Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * drivers/base/power/sysfs.c - sysfs entries for device PM |
| 3 | */ |
| 4 | |
| 5 | #include <linux/device.h> |
Tim Schmielau | 8c65b4a | 2005-11-07 00:59:43 -0800 | [diff] [blame] | 6 | #include <linux/string.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 7 | #include "power.h" |
| 8 | |
| 9 | |
David Brownell | 0ac8524 | 2005-09-12 19:39:34 -0700 | [diff] [blame] | 10 | /* |
| 11 | * wakeup - Report/change current wakeup option for device |
| 12 | * |
| 13 | * Some devices support "wakeup" events, which are hardware signals |
| 14 | * used to activate devices from suspended or low power states. Such |
| 15 | * devices have one of three values for the sysfs power/wakeup file: |
| 16 | * |
| 17 | * + "enabled\n" to issue the events; |
| 18 | * + "disabled\n" not to do so; or |
| 19 | * + "\n" for temporary or permanent inability to issue wakeup. |
| 20 | * |
| 21 | * (For example, unconfigured USB devices can't issue wakeups.) |
| 22 | * |
| 23 | * Familiar examples of devices that can issue wakeup events include |
| 24 | * keyboards and mice (both PS2 and USB styles), power buttons, modems, |
| 25 | * "Wake-On-LAN" Ethernet links, GPIO lines, and more. Some events |
| 26 | * will wake the entire system from a suspend state; others may just |
| 27 | * wake up the device (if the system as a whole is already active). |
| 28 | * Some wakeup events use normal IRQ lines; other use special out |
| 29 | * of band signaling. |
| 30 | * |
| 31 | * It is the responsibility of device drivers to enable (or disable) |
| 32 | * wakeup signaling as part of changing device power states, respecting |
| 33 | * the policy choices provided through the driver model. |
| 34 | * |
| 35 | * Devices may not be able to generate wakeup events from all power |
| 36 | * states. Also, the events may be ignored in some configurations; |
| 37 | * for example, they might need help from other devices that aren't |
| 38 | * active, or which may have wakeup disabled. Some drivers rely on |
| 39 | * wakeup events internally (unless they are disabled), keeping |
| 40 | * their hardware in low power modes whenever they're unused. This |
| 41 | * saves runtime power, without requiring system-wide sleep states. |
| 42 | */ |
| 43 | |
| 44 | static const char enabled[] = "enabled"; |
| 45 | static const char disabled[] = "disabled"; |
| 46 | |
| 47 | static ssize_t |
| 48 | wake_show(struct device * dev, struct device_attribute *attr, char * buf) |
| 49 | { |
| 50 | return sprintf(buf, "%s\n", device_can_wakeup(dev) |
| 51 | ? (device_may_wakeup(dev) ? enabled : disabled) |
| 52 | : ""); |
| 53 | } |
| 54 | |
| 55 | static ssize_t |
| 56 | wake_store(struct device * dev, struct device_attribute *attr, |
| 57 | const char * buf, size_t n) |
| 58 | { |
| 59 | char *cp; |
| 60 | int len = n; |
| 61 | |
| 62 | if (!device_can_wakeup(dev)) |
| 63 | return -EINVAL; |
| 64 | |
| 65 | cp = memchr(buf, '\n', n); |
| 66 | if (cp) |
| 67 | len = cp - buf; |
| 68 | if (len == sizeof enabled - 1 |
| 69 | && strncmp(buf, enabled, sizeof enabled - 1) == 0) |
| 70 | device_set_wakeup_enable(dev, 1); |
| 71 | else if (len == sizeof disabled - 1 |
| 72 | && strncmp(buf, disabled, sizeof disabled - 1) == 0) |
| 73 | device_set_wakeup_enable(dev, 0); |
| 74 | else |
| 75 | return -EINVAL; |
| 76 | return n; |
| 77 | } |
| 78 | |
| 79 | static DEVICE_ATTR(wakeup, 0644, wake_show, wake_store); |
| 80 | |
| 81 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 82 | static struct attribute * power_attrs[] = { |
David Brownell | 0ac8524 | 2005-09-12 19:39:34 -0700 | [diff] [blame] | 83 | &dev_attr_wakeup.attr, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 84 | NULL, |
| 85 | }; |
| 86 | static struct attribute_group pm_attr_group = { |
| 87 | .name = "power", |
| 88 | .attrs = power_attrs, |
| 89 | }; |
| 90 | |
| 91 | int dpm_sysfs_add(struct device * dev) |
| 92 | { |
| 93 | return sysfs_create_group(&dev->kobj, &pm_attr_group); |
| 94 | } |
| 95 | |
| 96 | void dpm_sysfs_remove(struct device * dev) |
| 97 | { |
| 98 | sysfs_remove_group(&dev->kobj, &pm_attr_group); |
| 99 | } |