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
scu_reg_access(u32 cmd,struct scu_ipc_data * data)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 */
scu_ipc_ioctl(struct file * fp,unsigned int cmd,unsigned long arg)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
scu_ipc_open(struct inode * inode,struct file * file)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
scu_ipc_release(struct inode * inode,struct file * file)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
ipc_module_init(void)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
ipc_module_exit(void)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