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Linux/drivers/platform/olpc/olpc-ec.c

  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 
 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 
 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  */
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 
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 
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 
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 
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 
251 static struct dentry *olpc_ec_setup_debugfs(void)
252 {
253         return NULL;
254 }
255 
256 #endif /* CONFIG_DEBUG_FS */
257 
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 
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 
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 
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 

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