PM / sleep: Asynchronous threads for suspend_noirq
[linux/fpc-iii.git] / drivers / platform / olpc / olpc-ec.c
blobf9119525f5570c2d041d563c0eefbc9a01e32c20
1 /*
2 * Generic driver for the OLPC Embedded Controller.
4 * Copyright (C) 2011-2012 One Laptop per Child Foundation.
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>
20 struct ec_cmd_desc {
21 u8 cmd;
22 u8 *inbuf, *outbuf;
23 size_t inlen, outlen;
25 int err;
26 struct completion finished;
27 struct list_head node;
29 void *priv;
32 struct olpc_ec_priv {
33 struct olpc_ec_driver *drv;
34 struct work_struct worker;
35 struct mutex cmd_lock;
37 /* Pending EC commands */
38 struct list_head cmd_q;
39 spinlock_t cmd_q_lock;
41 struct dentry *dbgfs_dir;
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.
52 bool suspended;
55 static struct olpc_ec_driver *ec_driver;
56 static struct olpc_ec_priv *ec_priv;
57 static void *ec_cb_arg;
59 void olpc_ec_driver_register(struct olpc_ec_driver *drv, void *arg)
61 ec_driver = drv;
62 ec_cb_arg = arg;
64 EXPORT_SYMBOL_GPL(olpc_ec_driver_register);
66 static void olpc_ec_worker(struct work_struct *w)
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;
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);
78 spin_unlock_irqrestore(&ec->cmd_q_lock, flags);
80 /* Do we actually have anything to do? */
81 if (!desc)
82 return;
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);
90 /* Finished, wake up olpc_ec_cmd() */
91 complete(&desc->finished);
93 /* Run the worker thread again in case there are more cmds pending */
94 schedule_work(&ec->worker);
98 * Throw a cmd descripter onto the list. We now have SMP OLPC machines, so
99 * locking is pretty critical.
101 static void queue_ec_descriptor(struct ec_cmd_desc *desc,
102 struct olpc_ec_priv *ec)
104 unsigned long flags;
106 INIT_LIST_HEAD(&desc->node);
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);
112 schedule_work(&ec->worker);
115 int olpc_ec_cmd(u8 cmd, u8 *inbuf, size_t inlen, u8 *outbuf, size_t outlen)
117 struct olpc_ec_priv *ec = ec_priv;
118 struct ec_cmd_desc desc;
120 /* Ensure a driver and ec hook have been registered */
121 if (WARN_ON(!ec_driver || !ec_driver->ec_cmd))
122 return -ENODEV;
124 if (!ec)
125 return -ENOMEM;
127 /* Suspending in the middle of a command hoses things really badly */
128 if (WARN_ON(ec->suspended))
129 return -EBUSY;
131 might_sleep();
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);
141 queue_ec_descriptor(&desc, ec);
143 /* Timeouts must be handled in the platform-specific EC hook */
144 wait_for_completion(&desc.finished);
146 /* The worker thread dequeues the cmd; no need to do anything here */
147 return desc.err;
149 EXPORT_SYMBOL_GPL(olpc_ec_cmd);
151 #ifdef CONFIG_DEBUG_FS
154 * debugfs support for "generic commands", to allow sending
155 * arbitrary EC commands from userspace.
158 #define EC_MAX_CMD_ARGS (5 + 1) /* cmd byte + 5 args */
159 #define EC_MAX_CMD_REPLY (8)
161 static DEFINE_MUTEX(ec_dbgfs_lock);
162 static unsigned char ec_dbgfs_resp[EC_MAX_CMD_REPLY];
163 static unsigned int ec_dbgfs_resp_bytes;
165 static ssize_t ec_dbgfs_cmd_write(struct file *file, const char __user *buf,
166 size_t size, loff_t *ppos)
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;
174 mutex_lock(&ec_dbgfs_lock);
176 size = simple_write_to_buffer(cmdbuf, sizeof(cmdbuf), ppos, buf, size);
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;
185 pr_debug("olpc-ec: bad ec cmd: cmd:response-count [arg1 [arg2 ...]]\n");
186 size = -EINVAL;
187 goto out;
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];
195 pr_debug("olpc-ec: debugfs cmd 0x%02x with %d args %02x %02x %02x %02x %02x, want %d returns\n",
196 ec_cmd[0], ec_cmd_bytes, ec_cmd[1], ec_cmd[2],
197 ec_cmd[3], ec_cmd[4], ec_cmd[5], ec_dbgfs_resp_bytes);
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);
202 pr_debug("olpc-ec: response %02x %02x %02x %02x %02x %02x %02x %02x (%d bytes expected)\n",
203 ec_dbgfs_resp[0], ec_dbgfs_resp[1], ec_dbgfs_resp[2],
204 ec_dbgfs_resp[3], ec_dbgfs_resp[4], ec_dbgfs_resp[5],
205 ec_dbgfs_resp[6], ec_dbgfs_resp[7],
206 ec_dbgfs_resp_bytes);
208 out:
209 mutex_unlock(&ec_dbgfs_lock);
210 return size;
213 static ssize_t ec_dbgfs_cmd_read(struct file *file, char __user *buf,
214 size_t size, loff_t *ppos)
216 unsigned int i, r;
217 char *rp;
218 char respbuf[64];
220 mutex_lock(&ec_dbgfs_lock);
221 rp = respbuf;
222 rp += sprintf(rp, "%02x", ec_dbgfs_resp[0]);
223 for (i = 1; i < ec_dbgfs_resp_bytes; i++)
224 rp += sprintf(rp, ", %02x", ec_dbgfs_resp[i]);
225 mutex_unlock(&ec_dbgfs_lock);
226 rp += sprintf(rp, "\n");
228 r = rp - respbuf;
229 return simple_read_from_buffer(buf, size, ppos, respbuf, r);
232 static const struct file_operations ec_dbgfs_ops = {
233 .write = ec_dbgfs_cmd_write,
234 .read = ec_dbgfs_cmd_read,
237 static struct dentry *olpc_ec_setup_debugfs(void)
239 struct dentry *dbgfs_dir;
241 dbgfs_dir = debugfs_create_dir("olpc-ec", NULL);
242 if (IS_ERR_OR_NULL(dbgfs_dir))
243 return NULL;
245 debugfs_create_file("cmd", 0600, dbgfs_dir, NULL, &ec_dbgfs_ops);
247 return dbgfs_dir;
250 #else
252 static struct dentry *olpc_ec_setup_debugfs(void)
254 return NULL;
257 #endif /* CONFIG_DEBUG_FS */
259 static int olpc_ec_probe(struct platform_device *pdev)
261 struct olpc_ec_priv *ec;
262 int err;
264 if (!ec_driver)
265 return -ENODEV;
267 ec = kzalloc(sizeof(*ec), GFP_KERNEL);
268 if (!ec)
269 return -ENOMEM;
271 ec->drv = ec_driver;
272 INIT_WORK(&ec->worker, olpc_ec_worker);
273 mutex_init(&ec->cmd_lock);
275 INIT_LIST_HEAD(&ec->cmd_q);
276 spin_lock_init(&ec->cmd_q_lock);
278 ec_priv = ec;
279 platform_set_drvdata(pdev, ec);
281 err = ec_driver->probe ? ec_driver->probe(pdev) : 0;
282 if (err) {
283 ec_priv = NULL;
284 kfree(ec);
285 } else {
286 ec->dbgfs_dir = olpc_ec_setup_debugfs();
289 return err;
292 static int olpc_ec_suspend(struct device *dev)
294 struct platform_device *pdev = to_platform_device(dev);
295 struct olpc_ec_priv *ec = platform_get_drvdata(pdev);
296 int err = 0;
298 if (ec_driver->suspend)
299 err = ec_driver->suspend(pdev);
300 if (!err)
301 ec->suspended = true;
303 return err;
306 static int olpc_ec_resume(struct device *dev)
308 struct platform_device *pdev = to_platform_device(dev);
309 struct olpc_ec_priv *ec = platform_get_drvdata(pdev);
311 ec->suspended = false;
312 return ec_driver->resume ? ec_driver->resume(pdev) : 0;
315 static const struct dev_pm_ops olpc_ec_pm_ops = {
316 .suspend_late = olpc_ec_suspend,
317 .resume_early = olpc_ec_resume,
320 static struct platform_driver olpc_ec_plat_driver = {
321 .probe = olpc_ec_probe,
322 .driver = {
323 .name = "olpc-ec",
324 .pm = &olpc_ec_pm_ops,
328 static int __init olpc_ec_init_module(void)
330 return platform_driver_register(&olpc_ec_plat_driver);
333 arch_initcall(olpc_ec_init_module);
335 MODULE_AUTHOR("Andres Salomon <dilinger@queued.net>");
336 MODULE_LICENSE("GPL");