xref: /linux/drivers/platform/chrome/cros_ec_lpc.c (revision ec63e2a4897075e427c121d863bd89c44578094f)
1 // SPDX-License-Identifier: GPL-2.0
2 // LPC interface for ChromeOS Embedded Controller
3 //
4 // Copyright (C) 2012-2015 Google, Inc
5 //
6 // This driver uses the ChromeOS EC byte-level message-based protocol for
7 // communicating the keyboard state (which keys are pressed) from a keyboard EC
8 // to the AP over some bus (such as i2c, lpc, spi).  The EC does debouncing,
9 // but everything else (including deghosting) is done here.  The main
10 // motivation for this is to keep the EC firmware as simple as possible, since
11 // it cannot be easily upgraded and EC flash/IRAM space is relatively
12 // expensive.
13 
14 #include <linux/acpi.h>
15 #include <linux/dmi.h>
16 #include <linux/delay.h>
17 #include <linux/io.h>
18 #include <linux/interrupt.h>
19 #include <linux/mfd/cros_ec.h>
20 #include <linux/mfd/cros_ec_commands.h>
21 #include <linux/module.h>
22 #include <linux/platform_device.h>
23 #include <linux/printk.h>
24 #include <linux/suspend.h>
25 
26 #include "cros_ec_lpc_reg.h"
27 
28 #define DRV_NAME "cros_ec_lpcs"
29 #define ACPI_DRV_NAME "GOOG0004"
30 
31 /* True if ACPI device is present */
32 static bool cros_ec_lpc_acpi_device_found;
33 
34 static int ec_response_timed_out(void)
35 {
36 	unsigned long one_second = jiffies + HZ;
37 	u8 data;
38 
39 	usleep_range(200, 300);
40 	do {
41 		if (!(cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_CMD, 1, &data) &
42 		    EC_LPC_STATUS_BUSY_MASK))
43 			return 0;
44 		usleep_range(100, 200);
45 	} while (time_before(jiffies, one_second));
46 
47 	return 1;
48 }
49 
50 static int cros_ec_pkt_xfer_lpc(struct cros_ec_device *ec,
51 				struct cros_ec_command *msg)
52 {
53 	struct ec_host_response response;
54 	u8 sum;
55 	int ret = 0;
56 	u8 *dout;
57 
58 	ret = cros_ec_prepare_tx(ec, msg);
59 
60 	/* Write buffer */
61 	cros_ec_lpc_write_bytes(EC_LPC_ADDR_HOST_PACKET, ret, ec->dout);
62 
63 	/* Here we go */
64 	sum = EC_COMMAND_PROTOCOL_3;
65 	cros_ec_lpc_write_bytes(EC_LPC_ADDR_HOST_CMD, 1, &sum);
66 
67 	if (ec_response_timed_out()) {
68 		dev_warn(ec->dev, "EC responsed timed out\n");
69 		ret = -EIO;
70 		goto done;
71 	}
72 
73 	/* Check result */
74 	msg->result = cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_DATA, 1, &sum);
75 	ret = cros_ec_check_result(ec, msg);
76 	if (ret)
77 		goto done;
78 
79 	/* Read back response */
80 	dout = (u8 *)&response;
81 	sum = cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_PACKET, sizeof(response),
82 				     dout);
83 
84 	msg->result = response.result;
85 
86 	if (response.data_len > msg->insize) {
87 		dev_err(ec->dev,
88 			"packet too long (%d bytes, expected %d)",
89 			response.data_len, msg->insize);
90 		ret = -EMSGSIZE;
91 		goto done;
92 	}
93 
94 	/* Read response and process checksum */
95 	sum += cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_PACKET +
96 				      sizeof(response), response.data_len,
97 				      msg->data);
98 
99 	if (sum) {
100 		dev_err(ec->dev,
101 			"bad packet checksum %02x\n",
102 			response.checksum);
103 		ret = -EBADMSG;
104 		goto done;
105 	}
106 
107 	/* Return actual amount of data received */
108 	ret = response.data_len;
109 done:
110 	return ret;
111 }
112 
113 static int cros_ec_cmd_xfer_lpc(struct cros_ec_device *ec,
114 				struct cros_ec_command *msg)
115 {
116 	struct ec_lpc_host_args args;
117 	u8 sum;
118 	int ret = 0;
119 
120 	if (msg->outsize > EC_PROTO2_MAX_PARAM_SIZE ||
121 	    msg->insize > EC_PROTO2_MAX_PARAM_SIZE) {
122 		dev_err(ec->dev,
123 			"invalid buffer sizes (out %d, in %d)\n",
124 			msg->outsize, msg->insize);
125 		return -EINVAL;
126 	}
127 
128 	/* Now actually send the command to the EC and get the result */
129 	args.flags = EC_HOST_ARGS_FLAG_FROM_HOST;
130 	args.command_version = msg->version;
131 	args.data_size = msg->outsize;
132 
133 	/* Initialize checksum */
134 	sum = msg->command + args.flags + args.command_version + args.data_size;
135 
136 	/* Copy data and update checksum */
137 	sum += cros_ec_lpc_write_bytes(EC_LPC_ADDR_HOST_PARAM, msg->outsize,
138 				       msg->data);
139 
140 	/* Finalize checksum and write args */
141 	args.checksum = sum;
142 	cros_ec_lpc_write_bytes(EC_LPC_ADDR_HOST_ARGS, sizeof(args),
143 				(u8 *)&args);
144 
145 	/* Here we go */
146 	sum = msg->command;
147 	cros_ec_lpc_write_bytes(EC_LPC_ADDR_HOST_CMD, 1, &sum);
148 
149 	if (ec_response_timed_out()) {
150 		dev_warn(ec->dev, "EC responsed timed out\n");
151 		ret = -EIO;
152 		goto done;
153 	}
154 
155 	/* Check result */
156 	msg->result = cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_DATA, 1, &sum);
157 	ret = cros_ec_check_result(ec, msg);
158 	if (ret)
159 		goto done;
160 
161 	/* Read back args */
162 	cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_ARGS, sizeof(args),
163 			       (u8 *)&args);
164 
165 	if (args.data_size > msg->insize) {
166 		dev_err(ec->dev,
167 			"packet too long (%d bytes, expected %d)",
168 			args.data_size, msg->insize);
169 		ret = -ENOSPC;
170 		goto done;
171 	}
172 
173 	/* Start calculating response checksum */
174 	sum = msg->command + args.flags + args.command_version + args.data_size;
175 
176 	/* Read response and update checksum */
177 	sum += cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_PARAM, args.data_size,
178 				      msg->data);
179 
180 	/* Verify checksum */
181 	if (args.checksum != sum) {
182 		dev_err(ec->dev,
183 			"bad packet checksum, expected %02x, got %02x\n",
184 			args.checksum, sum);
185 		ret = -EBADMSG;
186 		goto done;
187 	}
188 
189 	/* Return actual amount of data received */
190 	ret = args.data_size;
191 done:
192 	return ret;
193 }
194 
195 /* Returns num bytes read, or negative on error. Doesn't need locking. */
196 static int cros_ec_lpc_readmem(struct cros_ec_device *ec, unsigned int offset,
197 			       unsigned int bytes, void *dest)
198 {
199 	int i = offset;
200 	char *s = dest;
201 	int cnt = 0;
202 
203 	if (offset >= EC_MEMMAP_SIZE - bytes)
204 		return -EINVAL;
205 
206 	/* fixed length */
207 	if (bytes) {
208 		cros_ec_lpc_read_bytes(EC_LPC_ADDR_MEMMAP + offset, bytes, s);
209 		return bytes;
210 	}
211 
212 	/* string */
213 	for (; i < EC_MEMMAP_SIZE; i++, s++) {
214 		cros_ec_lpc_read_bytes(EC_LPC_ADDR_MEMMAP + i, 1, s);
215 		cnt++;
216 		if (!*s)
217 			break;
218 	}
219 
220 	return cnt;
221 }
222 
223 static void cros_ec_lpc_acpi_notify(acpi_handle device, u32 value, void *data)
224 {
225 	struct cros_ec_device *ec_dev = data;
226 
227 	if (ec_dev->mkbp_event_supported &&
228 	    cros_ec_get_next_event(ec_dev, NULL) > 0)
229 		blocking_notifier_call_chain(&ec_dev->event_notifier, 0,
230 					     ec_dev);
231 
232 	if (value == ACPI_NOTIFY_DEVICE_WAKE)
233 		pm_system_wakeup();
234 }
235 
236 static int cros_ec_lpc_probe(struct platform_device *pdev)
237 {
238 	struct device *dev = &pdev->dev;
239 	struct acpi_device *adev;
240 	acpi_status status;
241 	struct cros_ec_device *ec_dev;
242 	u8 buf[2];
243 	int irq, ret;
244 
245 	if (!devm_request_region(dev, EC_LPC_ADDR_MEMMAP, EC_MEMMAP_SIZE,
246 				 dev_name(dev))) {
247 		dev_err(dev, "couldn't reserve memmap region\n");
248 		return -EBUSY;
249 	}
250 
251 	cros_ec_lpc_read_bytes(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_ID, 2, buf);
252 	if (buf[0] != 'E' || buf[1] != 'C') {
253 		dev_err(dev, "EC ID not detected\n");
254 		return -ENODEV;
255 	}
256 
257 	if (!devm_request_region(dev, EC_HOST_CMD_REGION0,
258 				 EC_HOST_CMD_REGION_SIZE, dev_name(dev))) {
259 		dev_err(dev, "couldn't reserve region0\n");
260 		return -EBUSY;
261 	}
262 	if (!devm_request_region(dev, EC_HOST_CMD_REGION1,
263 				 EC_HOST_CMD_REGION_SIZE, dev_name(dev))) {
264 		dev_err(dev, "couldn't reserve region1\n");
265 		return -EBUSY;
266 	}
267 
268 	ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL);
269 	if (!ec_dev)
270 		return -ENOMEM;
271 
272 	platform_set_drvdata(pdev, ec_dev);
273 	ec_dev->dev = dev;
274 	ec_dev->phys_name = dev_name(dev);
275 	ec_dev->cmd_xfer = cros_ec_cmd_xfer_lpc;
276 	ec_dev->pkt_xfer = cros_ec_pkt_xfer_lpc;
277 	ec_dev->cmd_readmem = cros_ec_lpc_readmem;
278 	ec_dev->din_size = sizeof(struct ec_host_response) +
279 			   sizeof(struct ec_response_get_protocol_info);
280 	ec_dev->dout_size = sizeof(struct ec_host_request);
281 
282 	/*
283 	 * Some boards do not have an IRQ allotted for cros_ec_lpc,
284 	 * which makes ENXIO an expected (and safe) scenario.
285 	 */
286 	irq = platform_get_irq(pdev, 0);
287 	if (irq > 0)
288 		ec_dev->irq = irq;
289 	else if (irq != -ENXIO) {
290 		dev_err(dev, "couldn't retrieve IRQ number (%d)\n", irq);
291 		return irq;
292 	}
293 
294 	ret = cros_ec_register(ec_dev);
295 	if (ret) {
296 		dev_err(dev, "couldn't register ec_dev (%d)\n", ret);
297 		return ret;
298 	}
299 
300 	/*
301 	 * Connect a notify handler to process MKBP messages if we have a
302 	 * companion ACPI device.
303 	 */
304 	adev = ACPI_COMPANION(dev);
305 	if (adev) {
306 		status = acpi_install_notify_handler(adev->handle,
307 						     ACPI_ALL_NOTIFY,
308 						     cros_ec_lpc_acpi_notify,
309 						     ec_dev);
310 		if (ACPI_FAILURE(status))
311 			dev_warn(dev, "Failed to register notifier %08x\n",
312 				 status);
313 	}
314 
315 	return 0;
316 }
317 
318 static int cros_ec_lpc_remove(struct platform_device *pdev)
319 {
320 	struct acpi_device *adev;
321 
322 	adev = ACPI_COMPANION(&pdev->dev);
323 	if (adev)
324 		acpi_remove_notify_handler(adev->handle, ACPI_ALL_NOTIFY,
325 					   cros_ec_lpc_acpi_notify);
326 
327 	return 0;
328 }
329 
330 static const struct acpi_device_id cros_ec_lpc_acpi_device_ids[] = {
331 	{ ACPI_DRV_NAME, 0 },
332 	{ }
333 };
334 MODULE_DEVICE_TABLE(acpi, cros_ec_lpc_acpi_device_ids);
335 
336 static const struct dmi_system_id cros_ec_lpc_dmi_table[] __initconst = {
337 	{
338 		/*
339 		 * Today all Chromebooks/boxes ship with Google_* as version and
340 		 * coreboot as bios vendor. No other systems with this
341 		 * combination are known to date.
342 		 */
343 		.matches = {
344 			DMI_MATCH(DMI_BIOS_VENDOR, "coreboot"),
345 			DMI_MATCH(DMI_BIOS_VERSION, "Google_"),
346 		},
347 	},
348 	{
349 		/*
350 		 * If the box is running custom coreboot firmware then the
351 		 * DMI BIOS version string will not be matched by "Google_",
352 		 * but the system vendor string will still be matched by
353 		 * "GOOGLE".
354 		 */
355 		.matches = {
356 			DMI_MATCH(DMI_BIOS_VENDOR, "coreboot"),
357 			DMI_MATCH(DMI_SYS_VENDOR, "GOOGLE"),
358 		},
359 	},
360 	{
361 		/* x86-link, the Chromebook Pixel. */
362 		.matches = {
363 			DMI_MATCH(DMI_SYS_VENDOR, "GOOGLE"),
364 			DMI_MATCH(DMI_PRODUCT_NAME, "Link"),
365 		},
366 	},
367 	{
368 		/* x86-samus, the Chromebook Pixel 2. */
369 		.matches = {
370 			DMI_MATCH(DMI_SYS_VENDOR, "GOOGLE"),
371 			DMI_MATCH(DMI_PRODUCT_NAME, "Samus"),
372 		},
373 	},
374 	{
375 		/* x86-peppy, the Acer C720 Chromebook. */
376 		.matches = {
377 			DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
378 			DMI_MATCH(DMI_PRODUCT_NAME, "Peppy"),
379 		},
380 	},
381 	{
382 		/* x86-glimmer, the Lenovo Thinkpad Yoga 11e. */
383 		.matches = {
384 			DMI_MATCH(DMI_SYS_VENDOR, "GOOGLE"),
385 			DMI_MATCH(DMI_PRODUCT_NAME, "Glimmer"),
386 		},
387 	},
388 	{ /* sentinel */ }
389 };
390 MODULE_DEVICE_TABLE(dmi, cros_ec_lpc_dmi_table);
391 
392 #ifdef CONFIG_PM_SLEEP
393 static int cros_ec_lpc_suspend(struct device *dev)
394 {
395 	struct cros_ec_device *ec_dev = dev_get_drvdata(dev);
396 
397 	return cros_ec_suspend(ec_dev);
398 }
399 
400 static int cros_ec_lpc_resume(struct device *dev)
401 {
402 	struct cros_ec_device *ec_dev = dev_get_drvdata(dev);
403 
404 	return cros_ec_resume(ec_dev);
405 }
406 #endif
407 
408 const struct dev_pm_ops cros_ec_lpc_pm_ops = {
409 	SET_LATE_SYSTEM_SLEEP_PM_OPS(cros_ec_lpc_suspend, cros_ec_lpc_resume)
410 };
411 
412 static struct platform_driver cros_ec_lpc_driver = {
413 	.driver = {
414 		.name = DRV_NAME,
415 		.acpi_match_table = cros_ec_lpc_acpi_device_ids,
416 		.pm = &cros_ec_lpc_pm_ops,
417 	},
418 	.probe = cros_ec_lpc_probe,
419 	.remove = cros_ec_lpc_remove,
420 };
421 
422 static struct platform_device cros_ec_lpc_device = {
423 	.name = DRV_NAME
424 };
425 
426 static acpi_status cros_ec_lpc_parse_device(acpi_handle handle, u32 level,
427 					    void *context, void **retval)
428 {
429 	*(bool *)context = true;
430 	return AE_CTRL_TERMINATE;
431 }
432 
433 static int __init cros_ec_lpc_init(void)
434 {
435 	int ret;
436 	acpi_status status;
437 
438 	status = acpi_get_devices(ACPI_DRV_NAME, cros_ec_lpc_parse_device,
439 				  &cros_ec_lpc_acpi_device_found, NULL);
440 	if (ACPI_FAILURE(status))
441 		pr_warn(DRV_NAME ": Looking for %s failed\n", ACPI_DRV_NAME);
442 
443 	if (!cros_ec_lpc_acpi_device_found &&
444 	    !dmi_check_system(cros_ec_lpc_dmi_table)) {
445 		pr_err(DRV_NAME ": unsupported system.\n");
446 		return -ENODEV;
447 	}
448 
449 	cros_ec_lpc_reg_init();
450 
451 	/* Register the driver */
452 	ret = platform_driver_register(&cros_ec_lpc_driver);
453 	if (ret) {
454 		pr_err(DRV_NAME ": can't register driver: %d\n", ret);
455 		cros_ec_lpc_reg_destroy();
456 		return ret;
457 	}
458 
459 	if (!cros_ec_lpc_acpi_device_found) {
460 		/* Register the device, and it'll get hooked up automatically */
461 		ret = platform_device_register(&cros_ec_lpc_device);
462 		if (ret) {
463 			pr_err(DRV_NAME ": can't register device: %d\n", ret);
464 			platform_driver_unregister(&cros_ec_lpc_driver);
465 			cros_ec_lpc_reg_destroy();
466 		}
467 	}
468 
469 	return ret;
470 }
471 
472 static void __exit cros_ec_lpc_exit(void)
473 {
474 	if (!cros_ec_lpc_acpi_device_found)
475 		platform_device_unregister(&cros_ec_lpc_device);
476 	platform_driver_unregister(&cros_ec_lpc_driver);
477 	cros_ec_lpc_reg_destroy();
478 }
479 
480 module_init(cros_ec_lpc_init);
481 module_exit(cros_ec_lpc_exit);
482 
483 MODULE_LICENSE("GPL");
484 MODULE_DESCRIPTION("ChromeOS EC LPC driver");
485