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