summaryrefslogtreecommitdiffstats
path: root/drivers/platform/olpc/olpc-ec.c
blob: 374a8028fec772b406aef640fdc062fc5dd7d9b8 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
/*
 * Generic driver for the OLPC Embedded Controller.
 *
 * Author: Andres Salomon <dilinger@queued.net>
 *
 * Copyright (C) 2011-2012 One Laptop per Child Foundation.
 *
 * Licensed under the GPL v2 or later.
 */
#include <linux/completion.h>
#include <linux/debugfs.h>
#include <linux/spinlock.h>
#include <linux/mutex.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/workqueue.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/olpc-ec.h>
#include <asm/olpc.h>

struct ec_cmd_desc {
	u8 cmd;
	u8 *inbuf, *outbuf;
	size_t inlen, outlen;

	int err;
	struct completion finished;
	struct list_head node;

	void *priv;
};

struct olpc_ec_priv {
	struct olpc_ec_driver *drv;
	struct work_struct worker;
	struct mutex cmd_lock;

	/* Pending EC commands */
	struct list_head cmd_q;
	spinlock_t cmd_q_lock;

	struct dentry *dbgfs_dir;

	/*
	 * Running an EC command while suspending means we don't always finish
	 * the command before the machine suspends.  This means that the EC
	 * is expecting the command protocol to finish, but we after a period
	 * of time (while the OS is asleep) the EC times out and restarts its
	 * idle loop.  Meanwhile, the OS wakes up, thinks it's still in the
	 * middle of the command protocol, starts throwing random things at
	 * the EC... and everyone's uphappy.
	 */
	bool suspended;
};

static struct olpc_ec_driver *ec_driver;
static struct olpc_ec_priv *ec_priv;
static void *ec_cb_arg;

void olpc_ec_driver_register(struct olpc_ec_driver *drv, void *arg)
{
	ec_driver = drv;
	ec_cb_arg = arg;
}
EXPORT_SYMBOL_GPL(olpc_ec_driver_register);

static void olpc_ec_worker(struct work_struct *w)
{
	struct olpc_ec_priv *ec = container_of(w, struct olpc_ec_priv, worker);
	struct ec_cmd_desc *desc = NULL;
	unsigned long flags;

	/* Grab the first pending command from the queue */
	spin_lock_irqsave(&ec->cmd_q_lock, flags);
	if (!list_empty(&ec->cmd_q)) {
		desc = list_first_entry(&ec->cmd_q, struct ec_cmd_desc, node);
		list_del(&desc->node);
	}
	spin_unlock_irqrestore(&ec->cmd_q_lock, flags);

	/* Do we actually have anything to do? */
	if (!desc)
		return;

	/* Protect the EC hw with a mutex; only run one cmd at a time */
	mutex_lock(&ec->cmd_lock);
	desc->err = ec_driver->ec_cmd(desc->cmd, desc->inbuf, desc->inlen,
			desc->outbuf, desc->outlen, ec_cb_arg);
	mutex_unlock(&ec->cmd_lock);

	/* Finished, wake up olpc_ec_cmd() */
	complete(&desc->finished);

	/* Run the worker thread again in case there are more cmds pending */
	schedule_work(&ec->worker);
}

/*
 * Throw a cmd descripter onto the list.  We now have SMP OLPC machines, so
 * locking is pretty critical.
 */
static void queue_ec_descriptor(struct ec_cmd_desc *desc,
		struct olpc_ec_priv *ec)
{
	unsigned long flags;

	INIT_LIST_HEAD(&desc->node);

	spin_lock_irqsave(&ec->cmd_q_lock, flags);
	list_add_tail(&desc->node, &ec->cmd_q);
	spin_unlock_irqrestore(&ec->cmd_q_lock, flags);

	schedule_work(&ec->worker);
}

int olpc_ec_cmd(u8 cmd, u8 *inbuf, size_t inlen, u8 *outbuf, size_t outlen)
{
	struct olpc_ec_priv *ec = ec_priv;
	struct ec_cmd_desc desc;

	/* Ensure a driver and ec hook have been registered */
	if (WARN_ON(!ec_driver || !ec_driver->ec_cmd))
		return -ENODEV;

	if (!ec)
		return -ENOMEM;

	/* Suspending in the middle of a command hoses things really badly */
	if (WARN_ON(ec->suspended))
		return -EBUSY;

	might_sleep();

	desc.cmd = cmd;
	desc.inbuf = inbuf;
	desc.outbuf = outbuf;
	desc.inlen = inlen;
	desc.outlen = outlen;
	desc.err = 0;
	init_completion(&desc.finished);

	queue_ec_descriptor(&desc, ec);

	/* Timeouts must be handled in the platform-specific EC hook */
	wait_for_completion(&desc.finished);

	/* The worker thread dequeues the cmd; no need to do anything here */
	return desc.err;
}
EXPORT_SYMBOL_GPL(olpc_ec_cmd);

#ifdef CONFIG_DEBUG_FS

/*
 * debugfs support for "generic commands", to allow sending
 * arbitrary EC commands from userspace.
 */

#define EC_MAX_CMD_ARGS (5 + 1)		/* cmd byte + 5 args */
#define EC_MAX_CMD_REPLY (8)

static DEFINE_MUTEX(ec_dbgfs_lock);
static unsigned char ec_dbgfs_resp[EC_MAX_CMD_REPLY];
static unsigned int ec_dbgfs_resp_bytes;

static ssize_t ec_dbgfs_cmd_write(struct file *file, const char __user *buf,
		size_t size, loff_t *ppos)
{
	int i, m;
	unsigned char ec_cmd[EC_MAX_CMD_ARGS];
	unsigned int ec_cmd_int[EC_MAX_CMD_ARGS];
	char cmdbuf[64];
	int ec_cmd_bytes;

	mutex_lock(&ec_dbgfs_lock);

	size = simple_write_to_buffer(cmdbuf, sizeof(cmdbuf), ppos, buf, size);

	m = sscanf(cmdbuf, "%x:%u %x %x %x %x %x", &ec_cmd_int[0],
			&ec_dbgfs_resp_bytes, &ec_cmd_int[1], &ec_cmd_int[2],
			&ec_cmd_int[3], &ec_cmd_int[4], &ec_cmd_int[5]);
	if (m < 2 || ec_dbgfs_resp_bytes > EC_MAX_CMD_REPLY) {
		/* reset to prevent overflow on read */
		ec_dbgfs_resp_bytes = 0;

		pr_debug("olpc-ec: bad ec cmd:  cmd:response-count [arg1 [arg2 ...]]\n");
		size = -EINVAL;
		goto out;
	}

	/* convert scanf'd ints to char */
	ec_cmd_bytes = m - 2;
	for (i = 0; i <= ec_cmd_bytes; i++)
		ec_cmd[i] = ec_cmd_int[i];

	pr_debug("olpc-ec: debugfs cmd 0x%02x with %d args %5ph, want %d returns\n",
			ec_cmd[0], ec_cmd_bytes, ec_cmd + 1,
			ec_dbgfs_resp_bytes);

	olpc_ec_cmd(ec_cmd[0], (ec_cmd_bytes == 0) ? NULL : &ec_cmd[1],
			ec_cmd_bytes, ec_dbgfs_resp, ec_dbgfs_resp_bytes);

	pr_debug("olpc-ec: response %8ph (%d bytes expected)\n",
			ec_dbgfs_resp, ec_dbgfs_resp_bytes);

out:
	mutex_unlock(&ec_dbgfs_lock);
	return size;
}

static ssize_t ec_dbgfs_cmd_read(struct file *file, char __user *buf,
		size_t size, loff_t *ppos)
{
	unsigned int i, r;
	char *rp;
	char respbuf[64];

	mutex_lock(&ec_dbgfs_lock);
	rp = respbuf;
	rp += sprintf(rp, "%02x", ec_dbgfs_resp[0]);
	for (i = 1; i < ec_dbgfs_resp_bytes; i++)
		rp += sprintf(rp, ", %02x", ec_dbgfs_resp[i]);
	mutex_unlock(&ec_dbgfs_lock);
	rp += sprintf(rp, "\n");

	r = rp - respbuf;
	return simple_read_from_buffer(buf, size, ppos, respbuf, r);
}

static const struct file_operations ec_dbgfs_ops = {
	.write = ec_dbgfs_cmd_write,
	.read = ec_dbgfs_cmd_read,
};

static struct dentry *olpc_ec_setup_debugfs(void)
{
	struct dentry *dbgfs_dir;

	dbgfs_dir = debugfs_create_dir("olpc-ec", NULL);
	if (IS_ERR_OR_NULL(dbgfs_dir))
		return NULL;

	debugfs_create_file("cmd", 0600, dbgfs_dir, NULL, &ec_dbgfs_ops);

	return dbgfs_dir;
}

#else

static struct dentry *olpc_ec_setup_debugfs(void)
{
	return NULL;
}

#endif /* CONFIG_DEBUG_FS */

static int olpc_ec_probe(struct platform_device *pdev)
{
	struct olpc_ec_priv *ec;
	int err;

	if (!ec_driver)
		return -ENODEV;

	ec = kzalloc(sizeof(*ec), GFP_KERNEL);
	if (!ec)
		return -ENOMEM;

	ec->drv = ec_driver;
	INIT_WORK(&ec->worker, olpc_ec_worker);
	mutex_init(&ec->cmd_lock);

	INIT_LIST_HEAD(&ec->cmd_q);
	spin_lock_init(&ec->cmd_q_lock);

	ec_priv = ec;
	platform_set_drvdata(pdev, ec);

	err = ec_driver->probe ? ec_driver->probe(pdev) : 0;
	if (err) {
		ec_priv = NULL;
		kfree(ec);
	} else {
		ec->dbgfs_dir = olpc_ec_setup_debugfs();
	}

	return err;
}

static int olpc_ec_suspend(struct device *dev)
{
	struct platform_device *pdev = to_platform_device(dev);
	struct olpc_ec_priv *ec = platform_get_drvdata(pdev);
	int err = 0;

	if (ec_driver->suspend)
		err = ec_driver->suspend(pdev);
	if (!err)
		ec->suspended = true;

	return err;
}

static int olpc_ec_resume(struct device *dev)
{
	struct platform_device *pdev = to_platform_device(dev);
	struct olpc_ec_priv *ec = platform_get_drvdata(pdev);

	ec->suspended = false;
	return ec_driver->resume ? ec_driver->resume(pdev) : 0;
}

static const struct dev_pm_ops olpc_ec_pm_ops = {
	.suspend_late = olpc_ec_suspend,
	.resume_early = olpc_ec_resume,
};

static struct platform_driver olpc_ec_plat_driver = {
	.probe = olpc_ec_probe,
	.driver = {
		.name = "olpc-ec",
		.pm = &olpc_ec_pm_ops,
	},
};

static int __init olpc_ec_init_module(void)
{
	return platform_driver_register(&olpc_ec_plat_driver);
}
arch_initcall(olpc_ec_init_module);
OpenPOWER on IntegriCloud