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); 332