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/acpi.h>
25 #include <linux/dmi.h>
26 #include <linux/delay.h>
27 #include <linux/io.h>
28 #include <linux/mfd/cros_ec.h>
29 #include <linux/mfd/cros_ec_commands.h>
30 #include <linux/mfd/cros_ec_lpc_reg.h>
31 #include <linux/module.h>
32 #include <linux/platform_device.h>
33 #include <linux/printk.h>
34
35 #define DRV_NAME "cros_ec_lpcs"
36 #define ACPI_DRV_NAME "GOOG0004"
37
ec_response_timed_out(void)38 static int ec_response_timed_out(void)
39 {
40 unsigned long one_second = jiffies + HZ;
41 u8 data;
42
43 usleep_range(200, 300);
44 do {
45 if (!(cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_CMD, 1, &data) &
46 EC_LPC_STATUS_BUSY_MASK))
47 return 0;
48 usleep_range(100, 200);
49 } while (time_before(jiffies, one_second));
50
51 return 1;
52 }
53
cros_ec_pkt_xfer_lpc(struct cros_ec_device * ec,struct cros_ec_command * msg)54 static int cros_ec_pkt_xfer_lpc(struct cros_ec_device *ec,
55 struct cros_ec_command *msg)
56 {
57 struct ec_host_response response;
58 u8 sum;
59 int ret = 0;
60 u8 *dout;
61
62 ret = cros_ec_prepare_tx(ec, msg);
63
64 /* Write buffer */
65 cros_ec_lpc_write_bytes(EC_LPC_ADDR_HOST_PACKET, ret, ec->dout);
66
67 /* Here we go */
68 sum = EC_COMMAND_PROTOCOL_3;
69 cros_ec_lpc_write_bytes(EC_LPC_ADDR_HOST_CMD, 1, &sum);
70
71 if (ec_response_timed_out()) {
72 dev_warn(ec->dev, "EC responsed timed out\n");
73 ret = -EIO;
74 goto done;
75 }
76
77 /* Check result */
78 msg->result = cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_DATA, 1, &sum);
79 ret = cros_ec_check_result(ec, msg);
80 if (ret)
81 goto done;
82
83 /* Read back response */
84 dout = (u8 *)&response;
85 sum = cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_PACKET, sizeof(response),
86 dout);
87
88 msg->result = response.result;
89
90 if (response.data_len > msg->insize) {
91 dev_err(ec->dev,
92 "packet too long (%d bytes, expected %d)",
93 response.data_len, msg->insize);
94 ret = -EMSGSIZE;
95 goto done;
96 }
97
98 /* Read response and process checksum */
99 sum += cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_PACKET +
100 sizeof(response), response.data_len,
101 msg->data);
102
103 if (sum) {
104 dev_err(ec->dev,
105 "bad packet checksum %02x\n",
106 response.checksum);
107 ret = -EBADMSG;
108 goto done;
109 }
110
111 /* Return actual amount of data received */
112 ret = response.data_len;
113 done:
114 return ret;
115 }
116
cros_ec_cmd_xfer_lpc(struct cros_ec_device * ec,struct cros_ec_command * msg)117 static int cros_ec_cmd_xfer_lpc(struct cros_ec_device *ec,
118 struct cros_ec_command *msg)
119 {
120 struct ec_lpc_host_args args;
121 u8 sum;
122 int ret = 0;
123
124 if (msg->outsize > EC_PROTO2_MAX_PARAM_SIZE ||
125 msg->insize > EC_PROTO2_MAX_PARAM_SIZE) {
126 dev_err(ec->dev,
127 "invalid buffer sizes (out %d, in %d)\n",
128 msg->outsize, msg->insize);
129 return -EINVAL;
130 }
131
132 /* Now actually send the command to the EC and get the result */
133 args.flags = EC_HOST_ARGS_FLAG_FROM_HOST;
134 args.command_version = msg->version;
135 args.data_size = msg->outsize;
136
137 /* Initialize checksum */
138 sum = msg->command + args.flags + args.command_version + args.data_size;
139
140 /* Copy data and update checksum */
141 sum += cros_ec_lpc_write_bytes(EC_LPC_ADDR_HOST_PARAM, msg->outsize,
142 msg->data);
143
144 /* Finalize checksum and write args */
145 args.checksum = sum;
146 cros_ec_lpc_write_bytes(EC_LPC_ADDR_HOST_ARGS, sizeof(args),
147 (u8 *)&args);
148
149 /* Here we go */
150 sum = msg->command;
151 cros_ec_lpc_write_bytes(EC_LPC_ADDR_HOST_CMD, 1, &sum);
152
153 if (ec_response_timed_out()) {
154 dev_warn(ec->dev, "EC responsed timed out\n");
155 ret = -EIO;
156 goto done;
157 }
158
159 /* Check result */
160 msg->result = cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_DATA, 1, &sum);
161 ret = cros_ec_check_result(ec, msg);
162 if (ret)
163 goto done;
164
165 /* Read back args */
166 cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_ARGS, sizeof(args),
167 (u8 *)&args);
168
169 if (args.data_size > msg->insize) {
170 dev_err(ec->dev,
171 "packet too long (%d bytes, expected %d)",
172 args.data_size, msg->insize);
173 ret = -ENOSPC;
174 goto done;
175 }
176
177 /* Start calculating response checksum */
178 sum = msg->command + args.flags + args.command_version + args.data_size;
179
180 /* Read response and update checksum */
181 sum += cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_PARAM, args.data_size,
182 msg->data);
183
184 /* Verify checksum */
185 if (args.checksum != sum) {
186 dev_err(ec->dev,
187 "bad packet checksum, expected %02x, got %02x\n",
188 args.checksum, sum);
189 ret = -EBADMSG;
190 goto done;
191 }
192
193 /* Return actual amount of data received */
194 ret = args.data_size;
195 done:
196 return ret;
197 }
198
199 /* Returns num bytes read, or negative on error. Doesn't need locking. */
cros_ec_lpc_readmem(struct cros_ec_device * ec,unsigned int offset,unsigned int bytes,void * dest)200 static int cros_ec_lpc_readmem(struct cros_ec_device *ec, unsigned int offset,
201 unsigned int bytes, void *dest)
202 {
203 int i = offset;
204 char *s = dest;
205 int cnt = 0;
206
207 if (offset >= EC_MEMMAP_SIZE - bytes)
208 return -EINVAL;
209
210 /* fixed length */
211 if (bytes) {
212 cros_ec_lpc_read_bytes(EC_LPC_ADDR_MEMMAP + offset, bytes, s);
213 return bytes;
214 }
215
216 /* string */
217 for (; i < EC_MEMMAP_SIZE; i++, s++) {
218 cros_ec_lpc_read_bytes(EC_LPC_ADDR_MEMMAP + i, 1, s);
219 cnt++;
220 if (!*s)
221 break;
222 }
223
224 return cnt;
225 }
226
cros_ec_lpc_acpi_notify(acpi_handle device,u32 value,void * data)227 static void cros_ec_lpc_acpi_notify(acpi_handle device, u32 value, void *data)
228 {
229 struct cros_ec_device *ec_dev = data;
230
231 if (ec_dev->mkbp_event_supported &&
232 cros_ec_get_next_event(ec_dev, NULL) > 0)
233 blocking_notifier_call_chain(&ec_dev->event_notifier, 0,
234 ec_dev);
235 }
236
cros_ec_lpc_probe(struct platform_device * pdev)237 static int cros_ec_lpc_probe(struct platform_device *pdev)
238 {
239 struct device *dev = &pdev->dev;
240 struct acpi_device *adev;
241 acpi_status status;
242 struct cros_ec_device *ec_dev;
243 u8 buf[2];
244 int ret;
245
246 if (!devm_request_region(dev, EC_LPC_ADDR_MEMMAP, EC_MEMMAP_SIZE,
247 dev_name(dev))) {
248 dev_err(dev, "couldn't reserve memmap region\n");
249 return -EBUSY;
250 }
251
252 cros_ec_lpc_read_bytes(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_ID, 2, buf);
253 if (buf[0] != 'E' || buf[1] != 'C') {
254 dev_err(dev, "EC ID not detected\n");
255 return -ENODEV;
256 }
257
258 if (!devm_request_region(dev, EC_HOST_CMD_REGION0,
259 EC_HOST_CMD_REGION_SIZE, dev_name(dev))) {
260 dev_err(dev, "couldn't reserve region0\n");
261 return -EBUSY;
262 }
263 if (!devm_request_region(dev, EC_HOST_CMD_REGION1,
264 EC_HOST_CMD_REGION_SIZE, dev_name(dev))) {
265 dev_err(dev, "couldn't reserve region1\n");
266 return -EBUSY;
267 }
268
269 ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL);
270 if (!ec_dev)
271 return -ENOMEM;
272
273 platform_set_drvdata(pdev, ec_dev);
274 ec_dev->dev = dev;
275 ec_dev->phys_name = dev_name(dev);
276 ec_dev->cmd_xfer = cros_ec_cmd_xfer_lpc;
277 ec_dev->pkt_xfer = cros_ec_pkt_xfer_lpc;
278 ec_dev->cmd_readmem = cros_ec_lpc_readmem;
279 ec_dev->din_size = sizeof(struct ec_host_response) +
280 sizeof(struct ec_response_get_protocol_info);
281 ec_dev->dout_size = sizeof(struct ec_host_request);
282
283 ret = cros_ec_register(ec_dev);
284 if (ret) {
285 dev_err(dev, "couldn't register ec_dev (%d)\n", ret);
286 return ret;
287 }
288
289 /*
290 * Connect a notify handler to process MKBP messages if we have a
291 * companion ACPI device.
292 */
293 adev = ACPI_COMPANION(dev);
294 if (adev) {
295 status = acpi_install_notify_handler(adev->handle,
296 ACPI_ALL_NOTIFY,
297 cros_ec_lpc_acpi_notify,
298 ec_dev);
299 if (ACPI_FAILURE(status))
300 dev_warn(dev, "Failed to register notifier %08x\n",
301 status);
302 }
303
304 return 0;
305 }
306
cros_ec_lpc_remove(struct platform_device * pdev)307 static int cros_ec_lpc_remove(struct platform_device *pdev)
308 {
309 struct cros_ec_device *ec_dev;
310 struct acpi_device *adev;
311
312 adev = ACPI_COMPANION(&pdev->dev);
313 if (adev)
314 acpi_remove_notify_handler(adev->handle, ACPI_ALL_NOTIFY,
315 cros_ec_lpc_acpi_notify);
316
317 ec_dev = platform_get_drvdata(pdev);
318 cros_ec_remove(ec_dev);
319
320 return 0;
321 }
322
323 static const struct acpi_device_id cros_ec_lpc_acpi_device_ids[] = {
324 { ACPI_DRV_NAME, 0 },
325 { }
326 };
327 MODULE_DEVICE_TABLE(acpi, cros_ec_lpc_acpi_device_ids);
328
329 static const struct dmi_system_id cros_ec_lpc_dmi_table[] __initconst = {
330 {
331 /*
332 * Today all Chromebooks/boxes ship with Google_* as version and
333 * coreboot as bios vendor. No other systems with this
334 * combination are known to date.
335 */
336 .matches = {
337 DMI_MATCH(DMI_BIOS_VENDOR, "coreboot"),
338 DMI_MATCH(DMI_BIOS_VERSION, "Google_"),
339 },
340 },
341 {
342 /* x86-link, the Chromebook Pixel. */
343 .matches = {
344 DMI_MATCH(DMI_SYS_VENDOR, "GOOGLE"),
345 DMI_MATCH(DMI_PRODUCT_NAME, "Link"),
346 },
347 },
348 {
349 /* x86-samus, the Chromebook Pixel 2. */
350 .matches = {
351 DMI_MATCH(DMI_SYS_VENDOR, "GOOGLE"),
352 DMI_MATCH(DMI_PRODUCT_NAME, "Samus"),
353 },
354 },
355 {
356 /* x86-peppy, the Acer C720 Chromebook. */
357 .matches = {
358 DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
359 DMI_MATCH(DMI_PRODUCT_NAME, "Peppy"),
360 },
361 },
362 { /* sentinel */ }
363 };
364 MODULE_DEVICE_TABLE(dmi, cros_ec_lpc_dmi_table);
365
366 #ifdef CONFIG_PM_SLEEP
cros_ec_lpc_suspend(struct device * dev)367 static int cros_ec_lpc_suspend(struct device *dev)
368 {
369 struct cros_ec_device *ec_dev = dev_get_drvdata(dev);
370
371 return cros_ec_suspend(ec_dev);
372 }
373
cros_ec_lpc_resume(struct device * dev)374 static int cros_ec_lpc_resume(struct device *dev)
375 {
376 struct cros_ec_device *ec_dev = dev_get_drvdata(dev);
377
378 return cros_ec_resume(ec_dev);
379 }
380 #endif
381
382 const struct dev_pm_ops cros_ec_lpc_pm_ops = {
383 SET_LATE_SYSTEM_SLEEP_PM_OPS(cros_ec_lpc_suspend, cros_ec_lpc_resume)
384 };
385
386 static struct platform_driver cros_ec_lpc_driver = {
387 .driver = {
388 .name = DRV_NAME,
389 .acpi_match_table = cros_ec_lpc_acpi_device_ids,
390 .pm = &cros_ec_lpc_pm_ops,
391 },
392 .probe = cros_ec_lpc_probe,
393 .remove = cros_ec_lpc_remove,
394 };
395
cros_ec_lpc_init(void)396 static int __init cros_ec_lpc_init(void)
397 {
398 int ret;
399
400 if (!dmi_check_system(cros_ec_lpc_dmi_table)) {
401 pr_err(DRV_NAME ": unsupported system.\n");
402 return -ENODEV;
403 }
404
405 cros_ec_lpc_reg_init();
406
407 /* Register the driver */
408 ret = platform_driver_register(&cros_ec_lpc_driver);
409 if (ret) {
410 pr_err(DRV_NAME ": can't register driver: %d\n", ret);
411 cros_ec_lpc_reg_destroy();
412 return ret;
413 }
414
415 return 0;
416 }
417
cros_ec_lpc_exit(void)418 static void __exit cros_ec_lpc_exit(void)
419 {
420 platform_driver_unregister(&cros_ec_lpc_driver);
421 cros_ec_lpc_reg_destroy();
422 }
423
424 module_init(cros_ec_lpc_init);
425 module_exit(cros_ec_lpc_exit);
426
427 MODULE_LICENSE("GPL");
428 MODULE_DESCRIPTION("ChromeOS EC LPC driver");
429