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/olpc-ec.h>
  19 #include <asm/olpc.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         struct work_struct worker;
  36         struct mutex cmd_lock;
  37
  38         /* Pending EC commands */
  39         struct list_head cmd_q;
  40         spinlock_t cmd_q_lock;
  41
  42         struct dentry *dbgfs_dir;
  43
  44         /*
  45          * Running an EC command while suspending means we don't always finish
  46          * the command before the machine suspends.  This means that the EC
  47          * is expecting the command protocol to finish, but we after a period
  48          * of time (while the OS is asleep) the EC times out and restarts its
  49          * idle loop.  Meanwhile, the OS wakes up, thinks it's still in the
  50          * middle of the command protocol, starts throwing random things at
  51          * the EC... and everyone's uphappy.
  52          */
  53         bool suspended;
  54 };
  55
  56 static struct olpc_ec_driver *ec_driver;
  57 static struct olpc_ec_priv *ec_priv;
  58 static void *ec_cb_arg;
  59
  60 void olpc_ec_driver_register(struct olpc_ec_driver *drv, void *arg)
  61 {
  62         ec_driver = drv;
  63         ec_cb_arg = arg;
  64 }
  65 EXPORT_SYMBOL_GPL(olpc_ec_driver_register);
  66
  67 static void olpc_ec_worker(struct work_struct *w)
  68 {
  69         struct olpc_ec_priv *ec = container_of(w, struct olpc_ec_priv, worker);
  70         struct ec_cmd_desc *desc = NULL;
  71         unsigned long flags;
  72
  73         /* Grab the first pending command from the queue */
  74         spin_lock_irqsave(&ec->cmd_q_lock, flags);
  75         if (!list_empty(&ec->cmd_q)) {
  76                 desc = list_first_entry(&ec->cmd_q, struct ec_cmd_desc, node);
  77                 list_del(&desc->node);
  78         }
  79         spin_unlock_irqrestore(&ec->cmd_q_lock, flags);
  80
  81         /* Do we actually have anything to do? */
  82         if (!desc)
  83                 return;
  84
  85         /* Protect the EC hw with a mutex; only run one cmd at a time */
  86         mutex_lock(&ec->cmd_lock);
  87         desc->err = ec_driver->ec_cmd(desc->cmd, desc->inbuf, desc->inlen,
  88                         desc->outbuf, desc->outlen, ec_cb_arg);
  89         mutex_unlock(&ec->cmd_lock);
  90
  91         /* Finished, wake up olpc_ec_cmd() */
  92         complete(&desc->finished);
  93
  94         /* Run the worker thread again in case there are more cmds pending */
  95         schedule_work(&ec->worker);
  96 }
  97
  98 /*
  99  * Throw a cmd descripter onto the list.  We now have SMP OLPC machines, so
 100  * locking is pretty critical.
 101  */
 102 static void queue_ec_descriptor(struct ec_cmd_desc *desc,
 103                 struct olpc_ec_priv *ec)
 104 {
 105         unsigned long flags;
 106
 107         INIT_LIST_HEAD(&desc->node);
 108
 109         spin_lock_irqsave(&ec->cmd_q_lock, flags);
 110         list_add_tail(&desc->node, &ec->cmd_q);
 111         spin_unlock_irqrestore(&ec->cmd_q_lock, flags);
 112
 113         schedule_work(&ec->worker);
 114 }
 115
 116 int olpc_ec_cmd(u8 cmd, u8 *inbuf, size_t inlen, u8 *outbuf, size_t outlen)
 117 {
 118         struct olpc_ec_priv *ec = ec_priv;
 119         struct ec_cmd_desc desc;
 120
 121         /* Ensure a driver and ec hook have been registered */
 122         if (WARN_ON(!ec_driver || !ec_driver->ec_cmd))
 123                 return -ENODEV;
 124
 125         if (!ec)
 126                 return -ENOMEM;
 127
 128         /* Suspending in the middle of a command hoses things really badly */
 129         if (WARN_ON(ec->suspended))
 130                 return -EBUSY;
 131
 132         might_sleep();
 133
 134         desc.cmd = cmd;
 135         desc.inbuf = inbuf;
 136         desc.outbuf = outbuf;
 137         desc.inlen = inlen;
 138         desc.outlen = outlen;
 139         desc.err = 0;
 140         init_completion(&desc.finished);
 141
 142         queue_ec_descriptor(&desc, ec);
 143
 144         /* Timeouts must be handled in the platform-specific EC hook */
 145         wait_for_completion(&desc.finished);
 146
 147         /* The worker thread dequeues the cmd; no need to do anything here */
 148         return desc.err;
 149 }
 150 EXPORT_SYMBOL_GPL(olpc_ec_cmd);
 151
 152 #ifdef CONFIG_DEBUG_FS
 153
 154 /*
 155  * debugfs support for "generic commands", to allow sending
 156  * arbitrary EC commands from userspace.
 157  */
 158
 159 #define EC_MAX_CMD_ARGS (5 + 1)         /* cmd byte + 5 args */
 160 #define EC_MAX_CMD_REPLY (8)
 161
 162 static DEFINE_MUTEX(ec_dbgfs_lock);
 163 static unsigned char ec_dbgfs_resp[EC_MAX_CMD_REPLY];
 164 static unsigned int ec_dbgfs_resp_bytes;
 165
 166 static ssize_t ec_dbgfs_cmd_write(struct file *file, const char __user *buf,
 167                 size_t size, loff_t *ppos)
 168 {
 169         int i, m;
 170         unsigned char ec_cmd[EC_MAX_CMD_ARGS];
 171         unsigned int ec_cmd_int[EC_MAX_CMD_ARGS];
 172         char cmdbuf[64];
 173         int ec_cmd_bytes;
 174
 175         mutex_lock(&ec_dbgfs_lock);
 176
 177         size = simple_write_to_buffer(cmdbuf, sizeof(cmdbuf), ppos, buf, size);
 178
 179         m = sscanf(cmdbuf, "%x:%u %x %x %x %x %x", &ec_cmd_int[0],
 180                         &ec_dbgfs_resp_bytes, &ec_cmd_int[1], &ec_cmd_int[2],
 181                         &ec_cmd_int[3], &ec_cmd_int[4], &ec_cmd_int[5]);
 182         if (m < 2 || ec_dbgfs_resp_bytes > EC_MAX_CMD_REPLY) {
 183                 /* reset to prevent overflow on read */
 184                 ec_dbgfs_resp_bytes = 0;
 185
 186                 pr_debug("olpc-ec: bad ec cmd:  cmd:response-count [arg1 [arg2 ...]]\n");
 187                 size = -EINVAL;
 188                 goto out;
 189         }
 190
 191         /* convert scanf'd ints to char */
 192         ec_cmd_bytes = m - 2;
 193         for (i = 0; i <= ec_cmd_bytes; i++)
 194                 ec_cmd[i] = ec_cmd_int[i];
 195
 196         pr_debug("olpc-ec: debugfs cmd 0x%02x with %d args %5ph, want %d returns\n",
 197                         ec_cmd[0], ec_cmd_bytes, ec_cmd + 1,
 198                         ec_dbgfs_resp_bytes);
 199
 200         olpc_ec_cmd(ec_cmd[0], (ec_cmd_bytes == 0) ? NULL : &ec_cmd[1],
 201                         ec_cmd_bytes, ec_dbgfs_resp, ec_dbgfs_resp_bytes);
 202
 203         pr_debug("olpc-ec: response %8ph (%d bytes expected)\n",
 204                         ec_dbgfs_resp, ec_dbgfs_resp_bytes);
 205
 206 out:
 207         mutex_unlock(&ec_dbgfs_lock);
 208         return size;
 209 }
 210
 211 static ssize_t ec_dbgfs_cmd_read(struct file *file, char __user *buf,
 212                 size_t size, loff_t *ppos)
 213 {
 214         unsigned int i, r;
 215         char *rp;
 216         char respbuf[64];
 217
 218         mutex_lock(&ec_dbgfs_lock);
 219         rp = respbuf;
 220         rp += sprintf(rp, "%02x", ec_dbgfs_resp[0]);
 221         for (i = 1; i < ec_dbgfs_resp_bytes; i++)
 222                 rp += sprintf(rp, ", %02x", ec_dbgfs_resp[i]);
 223         mutex_unlock(&ec_dbgfs_lock);
 224         rp += sprintf(rp, "\n");
 225
 226         r = rp - respbuf;
 227         return simple_read_from_buffer(buf, size, ppos, respbuf, r);
 228 }
 229
 230 static const struct file_operations ec_dbgfs_ops = {
 231         .write = ec_dbgfs_cmd_write,
 232         .read = ec_dbgfs_cmd_read,
 233 };
 234
 235 static struct dentry *olpc_ec_setup_debugfs(void)
 236 {
 237         struct dentry *dbgfs_dir;
 238
 239         dbgfs_dir = debugfs_create_dir("olpc-ec", NULL);
 240         if (IS_ERR_OR_NULL(dbgfs_dir))
 241                 return NULL;
 242
 243         debugfs_create_file("cmd", 0600, dbgfs_dir, NULL, &ec_dbgfs_ops);
 244
 245         return dbgfs_dir;
 246 }
 247
 248 #else
 249
 250 static struct dentry *olpc_ec_setup_debugfs(void)
 251 {
 252         return NULL;
 253 }
 254
 255 #endif /* CONFIG_DEBUG_FS */
 256
 257 static int olpc_ec_probe(struct platform_device *pdev)
 258 {
 259         struct olpc_ec_priv *ec;
 260         int err;
 261
 262         if (!ec_driver)
 263                 return -ENODEV;
 264
 265         ec = kzalloc(sizeof(*ec), GFP_KERNEL);
 266         if (!ec)
 267                 return -ENOMEM;
 268
 269         ec->drv = ec_driver;
 270         INIT_WORK(&ec->worker, olpc_ec_worker);
 271         mutex_init(&ec->cmd_lock);
 272
 273         INIT_LIST_HEAD(&ec->cmd_q);
 274         spin_lock_init(&ec->cmd_q_lock);
 275
 276         ec_priv = ec;
 277         platform_set_drvdata(pdev, ec);
 278
 279         err = ec_driver->probe ? ec_driver->probe(pdev) : 0;
 280         if (err) {
 281                 ec_priv = NULL;
 282                 kfree(ec);
 283         } else {
 284                 ec->dbgfs_dir = olpc_ec_setup_debugfs();
 285         }
 286
 287         return err;
 288 }
 289
 290 static int olpc_ec_suspend(struct device *dev)
 291 {
 292         struct platform_device *pdev = to_platform_device(dev);
 293         struct olpc_ec_priv *ec = platform_get_drvdata(pdev);
 294         int err = 0;
 295
 296         if (ec_driver->suspend)
 297                 err = ec_driver->suspend(pdev);
 298         if (!err)
 299                 ec->suspended = true;
 300
 301         return err;
 302 }
 303
 304 static int olpc_ec_resume(struct device *dev)
 305 {
 306         struct platform_device *pdev = to_platform_device(dev);
 307         struct olpc_ec_priv *ec = platform_get_drvdata(pdev);
 308
 309         ec->suspended = false;
 310         return ec_driver->resume ? ec_driver->resume(pdev) : 0;
 311 }
 312
 313 static const struct dev_pm_ops olpc_ec_pm_ops = {
 314         .suspend_late = olpc_ec_suspend,
 315         .resume_early = olpc_ec_resume,
 316 };
 317
 318 static struct platform_driver olpc_ec_plat_driver = {
 319         .probe = olpc_ec_probe,
 320         .driver = {
 321                 .name = "olpc-ec",
 322                 .pm = &olpc_ec_pm_ops,
 323         },
 324 };
 325
 326 static int __init olpc_ec_init_module(void)
 327 {
 328         return platform_driver_register(&olpc_ec_plat_driver);
 329 }
 330 arch_initcall(olpc_ec_init_module);