1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * Generic driver for the OLPC Embedded Controller.
  4 *
  5 * Author: Andres Salomon <dilinger@queued.net>
  6 *
  7 * Copyright (C) 2011-2012 One Laptop per Child Foundation.
  8 */
  9#include <linux/completion.h>
 10#include <linux/debugfs.h>
 11#include <linux/spinlock.h>
 12#include <linux/mutex.h>
 13#include <linux/platform_device.h>
 14#include <linux/slab.h>
 15#include <linux/workqueue.h>
 16#include <linux/init.h>
 17#include <linux/list.h>
 18#include <linux/regulator/driver.h>
 19#include <linux/olpc-ec.h>
 20
 21struct ec_cmd_desc {
 22	u8 cmd;
 23	u8 *inbuf, *outbuf;
 24	size_t inlen, outlen;
 25
 26	int err;
 27	struct completion finished;
 28	struct list_head node;
 29
 30	void *priv;
 31};
 32
 33struct olpc_ec_priv {
 34	struct olpc_ec_driver *drv;
 35	u8 version;
 36	struct work_struct worker;
 37	struct mutex cmd_lock;
 38
 39	/* DCON regulator */
 40	bool dcon_enabled;
 41
 42	/* Pending EC commands */
 43	struct list_head cmd_q;
 44	spinlock_t cmd_q_lock;
 45
 46	struct dentry *dbgfs_dir;
 47
 48	/*
 49	 * EC event mask to be applied during suspend (defining wakeup
 50	 * sources).
 51	 */
 52	u16 ec_wakeup_mask;
 53
 54	/*
 55	 * Running an EC command while suspending means we don't always finish
 56	 * the command before the machine suspends.  This means that the EC
 57	 * is expecting the command protocol to finish, but we after a period
 58	 * of time (while the OS is asleep) the EC times out and restarts its
 59	 * idle loop.  Meanwhile, the OS wakes up, thinks it's still in the
 60	 * middle of the command protocol, starts throwing random things at
 61	 * the EC... and everyone's uphappy.
 62	 */
 63	bool suspended;
 64};
 65
 66static struct olpc_ec_driver *ec_driver;
 67static struct olpc_ec_priv *ec_priv;
 68static void *ec_cb_arg;
 69
 70void olpc_ec_driver_register(struct olpc_ec_driver *drv, void *arg)
 71{
 72	ec_driver = drv;
 73	ec_cb_arg = arg;
 74}
 75EXPORT_SYMBOL_GPL(olpc_ec_driver_register);
 76
 77static void olpc_ec_worker(struct work_struct *w)
 78{
 79	struct olpc_ec_priv *ec = container_of(w, struct olpc_ec_priv, worker);
 80	struct ec_cmd_desc *desc = NULL;
 81	unsigned long flags;
 82
 83	/* Grab the first pending command from the queue */
 84	spin_lock_irqsave(&ec->cmd_q_lock, flags);
 85	if (!list_empty(&ec->cmd_q)) {
 86		desc = list_first_entry(&ec->cmd_q, struct ec_cmd_desc, node);
 87		list_del(&desc->node);
 88	}
 89	spin_unlock_irqrestore(&ec->cmd_q_lock, flags);
 90
 91	/* Do we actually have anything to do? */
 92	if (!desc)
 93		return;
 94
 95	/* Protect the EC hw with a mutex; only run one cmd at a time */
 96	mutex_lock(&ec->cmd_lock);
 97	desc->err = ec_driver->ec_cmd(desc->cmd, desc->inbuf, desc->inlen,
 98			desc->outbuf, desc->outlen, ec_cb_arg);
 99	mutex_unlock(&ec->cmd_lock);
100
101	/* Finished, wake up olpc_ec_cmd() */
102	complete(&desc->finished);
103
104	/* Run the worker thread again in case there are more cmds pending */
105	schedule_work(&ec->worker);
106}
107
108/*
109 * Throw a cmd descripter onto the list.  We now have SMP OLPC machines, so
110 * locking is pretty critical.
111 */
112static void queue_ec_descriptor(struct ec_cmd_desc *desc,
113		struct olpc_ec_priv *ec)
114{
115	unsigned long flags;
116
117	INIT_LIST_HEAD(&desc->node);
118
119	spin_lock_irqsave(&ec->cmd_q_lock, flags);
120	list_add_tail(&desc->node, &ec->cmd_q);
121	spin_unlock_irqrestore(&ec->cmd_q_lock, flags);
122
123	schedule_work(&ec->worker);
124}
125
126int olpc_ec_cmd(u8 cmd, u8 *inbuf, size_t inlen, u8 *outbuf, size_t outlen)
127{
128	struct olpc_ec_priv *ec = ec_priv;
129	struct ec_cmd_desc desc;
130
131	/* Driver not yet registered. */
132	if (!ec_driver)
133		return -EPROBE_DEFER;
134
135	if (WARN_ON(!ec_driver->ec_cmd))
136		return -ENODEV;
137
138	if (!ec)
139		return -ENOMEM;
140
141	/* Suspending in the middle of a command hoses things really badly */
142	if (WARN_ON(ec->suspended))
143		return -EBUSY;
144
145	might_sleep();
146
147	desc.cmd = cmd;
148	desc.inbuf = inbuf;
149	desc.outbuf = outbuf;
150	desc.inlen = inlen;
151	desc.outlen = outlen;
152	desc.err = 0;
153	init_completion(&desc.finished);
154
155	queue_ec_descriptor(&desc, ec);
156
157	/* Timeouts must be handled in the platform-specific EC hook */
158	wait_for_completion(&desc.finished);
159
160	/* The worker thread dequeues the cmd; no need to do anything here */
161	return desc.err;
162}
163EXPORT_SYMBOL_GPL(olpc_ec_cmd);
164
165void olpc_ec_wakeup_set(u16 value)
166{
167	struct olpc_ec_priv *ec = ec_priv;
168
169	if (WARN_ON(!ec))
170		return;
171
172	ec->ec_wakeup_mask |= value;
173}
174EXPORT_SYMBOL_GPL(olpc_ec_wakeup_set);
175
176void olpc_ec_wakeup_clear(u16 value)
177{
178	struct olpc_ec_priv *ec = ec_priv;
179
180	if (WARN_ON(!ec))
181		return;
182
183	ec->ec_wakeup_mask &= ~value;
184}
185EXPORT_SYMBOL_GPL(olpc_ec_wakeup_clear);
186
187int olpc_ec_mask_write(u16 bits)
188{
189	struct olpc_ec_priv *ec = ec_priv;
190
191	if (WARN_ON(!ec))
192		return -ENODEV;
193
194	/* EC version 0x5f adds support for wide SCI mask */
195	if (ec->version >= 0x5f) {
196		__be16 ec_word = cpu_to_be16(bits);
197
198		return olpc_ec_cmd(EC_WRITE_EXT_SCI_MASK, (void *)&ec_word, 2, NULL, 0);
199	} else {
200		u8 ec_byte = bits & 0xff;
201
202		return olpc_ec_cmd(EC_WRITE_SCI_MASK, &ec_byte, 1, NULL, 0);
203	}
204}
205EXPORT_SYMBOL_GPL(olpc_ec_mask_write);
206
207/*
208 * Returns true if the compile and runtime configurations allow for EC events
209 * to wake the system.
210 */
211bool olpc_ec_wakeup_available(void)
212{
213	if (WARN_ON(!ec_driver))
214		return false;
215
216	return ec_driver->wakeup_available;
217}
218EXPORT_SYMBOL_GPL(olpc_ec_wakeup_available);
219
220int olpc_ec_sci_query(u16 *sci_value)
221{
222	struct olpc_ec_priv *ec = ec_priv;
223	int ret;
224
225	if (WARN_ON(!ec))
226		return -ENODEV;
227
228	/* EC version 0x5f adds support for wide SCI mask */
229	if (ec->version >= 0x5f) {
230		__be16 ec_word;
231
232		ret = olpc_ec_cmd(EC_EXT_SCI_QUERY, NULL, 0, (void *)&ec_word, 2);
233		if (ret == 0)
234			*sci_value = be16_to_cpu(ec_word);
235	} else {
236		u8 ec_byte;
237
238		ret = olpc_ec_cmd(EC_SCI_QUERY, NULL, 0, &ec_byte, 1);
239		if (ret == 0)
240			*sci_value = ec_byte;
241	}
242
243	return ret;
244}
245EXPORT_SYMBOL_GPL(olpc_ec_sci_query);
246
247#ifdef CONFIG_DEBUG_FS
248
249/*
250 * debugfs support for "generic commands", to allow sending
251 * arbitrary EC commands from userspace.
252 */
253
254#define EC_MAX_CMD_ARGS (5 + 1)		/* cmd byte + 5 args */
255#define EC_MAX_CMD_REPLY (8)
256
257static DEFINE_MUTEX(ec_dbgfs_lock);
258static unsigned char ec_dbgfs_resp[EC_MAX_CMD_REPLY];
259static unsigned int ec_dbgfs_resp_bytes;
260
261static ssize_t ec_dbgfs_cmd_write(struct file *file, const char __user *buf,
262		size_t size, loff_t *ppos)
263{
264	int i, m;
265	unsigned char ec_cmd[EC_MAX_CMD_ARGS];
266	unsigned int ec_cmd_int[EC_MAX_CMD_ARGS];
267	char cmdbuf[64] = "";
268	int ec_cmd_bytes;
269
270	mutex_lock(&ec_dbgfs_lock);
271
272	size = simple_write_to_buffer(cmdbuf, sizeof(cmdbuf), ppos, buf, size);
273
274	m = sscanf(cmdbuf, "%x:%u %x %x %x %x %x", &ec_cmd_int[0],
275			&ec_dbgfs_resp_bytes, &ec_cmd_int[1], &ec_cmd_int[2],
276			&ec_cmd_int[3], &ec_cmd_int[4], &ec_cmd_int[5]);
277	if (m < 2 || ec_dbgfs_resp_bytes > EC_MAX_CMD_REPLY) {
278		/* reset to prevent overflow on read */
279		ec_dbgfs_resp_bytes = 0;
280
281		pr_debug("olpc-ec: bad ec cmd:  cmd:response-count [arg1 [arg2 ...]]\n");
282		size = -EINVAL;
283		goto out;
284	}
285
286	/* convert scanf'd ints to char */
287	ec_cmd_bytes = m - 2;
288	for (i = 0; i <= ec_cmd_bytes; i++)
289		ec_cmd[i] = ec_cmd_int[i];
290
291	pr_debug("olpc-ec: debugfs cmd 0x%02x with %d args %5ph, want %d returns\n",
292			ec_cmd[0], ec_cmd_bytes, ec_cmd + 1,
293			ec_dbgfs_resp_bytes);
294
295	olpc_ec_cmd(ec_cmd[0], (ec_cmd_bytes == 0) ? NULL : &ec_cmd[1],
296			ec_cmd_bytes, ec_dbgfs_resp, ec_dbgfs_resp_bytes);
297
298	pr_debug("olpc-ec: response %8ph (%d bytes expected)\n",
299			ec_dbgfs_resp, ec_dbgfs_resp_bytes);
300
301out:
302	mutex_unlock(&ec_dbgfs_lock);
303	return size;
304}
305
306static ssize_t ec_dbgfs_cmd_read(struct file *file, char __user *buf,
307		size_t size, loff_t *ppos)
308{
309	unsigned int i, r;
310	char *rp;
311	char respbuf[64];
312
313	mutex_lock(&ec_dbgfs_lock);
314	rp = respbuf;
315	rp += sprintf(rp, "%02x", ec_dbgfs_resp[0]);
316	for (i = 1; i < ec_dbgfs_resp_bytes; i++)
317		rp += sprintf(rp, ", %02x", ec_dbgfs_resp[i]);
318	mutex_unlock(&ec_dbgfs_lock);
319	rp += sprintf(rp, "\n");
320
321	r = rp - respbuf;
322	return simple_read_from_buffer(buf, size, ppos, respbuf, r);
323}
324
325static const struct file_operations ec_dbgfs_ops = {
326	.write = ec_dbgfs_cmd_write,
327	.read = ec_dbgfs_cmd_read,
328};
329
330static struct dentry *olpc_ec_setup_debugfs(void)
331{
332	struct dentry *dbgfs_dir;
333
334	dbgfs_dir = debugfs_create_dir("olpc-ec", NULL);
335	if (IS_ERR_OR_NULL(dbgfs_dir))
336		return NULL;
337
338	debugfs_create_file("cmd", 0600, dbgfs_dir, NULL, &ec_dbgfs_ops);
339
340	return dbgfs_dir;
341}
342
343#else
344
345static struct dentry *olpc_ec_setup_debugfs(void)
346{
347	return NULL;
348}
349
350#endif /* CONFIG_DEBUG_FS */
351
352static int olpc_ec_set_dcon_power(struct olpc_ec_priv *ec, bool state)
353{
354	unsigned char ec_byte = state;
355	int ret;
356
357	if (ec->dcon_enabled == state)
358		return 0;
359
360	ret = olpc_ec_cmd(EC_DCON_POWER_MODE, &ec_byte, 1, NULL, 0);
361	if (ret)
362		return ret;
363
364	ec->dcon_enabled = state;
365	return 0;
366}
367
368static int dcon_regulator_enable(struct regulator_dev *rdev)
369{
370	struct olpc_ec_priv *ec = rdev_get_drvdata(rdev);
371
372	return olpc_ec_set_dcon_power(ec, true);
373}
374
375static int dcon_regulator_disable(struct regulator_dev *rdev)
376{
377	struct olpc_ec_priv *ec = rdev_get_drvdata(rdev);
378
379	return olpc_ec_set_dcon_power(ec, false);
380}
381
382static int dcon_regulator_is_enabled(struct regulator_dev *rdev)
383{
384	struct olpc_ec_priv *ec = rdev_get_drvdata(rdev);
385
386	return ec->dcon_enabled ? 1 : 0;
387}
388
389static const struct regulator_ops dcon_regulator_ops = {
390	.enable		= dcon_regulator_enable,
391	.disable	= dcon_regulator_disable,
392	.is_enabled	= dcon_regulator_is_enabled,
393};
394
395static const struct regulator_desc dcon_desc = {
396	.name		= "dcon",
397	.id		= 0,
398	.ops		= &dcon_regulator_ops,
399	.type		= REGULATOR_VOLTAGE,
400	.owner		= THIS_MODULE,
401	.enable_time	= 25000,
402};
403
404static int olpc_ec_probe(struct platform_device *pdev)
405{
406	struct olpc_ec_priv *ec;
407	struct regulator_config config = { };
408	struct regulator_dev *regulator;
409	int err;
410
411	if (!ec_driver)
412		return -ENODEV;
413
414	ec = kzalloc(sizeof(*ec), GFP_KERNEL);
415	if (!ec)
416		return -ENOMEM;
417
418	ec->drv = ec_driver;
419	INIT_WORK(&ec->worker, olpc_ec_worker);
420	mutex_init(&ec->cmd_lock);
421
422	INIT_LIST_HEAD(&ec->cmd_q);
423	spin_lock_init(&ec->cmd_q_lock);
424
425	ec_priv = ec;
426	platform_set_drvdata(pdev, ec);
427
428	/* get the EC revision */
429	err = olpc_ec_cmd(EC_FIRMWARE_REV, NULL, 0, &ec->version, 1);
430	if (err)
431		goto error;
432
433	config.dev = pdev->dev.parent;
434	config.driver_data = ec;
435	ec->dcon_enabled = true;
436	regulator = devm_regulator_register(&pdev->dev, &dcon_desc, &config);
437	if (IS_ERR(regulator)) {
438		dev_err(&pdev->dev, "failed to register DCON regulator\n");
439		err = PTR_ERR(regulator);
440		goto error;
441	}
442
443	ec->dbgfs_dir = olpc_ec_setup_debugfs();
444
445	return 0;
446
447error:
448	ec_priv = NULL;
449	kfree(ec);
450	return err;
451}
452
453static int olpc_ec_suspend(struct device *dev)
454{
455	struct platform_device *pdev = to_platform_device(dev);
456	struct olpc_ec_priv *ec = platform_get_drvdata(pdev);
457	int err = 0;
458
459	olpc_ec_mask_write(ec->ec_wakeup_mask);
460
461	if (ec_driver->suspend)
462		err = ec_driver->suspend(pdev);
463	if (!err)
464		ec->suspended = true;
465
466	return err;
467}
468
469static int olpc_ec_resume(struct device *dev)
470{
471	struct platform_device *pdev = to_platform_device(dev);
472	struct olpc_ec_priv *ec = platform_get_drvdata(pdev);
473
474	ec->suspended = false;
475	return ec_driver->resume ? ec_driver->resume(pdev) : 0;
476}
477
478static const struct dev_pm_ops olpc_ec_pm_ops = {
479	.suspend_late = olpc_ec_suspend,
480	.resume_early = olpc_ec_resume,
481};
482
483static struct platform_driver olpc_ec_plat_driver = {
484	.probe = olpc_ec_probe,
485	.driver = {
486		.name = "olpc-ec",
487		.pm = &olpc_ec_pm_ops,
488	},
489};
490
491static int __init olpc_ec_init_module(void)
492{
493	return platform_driver_register(&olpc_ec_plat_driver);
494}
495arch_initcall(olpc_ec_init_module);