drivers/platform/olpc/olpc-ec.c

   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
  20 struct 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
  32 struct 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
  55 static struct olpc_ec_driver *ec_driver;
  56 static struct olpc_ec_priv *ec_priv;
  57 static void *ec_cb_arg;
  58
  59 void olpc_ec_driver_register(struct olpc_ec_driver *drv, void *arg)
  60 {
  61         ec_driver = drv;
  62         ec_cb_arg = arg;
  63 }
  64 EXPORT_SYMBOL_GPL(olpc_ec_driver_register);
  65
  66 static 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  */
 101 static 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
 115 int 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 }
 149 EXPORT_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
 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;
 164
 165 static 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
 205 out:
 206         mutex_unlock(&ec_dbgfs_lock);
 207         return size;
 208 }
 209
 210 static 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
 229 static const struct file_operations ec_dbgfs_ops = {
 230         .write = ec_dbgfs_cmd_write,
 231         .read = ec_dbgfs_cmd_read,
 232 };
 233
 234 static 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
 249 static struct dentry *olpc_ec_setup_debugfs(void)
 250 {
 251         return NULL;
 252 }
 253
 254 #endif /* CONFIG_DEBUG_FS */
 255
 256 static 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
 289 static 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
 303 static 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
 312 static const struct dev_pm_ops olpc_ec_pm_ops = {
 313         .suspend_late = olpc_ec_suspend,
 314         .resume_early = olpc_ec_resume,
 315 };
 316
 317 static 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
 325 static int __init olpc_ec_init_module(void)
 326 {
 327         return platform_driver_register(&olpc_ec_plat_driver);
 328 }
 329
 330 arch_initcall(olpc_ec_init_module);
 331
 332 MODULE_AUTHOR("Andres Salomon <dilinger@queued.net>");
 333 MODULE_LICENSE("GPL");