| 1 | // SPDX-License-Identifier: GPL-2.0 |
| 2 | /* |
| 3 | * RTC subsystem, sysfs interface |
| 4 | * |
| 5 | * Copyright (C) 2005 Tower Technologies |
| 6 | * Author: Alessandro Zummo <a.zummo@towertech.it> |
| 7 | */ |
| 8 | |
| 9 | #include <linux/module.h> |
| 10 | #include <linux/rtc.h> |
| 11 | |
| 12 | #include "rtc-core.h" |
| 13 | |
| 14 | /* device attributes */ |
| 15 | |
| 16 | /* |
| 17 | * NOTE: RTC times displayed in sysfs use the RTC's timezone. That's |
| 18 | * ideally UTC. However, PCs that also boot to MS-Windows normally use |
| 19 | * the local time and change to match daylight savings time. That affects |
| 20 | * attributes including date, time, since_epoch, and wakealarm. |
| 21 | */ |
| 22 | |
| 23 | static ssize_t |
| 24 | name_show(struct device *dev, struct device_attribute *attr, char *buf) |
| 25 | { |
| 26 | return sprintf(buf, "%s %s\n", dev_driver_string(dev->parent), |
| 27 | dev_name(dev->parent)); |
| 28 | } |
| 29 | static DEVICE_ATTR_RO(name); |
| 30 | |
| 31 | static ssize_t |
| 32 | date_show(struct device *dev, struct device_attribute *attr, char *buf) |
| 33 | { |
| 34 | ssize_t retval; |
| 35 | struct rtc_time tm; |
| 36 | |
| 37 | retval = rtc_read_time(to_rtc_device(dev), &tm); |
| 38 | if (retval) |
| 39 | return retval; |
| 40 | |
| 41 | return sprintf(buf, "%ptRd\n", &tm); |
| 42 | } |
| 43 | static DEVICE_ATTR_RO(date); |
| 44 | |
| 45 | static ssize_t |
| 46 | time_show(struct device *dev, struct device_attribute *attr, char *buf) |
| 47 | { |
| 48 | ssize_t retval; |
| 49 | struct rtc_time tm; |
| 50 | |
| 51 | retval = rtc_read_time(to_rtc_device(dev), &tm); |
| 52 | if (retval) |
| 53 | return retval; |
| 54 | |
| 55 | return sprintf(buf, "%ptRt\n", &tm); |
| 56 | } |
| 57 | static DEVICE_ATTR_RO(time); |
| 58 | |
| 59 | static ssize_t |
| 60 | since_epoch_show(struct device *dev, struct device_attribute *attr, char *buf) |
| 61 | { |
| 62 | ssize_t retval; |
| 63 | struct rtc_time tm; |
| 64 | |
| 65 | retval = rtc_read_time(to_rtc_device(dev), &tm); |
| 66 | if (retval == 0) { |
| 67 | time64_t time; |
| 68 | |
| 69 | time = rtc_tm_to_time64(&tm); |
| 70 | retval = sprintf(buf, "%lld\n", time); |
| 71 | } |
| 72 | |
| 73 | return retval; |
| 74 | } |
| 75 | static DEVICE_ATTR_RO(since_epoch); |
| 76 | |
| 77 | static ssize_t |
| 78 | max_user_freq_show(struct device *dev, struct device_attribute *attr, char *buf) |
| 79 | { |
| 80 | return sprintf(buf, "%d\n", to_rtc_device(dev)->max_user_freq); |
| 81 | } |
| 82 | |
| 83 | static ssize_t |
| 84 | max_user_freq_store(struct device *dev, struct device_attribute *attr, |
| 85 | const char *buf, size_t n) |
| 86 | { |
| 87 | struct rtc_device *rtc = to_rtc_device(dev); |
| 88 | unsigned long val; |
| 89 | int err; |
| 90 | |
| 91 | err = kstrtoul(buf, 0, &val); |
| 92 | if (err) |
| 93 | return err; |
| 94 | |
| 95 | if (val >= 4096 || val == 0) |
| 96 | return -EINVAL; |
| 97 | |
| 98 | rtc->max_user_freq = (int)val; |
| 99 | |
| 100 | return n; |
| 101 | } |
| 102 | static DEVICE_ATTR_RW(max_user_freq); |
| 103 | |
| 104 | /** |
| 105 | * rtc_sysfs_show_hctosys - indicate if the given RTC set the system time |
| 106 | * @dev: The device that the attribute belongs to. |
| 107 | * @attr: The attribute being read. |
| 108 | * @buf: The result buffer. |
| 109 | * |
| 110 | * buf is "1" if the system clock was set by this RTC at the last |
| 111 | * boot or resume event. |
| 112 | */ |
| 113 | static ssize_t |
| 114 | hctosys_show(struct device *dev, struct device_attribute *attr, char *buf) |
| 115 | { |
| 116 | #ifdef CONFIG_RTC_HCTOSYS_DEVICE |
| 117 | if (rtc_hctosys_ret == 0 && |
| 118 | strcmp(dev_name(&to_rtc_device(dev)->dev), |
| 119 | CONFIG_RTC_HCTOSYS_DEVICE) == 0) |
| 120 | return sprintf(buf, "1\n"); |
| 121 | #endif |
| 122 | return sprintf(buf, "0\n"); |
| 123 | } |
| 124 | static DEVICE_ATTR_RO(hctosys); |
| 125 | |
| 126 | static ssize_t |
| 127 | wakealarm_show(struct device *dev, struct device_attribute *attr, char *buf) |
| 128 | { |
| 129 | ssize_t retval; |
| 130 | time64_t alarm; |
| 131 | struct rtc_wkalrm alm; |
| 132 | |
| 133 | /* Don't show disabled alarms. For uniformity, RTC alarms are |
| 134 | * conceptually one-shot, even though some common RTCs (on PCs) |
| 135 | * don't actually work that way. |
| 136 | * |
| 137 | * NOTE: RTC implementations where the alarm doesn't match an |
| 138 | * exact YYYY-MM-DD HH:MM[:SS] date *must* disable their RTC |
| 139 | * alarms after they trigger, to ensure one-shot semantics. |
| 140 | */ |
| 141 | retval = rtc_read_alarm(to_rtc_device(dev), &alm); |
| 142 | if (retval == 0 && alm.enabled) { |
| 143 | alarm = rtc_tm_to_time64(&alm.time); |
| 144 | retval = sprintf(buf, "%lld\n", alarm); |
| 145 | } |
| 146 | |
| 147 | return retval; |
| 148 | } |
| 149 | |
| 150 | static ssize_t |
| 151 | wakealarm_store(struct device *dev, struct device_attribute *attr, |
| 152 | const char *buf, size_t n) |
| 153 | { |
| 154 | ssize_t retval; |
| 155 | time64_t now, alarm; |
| 156 | time64_t push = 0; |
| 157 | struct rtc_wkalrm alm; |
| 158 | struct rtc_device *rtc = to_rtc_device(dev); |
| 159 | const char *buf_ptr; |
| 160 | int adjust = 0; |
| 161 | |
| 162 | /* Only request alarms that trigger in the future. Disable them |
| 163 | * by writing another time, e.g. 0 meaning Jan 1 1970 UTC. |
| 164 | */ |
| 165 | retval = rtc_read_time(rtc, &alm.time); |
| 166 | if (retval < 0) |
| 167 | return retval; |
| 168 | now = rtc_tm_to_time64(&alm.time); |
| 169 | |
| 170 | buf_ptr = buf; |
| 171 | if (*buf_ptr == '+') { |
| 172 | buf_ptr++; |
| 173 | if (*buf_ptr == '=') { |
| 174 | buf_ptr++; |
| 175 | push = 1; |
| 176 | } else { |
| 177 | adjust = 1; |
| 178 | } |
| 179 | } |
| 180 | retval = kstrtos64(buf_ptr, 0, &alarm); |
| 181 | if (retval) |
| 182 | return retval; |
| 183 | if (adjust) |
| 184 | alarm += now; |
| 185 | if (alarm > now || push) { |
| 186 | /* Avoid accidentally clobbering active alarms; we can't |
| 187 | * entirely prevent that here, without even the minimal |
| 188 | * locking from the /dev/rtcN api. |
| 189 | */ |
| 190 | retval = rtc_read_alarm(rtc, &alm); |
| 191 | if (retval < 0) |
| 192 | return retval; |
| 193 | if (alm.enabled) { |
| 194 | if (push) { |
| 195 | push = rtc_tm_to_time64(&alm.time); |
| 196 | alarm += push; |
| 197 | } else |
| 198 | return -EBUSY; |
| 199 | } else if (push) |
| 200 | return -EINVAL; |
| 201 | alm.enabled = 1; |
| 202 | } else { |
| 203 | alm.enabled = 0; |
| 204 | |
| 205 | /* Provide a valid future alarm time. Linux isn't EFI, |
| 206 | * this time won't be ignored when disabling the alarm. |
| 207 | */ |
| 208 | alarm = now + 300; |
| 209 | } |
| 210 | rtc_time64_to_tm(alarm, &alm.time); |
| 211 | |
| 212 | retval = rtc_set_alarm(rtc, &alm); |
| 213 | return (retval < 0) ? retval : n; |
| 214 | } |
| 215 | static DEVICE_ATTR_RW(wakealarm); |
| 216 | |
| 217 | static ssize_t |
| 218 | offset_show(struct device *dev, struct device_attribute *attr, char *buf) |
| 219 | { |
| 220 | ssize_t retval; |
| 221 | long offset; |
| 222 | |
| 223 | retval = rtc_read_offset(to_rtc_device(dev), &offset); |
| 224 | if (retval == 0) |
| 225 | retval = sprintf(buf, "%ld\n", offset); |
| 226 | |
| 227 | return retval; |
| 228 | } |
| 229 | |
| 230 | static ssize_t |
| 231 | offset_store(struct device *dev, struct device_attribute *attr, |
| 232 | const char *buf, size_t n) |
| 233 | { |
| 234 | ssize_t retval; |
| 235 | long offset; |
| 236 | |
| 237 | retval = kstrtol(buf, 10, &offset); |
| 238 | if (retval == 0) |
| 239 | retval = rtc_set_offset(to_rtc_device(dev), offset); |
| 240 | |
| 241 | return (retval < 0) ? retval : n; |
| 242 | } |
| 243 | static DEVICE_ATTR_RW(offset); |
| 244 | |
| 245 | static ssize_t |
| 246 | range_show(struct device *dev, struct device_attribute *attr, char *buf) |
| 247 | { |
| 248 | return sprintf(buf, "[%lld,%llu]\n", to_rtc_device(dev)->range_min, |
| 249 | to_rtc_device(dev)->range_max); |
| 250 | } |
| 251 | static DEVICE_ATTR_RO(range); |
| 252 | |
| 253 | static struct attribute *rtc_attrs[] = { |
| 254 | &dev_attr_name.attr, |
| 255 | &dev_attr_date.attr, |
| 256 | &dev_attr_time.attr, |
| 257 | &dev_attr_since_epoch.attr, |
| 258 | &dev_attr_max_user_freq.attr, |
| 259 | &dev_attr_hctosys.attr, |
| 260 | &dev_attr_wakealarm.attr, |
| 261 | &dev_attr_offset.attr, |
| 262 | &dev_attr_range.attr, |
| 263 | NULL, |
| 264 | }; |
| 265 | |
| 266 | /* The reason to trigger an alarm with no process watching it (via sysfs) |
| 267 | * is its side effect: waking from a system state like suspend-to-RAM or |
| 268 | * suspend-to-disk. So: no attribute unless that side effect is possible. |
| 269 | * (Userspace may disable that mechanism later.) |
| 270 | */ |
| 271 | static bool rtc_does_wakealarm(struct rtc_device *rtc) |
| 272 | { |
| 273 | if (!device_can_wakeup(rtc->dev.parent)) |
| 274 | return false; |
| 275 | |
| 276 | return !!test_bit(RTC_FEATURE_ALARM, rtc->features); |
| 277 | } |
| 278 | |
| 279 | static umode_t rtc_attr_is_visible(struct kobject *kobj, |
| 280 | struct attribute *attr, int n) |
| 281 | { |
| 282 | struct device *dev = kobj_to_dev(kobj); |
| 283 | struct rtc_device *rtc = to_rtc_device(dev); |
| 284 | umode_t mode = attr->mode; |
| 285 | |
| 286 | if (attr == &dev_attr_wakealarm.attr) { |
| 287 | if (!rtc_does_wakealarm(rtc)) |
| 288 | mode = 0; |
| 289 | } else if (attr == &dev_attr_offset.attr) { |
| 290 | if (!rtc->ops->set_offset) |
| 291 | mode = 0; |
| 292 | } else if (attr == &dev_attr_range.attr) { |
| 293 | if (!(rtc->range_max - rtc->range_min)) |
| 294 | mode = 0; |
| 295 | } |
| 296 | |
| 297 | return mode; |
| 298 | } |
| 299 | |
| 300 | static struct attribute_group rtc_attr_group = { |
| 301 | .is_visible = rtc_attr_is_visible, |
| 302 | .attrs = rtc_attrs, |
| 303 | }; |
| 304 | |
| 305 | static const struct attribute_group *rtc_attr_groups[] = { |
| 306 | &rtc_attr_group, |
| 307 | NULL |
| 308 | }; |
| 309 | |
| 310 | const struct attribute_group **rtc_get_dev_attribute_groups(void) |
| 311 | { |
| 312 | return rtc_attr_groups; |
| 313 | } |
| 314 | |
| 315 | int rtc_add_groups(struct rtc_device *rtc, const struct attribute_group **grps) |
| 316 | { |
| 317 | size_t old_cnt = 0, add_cnt = 0, new_cnt; |
| 318 | const struct attribute_group **groups, **old; |
| 319 | |
| 320 | if (!grps) |
| 321 | return -EINVAL; |
| 322 | |
| 323 | groups = rtc->dev.groups; |
| 324 | if (groups) |
| 325 | for (; *groups; groups++) |
| 326 | old_cnt++; |
| 327 | |
| 328 | for (groups = grps; *groups; groups++) |
| 329 | add_cnt++; |
| 330 | |
| 331 | new_cnt = old_cnt + add_cnt + 1; |
| 332 | groups = devm_kcalloc(&rtc->dev, new_cnt, sizeof(*groups), GFP_KERNEL); |
| 333 | if (!groups) |
| 334 | return -ENOMEM; |
| 335 | memcpy(groups, rtc->dev.groups, old_cnt * sizeof(*groups)); |
| 336 | memcpy(groups + old_cnt, grps, add_cnt * sizeof(*groups)); |
| 337 | groups[old_cnt + add_cnt] = NULL; |
| 338 | |
| 339 | old = rtc->dev.groups; |
| 340 | rtc->dev.groups = groups; |
| 341 | if (old && old != rtc_attr_groups) |
| 342 | devm_kfree(&rtc->dev, old); |
| 343 | |
| 344 | return 0; |
| 345 | } |
| 346 | EXPORT_SYMBOL(rtc_add_groups); |
| 347 | |
| 348 | int rtc_add_group(struct rtc_device *rtc, const struct attribute_group *grp) |
| 349 | { |
| 350 | const struct attribute_group *groups[] = { grp, NULL }; |
| 351 | |
| 352 | return rtc_add_groups(rtc, groups); |
| 353 | } |
| 354 | EXPORT_SYMBOL(rtc_add_group); |