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