aboutsummaryrefslogtreecommitdiff
path: root/drivers/platform/x86/ibm_rtl.c
blob: 42a7d603c870bb259a93a1630065de34d5c35a01 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
/*
 * IBM Real-Time Linux driver
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 * Copyright (C) IBM Corporation, 2010
 *
 * Author: Keith Mannthey <kmannth@us.ibm.com>
 *         Vernon Mauery <vernux@us.ibm.com>
 *
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/module.h>
#include <linux/io.h>
#include <linux/dmi.h>
#include <linux/efi.h>
#include <linux/mutex.h>
#include <asm/bios_ebda.h>

static bool force;
module_param(force, bool, 0);
MODULE_PARM_DESC(force, "Force driver load, ignore DMI data");

static bool debug;
module_param(debug, bool, 0644);
MODULE_PARM_DESC(debug, "Show debug output");

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Keith Mannthey <kmmanth@us.ibm.com>");
MODULE_AUTHOR("Vernon Mauery <vernux@us.ibm.com>");

#define RTL_ADDR_TYPE_IO    1
#define RTL_ADDR_TYPE_MMIO  2

#define RTL_CMD_ENTER_PRTM  1
#define RTL_CMD_EXIT_PRTM   2

/* The RTL table as presented by the EBDA: */
struct ibm_rtl_table {
	char signature[5]; /* signature should be "_RTL_" */
	u8 version;
	u8 rt_status;
	u8 command;
	u8 command_status;
	u8 cmd_address_type;
	u8 cmd_granularity;
	u8 cmd_offset;
	u16 reserve1;
	u32 cmd_port_address; /* platform dependent address */
	u32 cmd_port_value;   /* platform dependent value */
} __attribute__((packed));

/* to locate "_RTL_" signature do a masked 5-byte integer compare */
#define RTL_SIGNATURE 0x0000005f4c54525fULL
#define RTL_MASK      0x000000ffffffffffULL

#define RTL_DEBUG(fmt, ...)				\
do {							\
	if (debug)					\
		pr_info(fmt, ##__VA_ARGS__);		\
} while (0)

static DEFINE_MUTEX(rtl_lock);
static struct ibm_rtl_table __iomem *rtl_table;
static void __iomem *ebda_map;
static void __iomem *rtl_cmd_addr;
static u8 rtl_cmd_type;
static u8 rtl_cmd_width;

#ifndef readq
static inline __u64 readq(const volatile void __iomem *addr)
{
	const volatile u32 __iomem *p = addr;
	u32 low, high;

	low = readl(p);
	high = readl(p + 1);

	return low + ((u64)high << 32);
}
#endif

static void __iomem *rtl_port_map(phys_addr_t addr, unsigned long len)
{
	if (rtl_cmd_type == RTL_ADDR_TYPE_MMIO)
		return ioremap(addr, len);
	return ioport_map(addr, len);
}

static void rtl_port_unmap(void __iomem *addr)
{
	if (addr && rtl_cmd_type == RTL_ADDR_TYPE_MMIO)
		iounmap(addr);
	else
		ioport_unmap(addr);
}

static int ibm_rtl_write(u8 value)
{
	int ret = 0, count = 0;
	static u32 cmd_port_val;

	RTL_DEBUG("%s(%d)\n", __func__, value);

	value = value == 1 ? RTL_CMD_ENTER_PRTM : RTL_CMD_EXIT_PRTM;

	mutex_lock(&rtl_lock);

	if (ioread8(&rtl_table->rt_status) != value) {
		iowrite8(value, &rtl_table->command);

		switch (rtl_cmd_width) {
		case 8:
			cmd_port_val = ioread8(&rtl_table->cmd_port_value);
			RTL_DEBUG("cmd_port_val = %u\n", cmd_port_val);
			iowrite8((u8)cmd_port_val, rtl_cmd_addr);
			break;
		case 16:
			cmd_port_val = ioread16(&rtl_table->cmd_port_value);
			RTL_DEBUG("cmd_port_val = %u\n", cmd_port_val);
			iowrite16((u16)cmd_port_val, rtl_cmd_addr);
			break;
		case 32:
			cmd_port_val = ioread32(&rtl_table->cmd_port_value);
			RTL_DEBUG("cmd_port_val = %u\n", cmd_port_val);
			iowrite32(cmd_port_val, rtl_cmd_addr);
			break;
		}

		while (ioread8(&rtl_table->command)) {
			msleep(10);
			if (count++ > 500) {
				pr_err("Hardware not responding to "
				       "mode switch request\n");
				ret = -EIO;
				break;
			}

		}

		if (ioread8(&rtl_table->command_status)) {
			RTL_DEBUG("command_status reports failed command\n");
			ret = -EIO;
		}
	}

	mutex_unlock(&rtl_lock);
	return ret;
}

static ssize_t rtl_show_version(struct device *dev,
                                struct device_attribute *attr,
                                char *buf)
{
	return sprintf(buf, "%d\n", (int)ioread8(&rtl_table->version));
}

static ssize_t rtl_show_state(struct device *dev,
                              struct device_attribute *attr,
                              char *buf)
{
	return sprintf(buf, "%d\n", ioread8(&rtl_table->rt_status));
}

static ssize_t rtl_set_state(struct device *dev,
                             struct device_attribute *attr,
                             const char *buf,
                             size_t count)
{
	ssize_t ret;

	if (count < 1 || count > 2)
		return -EINVAL;

	switch (buf[0]) {
	case '0':
		ret = ibm_rtl_write(0);
		break;
	case '1':
		ret = ibm_rtl_write(1);
		break;
	default:
		ret = -EINVAL;
	}
	if (ret >= 0)
		ret = count;

	return ret;
}

static struct bus_type rtl_subsys = {
	.name = "ibm_rtl",
	.dev_name = "ibm_rtl",
};

static DEVICE_ATTR(version, S_IRUGO, rtl_show_version, NULL);
static DEVICE_ATTR(state, 0600, rtl_show_state, rtl_set_state);

static struct device_attribute *rtl_attributes[] = {
	&dev_attr_version,
	&dev_attr_state,
	NULL
};


static int rtl_setup_sysfs(void) {
	int ret, i;

	ret = subsys_system_register(&rtl_subsys, NULL);
	if (!ret) {
		for (i = 0; rtl_attributes[i]; i ++)
			device_create_file(rtl_subsys.dev_root, rtl_attributes[i]);
	}
	return ret;
}

static void rtl_teardown_sysfs(void) {
	int i;
	for (i = 0; rtl_attributes[i]; i ++)
		device_remove_file(rtl_subsys.dev_root, rtl_attributes[i]);
	bus_unregister(&rtl_subsys);
}


static struct dmi_system_id __initdata ibm_rtl_dmi_table[] = {
	{                                                  \
		.matches = {                               \
			DMI_MATCH(DMI_SYS_VENDOR, "IBM"),  \
		},                                         \
	},
	{ }
};

static int __init ibm_rtl_init(void) {
	unsigned long ebda_addr, ebda_size;
	unsigned int ebda_kb;
	int ret = -ENODEV, i;

	if (force)
		pr_warn("module loaded by force\n");
	/* first ensure that we are running on IBM HW */
	else if (efi_enabled || !dmi_check_system(ibm_rtl_dmi_table))
		return -ENODEV;

	/* Get the address for the Extended BIOS Data Area */
	ebda_addr = get_bios_ebda();
	if (!ebda_addr) {
		RTL_DEBUG("no BIOS EBDA found\n");
		return -ENODEV;
	}

	ebda_map = ioremap(ebda_addr, 4);
	if (!ebda_map)
		return -ENOMEM;

	/* First word in the EDBA is the Size in KB */
	ebda_kb = ioread16(ebda_map);
	RTL_DEBUG("EBDA is %d kB\n", ebda_kb);

	if (ebda_kb == 0)
		goto out;

	iounmap(ebda_map);
	ebda_size = ebda_kb*1024;

	/* Remap the whole table */
	ebda_map = ioremap(ebda_addr, ebda_size);
	if (!ebda_map)
		return -ENOMEM;

	/* search for the _RTL_ signature at the start of the table */
	for (i = 0 ; i < ebda_size/sizeof(unsigned int); i++) {
		struct ibm_rtl_table __iomem * tmp;
		tmp = (struct ibm_rtl_table __iomem *) (ebda_map+i);
		if ((readq(&tmp->signature) & RTL_MASK) == RTL_SIGNATURE) {
			phys_addr_t addr;
			unsigned int plen;
			RTL_DEBUG("found RTL_SIGNATURE at %p\n", tmp);
			rtl_table = tmp;
			/* The address, value, width and offset are platform
			 * dependent and found in the ibm_rtl_table */
			rtl_cmd_width = ioread8(&rtl_table->cmd_granularity);
			rtl_cmd_type = ioread8(&rtl_table->cmd_address_type);
			RTL_DEBUG("rtl_cmd_width = %u, rtl_cmd_type = %u\n",
				  rtl_cmd_width, rtl_cmd_type);
			addr = ioread32(&rtl_table->cmd_port_address);
			RTL_DEBUG("addr = %#llx\n", (unsigned long long)addr);
			plen = rtl_cmd_width/sizeof(char);
			rtl_cmd_addr = rtl_port_map(addr, plen);
			RTL_DEBUG("rtl_cmd_addr = %p\n", rtl_cmd_addr);
			if (!rtl_cmd_addr) {
				ret = -ENOMEM;
				break;
			}
			ret = rtl_setup_sysfs();
			break;
		}
	}

out:
	if (ret) {
		iounmap(ebda_map);
		rtl_port_unmap(rtl_cmd_addr);
	}

	return ret;
}

static void __exit ibm_rtl_exit(void)
{
	if (rtl_table) {
		RTL_DEBUG("cleaning up");
		/* do not leave the machine in SMI-free mode */
		ibm_rtl_write(0);
		/* unmap, unlink and remove all traces */
		rtl_teardown_sysfs();
		iounmap(ebda_map);
		rtl_port_unmap(rtl_cmd_addr);
	}
}

module_init(ibm_rtl_init);
module_exit(ibm_rtl_exit);