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ec2f33ab BR |
1 | /* |
2 | * cros_ec_lpc - LPC access to the Chrome OS Embedded Controller | |
3 | * | |
4 | * Copyright (C) 2012-2015 Google, Inc | |
5 | * | |
6 | * This software is licensed under the terms of the GNU General Public | |
7 | * License version 2, as published by the Free Software Foundation, and | |
8 | * may be copied, distributed, and modified under those terms. | |
9 | * | |
10 | * This program is distributed in the hope that it will be useful, | |
11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
13 | * GNU General Public License for more details. | |
14 | * | |
15 | * This driver uses the Chrome OS EC byte-level message-based protocol for | |
16 | * communicating the keyboard state (which keys are pressed) from a keyboard EC | |
17 | * to the AP over some bus (such as i2c, lpc, spi). The EC does debouncing, | |
18 | * but everything else (including deghosting) is done here. The main | |
19 | * motivation for this is to keep the EC firmware as simple as possible, since | |
20 | * it cannot be easily upgraded and EC flash/IRAM space is relatively | |
21 | * expensive. | |
22 | */ | |
23 | ||
24 | #include <linux/dmi.h> | |
25 | #include <linux/delay.h> | |
18d0dc24 | 26 | #include <linux/io.h> |
ec2f33ab BR |
27 | #include <linux/mfd/cros_ec.h> |
28 | #include <linux/mfd/cros_ec_commands.h> | |
29 | #include <linux/module.h> | |
30 | #include <linux/platform_device.h> | |
31 | #include <linux/printk.h> | |
32 | ||
33 | #define DRV_NAME "cros_ec_lpc" | |
34 | ||
35 | static int ec_response_timed_out(void) | |
36 | { | |
37 | unsigned long one_second = jiffies + HZ; | |
38 | ||
39 | usleep_range(200, 300); | |
40 | do { | |
41 | if (!(inb(EC_LPC_ADDR_HOST_CMD) & EC_LPC_STATUS_BUSY_MASK)) | |
42 | return 0; | |
43 | usleep_range(100, 200); | |
44 | } while (time_before(jiffies, one_second)); | |
45 | ||
46 | return 1; | |
47 | } | |
48 | ||
49 | static int cros_ec_cmd_xfer_lpc(struct cros_ec_device *ec, | |
50 | struct cros_ec_command *msg) | |
51 | { | |
52 | struct ec_lpc_host_args args; | |
53 | int csum; | |
54 | int i; | |
55 | int ret = 0; | |
56 | ||
57 | if (msg->outsize > EC_PROTO2_MAX_PARAM_SIZE || | |
58 | msg->insize > EC_PROTO2_MAX_PARAM_SIZE) { | |
59 | dev_err(ec->dev, | |
60 | "invalid buffer sizes (out %d, in %d)\n", | |
61 | msg->outsize, msg->insize); | |
62 | return -EINVAL; | |
63 | } | |
64 | ||
65 | /* Now actually send the command to the EC and get the result */ | |
66 | args.flags = EC_HOST_ARGS_FLAG_FROM_HOST; | |
67 | args.command_version = msg->version; | |
68 | args.data_size = msg->outsize; | |
69 | ||
70 | /* Initialize checksum */ | |
71 | csum = msg->command + args.flags + | |
72 | args.command_version + args.data_size; | |
73 | ||
74 | /* Copy data and update checksum */ | |
75 | for (i = 0; i < msg->outsize; i++) { | |
a8411784 JMC |
76 | outb(msg->data[i], EC_LPC_ADDR_HOST_PARAM + i); |
77 | csum += msg->data[i]; | |
ec2f33ab BR |
78 | } |
79 | ||
80 | /* Finalize checksum and write args */ | |
81 | args.checksum = csum & 0xFF; | |
82 | outb(args.flags, EC_LPC_ADDR_HOST_ARGS); | |
83 | outb(args.command_version, EC_LPC_ADDR_HOST_ARGS + 1); | |
84 | outb(args.data_size, EC_LPC_ADDR_HOST_ARGS + 2); | |
85 | outb(args.checksum, EC_LPC_ADDR_HOST_ARGS + 3); | |
86 | ||
87 | /* Here we go */ | |
88 | outb(msg->command, EC_LPC_ADDR_HOST_CMD); | |
89 | ||
90 | if (ec_response_timed_out()) { | |
91 | dev_warn(ec->dev, "EC responsed timed out\n"); | |
92 | ret = -EIO; | |
93 | goto done; | |
94 | } | |
95 | ||
96 | /* Check result */ | |
97 | msg->result = inb(EC_LPC_ADDR_HOST_DATA); | |
98 | ||
99 | switch (msg->result) { | |
100 | case EC_RES_SUCCESS: | |
101 | break; | |
102 | case EC_RES_IN_PROGRESS: | |
103 | ret = -EAGAIN; | |
104 | dev_dbg(ec->dev, "command 0x%02x in progress\n", | |
105 | msg->command); | |
106 | goto done; | |
107 | default: | |
108 | dev_dbg(ec->dev, "command 0x%02x returned %d\n", | |
109 | msg->command, msg->result); | |
110 | } | |
111 | ||
112 | /* Read back args */ | |
113 | args.flags = inb(EC_LPC_ADDR_HOST_ARGS); | |
114 | args.command_version = inb(EC_LPC_ADDR_HOST_ARGS + 1); | |
115 | args.data_size = inb(EC_LPC_ADDR_HOST_ARGS + 2); | |
116 | args.checksum = inb(EC_LPC_ADDR_HOST_ARGS + 3); | |
117 | ||
118 | if (args.data_size > msg->insize) { | |
119 | dev_err(ec->dev, | |
120 | "packet too long (%d bytes, expected %d)", | |
121 | args.data_size, msg->insize); | |
122 | ret = -ENOSPC; | |
123 | goto done; | |
124 | } | |
125 | ||
126 | /* Start calculating response checksum */ | |
127 | csum = msg->command + args.flags + | |
128 | args.command_version + args.data_size; | |
129 | ||
130 | /* Read response and update checksum */ | |
131 | for (i = 0; i < args.data_size; i++) { | |
a8411784 JMC |
132 | msg->data[i] = inb(EC_LPC_ADDR_HOST_PARAM + i); |
133 | csum += msg->data[i]; | |
ec2f33ab BR |
134 | } |
135 | ||
136 | /* Verify checksum */ | |
137 | if (args.checksum != (csum & 0xFF)) { | |
138 | dev_err(ec->dev, | |
139 | "bad packet checksum, expected %02x, got %02x\n", | |
140 | args.checksum, csum & 0xFF); | |
141 | ret = -EBADMSG; | |
142 | goto done; | |
143 | } | |
144 | ||
145 | /* Return actual amount of data received */ | |
146 | ret = args.data_size; | |
147 | done: | |
148 | return ret; | |
149 | } | |
150 | ||
151 | /* Returns num bytes read, or negative on error. Doesn't need locking. */ | |
152 | static int cros_ec_lpc_readmem(struct cros_ec_device *ec, unsigned int offset, | |
153 | unsigned int bytes, void *dest) | |
154 | { | |
155 | int i = offset; | |
156 | char *s = dest; | |
157 | int cnt = 0; | |
158 | ||
159 | if (offset >= EC_MEMMAP_SIZE - bytes) | |
160 | return -EINVAL; | |
161 | ||
162 | /* fixed length */ | |
163 | if (bytes) { | |
164 | for (; cnt < bytes; i++, s++, cnt++) | |
165 | *s = inb(EC_LPC_ADDR_MEMMAP + i); | |
166 | return cnt; | |
167 | } | |
168 | ||
169 | /* string */ | |
170 | for (; i < EC_MEMMAP_SIZE; i++, s++) { | |
171 | *s = inb(EC_LPC_ADDR_MEMMAP + i); | |
172 | cnt++; | |
173 | if (!*s) | |
174 | break; | |
175 | } | |
176 | ||
177 | return cnt; | |
178 | } | |
179 | ||
180 | static int cros_ec_lpc_probe(struct platform_device *pdev) | |
181 | { | |
182 | struct device *dev = &pdev->dev; | |
183 | struct cros_ec_device *ec_dev; | |
184 | int ret; | |
185 | ||
186 | if (!devm_request_region(dev, EC_LPC_ADDR_MEMMAP, EC_MEMMAP_SIZE, | |
187 | dev_name(dev))) { | |
188 | dev_err(dev, "couldn't reserve memmap region\n"); | |
189 | return -EBUSY; | |
190 | } | |
191 | ||
192 | if ((inb(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_ID) != 'E') || | |
193 | (inb(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_ID + 1) != 'C')) { | |
194 | dev_err(dev, "EC ID not detected\n"); | |
195 | return -ENODEV; | |
196 | } | |
197 | ||
198 | if (!devm_request_region(dev, EC_HOST_CMD_REGION0, | |
199 | EC_HOST_CMD_REGION_SIZE, dev_name(dev))) { | |
200 | dev_err(dev, "couldn't reserve region0\n"); | |
201 | return -EBUSY; | |
202 | } | |
203 | if (!devm_request_region(dev, EC_HOST_CMD_REGION1, | |
204 | EC_HOST_CMD_REGION_SIZE, dev_name(dev))) { | |
205 | dev_err(dev, "couldn't reserve region1\n"); | |
206 | return -EBUSY; | |
207 | } | |
208 | ||
209 | ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL); | |
210 | if (!ec_dev) | |
211 | return -ENOMEM; | |
212 | ||
213 | platform_set_drvdata(pdev, ec_dev); | |
214 | ec_dev->dev = dev; | |
215 | ec_dev->ec_name = pdev->name; | |
216 | ec_dev->phys_name = dev_name(dev); | |
ec2f33ab | 217 | ec_dev->cmd_xfer = cros_ec_cmd_xfer_lpc; |
2c7589af | 218 | ec_dev->pkt_xfer = NULL; |
ec2f33ab | 219 | ec_dev->cmd_readmem = cros_ec_lpc_readmem; |
2c7589af SB |
220 | ec_dev->din_size = sizeof(struct ec_host_response) + |
221 | sizeof(struct ec_response_get_protocol_info); | |
222 | ec_dev->dout_size = sizeof(struct ec_host_request); | |
ec2f33ab BR |
223 | |
224 | ret = cros_ec_register(ec_dev); | |
225 | if (ret) { | |
226 | dev_err(dev, "couldn't register ec_dev (%d)\n", ret); | |
227 | return ret; | |
228 | } | |
229 | ||
230 | return 0; | |
231 | } | |
232 | ||
233 | static int cros_ec_lpc_remove(struct platform_device *pdev) | |
234 | { | |
235 | struct cros_ec_device *ec_dev; | |
236 | ||
237 | ec_dev = platform_get_drvdata(pdev); | |
238 | cros_ec_remove(ec_dev); | |
239 | ||
240 | return 0; | |
241 | } | |
242 | ||
243 | static struct dmi_system_id cros_ec_lpc_dmi_table[] __initdata = { | |
244 | { | |
245 | /* | |
246 | * Today all Chromebooks/boxes ship with Google_* as version and | |
247 | * coreboot as bios vendor. No other systems with this | |
248 | * combination are known to date. | |
249 | */ | |
250 | .matches = { | |
251 | DMI_MATCH(DMI_BIOS_VENDOR, "coreboot"), | |
252 | DMI_MATCH(DMI_BIOS_VERSION, "Google_"), | |
253 | }, | |
254 | }, | |
255 | { | |
256 | /* x86-link, the Chromebook Pixel. */ | |
257 | .matches = { | |
258 | DMI_MATCH(DMI_SYS_VENDOR, "GOOGLE"), | |
259 | DMI_MATCH(DMI_PRODUCT_NAME, "Link"), | |
260 | }, | |
261 | }, | |
262 | { | |
263 | /* x86-peppy, the Acer C720 Chromebook. */ | |
264 | .matches = { | |
265 | DMI_MATCH(DMI_SYS_VENDOR, "Acer"), | |
266 | DMI_MATCH(DMI_PRODUCT_NAME, "Peppy"), | |
267 | }, | |
268 | }, | |
269 | { /* sentinel */ } | |
270 | }; | |
271 | MODULE_DEVICE_TABLE(dmi, cros_ec_lpc_dmi_table); | |
272 | ||
273 | static struct platform_driver cros_ec_lpc_driver = { | |
274 | .driver = { | |
275 | .name = DRV_NAME, | |
ec2f33ab BR |
276 | }, |
277 | .probe = cros_ec_lpc_probe, | |
278 | .remove = cros_ec_lpc_remove, | |
279 | }; | |
280 | ||
281 | static struct platform_device cros_ec_lpc_device = { | |
282 | .name = DRV_NAME | |
283 | }; | |
284 | ||
285 | static int __init cros_ec_lpc_init(void) | |
286 | { | |
287 | int ret; | |
288 | ||
289 | if (!dmi_check_system(cros_ec_lpc_dmi_table)) { | |
290 | pr_err(DRV_NAME ": unsupported system.\n"); | |
291 | return -ENODEV; | |
292 | } | |
293 | ||
294 | /* Register the driver */ | |
295 | ret = platform_driver_register(&cros_ec_lpc_driver); | |
296 | if (ret) { | |
297 | pr_err(DRV_NAME ": can't register driver: %d\n", ret); | |
298 | return ret; | |
299 | } | |
300 | ||
301 | /* Register the device, and it'll get hooked up automatically */ | |
302 | ret = platform_device_register(&cros_ec_lpc_device); | |
303 | if (ret) { | |
304 | pr_err(DRV_NAME ": can't register device: %d\n", ret); | |
305 | platform_driver_unregister(&cros_ec_lpc_driver); | |
306 | return ret; | |
307 | } | |
308 | ||
309 | return 0; | |
310 | } | |
311 | ||
312 | static void __exit cros_ec_lpc_exit(void) | |
313 | { | |
314 | platform_device_unregister(&cros_ec_lpc_device); | |
315 | platform_driver_unregister(&cros_ec_lpc_driver); | |
316 | } | |
317 | ||
318 | module_init(cros_ec_lpc_init); | |
319 | module_exit(cros_ec_lpc_exit); | |
320 | ||
321 | MODULE_LICENSE("GPL"); | |
322 | MODULE_DESCRIPTION("ChromeOS EC LPC driver"); |