1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * IBM Real-Time Linux driver
4 *
5 * Copyright (C) IBM Corporation, 2010
6 *
7 * Author: Keith Mannthey <kmannth@us.ibm.com>
8 * Vernon Mauery <vernux@us.ibm.com>
9 */
10
11 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
12
13 #include <linux/kernel.h>
14 #include <linux/delay.h>
15 #include <linux/module.h>
16 #include <linux/io.h>
17 #include <linux/dmi.h>
18 #include <linux/efi.h>
19 #include <linux/mutex.h>
20 #include <asm/bios_ebda.h>
21
22 #include <linux/io-64-nonatomic-lo-hi.h>
23
24 static bool force;
25 module_param(force, bool, 0);
26 MODULE_PARM_DESC(force, "Force driver load, ignore DMI data");
27
28 static bool debug;
29 module_param(debug, bool, 0644);
30 MODULE_PARM_DESC(debug, "Show debug output");
31
32 MODULE_LICENSE("GPL");
33 MODULE_AUTHOR("Keith Mannthey <kmmanth@us.ibm.com>");
34 MODULE_AUTHOR("Vernon Mauery <vernux@us.ibm.com>");
35
36 #define RTL_ADDR_TYPE_IO 1
37 #define RTL_ADDR_TYPE_MMIO 2
38
39 #define RTL_CMD_ENTER_PRTM 1
40 #define RTL_CMD_EXIT_PRTM 2
41
42 /* The RTL table as presented by the EBDA: */
43 struct ibm_rtl_table {
44 char signature[5]; /* signature should be "_RTL_" */
45 u8 version;
46 u8 rt_status;
47 u8 command;
48 u8 command_status;
49 u8 cmd_address_type;
50 u8 cmd_granularity;
51 u8 cmd_offset;
52 u16 reserve1;
53 u32 cmd_port_address; /* platform dependent address */
54 u32 cmd_port_value; /* platform dependent value */
55 } __attribute__((packed));
56
57 /* to locate "_RTL_" signature do a masked 5-byte integer compare */
58 #define RTL_SIGNATURE 0x0000005f4c54525fULL
59 #define RTL_MASK 0x000000ffffffffffULL
60
61 #define RTL_DEBUG(fmt, ...) \
62 do { \
63 if (debug) \
64 pr_info(fmt, ##__VA_ARGS__); \
65 } while (0)
66
67 static DEFINE_MUTEX(rtl_lock);
68 static struct ibm_rtl_table __iomem *rtl_table;
69 static void __iomem *ebda_map;
70 static void __iomem *rtl_cmd_addr;
71 static u8 rtl_cmd_type;
72 static u8 rtl_cmd_width;
73
rtl_port_map(phys_addr_t addr,unsigned long len)74 static void __iomem *rtl_port_map(phys_addr_t addr, unsigned long len)
75 {
76 if (rtl_cmd_type == RTL_ADDR_TYPE_MMIO)
77 return ioremap(addr, len);
78 return ioport_map(addr, len);
79 }
80
rtl_port_unmap(void __iomem * addr)81 static void rtl_port_unmap(void __iomem *addr)
82 {
83 if (addr && rtl_cmd_type == RTL_ADDR_TYPE_MMIO)
84 iounmap(addr);
85 else
86 ioport_unmap(addr);
87 }
88
ibm_rtl_write(u8 value)89 static int ibm_rtl_write(u8 value)
90 {
91 int ret = 0, count = 0;
92 u32 cmd_port_val;
93
94 RTL_DEBUG("%s(%d)\n", __func__, value);
95
96 value = value == 1 ? RTL_CMD_ENTER_PRTM : RTL_CMD_EXIT_PRTM;
97
98 mutex_lock(&rtl_lock);
99
100 if (ioread8(&rtl_table->rt_status) != value) {
101 iowrite8(value, &rtl_table->command);
102
103 switch (rtl_cmd_width) {
104 case 8:
105 cmd_port_val = ioread8(&rtl_table->cmd_port_value);
106 RTL_DEBUG("cmd_port_val = %u\n", cmd_port_val);
107 iowrite8((u8)cmd_port_val, rtl_cmd_addr);
108 break;
109 case 16:
110 cmd_port_val = ioread16(&rtl_table->cmd_port_value);
111 RTL_DEBUG("cmd_port_val = %u\n", cmd_port_val);
112 iowrite16((u16)cmd_port_val, rtl_cmd_addr);
113 break;
114 case 32:
115 cmd_port_val = ioread32(&rtl_table->cmd_port_value);
116 RTL_DEBUG("cmd_port_val = %u\n", cmd_port_val);
117 iowrite32(cmd_port_val, rtl_cmd_addr);
118 break;
119 }
120
121 while (ioread8(&rtl_table->command)) {
122 msleep(10);
123 if (count++ > 500) {
124 pr_err("Hardware not responding to "
125 "mode switch request\n");
126 ret = -EIO;
127 break;
128 }
129
130 }
131
132 if (ioread8(&rtl_table->command_status)) {
133 RTL_DEBUG("command_status reports failed command\n");
134 ret = -EIO;
135 }
136 }
137
138 mutex_unlock(&rtl_lock);
139 return ret;
140 }
141
rtl_show_version(struct device * dev,struct device_attribute * attr,char * buf)142 static ssize_t rtl_show_version(struct device *dev,
143 struct device_attribute *attr,
144 char *buf)
145 {
146 return sprintf(buf, "%d\n", (int)ioread8(&rtl_table->version));
147 }
148
rtl_show_state(struct device * dev,struct device_attribute * attr,char * buf)149 static ssize_t rtl_show_state(struct device *dev,
150 struct device_attribute *attr,
151 char *buf)
152 {
153 return sprintf(buf, "%d\n", ioread8(&rtl_table->rt_status));
154 }
155
rtl_set_state(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)156 static ssize_t rtl_set_state(struct device *dev,
157 struct device_attribute *attr,
158 const char *buf,
159 size_t count)
160 {
161 ssize_t ret;
162
163 if (count < 1 || count > 2)
164 return -EINVAL;
165
166 switch (buf[0]) {
167 case '0':
168 ret = ibm_rtl_write(0);
169 break;
170 case '1':
171 ret = ibm_rtl_write(1);
172 break;
173 default:
174 ret = -EINVAL;
175 }
176 if (ret >= 0)
177 ret = count;
178
179 return ret;
180 }
181
182 static struct bus_type rtl_subsys = {
183 .name = "ibm_rtl",
184 .dev_name = "ibm_rtl",
185 };
186
187 static DEVICE_ATTR(version, S_IRUGO, rtl_show_version, NULL);
188 static DEVICE_ATTR(state, 0600, rtl_show_state, rtl_set_state);
189
190 static struct device_attribute *rtl_attributes[] = {
191 &dev_attr_version,
192 &dev_attr_state,
193 NULL
194 };
195
196
rtl_setup_sysfs(void)197 static int rtl_setup_sysfs(void) {
198 int ret, i;
199
200 ret = subsys_system_register(&rtl_subsys, NULL);
201 if (!ret) {
202 for (i = 0; rtl_attributes[i]; i ++)
203 device_create_file(rtl_subsys.dev_root, rtl_attributes[i]);
204 }
205 return ret;
206 }
207
rtl_teardown_sysfs(void)208 static void rtl_teardown_sysfs(void) {
209 int i;
210 for (i = 0; rtl_attributes[i]; i ++)
211 device_remove_file(rtl_subsys.dev_root, rtl_attributes[i]);
212 bus_unregister(&rtl_subsys);
213 }
214
215
216 static const struct dmi_system_id ibm_rtl_dmi_table[] __initconst = {
217 { \
218 .matches = { \
219 DMI_MATCH(DMI_SYS_VENDOR, "IBM"), \
220 }, \
221 },
222 { }
223 };
224
ibm_rtl_init(void)225 static int __init ibm_rtl_init(void) {
226 unsigned long ebda_addr, ebda_size;
227 unsigned int ebda_kb;
228 int ret = -ENODEV, i;
229
230 if (force)
231 pr_warn("module loaded by force\n");
232 /* first ensure that we are running on IBM HW */
233 else if (efi_enabled(EFI_BOOT) || !dmi_check_system(ibm_rtl_dmi_table))
234 return -ENODEV;
235
236 /* Get the address for the Extended BIOS Data Area */
237 ebda_addr = get_bios_ebda();
238 if (!ebda_addr) {
239 RTL_DEBUG("no BIOS EBDA found\n");
240 return -ENODEV;
241 }
242
243 ebda_map = ioremap(ebda_addr, 4);
244 if (!ebda_map)
245 return -ENOMEM;
246
247 /* First word in the EDBA is the Size in KB */
248 ebda_kb = ioread16(ebda_map);
249 RTL_DEBUG("EBDA is %d kB\n", ebda_kb);
250
251 if (ebda_kb == 0)
252 goto out;
253
254 iounmap(ebda_map);
255 ebda_size = ebda_kb*1024;
256
257 /* Remap the whole table */
258 ebda_map = ioremap(ebda_addr, ebda_size);
259 if (!ebda_map)
260 return -ENOMEM;
261
262 /* search for the _RTL_ signature at the start of the table */
263 for (i = 0 ; i < ebda_size/sizeof(unsigned int); i++) {
264 struct ibm_rtl_table __iomem * tmp;
265 tmp = (struct ibm_rtl_table __iomem *) (ebda_map+i);
266 if ((readq(&tmp->signature) & RTL_MASK) == RTL_SIGNATURE) {
267 phys_addr_t addr;
268 unsigned int plen;
269 RTL_DEBUG("found RTL_SIGNATURE at %p\n", tmp);
270 rtl_table = tmp;
271 /* The address, value, width and offset are platform
272 * dependent and found in the ibm_rtl_table */
273 rtl_cmd_width = ioread8(&rtl_table->cmd_granularity);
274 rtl_cmd_type = ioread8(&rtl_table->cmd_address_type);
275 RTL_DEBUG("rtl_cmd_width = %u, rtl_cmd_type = %u\n",
276 rtl_cmd_width, rtl_cmd_type);
277 addr = ioread32(&rtl_table->cmd_port_address);
278 RTL_DEBUG("addr = %#llx\n", (unsigned long long)addr);
279 plen = rtl_cmd_width/sizeof(char);
280 rtl_cmd_addr = rtl_port_map(addr, plen);
281 RTL_DEBUG("rtl_cmd_addr = %p\n", rtl_cmd_addr);
282 if (!rtl_cmd_addr) {
283 ret = -ENOMEM;
284 break;
285 }
286 ret = rtl_setup_sysfs();
287 break;
288 }
289 }
290
291 out:
292 if (ret) {
293 iounmap(ebda_map);
294 rtl_port_unmap(rtl_cmd_addr);
295 }
296
297 return ret;
298 }
299
ibm_rtl_exit(void)300 static void __exit ibm_rtl_exit(void)
301 {
302 if (rtl_table) {
303 RTL_DEBUG("cleaning up");
304 /* do not leave the machine in SMI-free mode */
305 ibm_rtl_write(0);
306 /* unmap, unlink and remove all traces */
307 rtl_teardown_sysfs();
308 iounmap(ebda_map);
309 rtl_port_unmap(rtl_cmd_addr);
310 }
311 }
312
313 module_init(ibm_rtl_init);
314 module_exit(ibm_rtl_exit);
315