1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Privileged ADI driver for sparc64
4 *
5 * Author: Tom Hromatka <tom.hromatka@oracle.com>
6 */
7#include <linux/kernel.h>
8#include <linux/miscdevice.h>
9#include <linux/module.h>
10#include <linux/proc_fs.h>
11#include <linux/slab.h>
12#include <linux/uaccess.h>
13#include <asm/asi.h>
14
15#define MAX_BUF_SZ	PAGE_SIZE
16
17static int adi_open(struct inode *inode, struct file *file)
18{
19	file->f_mode |= FMODE_UNSIGNED_OFFSET;
20	return 0;
21}
22
23static int read_mcd_tag(unsigned long addr)
24{
25	long err;
26	int ver;
27
28	__asm__ __volatile__(
29		"1:	ldxa [%[addr]] %[asi], %[ver]\n"
30		"	mov 0, %[err]\n"
31		"2:\n"
32		"	.section .fixup,#alloc,#execinstr\n"
33		"	.align 4\n"
34		"3:	sethi %%hi(2b), %%g1\n"
35		"	jmpl  %%g1 + %%lo(2b), %%g0\n"
36		"	mov %[invalid], %[err]\n"
37		"	.previous\n"
38		"	.section __ex_table, \"a\"\n"
39		"	.align 4\n"
40		"	.word  1b, 3b\n"
41		"	.previous\n"
42		: [ver] "=r" (ver), [err] "=r" (err)
43		: [addr] "r"  (addr), [invalid] "i" (EFAULT),
44		  [asi] "i" (ASI_MCD_REAL)
45		: "memory", "g1"
46		);
47
48	if (err)
49		return -EFAULT;
50	else
51		return ver;
52}
53
54static ssize_t adi_read(struct file *file, char __user *buf,
55			size_t count, loff_t *offp)
56{
57	size_t ver_buf_sz, bytes_read = 0;
58	int ver_buf_idx = 0;
59	loff_t offset;
60	u8 *ver_buf;
61	ssize_t ret;
62
63	ver_buf_sz = min_t(size_t, count, MAX_BUF_SZ);
64	ver_buf = kmalloc(ver_buf_sz, GFP_KERNEL);
65	if (!ver_buf)
66		return -ENOMEM;
67
68	offset = (*offp) * adi_blksize();
69
70	while (bytes_read < count) {
71		ret = read_mcd_tag(offset);
72		if (ret < 0)
73			goto out;
74
75		ver_buf[ver_buf_idx] = (u8)ret;
76		ver_buf_idx++;
77		offset += adi_blksize();
78
79		if (ver_buf_idx >= ver_buf_sz) {
80			if (copy_to_user(buf + bytes_read, ver_buf,
81					 ver_buf_sz)) {
82				ret = -EFAULT;
83				goto out;
84			}
85
86			bytes_read += ver_buf_sz;
87			ver_buf_idx = 0;
88
89			ver_buf_sz = min(count - bytes_read,
90					 (size_t)MAX_BUF_SZ);
91		}
92	}
93
94	(*offp) += bytes_read;
95	ret = bytes_read;
96out:
97	kfree(ver_buf);
98	return ret;
99}
100
101static int set_mcd_tag(unsigned long addr, u8 ver)
102{
103	long err;
104
105	__asm__ __volatile__(
106		"1:	stxa %[ver], [%[addr]] %[asi]\n"
107		"	mov 0, %[err]\n"
108		"2:\n"
109		"	.section .fixup,#alloc,#execinstr\n"
110		"	.align 4\n"
111		"3:	sethi %%hi(2b), %%g1\n"
112		"	jmpl %%g1 + %%lo(2b), %%g0\n"
113		"	mov %[invalid], %[err]\n"
114		"	.previous\n"
115		"	.section __ex_table, \"a\"\n"
116		"	.align 4\n"
117		"	.word 1b, 3b\n"
118		"	.previous\n"
119		: [err] "=r" (err)
120		: [ver] "r" (ver), [addr] "r"  (addr),
121		  [invalid] "i" (EFAULT), [asi] "i" (ASI_MCD_REAL)
122		: "memory", "g1"
123		);
124
125	if (err)
126		return -EFAULT;
127	else
128		return ver;
129}
130
131static ssize_t adi_write(struct file *file, const char __user *buf,
132			 size_t count, loff_t *offp)
133{
134	size_t ver_buf_sz, bytes_written = 0;
135	loff_t offset;
136	u8 *ver_buf;
137	ssize_t ret;
138	int i;
139
140	if (count <= 0)
141		return -EINVAL;
142
143	ver_buf_sz = min_t(size_t, count, MAX_BUF_SZ);
144	ver_buf = kmalloc(ver_buf_sz, GFP_KERNEL);
145	if (!ver_buf)
146		return -ENOMEM;
147
148	offset = (*offp) * adi_blksize();
149
150	do {
151		if (copy_from_user(ver_buf, &buf[bytes_written],
152				   ver_buf_sz)) {
153			ret = -EFAULT;
154			goto out;
155		}
156
157		for (i = 0; i < ver_buf_sz; i++) {
158			ret = set_mcd_tag(offset, ver_buf[i]);
159			if (ret < 0)
160				goto out;
161
162			offset += adi_blksize();
163		}
164
165		bytes_written += ver_buf_sz;
166		ver_buf_sz = min(count - bytes_written, (size_t)MAX_BUF_SZ);
167	} while (bytes_written < count);
168
169	(*offp) += bytes_written;
170	ret = bytes_written;
171out:
172	__asm__ __volatile__("membar #Sync");
173	kfree(ver_buf);
174	return ret;
175}
176
177static loff_t adi_llseek(struct file *file, loff_t offset, int whence)
178{
179	loff_t ret = -EINVAL;
180
181	switch (whence) {
182	case SEEK_END:
183	case SEEK_DATA:
184	case SEEK_HOLE:
185		/* unsupported */
186		return -EINVAL;
187	case SEEK_CUR:
188		if (offset == 0)
189			return file->f_pos;
190
191		offset += file->f_pos;
192		break;
193	case SEEK_SET:
194		break;
195	}
196
197	if (offset != file->f_pos) {
198		file->f_pos = offset;
199		file->f_version = 0;
200		ret = offset;
201	}
202
203	return ret;
204}
205
206static const struct file_operations adi_fops = {
207	.owner		= THIS_MODULE,
208	.llseek		= adi_llseek,
209	.open		= adi_open,
210	.read		= adi_read,
211	.write		= adi_write,
212};
213
214static struct miscdevice adi_miscdev = {
215	.minor = MISC_DYNAMIC_MINOR,
216	.name = KBUILD_MODNAME,
217	.fops = &adi_fops,
218};
219
220static int __init adi_init(void)
221{
222	if (!adi_capable())
223		return -EPERM;
224
225	return misc_register(&adi_miscdev);
226}
227
228static void __exit adi_exit(void)
229{
230	misc_deregister(&adi_miscdev);
231}
232
233module_init(adi_init);
234module_exit(adi_exit);
235
236MODULE_AUTHOR("Tom Hromatka <tom.hromatka@oracle.com>");
237MODULE_DESCRIPTION("Privileged interface to ADI");
238MODULE_VERSION("1.0");
239MODULE_LICENSE("GPL v2");
240