olpc-ec.c revision 6cca83d498bda0999302079bd59786370590c5c2 
1/*
2 * Generic driver for the OLPC Embedded Controller.
3 *
4 * Copyright (C) 2011-2012 One Laptop per Child Foundation.
5 *
6 * Licensed under the GPL v2 or later.
7 */
8#include <linux/completion.h>
9#include <linux/debugfs.h>
10#include <linux/spinlock.h>
11#include <linux/mutex.h>
12#include <linux/platform_device.h>
13#include <linux/slab.h>
14#include <linux/workqueue.h>
15#include <linux/module.h>
16#include <linux/list.h>
17#include <linux/olpc-ec.h>
18#include <asm/olpc.h>
19
20struct ec_cmd_desc {
21	u8 cmd;
22	u8 *inbuf, *outbuf;
23	size_t inlen, outlen;
24
25	int err;
26	struct completion finished;
27	struct list_head node;
28
29	void *priv;
30};
31
32struct olpc_ec_priv {
33	struct olpc_ec_driver *drv;
34
35	struct dentry *dbgfs_dir;
36
37	/*
38	 * Running an EC command while suspending means we don't always finish
39	 * the command before the machine suspends.  This means that the EC
40	 * is expecting the command protocol to finish, but we after a period
41	 * of time (while the OS is asleep) the EC times out and restarts its
42	 * idle loop.  Meanwhile, the OS wakes up, thinks it's still in the
43	 * middle of the command protocol, starts throwing random things at
44	 * the EC... and everyone's uphappy.
45	 */
46	bool suspended;
47};
48
49static void olpc_ec_worker(struct work_struct *w);
50
51static DECLARE_WORK(ec_worker, olpc_ec_worker);
52static LIST_HEAD(ec_cmd_q);
53static DEFINE_SPINLOCK(ec_cmd_q_lock);
54
55static struct olpc_ec_driver *ec_driver;
56static struct olpc_ec_priv *ec_priv;
57static void *ec_cb_arg;
58static DEFINE_MUTEX(ec_cb_lock);
59
60void olpc_ec_driver_register(struct olpc_ec_driver *drv, void *arg)
61{
62	ec_driver = drv;
63	ec_cb_arg = arg;
64}
65EXPORT_SYMBOL_GPL(olpc_ec_driver_register);
66
67static void olpc_ec_worker(struct work_struct *w)
68{
69	struct ec_cmd_desc *desc = NULL;
70	unsigned long flags;
71
72	/* Grab the first pending command from the queue */
73	spin_lock_irqsave(&ec_cmd_q_lock, flags);
74	if (!list_empty(&ec_cmd_q)) {
75		desc = list_first_entry(&ec_cmd_q, struct ec_cmd_desc, node);
76		list_del(&desc->node);
77	}
78	spin_unlock_irqrestore(&ec_cmd_q_lock, flags);
79
80	/* Do we actually have anything to do? */
81	if (!desc)
82		return;
83
84	/* Protect the EC hw with a mutex; only run one cmd at a time */
85	mutex_lock(&ec_cb_lock);
86	desc->err = ec_driver->ec_cmd(desc->cmd, desc->inbuf, desc->inlen,
87			desc->outbuf, desc->outlen, ec_cb_arg);
88	mutex_unlock(&ec_cb_lock);
89
90	/* Finished, wake up olpc_ec_cmd() */
91	complete(&desc->finished);
92
93	/* Run the worker thread again in case there are more cmds pending */
94	schedule_work(&ec_worker);
95}
96
97/*
98 * Throw a cmd descripter onto the list.  We now have SMP OLPC machines, so
99 * locking is pretty critical.
100 */
101static void queue_ec_descriptor(struct ec_cmd_desc *desc)
102{
103	unsigned long flags;
104
105	INIT_LIST_HEAD(&desc->node);
106
107	spin_lock_irqsave(&ec_cmd_q_lock, flags);
108	list_add_tail(&desc->node, &ec_cmd_q);
109	spin_unlock_irqrestore(&ec_cmd_q_lock, flags);
110
111	schedule_work(&ec_worker);
112}
113
114int olpc_ec_cmd(u8 cmd, u8 *inbuf, size_t inlen, u8 *outbuf, size_t outlen)
115{
116	struct olpc_ec_priv *ec = ec_priv;
117	struct ec_cmd_desc desc;
118
119	/* Ensure a driver and ec hook have been registered */
120	if (WARN_ON(!ec_driver || !ec_driver->ec_cmd))
121		return -ENODEV;
122
123	if (!ec)
124		return -ENOMEM;
125
126	/* Suspending in the middle of a command hoses things really badly */
127	if (WARN_ON(ec->suspended))
128		return -EBUSY;
129
130	might_sleep();
131
132	desc.cmd = cmd;
133	desc.inbuf = inbuf;
134	desc.outbuf = outbuf;
135	desc.inlen = inlen;
136	desc.outlen = outlen;
137	desc.err = 0;
138	init_completion(&desc.finished);
139
140	queue_ec_descriptor(&desc);
141
142	/* Timeouts must be handled in the platform-specific EC hook */
143	wait_for_completion(&desc.finished);
144
145	/* The worker thread dequeues the cmd; no need to do anything here */
146	return desc.err;
147}
148EXPORT_SYMBOL_GPL(olpc_ec_cmd);
149
150#ifdef CONFIG_DEBUG_FS
151
152/*
153 * debugfs support for "generic commands", to allow sending
154 * arbitrary EC commands from userspace.
155 */
156
157#define EC_MAX_CMD_ARGS (5 + 1)		/* cmd byte + 5 args */
158#define EC_MAX_CMD_REPLY (8)
159
160static DEFINE_MUTEX(ec_dbgfs_lock);
161static unsigned char ec_dbgfs_resp[EC_MAX_CMD_REPLY];
162static unsigned int ec_dbgfs_resp_bytes;
163
164static ssize_t ec_dbgfs_cmd_write(struct file *file, const char __user *buf,
165		size_t size, loff_t *ppos)
166{
167	int i, m;
168	unsigned char ec_cmd[EC_MAX_CMD_ARGS];
169	unsigned int ec_cmd_int[EC_MAX_CMD_ARGS];
170	char cmdbuf[64];
171	int ec_cmd_bytes;
172
173	mutex_lock(&ec_dbgfs_lock);
174
175	size = simple_write_to_buffer(cmdbuf, sizeof(cmdbuf), ppos, buf, size);
176
177	m = sscanf(cmdbuf, "%x:%u %x %x %x %x %x", &ec_cmd_int[0],
178			&ec_dbgfs_resp_bytes, &ec_cmd_int[1], &ec_cmd_int[2],
179			&ec_cmd_int[3], &ec_cmd_int[4], &ec_cmd_int[5]);
180	if (m < 2 || ec_dbgfs_resp_bytes > EC_MAX_CMD_REPLY) {
181		/* reset to prevent overflow on read */
182		ec_dbgfs_resp_bytes = 0;
183
184		pr_debug("olpc-ec: bad ec cmd:  cmd:response-count [arg1 [arg2 ...]]\n");
185		size = -EINVAL;
186		goto out;
187	}
188
189	/* convert scanf'd ints to char */
190	ec_cmd_bytes = m - 2;
191	for (i = 0; i <= ec_cmd_bytes; i++)
192		ec_cmd[i] = ec_cmd_int[i];
193
194	pr_debug("olpc-ec: debugfs cmd 0x%02x with %d args %02x %02x %02x %02x %02x, want %d returns\n",
195			ec_cmd[0], ec_cmd_bytes, ec_cmd[1], ec_cmd[2],
196			ec_cmd[3], ec_cmd[4], ec_cmd[5], ec_dbgfs_resp_bytes);
197
198	olpc_ec_cmd(ec_cmd[0], (ec_cmd_bytes == 0) ? NULL : &ec_cmd[1],
199			ec_cmd_bytes, ec_dbgfs_resp, ec_dbgfs_resp_bytes);
200
201	pr_debug("olpc-ec: response %02x %02x %02x %02x %02x %02x %02x %02x (%d bytes expected)\n",
202			ec_dbgfs_resp[0], ec_dbgfs_resp[1], ec_dbgfs_resp[2],
203			ec_dbgfs_resp[3], ec_dbgfs_resp[4], ec_dbgfs_resp[5],
204			ec_dbgfs_resp[6], ec_dbgfs_resp[7],
205			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	ec->drv = ec_driver;
270	ec_priv = ec;
271	platform_set_drvdata(pdev, ec);
272
273	err = ec_driver->probe ? ec_driver->probe(pdev) : 0;
274	if (err) {
275		ec_priv = NULL;
276		kfree(ec);
277	} else {
278		ec->dbgfs_dir = olpc_ec_setup_debugfs();
279	}
280
281	return err;
282}
283
284static int olpc_ec_suspend(struct device *dev)
285{
286	struct platform_device *pdev = to_platform_device(dev);
287	struct olpc_ec_priv *ec = platform_get_drvdata(pdev);
288	int err = 0;
289
290	if (ec_driver->suspend)
291		err = ec_driver->suspend(pdev);
292	if (!err)
293		ec->suspended = true;
294
295	return err;
296}
297
298static int olpc_ec_resume(struct device *dev)
299{
300	struct platform_device *pdev = to_platform_device(dev);
301	struct olpc_ec_priv *ec = platform_get_drvdata(pdev);
302
303	ec->suspended = false;
304	return ec_driver->resume ? ec_driver->resume(pdev) : 0;
305}
306
307static const struct dev_pm_ops olpc_ec_pm_ops = {
308	.suspend_late = olpc_ec_suspend,
309	.resume_early = olpc_ec_resume,
310};
311
312static struct platform_driver olpc_ec_plat_driver = {
313	.probe = olpc_ec_probe,
314	.driver = {
315		.name = "olpc-ec",
316		.pm = &olpc_ec_pm_ops,
317	},
318};
319
320static int __init olpc_ec_init_module(void)
321{
322	return platform_driver_register(&olpc_ec_plat_driver);
323}
324
325module_init(olpc_ec_init_module);
326
327MODULE_AUTHOR("Andres Salomon <dilinger@queued.net>");
328MODULE_LICENSE("GPL");
329