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
23static int major;
24
25static struct intel_scu_ipc_dev *scu;
26static 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
33struct 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
49static 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 */
77static 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
97static 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
112unlock:
113	mutex_unlock(&scu_lock);
114	return ret;
115}
116
117static 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
127static 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
133static 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
142static void __exit ipc_module_exit(void)
143{
144	unregister_chrdev(major, "intel_mid_scu");
145}
146
147module_init(ipc_module_init);
148module_exit(ipc_module_exit);
149
150MODULE_LICENSE("GPL v2");
151MODULE_DESCRIPTION("Utility driver for intel scu ipc");
152MODULE_AUTHOR("Sreedhara <sreedhara.ds@intel.com>");
153