1/*
  2 * Generic driver for the OLPC Embedded Controller.
  3 *
  4 * Author: Andres Salomon <dilinger@queued.net>
  5 *
  6 * Copyright (C) 2011-2012 One Laptop per Child Foundation.
  7 *
  8 * Licensed under the GPL v2 or later.
  9 */
 10#include <linux/completion.h>
 11#include <linux/debugfs.h>
 12#include <linux/spinlock.h>
 13#include <linux/mutex.h>
 14#include <linux/platform_device.h>
 15#include <linux/slab.h>
 16#include <linux/workqueue.h>
 17#include <linux/init.h>
 18#include <linux/list.h>
 19#include <linux/olpc-ec.h>
 20#include <asm/olpc.h>
 21
 22struct ec_cmd_desc {
 23	u8 cmd;
 24	u8 *inbuf, *outbuf;
 25	size_t inlen, outlen;
 26
 27	int err;
 28	struct completion finished;
 29	struct list_head node;
 30
 31	void *priv;
 32};
 33
 34struct olpc_ec_priv {
 35	struct olpc_ec_driver *drv;
 36	struct work_struct worker;
 37	struct mutex cmd_lock;
 38
 39	/* Pending EC commands */
 40	struct list_head cmd_q;
 41	spinlock_t cmd_q_lock;
 42
 43	struct dentry *dbgfs_dir;
 44
 45	/*
 46	 * Running an EC command while suspending means we don't always finish
 47	 * the command before the machine suspends.  This means that the EC
 48	 * is expecting the command protocol to finish, but we after a period
 49	 * of time (while the OS is asleep) the EC times out and restarts its
 50	 * idle loop.  Meanwhile, the OS wakes up, thinks it's still in the
 51	 * middle of the command protocol, starts throwing random things at
 52	 * the EC... and everyone's uphappy.
 53	 */
 54	bool suspended;
 55};
 56
 57static struct olpc_ec_driver *ec_driver;
 58static struct olpc_ec_priv *ec_priv;
 59static void *ec_cb_arg;
 60
 61void olpc_ec_driver_register(struct olpc_ec_driver *drv, void *arg)
 62{
 63	ec_driver = drv;
 64	ec_cb_arg = arg;
 65}
 66EXPORT_SYMBOL_GPL(olpc_ec_driver_register);
 67
 68static void olpc_ec_worker(struct work_struct *w)
 69{
 70	struct olpc_ec_priv *ec = container_of(w, struct olpc_ec_priv, worker);
 71	struct ec_cmd_desc *desc = NULL;
 72	unsigned long flags;
 73
 74	/* Grab the first pending command from the queue */
 75	spin_lock_irqsave(&ec->cmd_q_lock, flags);
 76	if (!list_empty(&ec->cmd_q)) {
 77		desc = list_first_entry(&ec->cmd_q, struct ec_cmd_desc, node);
 78		list_del(&desc->node);
 79	}
 80	spin_unlock_irqrestore(&ec->cmd_q_lock, flags);
 81
 82	/* Do we actually have anything to do? */
 83	if (!desc)
 84		return;
 85
 86	/* Protect the EC hw with a mutex; only run one cmd at a time */
 87	mutex_lock(&ec->cmd_lock);
 88	desc->err = ec_driver->ec_cmd(desc->cmd, desc->inbuf, desc->inlen,
 89			desc->outbuf, desc->outlen, ec_cb_arg);
 90	mutex_unlock(&ec->cmd_lock);
 91
 92	/* Finished, wake up olpc_ec_cmd() */
 93	complete(&desc->finished);
 94
 95	/* Run the worker thread again in case there are more cmds pending */
 96	schedule_work(&ec->worker);
 97}
 98
 99/*
100 * Throw a cmd descripter onto the list.  We now have SMP OLPC machines, so
101 * locking is pretty critical.
102 */
103static void queue_ec_descriptor(struct ec_cmd_desc *desc,
104		struct olpc_ec_priv *ec)
105{
106	unsigned long flags;
107
108	INIT_LIST_HEAD(&desc->node);
109
110	spin_lock_irqsave(&ec->cmd_q_lock, flags);
111	list_add_tail(&desc->node, &ec->cmd_q);
112	spin_unlock_irqrestore(&ec->cmd_q_lock, flags);
113
114	schedule_work(&ec->worker);
115}
116
117int olpc_ec_cmd(u8 cmd, u8 *inbuf, size_t inlen, u8 *outbuf, size_t outlen)
118{
119	struct olpc_ec_priv *ec = ec_priv;
120	struct ec_cmd_desc desc;
121
122	/* Ensure a driver and ec hook have been registered */
123	if (WARN_ON(!ec_driver || !ec_driver->ec_cmd))
124		return -ENODEV;
125
126	if (!ec)
127		return -ENOMEM;
128
129	/* Suspending in the middle of a command hoses things really badly */
130	if (WARN_ON(ec->suspended))
131		return -EBUSY;
132
133	might_sleep();
134
135	desc.cmd = cmd;
136	desc.inbuf = inbuf;
137	desc.outbuf = outbuf;
138	desc.inlen = inlen;
139	desc.outlen = outlen;
140	desc.err = 0;
141	init_completion(&desc.finished);
142
143	queue_ec_descriptor(&desc, ec);
144
145	/* Timeouts must be handled in the platform-specific EC hook */
146	wait_for_completion(&desc.finished);
147
148	/* The worker thread dequeues the cmd; no need to do anything here */
149	return desc.err;
150}
151EXPORT_SYMBOL_GPL(olpc_ec_cmd);
152
153#ifdef CONFIG_DEBUG_FS
154
155/*
156 * debugfs support for "generic commands", to allow sending
157 * arbitrary EC commands from userspace.
158 */
159
160#define EC_MAX_CMD_ARGS (5 + 1)		/* cmd byte + 5 args */
161#define EC_MAX_CMD_REPLY (8)
162
163static DEFINE_MUTEX(ec_dbgfs_lock);
164static unsigned char ec_dbgfs_resp[EC_MAX_CMD_REPLY];
165static unsigned int ec_dbgfs_resp_bytes;
166
167static ssize_t ec_dbgfs_cmd_write(struct file *file, const char __user *buf,
168		size_t size, loff_t *ppos)
169{
170	int i, m;
171	unsigned char ec_cmd[EC_MAX_CMD_ARGS];
172	unsigned int ec_cmd_int[EC_MAX_CMD_ARGS];
173	char cmdbuf[64];
174	int ec_cmd_bytes;
175
176	mutex_lock(&ec_dbgfs_lock);
177
178	size = simple_write_to_buffer(cmdbuf, sizeof(cmdbuf), ppos, buf, size);
179
180	m = sscanf(cmdbuf, "%x:%u %x %x %x %x %x", &ec_cmd_int[0],
181			&ec_dbgfs_resp_bytes, &ec_cmd_int[1], &ec_cmd_int[2],
182			&ec_cmd_int[3], &ec_cmd_int[4], &ec_cmd_int[5]);
183	if (m < 2 || ec_dbgfs_resp_bytes > EC_MAX_CMD_REPLY) {
184		/* reset to prevent overflow on read */
185		ec_dbgfs_resp_bytes = 0;
186
187		pr_debug("olpc-ec: bad ec cmd:  cmd:response-count [arg1 [arg2 ...]]\n");
188		size = -EINVAL;
189		goto out;
190	}
191
192	/* convert scanf'd ints to char */
193	ec_cmd_bytes = m - 2;
194	for (i = 0; i <= ec_cmd_bytes; i++)
195		ec_cmd[i] = ec_cmd_int[i];
196
197	pr_debug("olpc-ec: debugfs cmd 0x%02x with %d args %5ph, want %d returns\n",
198			ec_cmd[0], ec_cmd_bytes, ec_cmd + 1,
199			ec_dbgfs_resp_bytes);
200
201	olpc_ec_cmd(ec_cmd[0], (ec_cmd_bytes == 0) ? NULL : &ec_cmd[1],
202			ec_cmd_bytes, ec_dbgfs_resp, ec_dbgfs_resp_bytes);
203
204	pr_debug("olpc-ec: response %8ph (%d bytes expected)\n",
205			ec_dbgfs_resp, ec_dbgfs_resp_bytes);
206
207out:
208	mutex_unlock(&ec_dbgfs_lock);
209	return size;
210}
211
212static ssize_t ec_dbgfs_cmd_read(struct file *file, char __user *buf,
213		size_t size, loff_t *ppos)
214{
215	unsigned int i, r;
216	char *rp;
217	char respbuf[64];
218
219	mutex_lock(&ec_dbgfs_lock);
220	rp = respbuf;
221	rp += sprintf(rp, "%02x", ec_dbgfs_resp[0]);
222	for (i = 1; i < ec_dbgfs_resp_bytes; i++)
223		rp += sprintf(rp, ", %02x", ec_dbgfs_resp[i]);
224	mutex_unlock(&ec_dbgfs_lock);
225	rp += sprintf(rp, "\n");
226
227	r = rp - respbuf;
228	return simple_read_from_buffer(buf, size, ppos, respbuf, r);
229}
230
231static const struct file_operations ec_dbgfs_ops = {
232	.write = ec_dbgfs_cmd_write,
233	.read = ec_dbgfs_cmd_read,
234};
235
236static struct dentry *olpc_ec_setup_debugfs(void)
237{
238	struct dentry *dbgfs_dir;
239
240	dbgfs_dir = debugfs_create_dir("olpc-ec", NULL);
241	if (IS_ERR_OR_NULL(dbgfs_dir))
242		return NULL;
243
244	debugfs_create_file("cmd", 0600, dbgfs_dir, NULL, &ec_dbgfs_ops);
245
246	return dbgfs_dir;
247}
248
249#else
250
251static struct dentry *olpc_ec_setup_debugfs(void)
252{
253	return NULL;
254}
255
256#endif /* CONFIG_DEBUG_FS */
257
258static int olpc_ec_probe(struct platform_device *pdev)
259{
260	struct olpc_ec_priv *ec;
261	int err;
262
263	if (!ec_driver)
264		return -ENODEV;
265
266	ec = kzalloc(sizeof(*ec), GFP_KERNEL);
267	if (!ec)
268		return -ENOMEM;
269
270	ec->drv = ec_driver;
271	INIT_WORK(&ec->worker, olpc_ec_worker);
272	mutex_init(&ec->cmd_lock);
273
274	INIT_LIST_HEAD(&ec->cmd_q);
275	spin_lock_init(&ec->cmd_q_lock);
276
277	ec_priv = ec;
278	platform_set_drvdata(pdev, ec);
279
280	err = ec_driver->probe ? ec_driver->probe(pdev) : 0;
281	if (err) {
282		ec_priv = NULL;
283		kfree(ec);
284	} else {
285		ec->dbgfs_dir = olpc_ec_setup_debugfs();
286	}
287
288	return err;
289}
290
291static int olpc_ec_suspend(struct device *dev)
292{
293	struct platform_device *pdev = to_platform_device(dev);
294	struct olpc_ec_priv *ec = platform_get_drvdata(pdev);
295	int err = 0;
296
297	if (ec_driver->suspend)
298		err = ec_driver->suspend(pdev);
299	if (!err)
300		ec->suspended = true;
301
302	return err;
303}
304
305static int olpc_ec_resume(struct device *dev)
306{
307	struct platform_device *pdev = to_platform_device(dev);
308	struct olpc_ec_priv *ec = platform_get_drvdata(pdev);
309
310	ec->suspended = false;
311	return ec_driver->resume ? ec_driver->resume(pdev) : 0;
312}
313
314static const struct dev_pm_ops olpc_ec_pm_ops = {
315	.suspend_late = olpc_ec_suspend,
316	.resume_early = olpc_ec_resume,
317};
318
319static struct platform_driver olpc_ec_plat_driver = {
320	.probe = olpc_ec_probe,
321	.driver = {
322		.name = "olpc-ec",
323		.pm = &olpc_ec_pm_ops,
324	},
325};
326
327static int __init olpc_ec_init_module(void)
328{
329	return platform_driver_register(&olpc_ec_plat_driver);
330}
331arch_initcall(olpc_ec_init_module);