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
22 struct 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
34 struct 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
57 static struct olpc_ec_driver *ec_driver;
58 static struct olpc_ec_priv *ec_priv;
59 static void *ec_cb_arg;
60
olpc_ec_driver_register(struct olpc_ec_driver * drv,void * arg)61 void olpc_ec_driver_register(struct olpc_ec_driver *drv, void *arg)
62 {
63 ec_driver = drv;
64 ec_cb_arg = arg;
65 }
66 EXPORT_SYMBOL_GPL(olpc_ec_driver_register);
67
olpc_ec_worker(struct work_struct * w)68 static 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 */
queue_ec_descriptor(struct ec_cmd_desc * desc,struct olpc_ec_priv * ec)103 static 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
olpc_ec_cmd(u8 cmd,u8 * inbuf,size_t inlen,u8 * outbuf,size_t outlen)117 int 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 }
151 EXPORT_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
163 static DEFINE_MUTEX(ec_dbgfs_lock);
164 static unsigned char ec_dbgfs_resp[EC_MAX_CMD_REPLY];
165 static unsigned int ec_dbgfs_resp_bytes;
166
ec_dbgfs_cmd_write(struct file * file,const char __user * buf,size_t size,loff_t * ppos)167 static 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
207 out:
208 mutex_unlock(&ec_dbgfs_lock);
209 return size;
210 }
211
ec_dbgfs_cmd_read(struct file * file,char __user * buf,size_t size,loff_t * ppos)212 static 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
231 static const struct file_operations ec_dbgfs_ops = {
232 .write = ec_dbgfs_cmd_write,
233 .read = ec_dbgfs_cmd_read,
234 };
235
olpc_ec_setup_debugfs(void)236 static 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
olpc_ec_setup_debugfs(void)251 static struct dentry *olpc_ec_setup_debugfs(void)
252 {
253 return NULL;
254 }
255
256 #endif /* CONFIG_DEBUG_FS */
257
olpc_ec_probe(struct platform_device * pdev)258 static 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
olpc_ec_suspend(struct device * dev)291 static 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
olpc_ec_resume(struct device * dev)305 static 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
314 static const struct dev_pm_ops olpc_ec_pm_ops = {
315 .suspend_late = olpc_ec_suspend,
316 .resume_early = olpc_ec_resume,
317 };
318
319 static 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
olpc_ec_init_module(void)327 static int __init olpc_ec_init_module(void)
328 {
329 return platform_driver_register(&olpc_ec_plat_driver);
330 }
331 arch_initcall(olpc_ec_init_module);
332