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);