sreedhara.ds@intel.com>");
153