drivers/platform/chrome/cros_ec_lightbar.c

   1 /*
   2  * cros_ec_lightbar - expose the Chromebook Pixel lightbar to userspace
   3  *
   4  * Copyright (C) 2014 Google, Inc.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #define pr_fmt(fmt) "cros_ec_lightbar: " fmt
  21
  22 #include <linux/ctype.h>
  23 #include <linux/delay.h>
  24 #include <linux/device.h>
  25 #include <linux/fs.h>
  26 #include <linux/kobject.h>
  27 #include <linux/mfd/cros_ec.h>
  28 #include <linux/mfd/cros_ec_commands.h>
  29 #include <linux/module.h>
  30 #include <linux/platform_device.h>
  31 #include <linux/sched.h>
  32 #include <linux/types.h>
  33 #include <linux/uaccess.h>
  34
  35 #include "cros_ec_dev.h"
  36
  37 /* Rate-limit the lightbar interface to prevent DoS. */
  38 static unsigned long lb_interval_jiffies = 50 * HZ / 1000;
  39
  40 static ssize_t interval_msec_show(struct device *dev,
  41                                   struct device_attribute *attr, char *buf)
  42 {
  43         unsigned long msec = lb_interval_jiffies * 1000 / HZ;
  44
  45         return scnprintf(buf, PAGE_SIZE, "%lu\n", msec);
  46 }
  47
  48 static ssize_t interval_msec_store(struct device *dev,
  49                                    struct device_attribute *attr,
  50                                    const char *buf, size_t count)
  51 {
  52         unsigned long msec;
  53
  54         if (kstrtoul(buf, 0, &msec))
  55                 return -EINVAL;
  56
  57         lb_interval_jiffies = msec * HZ / 1000;
  58
  59         return count;
  60 }
  61
  62 static DEFINE_MUTEX(lb_mutex);
  63 /* Return 0 if able to throttle correctly, error otherwise */
  64 static int lb_throttle(void)
  65 {
  66         static unsigned long last_access;
  67         unsigned long now, next_timeslot;
  68         long delay;
  69         int ret = 0;
  70
  71         mutex_lock(&lb_mutex);
  72
  73         now = jiffies;
  74         next_timeslot = last_access + lb_interval_jiffies;
  75
  76         if (time_before(now, next_timeslot)) {
  77                 delay = (long)(next_timeslot) - (long)now;
  78                 set_current_state(TASK_INTERRUPTIBLE);
  79                 if (schedule_timeout(delay) > 0) {
  80                         /* interrupted - just abort */
  81                         ret = -EINTR;
  82                         goto out;
  83                 }
  84                 now = jiffies;
  85         }
  86
  87         last_access = now;
  88 out:
  89         mutex_unlock(&lb_mutex);
  90
  91         return ret;
  92 }
  93
  94 #define INIT_MSG(P, R) { \
  95                 .command = EC_CMD_LIGHTBAR_CMD, \
  96                 .outsize = sizeof(*P), \
  97                 .insize = sizeof(*R), \
  98         }
  99
 100 static int get_lightbar_version(struct cros_ec_device *ec,
 101                                 uint32_t *ver_ptr, uint32_t *flg_ptr)
 102 {
 103         struct ec_params_lightbar *param;
 104         struct ec_response_lightbar *resp;
 105         struct cros_ec_command msg = INIT_MSG(param, resp);
 106         int ret;
 107
 108         param = (struct ec_params_lightbar *)msg.outdata;
 109         param->cmd = LIGHTBAR_CMD_VERSION;
 110         ret = cros_ec_cmd_xfer(ec, &msg);
 111         if (ret < 0)
 112                 return 0;
 113
 114         switch (msg.result) {
 115         case EC_RES_INVALID_PARAM:
 116                 /* Pixel had no version command. */
 117                 if (ver_ptr)
 118                         *ver_ptr = 0;
 119                 if (flg_ptr)
 120                         *flg_ptr = 0;
 121                 return 1;
 122
 123         case EC_RES_SUCCESS:
 124                 resp = (struct ec_response_lightbar *)msg.indata;
 125
 126                 /* Future devices w/lightbars should implement this command */
 127                 if (ver_ptr)
 128                         *ver_ptr = resp->version.num;
 129                 if (flg_ptr)
 130                         *flg_ptr = resp->version.flags;
 131                 return 1;
 132         }
 133
 134         /* Anything else (ie, EC_RES_INVALID_COMMAND) - no lightbar */
 135         return 0;
 136 }
 137
 138 static ssize_t version_show(struct device *dev,
 139                             struct device_attribute *attr, char *buf)
 140 {
 141         uint32_t version, flags;
 142         struct cros_ec_device *ec = dev_get_drvdata(dev);
 143         int ret;
 144
 145         ret = lb_throttle();
 146         if (ret)
 147                 return ret;
 148
 149         /* This should always succeed, because we check during init. */
 150         if (!get_lightbar_version(ec, &version, &flags))
 151                 return -EIO;
 152
 153         return scnprintf(buf, PAGE_SIZE, "%d %d\n", version, flags);
 154 }
 155
 156 static ssize_t brightness_store(struct device *dev,
 157                                 struct device_attribute *attr,
 158                                 const char *buf, size_t count)
 159 {
 160         struct ec_params_lightbar *param;
 161         struct ec_response_lightbar *resp;
 162         struct cros_ec_command msg = INIT_MSG(param, resp);
 163         int ret;
 164         unsigned int val;
 165         struct cros_ec_device *ec = dev_get_drvdata(dev);
 166
 167         if (kstrtouint(buf, 0, &val))
 168                 return -EINVAL;
 169
 170         param = (struct ec_params_lightbar *)msg.outdata;
 171         param->cmd = LIGHTBAR_CMD_BRIGHTNESS;
 172         param->brightness.num = val;
 173         ret = lb_throttle();
 174         if (ret)
 175                 return ret;
 176
 177         ret = cros_ec_cmd_xfer(ec, &msg);
 178         if (ret < 0)
 179                 return ret;
 180
 181         if (msg.result != EC_RES_SUCCESS)
 182                 return -EINVAL;
 183
 184         return count;
 185 }
 186
 187
 188 /*
 189  * We expect numbers, and we'll keep reading until we find them, skipping over
 190  * any whitespace (sysfs guarantees that the input is null-terminated). Every
 191  * four numbers are sent to the lightbar as <LED,R,G,B>. We fail at the first
 192  * parsing error, if we don't parse any numbers, or if we have numbers left
 193  * over.
 194  */
 195 static ssize_t led_rgb_store(struct device *dev, struct device_attribute *attr,
 196                              const char *buf, size_t count)
 197 {
 198         struct ec_params_lightbar *param;
 199         struct ec_response_lightbar *resp;
 200         struct cros_ec_command msg = INIT_MSG(param, resp);
 201         struct cros_ec_device *ec = dev_get_drvdata(dev);
 202         unsigned int val[4];
 203         int ret, i = 0, j = 0, ok = 0;
 204
 205         do {
 206                 /* Skip any whitespace */
 207                 while (*buf && isspace(*buf))
 208                         buf++;
 209
 210                 if (!*buf)
 211                         break;
 212
 213                 ret = sscanf(buf, "%i", &val[i++]);
 214                 if (ret == 0)
 215                         return -EINVAL;
 216
 217                 if (i == 4) {
 218                         param = (struct ec_params_lightbar *)msg.outdata;
 219                         param->cmd = LIGHTBAR_CMD_RGB;
 220                         param->rgb.led = val[0];
 221                         param->rgb.red = val[1];
 222                         param->rgb.green = val[2];
 223                         param->rgb.blue = val[3];
 224                         /*
 225                          * Throttle only the first of every four transactions,
 226                          * so that the user can update all four LEDs at once.
 227                          */
 228                         if ((j++ % 4) == 0) {
 229                                 ret = lb_throttle();
 230                                 if (ret)
 231                                         return ret;
 232                         }
 233
 234                         ret = cros_ec_cmd_xfer(ec, &msg);
 235                         if (ret < 0)
 236                                 return ret;
 237
 238                         if (msg.result != EC_RES_SUCCESS)
 239                                 return -EINVAL;
 240
 241                         i = 0;
 242                         ok = 1;
 243                 }
 244
 245                 /* Skip over the number we just read */
 246                 while (*buf && !isspace(*buf))
 247                         buf++;
 248
 249         } while (*buf);
 250
 251         return (ok && i == 0) ? count : -EINVAL;
 252 }
 253
 254 static char const *seqname[] = {
 255         "ERROR", "S5", "S3", "S0", "S5S3", "S3S0",
 256         "S0S3", "S3S5", "STOP", "RUN", "PULSE", "TEST", "KONAMI",
 257 };
 258
 259 static ssize_t sequence_show(struct device *dev,
 260                              struct device_attribute *attr, char *buf)
 261 {
 262         struct ec_params_lightbar *param;
 263         struct ec_response_lightbar *resp;
 264         struct cros_ec_command msg = INIT_MSG(param, resp);
 265         int ret;
 266         struct cros_ec_device *ec = dev_get_drvdata(dev);
 267
 268         param = (struct ec_params_lightbar *)msg.outdata;
 269         param->cmd = LIGHTBAR_CMD_GET_SEQ;
 270         ret = lb_throttle();
 271         if (ret)
 272                 return ret;
 273
 274         ret = cros_ec_cmd_xfer(ec, &msg);
 275         if (ret < 0)
 276                 return ret;
 277
 278         if (msg.result != EC_RES_SUCCESS)
 279                 return scnprintf(buf, PAGE_SIZE,
 280                                  "ERROR: EC returned %d\n", msg.result);
 281
 282         resp = (struct ec_response_lightbar *)msg.indata;
 283         if (resp->get_seq.num >= ARRAY_SIZE(seqname))
 284                 return scnprintf(buf, PAGE_SIZE, "%d\n", resp->get_seq.num);
 285         else
 286                 return scnprintf(buf, PAGE_SIZE, "%s\n",
 287                                  seqname[resp->get_seq.num]);
 288 }
 289
 290 static ssize_t sequence_store(struct device *dev, struct device_attribute *attr,
 291                               const char *buf, size_t count)
 292 {
 293         struct ec_params_lightbar *param;
 294         struct ec_response_lightbar *resp;
 295         struct cros_ec_command msg = INIT_MSG(param, resp);
 296         unsigned int num;
 297         int ret, len;
 298         struct cros_ec_device *ec = dev_get_drvdata(dev);
 299
 300         for (len = 0; len < count; len++)
 301                 if (!isalnum(buf[len]))
 302                         break;
 303
 304         for (num = 0; num < ARRAY_SIZE(seqname); num++)
 305                 if (!strncasecmp(seqname[num], buf, len))
 306                         break;
 307
 308         if (num >= ARRAY_SIZE(seqname)) {
 309                 ret = kstrtouint(buf, 0, &num);
 310                 if (ret)
 311                         return ret;
 312         }
 313
 314         param = (struct ec_params_lightbar *)msg.outdata;
 315         param->cmd = LIGHTBAR_CMD_SEQ;
 316         param->seq.num = num;
 317         ret = lb_throttle();
 318         if (ret)
 319                 return ret;
 320
 321         ret = cros_ec_cmd_xfer(ec, &msg);
 322         if (ret < 0)
 323                 return ret;
 324
 325         if (msg.result != EC_RES_SUCCESS)
 326                 return -EINVAL;
 327
 328         return count;
 329 }
 330
 331 /* Module initialization */
 332
 333 static DEVICE_ATTR_RW(interval_msec);
 334 static DEVICE_ATTR_RO(version);
 335 static DEVICE_ATTR_WO(brightness);
 336 static DEVICE_ATTR_WO(led_rgb);
 337 static DEVICE_ATTR_RW(sequence);
 338 static struct attribute *__lb_cmds_attrs[] = {
 339         &dev_attr_interval_msec.attr,
 340         &dev_attr_version.attr,
 341         &dev_attr_brightness.attr,
 342         &dev_attr_led_rgb.attr,
 343         &dev_attr_sequence.attr,
 344         NULL,
 345 };
 346 static struct attribute_group lb_cmds_attr_group = {
 347         .name = "lightbar",
 348         .attrs = __lb_cmds_attrs,
 349 };
 350
 351 void ec_dev_lightbar_init(struct cros_ec_device *ec)
 352 {
 353         int ret = 0;
 354
 355         /* Only instantiate this stuff if the EC has a lightbar */
 356         if (!get_lightbar_version(ec, NULL, NULL))
 357                 return;
 358
 359         ret = sysfs_create_group(&ec->vdev->kobj, &lb_cmds_attr_group);
 360         if (ret)
 361                 pr_warn("sysfs_create_group() failed: %d\n", ret);
 362 }
 363
 364 void ec_dev_lightbar_remove(struct cros_ec_device *ec)
 365 {
 366         sysfs_remove_group(&ec->vdev->kobj, &lb_cmds_attr_group);
 367 }