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	struct work_struct worker;
35	struct mutex cmd_lock;
36
37	/* Pending EC commands */
38	struct list_head cmd_q;
39	spinlock_t cmd_q_lock;
40
41	struct dentry *dbgfs_dir;
42
43	/*
44	 * Running an EC command while suspending means we don't always finish
45	 * the command before the machine suspends.  This means that the EC
46	 * is expecting the command protocol to finish, but we after a period
47	 * of time (while the OS is asleep) the EC times out and restarts its
48	 * idle loop.  Meanwhile, the OS wakes up, thinks it's still in the
49	 * middle of the command protocol, starts throwing random things at
50	 * the EC... and everyone's uphappy.
51	 */
52	bool suspended;
53};
54
55static struct olpc_ec_driver *ec_driver;
56static struct olpc_ec_priv *ec_priv;
57static void *ec_cb_arg;
58
59void olpc_ec_driver_register(struct olpc_ec_driver *drv, void *arg)
60{
61	ec_driver = drv;
62	ec_cb_arg = arg;
63}
64EXPORT_SYMBOL_GPL(olpc_ec_driver_register);
65
66static void olpc_ec_worker(struct work_struct *w)
67{
68	struct olpc_ec_priv *ec = container_of(w, struct olpc_ec_priv, worker);
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->cmd_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->cmd_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		struct olpc_ec_priv *ec)
103{
104	unsigned long flags;
105
106	INIT_LIST_HEAD(&desc->node);
107
108	spin_lock_irqsave(&ec->cmd_q_lock, flags);
109	list_add_tail(&desc->node, &ec->cmd_q);
110	spin_unlock_irqrestore(&ec->cmd_q_lock, flags);
111
112	schedule_work(&ec->worker);
113}
114
115int olpc_ec_cmd(u8 cmd, u8 *inbuf, size_t inlen, u8 *outbuf, size_t outlen)
116{
117	struct olpc_ec_priv *ec = ec_priv;
118	struct ec_cmd_desc desc;
119
120	/* Ensure a driver and ec hook have been registered */
121	if (WARN_ON(!ec_driver || !ec_driver->ec_cmd))
122		return -ENODEV;
123
124	if (!ec)
125		return -ENOMEM;
126
127	/* Suspending in the middle of a command hoses things really badly */
128	if (WARN_ON(ec->suspended))
129		return -EBUSY;
130
131	might_sleep();
132
133	desc.cmd = cmd;
134	desc.inbuf = inbuf;
135	desc.outbuf = outbuf;
136	desc.inlen = inlen;
137	desc.outlen = outlen;
138	desc.err = 0;
139	init_completion(&desc.finished);
140
141	queue_ec_descriptor(&desc, ec);
142
143	/* Timeouts must be handled in the platform-specific EC hook */
144	wait_for_completion(&desc.finished);
145
146	/* The worker thread dequeues the cmd; no need to do anything here */
147	return desc.err;
148}
149EXPORT_SYMBOL_GPL(olpc_ec_cmd);
150
151#ifdef CONFIG_DEBUG_FS
152
153/*
154 * debugfs support for "generic commands", to allow sending
155 * arbitrary EC commands from userspace.
156 */
157
158#define EC_MAX_CMD_ARGS (5 + 1)		/* cmd byte + 5 args */
159#define EC_MAX_CMD_REPLY (8)
160
161static DEFINE_MUTEX(ec_dbgfs_lock);
162static unsigned char ec_dbgfs_resp[EC_MAX_CMD_REPLY];
163static unsigned int ec_dbgfs_resp_bytes;
164
165static ssize_t ec_dbgfs_cmd_write(struct file *file, const char __user *buf,
166		size_t size, loff_t *ppos)
167{
168	int i, m;
169	unsigned char ec_cmd[EC_MAX_CMD_ARGS];
170	unsigned int ec_cmd_int[EC_MAX_CMD_ARGS];
171	char cmdbuf[64];
172	int ec_cmd_bytes;
173
174	mutex_lock(&ec_dbgfs_lock);
175
176	size = simple_write_to_buffer(cmdbuf, sizeof(cmdbuf), ppos, buf, size);
177
178	m = sscanf(cmdbuf, "%x:%u %x %x %x %x %x", &ec_cmd_int[0],
179			&ec_dbgfs_resp_bytes, &ec_cmd_int[1], &ec_cmd_int[2],
180			&ec_cmd_int[3], &ec_cmd_int[4], &ec_cmd_int[5]);
181	if (m < 2 || ec_dbgfs_resp_bytes > EC_MAX_CMD_REPLY) {
182		/* reset to prevent overflow on read */
183		ec_dbgfs_resp_bytes = 0;
184
185		pr_debug("olpc-ec: bad ec cmd:  cmd:response-count [arg1 [arg2 ...]]\n");
186		size = -EINVAL;
187		goto out;
188	}
189
190	/* convert scanf'd ints to char */
191	ec_cmd_bytes = m - 2;
192	for (i = 0; i <= ec_cmd_bytes; i++)
193		ec_cmd[i] = ec_cmd_int[i];
194
195	pr_debug("olpc-ec: debugfs cmd 0x%02x with %d args %5ph, want %d returns\n",
196			ec_cmd[0], ec_cmd_bytes, ec_cmd + 1,
197			ec_dbgfs_resp_bytes);
198
199	olpc_ec_cmd(ec_cmd[0], (ec_cmd_bytes == 0) ? NULL : &ec_cmd[1],
200			ec_cmd_bytes, ec_dbgfs_resp, ec_dbgfs_resp_bytes);
201
202	pr_debug("olpc-ec: response %8ph (%d bytes expected)\n",
203			ec_dbgfs_resp, ec_dbgfs_resp_bytes);
204
205out:
206	mutex_unlock(&ec_dbgfs_lock);
207	return size;
208}
209
210static ssize_t ec_dbgfs_cmd_read(struct file *file, char __user *buf,
211		size_t size, loff_t *ppos)
212{
213	unsigned int i, r;
214	char *rp;
215	char respbuf[64];
216
217	mutex_lock(&ec_dbgfs_lock);
218	rp = respbuf;
219	rp += sprintf(rp, "%02x", ec_dbgfs_resp[0]);
220	for (i = 1; i < ec_dbgfs_resp_bytes; i++)
221		rp += sprintf(rp, ", %02x", ec_dbgfs_resp[i]);
222	mutex_unlock(&ec_dbgfs_lock);
223	rp += sprintf(rp, "\n");
224
225	r = rp - respbuf;
226	return simple_read_from_buffer(buf, size, ppos, respbuf, r);
227}
228
229static const struct file_operations ec_dbgfs_ops = {
230	.write = ec_dbgfs_cmd_write,
231	.read = ec_dbgfs_cmd_read,
232};
233
234static struct dentry *olpc_ec_setup_debugfs(void)
235{
236	struct dentry *dbgfs_dir;
237
238	dbgfs_dir = debugfs_create_dir("olpc-ec", NULL);
239	if (IS_ERR_OR_NULL(dbgfs_dir))
240		return NULL;
241
242	debugfs_create_file("cmd", 0600, dbgfs_dir, NULL, &ec_dbgfs_ops);
243
244	return dbgfs_dir;
245}
246
247#else
248
249static struct dentry *olpc_ec_setup_debugfs(void)
250{
251	return NULL;
252}
253
254#endif /* CONFIG_DEBUG_FS */
255
256static int olpc_ec_probe(struct platform_device *pdev)
257{
258	struct olpc_ec_priv *ec;
259	int err;
260
261	if (!ec_driver)
262		return -ENODEV;
263
264	ec = kzalloc(sizeof(*ec), GFP_KERNEL);
265	if (!ec)
266		return -ENOMEM;
267
268	ec->drv = ec_driver;
269	INIT_WORK(&ec->worker, olpc_ec_worker);
270	mutex_init(&ec->cmd_lock);
271
272	INIT_LIST_HEAD(&ec->cmd_q);
273	spin_lock_init(&ec->cmd_q_lock);
274
275	ec_priv = ec;
276	platform_set_drvdata(pdev, ec);
277
278	err = ec_driver->probe ? ec_driver->probe(pdev) : 0;
279	if (err) {
280		ec_priv = NULL;
281		kfree(ec);
282	} else {
283		ec->dbgfs_dir = olpc_ec_setup_debugfs();
284	}
285
286	return err;
287}
288
289static int olpc_ec_suspend(struct device *dev)
290{
291	struct platform_device *pdev = to_platform_device(dev);
292	struct olpc_ec_priv *ec = platform_get_drvdata(pdev);
293	int err = 0;
294
295	if (ec_driver->suspend)
296		err = ec_driver->suspend(pdev);
297	if (!err)
298		ec->suspended = true;
299
300	return err;
301}
302
303static int olpc_ec_resume(struct device *dev)
304{
305	struct platform_device *pdev = to_platform_device(dev);
306	struct olpc_ec_priv *ec = platform_get_drvdata(pdev);
307
308	ec->suspended = false;
309	return ec_driver->resume ? ec_driver->resume(pdev) : 0;
310}
311
312static const struct dev_pm_ops olpc_ec_pm_ops = {
313	.suspend_late = olpc_ec_suspend,
314	.resume_early = olpc_ec_resume,
315};
316
317static struct platform_driver olpc_ec_plat_driver = {
318	.probe = olpc_ec_probe,
319	.driver = {
320		.name = "olpc-ec",
321		.pm = &olpc_ec_pm_ops,
322	},
323};
324
325static int __init olpc_ec_init_module(void)
326{
327	return platform_driver_register(&olpc_ec_plat_driver);
328}
329
330arch_initcall(olpc_ec_init_module);
331
332MODULE_AUTHOR("Andres Salomon <dilinger@queued.net>");
333MODULE_LICENSE("GPL");
334