drivers/platform/olpc/olpc-ec.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Generic driver for the OLPC Embedded Controller.
   4  *
   5  * Author: Andres Salomon <dilinger@queued.net>
   6  *
   7  * Copyright (C) 2011-2012 One Laptop per Child Foundation.
   8  */
   9 #include <linux/completion.h>
  10 #include <linux/debugfs.h>
  11 #include <linux/spinlock.h>
  12 #include <linux/mutex.h>
  13 #include <linux/platform_device.h>
  14 #include <linux/slab.h>
  15 #include <linux/workqueue.h>
  16 #include <linux/init.h>
  17 #include <linux/list.h>
  18 #include <linux/regulator/driver.h>
  19 #include <linux/olpc-ec.h>
  20
  21 struct ec_cmd_desc {
  22         u8 cmd;
  23         u8 *inbuf, *outbuf;
  24         size_t inlen, outlen;
  25
  26         int err;
  27         struct completion finished;
  28         struct list_head node;
  29
  30         void *priv;
  31 };
  32
  33 struct olpc_ec_priv {
  34         struct olpc_ec_driver *drv;
  35         u8 version;
  36         struct work_struct worker;
  37         struct mutex cmd_lock;
  38
  39         /* DCON regulator */
  40         struct regulator_dev *dcon_rdev;
  41         bool dcon_enabled;
  42
  43         /* Pending EC commands */
  44         struct list_head cmd_q;
  45         spinlock_t cmd_q_lock;
  46
  47         struct dentry *dbgfs_dir;
  48
  49         /*
  50          * EC event mask to be applied during suspend (defining wakeup
  51          * sources).
  52          */
  53         u16 ec_wakeup_mask;
  54
  55         /*
  56          * Running an EC command while suspending means we don't always finish
  57          * the command before the machine suspends.  This means that the EC
  58          * is expecting the command protocol to finish, but we after a period
  59          * of time (while the OS is asleep) the EC times out and restarts its
  60          * idle loop.  Meanwhile, the OS wakes up, thinks it's still in the
  61          * middle of the command protocol, starts throwing random things at
  62          * the EC... and everyone's uphappy.
  63          */
  64         bool suspended;
  65 };
  66
  67 static struct olpc_ec_driver *ec_driver;
  68 static struct olpc_ec_priv *ec_priv;
  69 static void *ec_cb_arg;
  70
  71 void olpc_ec_driver_register(struct olpc_ec_driver *drv, void *arg)
  72 {
  73         ec_driver = drv;
  74         ec_cb_arg = arg;
  75 }
  76 EXPORT_SYMBOL_GPL(olpc_ec_driver_register);
  77
  78 static void olpc_ec_worker(struct work_struct *w)
  79 {
  80         struct olpc_ec_priv *ec = container_of(w, struct olpc_ec_priv, worker);
  81         struct ec_cmd_desc *desc = NULL;
  82         unsigned long flags;
  83
  84         /* Grab the first pending command from the queue */
  85         spin_lock_irqsave(&ec->cmd_q_lock, flags);
  86         if (!list_empty(&ec->cmd_q)) {
  87                 desc = list_first_entry(&ec->cmd_q, struct ec_cmd_desc, node);
  88                 list_del(&desc->node);
  89         }
  90         spin_unlock_irqrestore(&ec->cmd_q_lock, flags);
  91
  92         /* Do we actually have anything to do? */
  93         if (!desc)
  94                 return;
  95
  96         /* Protect the EC hw with a mutex; only run one cmd at a time */
  97         mutex_lock(&ec->cmd_lock);
  98         desc->err = ec_driver->ec_cmd(desc->cmd, desc->inbuf, desc->inlen,
  99                         desc->outbuf, desc->outlen, ec_cb_arg);
 100         mutex_unlock(&ec->cmd_lock);
 101
 102         /* Finished, wake up olpc_ec_cmd() */
 103         complete(&desc->finished);
 104
 105         /* Run the worker thread again in case there are more cmds pending */
 106         schedule_work(&ec->worker);
 107 }
 108
 109 /*
 110  * Throw a cmd descripter onto the list.  We now have SMP OLPC machines, so
 111  * locking is pretty critical.
 112  */
 113 static void queue_ec_descriptor(struct ec_cmd_desc *desc,
 114                 struct olpc_ec_priv *ec)
 115 {
 116         unsigned long flags;
 117
 118         INIT_LIST_HEAD(&desc->node);
 119
 120         spin_lock_irqsave(&ec->cmd_q_lock, flags);
 121         list_add_tail(&desc->node, &ec->cmd_q);
 122         spin_unlock_irqrestore(&ec->cmd_q_lock, flags);
 123
 124         schedule_work(&ec->worker);
 125 }
 126
 127 int olpc_ec_cmd(u8 cmd, u8 *inbuf, size_t inlen, u8 *outbuf, size_t outlen)
 128 {
 129         struct olpc_ec_priv *ec = ec_priv;
 130         struct ec_cmd_desc desc;
 131
 132         /* Driver not yet registered. */
 133         if (!ec_driver)
 134                 return -EPROBE_DEFER;
 135
 136         if (WARN_ON(!ec_driver->ec_cmd))
 137                 return -ENODEV;
 138
 139         if (!ec)
 140                 return -ENOMEM;
 141
 142         /* Suspending in the middle of a command hoses things really badly */
 143         if (WARN_ON(ec->suspended))
 144                 return -EBUSY;
 145
 146         might_sleep();
 147
 148         desc.cmd = cmd;
 149         desc.inbuf = inbuf;
 150         desc.outbuf = outbuf;
 151         desc.inlen = inlen;
 152         desc.outlen = outlen;
 153         desc.err = 0;
 154         init_completion(&desc.finished);
 155
 156         queue_ec_descriptor(&desc, ec);
 157
 158         /* Timeouts must be handled in the platform-specific EC hook */
 159         wait_for_completion(&desc.finished);
 160
 161         /* The worker thread dequeues the cmd; no need to do anything here */
 162         return desc.err;
 163 }
 164 EXPORT_SYMBOL_GPL(olpc_ec_cmd);
 165
 166 void olpc_ec_wakeup_set(u16 value)
 167 {
 168         struct olpc_ec_priv *ec = ec_priv;
 169
 170         if (WARN_ON(!ec))
 171                 return;
 172
 173         ec->ec_wakeup_mask |= value;
 174 }
 175 EXPORT_SYMBOL_GPL(olpc_ec_wakeup_set);
 176
 177 void olpc_ec_wakeup_clear(u16 value)
 178 {
 179         struct olpc_ec_priv *ec = ec_priv;
 180
 181         if (WARN_ON(!ec))
 182                 return;
 183
 184         ec->ec_wakeup_mask &= ~value;
 185 }
 186 EXPORT_SYMBOL_GPL(olpc_ec_wakeup_clear);
 187
 188 int olpc_ec_mask_write(u16 bits)
 189 {
 190         struct olpc_ec_priv *ec = ec_priv;
 191
 192         if (WARN_ON(!ec))
 193                 return -ENODEV;
 194
 195         /* EC version 0x5f adds support for wide SCI mask */
 196         if (ec->version >= 0x5f) {
 197                 __be16 ec_word = cpu_to_be16(bits);
 198
 199                 return olpc_ec_cmd(EC_WRITE_EXT_SCI_MASK, (void *)&ec_word, 2, NULL, 0);
 200         } else {
 201                 u8 ec_byte = bits & 0xff;
 202
 203                 return olpc_ec_cmd(EC_WRITE_SCI_MASK, &ec_byte, 1, NULL, 0);
 204         }
 205 }
 206 EXPORT_SYMBOL_GPL(olpc_ec_mask_write);
 207
 208 /*
 209  * Returns true if the compile and runtime configurations allow for EC events
 210  * to wake the system.
 211  */
 212 bool olpc_ec_wakeup_available(void)
 213 {
 214         if (WARN_ON(!ec_driver))
 215                 return false;
 216
 217         return ec_driver->wakeup_available;
 218 }
 219 EXPORT_SYMBOL_GPL(olpc_ec_wakeup_available);
 220
 221 int olpc_ec_sci_query(u16 *sci_value)
 222 {
 223         struct olpc_ec_priv *ec = ec_priv;
 224         int ret;
 225
 226         if (WARN_ON(!ec))
 227                 return -ENODEV;
 228
 229         /* EC version 0x5f adds support for wide SCI mask */
 230         if (ec->version >= 0x5f) {
 231                 __be16 ec_word;
 232
 233                 ret = olpc_ec_cmd(EC_EXT_SCI_QUERY, NULL, 0, (void *)&ec_word, 2);
 234                 if (ret == 0)
 235                         *sci_value = be16_to_cpu(ec_word);
 236         } else {
 237                 u8 ec_byte;
 238
 239                 ret = olpc_ec_cmd(EC_SCI_QUERY, NULL, 0, &ec_byte, 1);
 240                 if (ret == 0)
 241                         *sci_value = ec_byte;
 242         }
 243
 244         return ret;
 245 }
 246 EXPORT_SYMBOL_GPL(olpc_ec_sci_query);
 247
 248 #ifdef CONFIG_DEBUG_FS
 249
 250 /*
 251  * debugfs support for "generic commands", to allow sending
 252  * arbitrary EC commands from userspace.
 253  */
 254
 255 #define EC_MAX_CMD_ARGS (5 + 1)         /* cmd byte + 5 args */
 256 #define EC_MAX_CMD_REPLY (8)
 257
 258 static DEFINE_MUTEX(ec_dbgfs_lock);
 259 static unsigned char ec_dbgfs_resp[EC_MAX_CMD_REPLY];
 260 static unsigned int ec_dbgfs_resp_bytes;
 261
 262 static ssize_t ec_dbgfs_cmd_write(struct file *file, const char __user *buf,
 263                 size_t size, loff_t *ppos)
 264 {
 265         int i, m;
 266         unsigned char ec_cmd[EC_MAX_CMD_ARGS];
 267         unsigned int ec_cmd_int[EC_MAX_CMD_ARGS];
 268         char cmdbuf[64];
 269         int ec_cmd_bytes;
 270
 271         mutex_lock(&ec_dbgfs_lock);
 272
 273         size = simple_write_to_buffer(cmdbuf, sizeof(cmdbuf), ppos, buf, size);
 274
 275         m = sscanf(cmdbuf, "%x:%u %x %x %x %x %x", &ec_cmd_int[0],
 276                         &ec_dbgfs_resp_bytes, &ec_cmd_int[1], &ec_cmd_int[2],
 277                         &ec_cmd_int[3], &ec_cmd_int[4], &ec_cmd_int[5]);
 278         if (m < 2 || ec_dbgfs_resp_bytes > EC_MAX_CMD_REPLY) {
 279                 /* reset to prevent overflow on read */
 280                 ec_dbgfs_resp_bytes = 0;
 281
 282                 pr_debug("olpc-ec: bad ec cmd:  cmd:response-count [arg1 [arg2 ...]]\n");
 283                 size = -EINVAL;
 284                 goto out;
 285         }
 286
 287         /* convert scanf'd ints to char */
 288         ec_cmd_bytes = m - 2;
 289         for (i = 0; i <= ec_cmd_bytes; i++)
 290                 ec_cmd[i] = ec_cmd_int[i];
 291
 292         pr_debug("olpc-ec: debugfs cmd 0x%02x with %d args %5ph, want %d returns\n",
 293                         ec_cmd[0], ec_cmd_bytes, ec_cmd + 1,
 294                         ec_dbgfs_resp_bytes);
 295
 296         olpc_ec_cmd(ec_cmd[0], (ec_cmd_bytes == 0) ? NULL : &ec_cmd[1],
 297                         ec_cmd_bytes, ec_dbgfs_resp, ec_dbgfs_resp_bytes);
 298
 299         pr_debug("olpc-ec: response %8ph (%d bytes expected)\n",
 300                         ec_dbgfs_resp, ec_dbgfs_resp_bytes);
 301
 302 out:
 303         mutex_unlock(&ec_dbgfs_lock);
 304         return size;
 305 }
 306
 307 static ssize_t ec_dbgfs_cmd_read(struct file *file, char __user *buf,
 308                 size_t size, loff_t *ppos)
 309 {
 310         unsigned int i, r;
 311         char *rp;
 312         char respbuf[64];
 313
 314         mutex_lock(&ec_dbgfs_lock);
 315         rp = respbuf;
 316         rp += sprintf(rp, "%02x", ec_dbgfs_resp[0]);
 317         for (i = 1; i < ec_dbgfs_resp_bytes; i++)
 318                 rp += sprintf(rp, ", %02x", ec_dbgfs_resp[i]);
 319         mutex_unlock(&ec_dbgfs_lock);
 320         rp += sprintf(rp, "\n");
 321
 322         r = rp - respbuf;
 323         return simple_read_from_buffer(buf, size, ppos, respbuf, r);
 324 }
 325
 326 static const struct file_operations ec_dbgfs_ops = {
 327         .write = ec_dbgfs_cmd_write,
 328         .read = ec_dbgfs_cmd_read,
 329 };
 330
 331 static struct dentry *olpc_ec_setup_debugfs(void)
 332 {
 333         struct dentry *dbgfs_dir;
 334
 335         dbgfs_dir = debugfs_create_dir("olpc-ec", NULL);
 336         if (IS_ERR_OR_NULL(dbgfs_dir))
 337                 return NULL;
 338
 339         debugfs_create_file("cmd", 0600, dbgfs_dir, NULL, &ec_dbgfs_ops);
 340
 341         return dbgfs_dir;
 342 }
 343
 344 #else
 345
 346 static struct dentry *olpc_ec_setup_debugfs(void)
 347 {
 348         return NULL;
 349 }
 350
 351 #endif /* CONFIG_DEBUG_FS */
 352
 353 static int olpc_ec_set_dcon_power(struct olpc_ec_priv *ec, bool state)
 354 {
 355         unsigned char ec_byte = state;
 356         int ret;
 357
 358         if (ec->dcon_enabled == state)
 359                 return 0;
 360
 361         ret = olpc_ec_cmd(EC_DCON_POWER_MODE, &ec_byte, 1, NULL, 0);
 362         if (ret)
 363                 return ret;
 364
 365         ec->dcon_enabled = state;
 366         return 0;
 367 }
 368
 369 static int dcon_regulator_enable(struct regulator_dev *rdev)
 370 {
 371         struct olpc_ec_priv *ec = rdev_get_drvdata(rdev);
 372
 373         return olpc_ec_set_dcon_power(ec, true);
 374 }
 375
 376 static int dcon_regulator_disable(struct regulator_dev *rdev)
 377 {
 378         struct olpc_ec_priv *ec = rdev_get_drvdata(rdev);
 379
 380         return olpc_ec_set_dcon_power(ec, false);
 381 }
 382
 383 static int dcon_regulator_is_enabled(struct regulator_dev *rdev)
 384 {
 385         struct olpc_ec_priv *ec = rdev_get_drvdata(rdev);
 386
 387         return ec->dcon_enabled ? 1 : 0;
 388 }
 389
 390 static struct regulator_ops dcon_regulator_ops = {
 391         .enable         = dcon_regulator_enable,
 392         .disable        = dcon_regulator_disable,
 393         .is_enabled     = dcon_regulator_is_enabled,
 394 };
 395
 396 static const struct regulator_desc dcon_desc = {
 397         .name   = "dcon",
 398         .id     = 0,
 399         .ops    = &dcon_regulator_ops,
 400         .type   = REGULATOR_VOLTAGE,
 401         .owner  = THIS_MODULE,
 402 };
 403
 404 static int olpc_ec_probe(struct platform_device *pdev)
 405 {
 406         struct olpc_ec_priv *ec;
 407         struct regulator_config config = { };
 408         int err;
 409
 410         if (!ec_driver)
 411                 return -ENODEV;
 412
 413         ec = kzalloc(sizeof(*ec), GFP_KERNEL);
 414         if (!ec)
 415                 return -ENOMEM;
 416
 417         ec->drv = ec_driver;
 418         INIT_WORK(&ec->worker, olpc_ec_worker);
 419         mutex_init(&ec->cmd_lock);
 420
 421         INIT_LIST_HEAD(&ec->cmd_q);
 422         spin_lock_init(&ec->cmd_q_lock);
 423
 424         ec_priv = ec;
 425         platform_set_drvdata(pdev, ec);
 426
 427         /* get the EC revision */
 428         err = olpc_ec_cmd(EC_FIRMWARE_REV, NULL, 0, &ec->version, 1);
 429         if (err) {
 430                 ec_priv = NULL;
 431                 kfree(ec);
 432                 return err;
 433         }
 434
 435         config.dev = pdev->dev.parent;
 436         config.driver_data = ec;
 437         ec->dcon_enabled = true;
 438         ec->dcon_rdev = devm_regulator_register(&pdev->dev, &dcon_desc,
 439                                                                 &config);
 440         if (IS_ERR(ec->dcon_rdev)) {
 441                 dev_err(&pdev->dev, "failed to register DCON regulator\n");
 442                 err = PTR_ERR(ec->dcon_rdev);
 443                 kfree(ec);
 444                 return err;
 445         }
 446
 447         ec->dbgfs_dir = olpc_ec_setup_debugfs();
 448
 449         return err;
 450 }
 451
 452 static int olpc_ec_suspend(struct device *dev)
 453 {
 454         struct platform_device *pdev = to_platform_device(dev);
 455         struct olpc_ec_priv *ec = platform_get_drvdata(pdev);
 456         int err = 0;
 457
 458         olpc_ec_mask_write(ec->ec_wakeup_mask);
 459
 460         if (ec_driver->suspend)
 461                 err = ec_driver->suspend(pdev);
 462         if (!err)
 463                 ec->suspended = true;
 464
 465         return err;
 466 }
 467
 468 static int olpc_ec_resume(struct device *dev)
 469 {
 470         struct platform_device *pdev = to_platform_device(dev);
 471         struct olpc_ec_priv *ec = platform_get_drvdata(pdev);
 472
 473         ec->suspended = false;
 474         return ec_driver->resume ? ec_driver->resume(pdev) : 0;
 475 }
 476
 477 static const struct dev_pm_ops olpc_ec_pm_ops = {
 478         .suspend_late = olpc_ec_suspend,
 479         .resume_early = olpc_ec_resume,
 480 };
 481
 482 static struct platform_driver olpc_ec_plat_driver = {
 483         .probe = olpc_ec_probe,
 484         .driver = {
 485                 .name = "olpc-ec",
 486                 .pm = &olpc_ec_pm_ops,
 487         },
 488 };
 489
 490 static int __init olpc_ec_init_module(void)
 491 {
 492         return platform_driver_register(&olpc_ec_plat_driver);
 493 }
 494 arch_initcall(olpc_ec_init_module);