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, addr: data->addr, data: data->data, len: count); |
59 | case INTE_SCU_IPC_REGISTER_WRITE: |
60 | return intel_scu_ipc_dev_writev(scu, addr: data->addr, data: data->data, len: count); |
61 | case INTE_SCU_IPC_REGISTER_UPDATE: |
62 | return intel_scu_ipc_dev_update(scu, addr: data->addr[0], data: data->data[0], |
63 | mask: 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(to: &data, from: argp, n: sizeof(struct scu_ipc_data))) |
88 | return -EFAULT; |
89 | ret = scu_reg_access(cmd, data: &data); |
90 | if (ret < 0) |
91 | return ret; |
92 | if (copy_to_user(to: argp, from: &data, n: 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(lock: &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(lock: &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(major: 0, name: "intel_mid_scu" , fops: &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, name: "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 | |