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#include <linux/suspend.h>
 35
 36#define DRV_NAME "cros_ec_lpcs"
 37#define ACPI_DRV_NAME "GOOG0004"
 38
 39/* True if ACPI device is present */
 40static bool cros_ec_lpc_acpi_device_found;
 41
 42static int ec_response_timed_out(void)
 43{
 44	unsigned long one_second = jiffies + HZ;
 45	u8 data;
 46
 47	usleep_range(200, 300);
 48	do {
 49		if (!(cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_CMD, 1, &data) &
 50		    EC_LPC_STATUS_BUSY_MASK))
 51			return 0;
 52		usleep_range(100, 200);
 53	} while (time_before(jiffies, one_second));
 54
 55	return 1;
 56}
 57
 58static int cros_ec_pkt_xfer_lpc(struct cros_ec_device *ec,
 59				struct cros_ec_command *msg)
 60{
 61	struct ec_host_response response;
 62	u8 sum;
 63	int ret = 0;
 64	u8 *dout;
 65
 66	ret = cros_ec_prepare_tx(ec, msg);
 67
 68	/* Write buffer */
 69	cros_ec_lpc_write_bytes(EC_LPC_ADDR_HOST_PACKET, ret, ec->dout);
 70
 71	/* Here we go */
 72	sum = EC_COMMAND_PROTOCOL_3;
 73	cros_ec_lpc_write_bytes(EC_LPC_ADDR_HOST_CMD, 1, &sum);
 74
 75	if (ec_response_timed_out()) {
 76		dev_warn(ec->dev, "EC responsed timed out\n");
 77		ret = -EIO;
 78		goto done;
 79	}
 80
 81	/* Check result */
 82	msg->result = cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_DATA, 1, &sum);
 83	ret = cros_ec_check_result(ec, msg);
 84	if (ret)
 85		goto done;
 86
 87	/* Read back response */
 88	dout = (u8 *)&response;
 89	sum = cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_PACKET, sizeof(response),
 90				     dout);
 91
 92	msg->result = response.result;
 93
 94	if (response.data_len > msg->insize) {
 95		dev_err(ec->dev,
 96			"packet too long (%d bytes, expected %d)",
 97			response.data_len, msg->insize);
 98		ret = -EMSGSIZE;
 99		goto done;
100	}
101
102	/* Read response and process checksum */
103	sum += cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_PACKET +
104				      sizeof(response), response.data_len,
105				      msg->data);
106
107	if (sum) {
108		dev_err(ec->dev,
109			"bad packet checksum %02x\n",
110			response.checksum);
111		ret = -EBADMSG;
112		goto done;
113	}
114
115	/* Return actual amount of data received */
116	ret = response.data_len;
117done:
118	return ret;
119}
120
121static int cros_ec_cmd_xfer_lpc(struct cros_ec_device *ec,
122				struct cros_ec_command *msg)
123{
124	struct ec_lpc_host_args args;
125	u8 sum;
126	int ret = 0;
127
128	if (msg->outsize > EC_PROTO2_MAX_PARAM_SIZE ||
129	    msg->insize > EC_PROTO2_MAX_PARAM_SIZE) {
130		dev_err(ec->dev,
131			"invalid buffer sizes (out %d, in %d)\n",
132			msg->outsize, msg->insize);
133		return -EINVAL;
134	}
135
136	/* Now actually send the command to the EC and get the result */
137	args.flags = EC_HOST_ARGS_FLAG_FROM_HOST;
138	args.command_version = msg->version;
139	args.data_size = msg->outsize;
140
141	/* Initialize checksum */
142	sum = msg->command + args.flags + args.command_version + args.data_size;
143
144	/* Copy data and update checksum */
145	sum += cros_ec_lpc_write_bytes(EC_LPC_ADDR_HOST_PARAM, msg->outsize,
146				       msg->data);
147
148	/* Finalize checksum and write args */
149	args.checksum = sum;
150	cros_ec_lpc_write_bytes(EC_LPC_ADDR_HOST_ARGS, sizeof(args),
151				(u8 *)&args);
152
153	/* Here we go */
154	sum = msg->command;
155	cros_ec_lpc_write_bytes(EC_LPC_ADDR_HOST_CMD, 1, &sum);
156
157	if (ec_response_timed_out()) {
158		dev_warn(ec->dev, "EC responsed timed out\n");
159		ret = -EIO;
160		goto done;
161	}
162
163	/* Check result */
164	msg->result = cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_DATA, 1, &sum);
165	ret = cros_ec_check_result(ec, msg);
166	if (ret)
167		goto done;
168
169	/* Read back args */
170	cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_ARGS, sizeof(args),
171			       (u8 *)&args);
172
173	if (args.data_size > msg->insize) {
174		dev_err(ec->dev,
175			"packet too long (%d bytes, expected %d)",
176			args.data_size, msg->insize);
177		ret = -ENOSPC;
178		goto done;
179	}
180
181	/* Start calculating response checksum */
182	sum = msg->command + args.flags + args.command_version + args.data_size;
183
184	/* Read response and update checksum */
185	sum += cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_PARAM, args.data_size,
186				      msg->data);
187
188	/* Verify checksum */
189	if (args.checksum != sum) {
190		dev_err(ec->dev,
191			"bad packet checksum, expected %02x, got %02x\n",
192			args.checksum, sum);
193		ret = -EBADMSG;
194		goto done;
195	}
196
197	/* Return actual amount of data received */
198	ret = args.data_size;
199done:
200	return ret;
201}
202
203/* Returns num bytes read, or negative on error. Doesn't need locking. */
204static int cros_ec_lpc_readmem(struct cros_ec_device *ec, unsigned int offset,
205			       unsigned int bytes, void *dest)
206{
207	int i = offset;
208	char *s = dest;
209	int cnt = 0;
210
211	if (offset >= EC_MEMMAP_SIZE - bytes)
212		return -EINVAL;
213
214	/* fixed length */
215	if (bytes) {
216		cros_ec_lpc_read_bytes(EC_LPC_ADDR_MEMMAP + offset, bytes, s);
217		return bytes;
218	}
219
220	/* string */
221	for (; i < EC_MEMMAP_SIZE; i++, s++) {
222		cros_ec_lpc_read_bytes(EC_LPC_ADDR_MEMMAP + i, 1, s);
223		cnt++;
224		if (!*s)
225			break;
226	}
227
228	return cnt;
229}
230
231static void cros_ec_lpc_acpi_notify(acpi_handle device, u32 value, void *data)
232{
233	struct cros_ec_device *ec_dev = data;
234
235	if (ec_dev->mkbp_event_supported &&
236	    cros_ec_get_next_event(ec_dev, NULL) > 0)
237		blocking_notifier_call_chain(&ec_dev->event_notifier, 0,
238					     ec_dev);
239
240	if (value == ACPI_NOTIFY_DEVICE_WAKE)
241		pm_system_wakeup();
242}
243
244static int cros_ec_lpc_probe(struct platform_device *pdev)
245{
246	struct device *dev = &pdev->dev;
247	struct acpi_device *adev;
248	acpi_status status;
249	struct cros_ec_device *ec_dev;
250	u8 buf[2];
251	int ret;
252
253	if (!devm_request_region(dev, EC_LPC_ADDR_MEMMAP, EC_MEMMAP_SIZE,
254				 dev_name(dev))) {
255		dev_err(dev, "couldn't reserve memmap region\n");
256		return -EBUSY;
257	}
258
259	cros_ec_lpc_read_bytes(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_ID, 2, buf);
260	if (buf[0] != 'E' || buf[1] != 'C') {
261		dev_err(dev, "EC ID not detected\n");
262		return -ENODEV;
263	}
264
265	if (!devm_request_region(dev, EC_HOST_CMD_REGION0,
266				 EC_HOST_CMD_REGION_SIZE, dev_name(dev))) {
267		dev_err(dev, "couldn't reserve region0\n");
268		return -EBUSY;
269	}
270	if (!devm_request_region(dev, EC_HOST_CMD_REGION1,
271				 EC_HOST_CMD_REGION_SIZE, dev_name(dev))) {
272		dev_err(dev, "couldn't reserve region1\n");
273		return -EBUSY;
274	}
275
276	ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL);
277	if (!ec_dev)
278		return -ENOMEM;
279
280	platform_set_drvdata(pdev, ec_dev);
281	ec_dev->dev = dev;
282	ec_dev->phys_name = dev_name(dev);
283	ec_dev->cmd_xfer = cros_ec_cmd_xfer_lpc;
284	ec_dev->pkt_xfer = cros_ec_pkt_xfer_lpc;
285	ec_dev->cmd_readmem = cros_ec_lpc_readmem;
286	ec_dev->din_size = sizeof(struct ec_host_response) +
287			   sizeof(struct ec_response_get_protocol_info);
288	ec_dev->dout_size = sizeof(struct ec_host_request);
289
290	ret = cros_ec_register(ec_dev);
291	if (ret) {
292		dev_err(dev, "couldn't register ec_dev (%d)\n", ret);
293		return ret;
294	}
295
296	/*
297	 * Connect a notify handler to process MKBP messages if we have a
298	 * companion ACPI device.
299	 */
300	adev = ACPI_COMPANION(dev);
301	if (adev) {
302		status = acpi_install_notify_handler(adev->handle,
303						     ACPI_ALL_NOTIFY,
304						     cros_ec_lpc_acpi_notify,
305						     ec_dev);
306		if (ACPI_FAILURE(status))
307			dev_warn(dev, "Failed to register notifier %08x\n",
308				 status);
309	}
310
311	return 0;
312}
313
314static int cros_ec_lpc_remove(struct platform_device *pdev)
315{
316	struct cros_ec_device *ec_dev;
317	struct acpi_device *adev;
318
319	adev = ACPI_COMPANION(&pdev->dev);
320	if (adev)
321		acpi_remove_notify_handler(adev->handle, ACPI_ALL_NOTIFY,
322					   cros_ec_lpc_acpi_notify);
323
324	ec_dev = platform_get_drvdata(pdev);
325	cros_ec_remove(ec_dev);
326
327	return 0;
328}
329
330static const struct acpi_device_id cros_ec_lpc_acpi_device_ids[] = {
331	{ ACPI_DRV_NAME, 0 },
332	{ }
333};
334MODULE_DEVICE_TABLE(acpi, cros_ec_lpc_acpi_device_ids);
335
336static 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};
390MODULE_DEVICE_TABLE(dmi, cros_ec_lpc_dmi_table);
391
392#ifdef CONFIG_PM_SLEEP
393static 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
400static 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
408const 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
412static 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
422static struct platform_device cros_ec_lpc_device = {
423	.name = DRV_NAME
424};
425
426static 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
433static int __init cros_ec_lpc_init(void)
434{
435	int ret;
436	acpi_status status;
437
438	if (!dmi_check_system(cros_ec_lpc_dmi_table)) {
439		pr_err(DRV_NAME ": unsupported system.\n");
440		return -ENODEV;
441	}
442
443	cros_ec_lpc_reg_init();
444
445	/* Register the driver */
446	ret = platform_driver_register(&cros_ec_lpc_driver);
447	if (ret) {
448		pr_err(DRV_NAME ": can't register driver: %d\n", ret);
449		cros_ec_lpc_reg_destroy();
450		return ret;
451	}
452
453	status = acpi_get_devices(ACPI_DRV_NAME, cros_ec_lpc_parse_device,
454				  &cros_ec_lpc_acpi_device_found, NULL);
455	if (ACPI_FAILURE(status))
456		pr_warn(DRV_NAME ": Looking for %s failed\n", ACPI_DRV_NAME);
457
458	if (!cros_ec_lpc_acpi_device_found) {
459		/* Register the device, and it'll get hooked up automatically */
460		ret = platform_device_register(&cros_ec_lpc_device);
461		if (ret) {
462			pr_err(DRV_NAME ": can't register device: %d\n", ret);
463			platform_driver_unregister(&cros_ec_lpc_driver);
464			cros_ec_lpc_reg_destroy();
465		}
466	}
467
468	return ret;
469}
470
471static void __exit cros_ec_lpc_exit(void)
472{
473	if (!cros_ec_lpc_acpi_device_found)
474		platform_device_unregister(&cros_ec_lpc_device);
475	platform_driver_unregister(&cros_ec_lpc_driver);
476	cros_ec_lpc_reg_destroy();
477}
478
479module_init(cros_ec_lpc_init);
480module_exit(cros_ec_lpc_exit);
481
482MODULE_LICENSE("GPL");
483MODULE_DESCRIPTION("ChromeOS EC LPC driver");