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"); 334