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/module.h>
 20#include <linux/platform_data/cros_ec_commands.h>
 21#include <linux/platform_data/cros_ec_proto.h>
 22#include <linux/platform_device.h>
 23#include <linux/printk.h>
 24#include <linux/suspend.h>
 25
 26#include "cros_ec_lpc_mec.h"
 27
 28#define DRV_NAME "cros_ec_lpcs"
 29#define ACPI_DRV_NAME "GOOG0004"
 30
 31/* True if ACPI device is present */
 32static bool cros_ec_lpc_acpi_device_found;
 33
 34/**
 35 * struct lpc_driver_ops - LPC driver operations
 36 * @read: Copy length bytes from EC address offset into buffer dest. Returns
 37 *        the 8-bit checksum of all bytes read.
 38 * @write: Copy length bytes from buffer msg into EC address offset. Returns
 39 *         the 8-bit checksum of all bytes written.
 40 */
 41struct lpc_driver_ops {
 42	u8 (*read)(unsigned int offset, unsigned int length, u8 *dest);
 43	u8 (*write)(unsigned int offset, unsigned int length, const u8 *msg);
 44};
 45
 46static struct lpc_driver_ops cros_ec_lpc_ops = { };
 47
 48/*
 49 * A generic instance of the read function of struct lpc_driver_ops, used for
 50 * the LPC EC.
 51 */
 52static u8 cros_ec_lpc_read_bytes(unsigned int offset, unsigned int length,
 53				 u8 *dest)
 54{
 55	int sum = 0;
 56	int i;
 57
 58	for (i = 0; i < length; ++i) {
 59		dest[i] = inb(offset + i);
 60		sum += dest[i];
 61	}
 62
 63	/* Return checksum of all bytes read */
 64	return sum;
 65}
 66
 67/*
 68 * A generic instance of the write function of struct lpc_driver_ops, used for
 69 * the LPC EC.
 70 */
 71static u8 cros_ec_lpc_write_bytes(unsigned int offset, unsigned int length,
 72				  const u8 *msg)
 73{
 74	int sum = 0;
 75	int i;
 76
 77	for (i = 0; i < length; ++i) {
 78		outb(msg[i], offset + i);
 79		sum += msg[i];
 80	}
 81
 82	/* Return checksum of all bytes written */
 83	return sum;
 84}
 85
 86/*
 87 * An instance of the read function of struct lpc_driver_ops, used for the
 88 * MEC variant of LPC EC.
 89 */
 90static u8 cros_ec_lpc_mec_read_bytes(unsigned int offset, unsigned int length,
 91				     u8 *dest)
 92{
 93	int in_range = cros_ec_lpc_mec_in_range(offset, length);
 94
 95	if (in_range < 0)
 96		return 0;
 97
 98	return in_range ?
 99		cros_ec_lpc_io_bytes_mec(MEC_IO_READ,
100					 offset - EC_HOST_CMD_REGION0,
101					 length, dest) :
102		cros_ec_lpc_read_bytes(offset, length, dest);
103}
104
105/*
106 * An instance of the write function of struct lpc_driver_ops, used for the
107 * MEC variant of LPC EC.
108 */
109static u8 cros_ec_lpc_mec_write_bytes(unsigned int offset, unsigned int length,
110				      const u8 *msg)
111{
112	int in_range = cros_ec_lpc_mec_in_range(offset, length);
113
114	if (in_range < 0)
115		return 0;
116
117	return in_range ?
118		cros_ec_lpc_io_bytes_mec(MEC_IO_WRITE,
119					 offset - EC_HOST_CMD_REGION0,
120					 length, (u8 *)msg) :
121		cros_ec_lpc_write_bytes(offset, length, msg);
122}
123
124static int ec_response_timed_out(void)
125{
126	unsigned long one_second = jiffies + HZ;
127	u8 data;
128
129	usleep_range(200, 300);
130	do {
131		if (!(cros_ec_lpc_ops.read(EC_LPC_ADDR_HOST_CMD, 1, &data) &
132		    EC_LPC_STATUS_BUSY_MASK))
133			return 0;
134		usleep_range(100, 200);
135	} while (time_before(jiffies, one_second));
136
137	return 1;
138}
139
140static int cros_ec_pkt_xfer_lpc(struct cros_ec_device *ec,
141				struct cros_ec_command *msg)
142{
143	struct ec_host_response response;
144	u8 sum;
145	int ret = 0;
146	u8 *dout;
147
148	ret = cros_ec_prepare_tx(ec, msg);
149
150	/* Write buffer */
151	cros_ec_lpc_ops.write(EC_LPC_ADDR_HOST_PACKET, ret, ec->dout);
152
153	/* Here we go */
154	sum = EC_COMMAND_PROTOCOL_3;
155	cros_ec_lpc_ops.write(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_ops.read(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 response */
170	dout = (u8 *)&response;
171	sum = cros_ec_lpc_ops.read(EC_LPC_ADDR_HOST_PACKET, sizeof(response),
172				   dout);
173
174	msg->result = response.result;
175
176	if (response.data_len > msg->insize) {
177		dev_err(ec->dev,
178			"packet too long (%d bytes, expected %d)",
179			response.data_len, msg->insize);
180		ret = -EMSGSIZE;
181		goto done;
182	}
183
184	/* Read response and process checksum */
185	sum += cros_ec_lpc_ops.read(EC_LPC_ADDR_HOST_PACKET +
186				    sizeof(response), response.data_len,
187				    msg->data);
188
189	if (sum) {
190		dev_err(ec->dev,
191			"bad packet checksum %02x\n",
192			response.checksum);
193		ret = -EBADMSG;
194		goto done;
195	}
196
197	/* Return actual amount of data received */
198	ret = response.data_len;
199done:
200	return ret;
201}
202
203static int cros_ec_cmd_xfer_lpc(struct cros_ec_device *ec,
204				struct cros_ec_command *msg)
205{
206	struct ec_lpc_host_args args;
207	u8 sum;
208	int ret = 0;
209
210	if (msg->outsize > EC_PROTO2_MAX_PARAM_SIZE ||
211	    msg->insize > EC_PROTO2_MAX_PARAM_SIZE) {
212		dev_err(ec->dev,
213			"invalid buffer sizes (out %d, in %d)\n",
214			msg->outsize, msg->insize);
215		return -EINVAL;
216	}
217
218	/* Now actually send the command to the EC and get the result */
219	args.flags = EC_HOST_ARGS_FLAG_FROM_HOST;
220	args.command_version = msg->version;
221	args.data_size = msg->outsize;
222
223	/* Initialize checksum */
224	sum = msg->command + args.flags + args.command_version + args.data_size;
225
226	/* Copy data and update checksum */
227	sum += cros_ec_lpc_ops.write(EC_LPC_ADDR_HOST_PARAM, msg->outsize,
228				     msg->data);
229
230	/* Finalize checksum and write args */
231	args.checksum = sum;
232	cros_ec_lpc_ops.write(EC_LPC_ADDR_HOST_ARGS, sizeof(args),
233			      (u8 *)&args);
234
235	/* Here we go */
236	sum = msg->command;
237	cros_ec_lpc_ops.write(EC_LPC_ADDR_HOST_CMD, 1, &sum);
238
239	if (ec_response_timed_out()) {
240		dev_warn(ec->dev, "EC responsed timed out\n");
241		ret = -EIO;
242		goto done;
243	}
244
245	/* Check result */
246	msg->result = cros_ec_lpc_ops.read(EC_LPC_ADDR_HOST_DATA, 1, &sum);
247	ret = cros_ec_check_result(ec, msg);
248	if (ret)
249		goto done;
250
251	/* Read back args */
252	cros_ec_lpc_ops.read(EC_LPC_ADDR_HOST_ARGS, sizeof(args), (u8 *)&args);
253
254	if (args.data_size > msg->insize) {
255		dev_err(ec->dev,
256			"packet too long (%d bytes, expected %d)",
257			args.data_size, msg->insize);
258		ret = -ENOSPC;
259		goto done;
260	}
261
262	/* Start calculating response checksum */
263	sum = msg->command + args.flags + args.command_version + args.data_size;
264
265	/* Read response and update checksum */
266	sum += cros_ec_lpc_ops.read(EC_LPC_ADDR_HOST_PARAM, args.data_size,
267				    msg->data);
268
269	/* Verify checksum */
270	if (args.checksum != sum) {
271		dev_err(ec->dev,
272			"bad packet checksum, expected %02x, got %02x\n",
273			args.checksum, sum);
274		ret = -EBADMSG;
275		goto done;
276	}
277
278	/* Return actual amount of data received */
279	ret = args.data_size;
280done:
281	return ret;
282}
283
284/* Returns num bytes read, or negative on error. Doesn't need locking. */
285static int cros_ec_lpc_readmem(struct cros_ec_device *ec, unsigned int offset,
286			       unsigned int bytes, void *dest)
287{
288	int i = offset;
289	char *s = dest;
290	int cnt = 0;
291
292	if (offset >= EC_MEMMAP_SIZE - bytes)
293		return -EINVAL;
294
295	/* fixed length */
296	if (bytes) {
297		cros_ec_lpc_ops.read(EC_LPC_ADDR_MEMMAP + offset, bytes, s);
298		return bytes;
299	}
300
301	/* string */
302	for (; i < EC_MEMMAP_SIZE; i++, s++) {
303		cros_ec_lpc_ops.read(EC_LPC_ADDR_MEMMAP + i, 1, s);
304		cnt++;
305		if (!*s)
306			break;
307	}
308
309	return cnt;
310}
311
312static void cros_ec_lpc_acpi_notify(acpi_handle device, u32 value, void *data)
313{
314	struct cros_ec_device *ec_dev = data;
315
316	if (ec_dev->mkbp_event_supported &&
317	    cros_ec_get_next_event(ec_dev, NULL) > 0)
318		blocking_notifier_call_chain(&ec_dev->event_notifier, 0,
319					     ec_dev);
320
321	if (value == ACPI_NOTIFY_DEVICE_WAKE)
322		pm_system_wakeup();
323}
324
325static int cros_ec_lpc_probe(struct platform_device *pdev)
326{
327	struct device *dev = &pdev->dev;
328	struct acpi_device *adev;
329	acpi_status status;
330	struct cros_ec_device *ec_dev;
331	u8 buf[2];
332	int irq, ret;
333
334	if (!devm_request_region(dev, EC_LPC_ADDR_MEMMAP, EC_MEMMAP_SIZE,
335				 dev_name(dev))) {
336		dev_err(dev, "couldn't reserve memmap region\n");
337		return -EBUSY;
338	}
339
340	/*
341	 * Read the mapped ID twice, the first one is assuming the
342	 * EC is a Microchip Embedded Controller (MEC) variant, if the
343	 * protocol fails, fallback to the non MEC variant and try to
344	 * read again the ID.
345	 */
346	cros_ec_lpc_ops.read = cros_ec_lpc_mec_read_bytes;
347	cros_ec_lpc_ops.write = cros_ec_lpc_mec_write_bytes;
348	cros_ec_lpc_ops.read(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_ID, 2, buf);
349	if (buf[0] != 'E' || buf[1] != 'C') {
350		/* Re-assign read/write operations for the non MEC variant */
351		cros_ec_lpc_ops.read = cros_ec_lpc_read_bytes;
352		cros_ec_lpc_ops.write = cros_ec_lpc_write_bytes;
353		cros_ec_lpc_ops.read(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_ID, 2,
354				     buf);
355		if (buf[0] != 'E' || buf[1] != 'C') {
356			dev_err(dev, "EC ID not detected\n");
357			return -ENODEV;
358		}
359	}
360
361	if (!devm_request_region(dev, EC_HOST_CMD_REGION0,
362				 EC_HOST_CMD_REGION_SIZE, dev_name(dev))) {
363		dev_err(dev, "couldn't reserve region0\n");
364		return -EBUSY;
365	}
366	if (!devm_request_region(dev, EC_HOST_CMD_REGION1,
367				 EC_HOST_CMD_REGION_SIZE, dev_name(dev))) {
368		dev_err(dev, "couldn't reserve region1\n");
369		return -EBUSY;
370	}
371
372	ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL);
373	if (!ec_dev)
374		return -ENOMEM;
375
376	platform_set_drvdata(pdev, ec_dev);
377	ec_dev->dev = dev;
378	ec_dev->phys_name = dev_name(dev);
379	ec_dev->cmd_xfer = cros_ec_cmd_xfer_lpc;
380	ec_dev->pkt_xfer = cros_ec_pkt_xfer_lpc;
381	ec_dev->cmd_readmem = cros_ec_lpc_readmem;
382	ec_dev->din_size = sizeof(struct ec_host_response) +
383			   sizeof(struct ec_response_get_protocol_info);
384	ec_dev->dout_size = sizeof(struct ec_host_request);
385
386	/*
387	 * Some boards do not have an IRQ allotted for cros_ec_lpc,
388	 * which makes ENXIO an expected (and safe) scenario.
389	 */
390	irq = platform_get_irq(pdev, 0);
391	if (irq > 0)
392		ec_dev->irq = irq;
393	else if (irq != -ENXIO) {
394		dev_err(dev, "couldn't retrieve IRQ number (%d)\n", irq);
395		return irq;
396	}
397
398	ret = cros_ec_register(ec_dev);
399	if (ret) {
400		dev_err(dev, "couldn't register ec_dev (%d)\n", ret);
401		return ret;
402	}
403
404	/*
405	 * Connect a notify handler to process MKBP messages if we have a
406	 * companion ACPI device.
407	 */
408	adev = ACPI_COMPANION(dev);
409	if (adev) {
410		status = acpi_install_notify_handler(adev->handle,
411						     ACPI_ALL_NOTIFY,
412						     cros_ec_lpc_acpi_notify,
413						     ec_dev);
414		if (ACPI_FAILURE(status))
415			dev_warn(dev, "Failed to register notifier %08x\n",
416				 status);
417	}
418
419	return 0;
420}
421
422static int cros_ec_lpc_remove(struct platform_device *pdev)
423{
424	struct cros_ec_device *ec_dev = platform_get_drvdata(pdev);
425	struct acpi_device *adev;
426
427	adev = ACPI_COMPANION(&pdev->dev);
428	if (adev)
429		acpi_remove_notify_handler(adev->handle, ACPI_ALL_NOTIFY,
430					   cros_ec_lpc_acpi_notify);
431
432	return cros_ec_unregister(ec_dev);
433}
434
435static const struct acpi_device_id cros_ec_lpc_acpi_device_ids[] = {
436	{ ACPI_DRV_NAME, 0 },
437	{ }
438};
439MODULE_DEVICE_TABLE(acpi, cros_ec_lpc_acpi_device_ids);
440
441static const struct dmi_system_id cros_ec_lpc_dmi_table[] __initconst = {
442	{
443		/*
444		 * Today all Chromebooks/boxes ship with Google_* as version and
445		 * coreboot as bios vendor. No other systems with this
446		 * combination are known to date.
447		 */
448		.matches = {
449			DMI_MATCH(DMI_BIOS_VENDOR, "coreboot"),
450			DMI_MATCH(DMI_BIOS_VERSION, "Google_"),
451		},
452	},
453	{
454		/*
455		 * If the box is running custom coreboot firmware then the
456		 * DMI BIOS version string will not be matched by "Google_",
457		 * but the system vendor string will still be matched by
458		 * "GOOGLE".
459		 */
460		.matches = {
461			DMI_MATCH(DMI_BIOS_VENDOR, "coreboot"),
462			DMI_MATCH(DMI_SYS_VENDOR, "GOOGLE"),
463		},
464	},
465	{
466		/* x86-link, the Chromebook Pixel. */
467		.matches = {
468			DMI_MATCH(DMI_SYS_VENDOR, "GOOGLE"),
469			DMI_MATCH(DMI_PRODUCT_NAME, "Link"),
470		},
471	},
472	{
473		/* x86-samus, the Chromebook Pixel 2. */
474		.matches = {
475			DMI_MATCH(DMI_SYS_VENDOR, "GOOGLE"),
476			DMI_MATCH(DMI_PRODUCT_NAME, "Samus"),
477		},
478	},
479	{
480		/* x86-peppy, the Acer C720 Chromebook. */
481		.matches = {
482			DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
483			DMI_MATCH(DMI_PRODUCT_NAME, "Peppy"),
484		},
485	},
486	{
487		/* x86-glimmer, the Lenovo Thinkpad Yoga 11e. */
488		.matches = {
489			DMI_MATCH(DMI_SYS_VENDOR, "GOOGLE"),
490			DMI_MATCH(DMI_PRODUCT_NAME, "Glimmer"),
491		},
492	},
493	{ /* sentinel */ }
494};
495MODULE_DEVICE_TABLE(dmi, cros_ec_lpc_dmi_table);
496
497#ifdef CONFIG_PM_SLEEP
498static int cros_ec_lpc_suspend(struct device *dev)
499{
500	struct cros_ec_device *ec_dev = dev_get_drvdata(dev);
501
502	return cros_ec_suspend(ec_dev);
503}
504
505static int cros_ec_lpc_resume(struct device *dev)
506{
507	struct cros_ec_device *ec_dev = dev_get_drvdata(dev);
508
509	return cros_ec_resume(ec_dev);
510}
511#endif
512
513static const struct dev_pm_ops cros_ec_lpc_pm_ops = {
514	SET_LATE_SYSTEM_SLEEP_PM_OPS(cros_ec_lpc_suspend, cros_ec_lpc_resume)
515};
516
517static struct platform_driver cros_ec_lpc_driver = {
518	.driver = {
519		.name = DRV_NAME,
520		.acpi_match_table = cros_ec_lpc_acpi_device_ids,
521		.pm = &cros_ec_lpc_pm_ops,
522	},
523	.probe = cros_ec_lpc_probe,
524	.remove = cros_ec_lpc_remove,
525};
526
527static struct platform_device cros_ec_lpc_device = {
528	.name = DRV_NAME
529};
530
531static acpi_status cros_ec_lpc_parse_device(acpi_handle handle, u32 level,
532					    void *context, void **retval)
533{
534	*(bool *)context = true;
535	return AE_CTRL_TERMINATE;
536}
537
538static int __init cros_ec_lpc_init(void)
539{
540	int ret;
541	acpi_status status;
542
543	status = acpi_get_devices(ACPI_DRV_NAME, cros_ec_lpc_parse_device,
544				  &cros_ec_lpc_acpi_device_found, NULL);
545	if (ACPI_FAILURE(status))
546		pr_warn(DRV_NAME ": Looking for %s failed\n", ACPI_DRV_NAME);
547
548	if (!cros_ec_lpc_acpi_device_found &&
549	    !dmi_check_system(cros_ec_lpc_dmi_table)) {
550		pr_err(DRV_NAME ": unsupported system.\n");
551		return -ENODEV;
552	}
553
554	cros_ec_lpc_mec_init(EC_HOST_CMD_REGION0,
555			     EC_LPC_ADDR_MEMMAP + EC_MEMMAP_SIZE);
556
557	/* Register the driver */
558	ret = platform_driver_register(&cros_ec_lpc_driver);
559	if (ret) {
560		pr_err(DRV_NAME ": can't register driver: %d\n", ret);
561		cros_ec_lpc_mec_destroy();
562		return ret;
563	}
564
565	if (!cros_ec_lpc_acpi_device_found) {
566		/* Register the device, and it'll get hooked up automatically */
567		ret = platform_device_register(&cros_ec_lpc_device);
568		if (ret) {
569			pr_err(DRV_NAME ": can't register device: %d\n", ret);
570			platform_driver_unregister(&cros_ec_lpc_driver);
571			cros_ec_lpc_mec_destroy();
572		}
573	}
574
575	return ret;
576}
577
578static void __exit cros_ec_lpc_exit(void)
579{
580	if (!cros_ec_lpc_acpi_device_found)
581		platform_device_unregister(&cros_ec_lpc_device);
582	platform_driver_unregister(&cros_ec_lpc_driver);
583	cros_ec_lpc_mec_destroy();
584}
585
586module_init(cros_ec_lpc_init);
587module_exit(cros_ec_lpc_exit);
588
589MODULE_LICENSE("GPL");
590MODULE_DESCRIPTION("ChromeOS EC LPC driver");