diff options
Diffstat (limited to 'Documentation/ABI')
| -rw-r--r-- | Documentation/ABI/testing/dev-kmsg | 90 | ||||
| -rw-r--r-- | Documentation/ABI/testing/sysfs-class-extcon | 97 |
2 files changed, 187 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/dev-kmsg b/Documentation/ABI/testing/dev-kmsg new file mode 100644 index 000000000000..281ecc5f9709 --- /dev/null +++ b/Documentation/ABI/testing/dev-kmsg @@ -0,0 +1,90 @@ +What: /dev/kmsg +Date: Mai 2012 +KernelVersion: 3.5 +Contact: Kay Sievers <kay@vrfy.org> +Description: The /dev/kmsg character device node provides userspace access + to the kernel's printk buffer. + + Injecting messages: + Every write() to the opened device node places a log entry in + the kernel's printk buffer. + + The logged line can be prefixed with a <N> syslog prefix, which + carries the syslog priority and facility. The single decimal + prefix number is composed of the 3 lowest bits being the syslog + priority and the higher bits the syslog facility number. + + If no prefix is given, the priority number is the default kernel + log priority and the facility number is set to LOG_USER (1). It + is not possible to inject messages from userspace with the + facility number LOG_KERN (0), to make sure that the origin of + the messages can always be reliably determined. + + Accessing the buffer: + Every read() from the opened device node receives one record + of the kernel's printk buffer. + + The first read() directly following an open() always returns + first message in the buffer; there is no kernel-internal + persistent state; many readers can concurrently open the device + and read from it, without affecting other readers. + + Every read() will receive the next available record. If no more + records are available read() will block, or if O_NONBLOCK is + used -EAGAIN returned. + + Messages in the record ring buffer get overwritten as whole, + there are never partial messages received by read(). + + In case messages get overwritten in the circular buffer while + the device is kept open, the next read() will return -EPIPE, + and the seek position be updated to the next available record. + Subsequent reads() will return available records again. + + Unlike the classic syslog() interface, the 64 bit record + sequence numbers allow to calculate the amount of lost + messages, in case the buffer gets overwritten. And they allow + to reconnect to the buffer and reconstruct the read position + if needed, without limiting the interface to a single reader. + + The device supports seek with the following parameters: + SEEK_SET, 0 + seek to the first entry in the buffer + SEEK_END, 0 + seek after the last entry in the buffer + SEEK_DATA, 0 + seek after the last record available at the time + the last SYSLOG_ACTION_CLEAR was issued. + + The output format consists of a prefix carrying the syslog + prefix including priority and facility, the 64 bit message + sequence number and the monotonic timestamp in microseconds. + The values are separated by a ','. Future extensions might + add more comma separated values before the terminating ';'. + Unknown values should be gracefully ignored. + + The human readable text string starts directly after the ';' + and is terminated by a '\n'. Untrusted values derived from + hardware or other facilities are printed, therefore + all non-printable characters in the log message are escaped + by "\x00" C-style hex encoding. + + A line starting with ' ', is a continuation line, adding + key/value pairs to the log message, which provide the machine + readable context of the message, for reliable processing in + userspace. + + Example: + 7,160,424069;pci_root PNP0A03:00: host bridge window [io 0x0000-0x0cf7] (ignored) + SUBSYSTEM=acpi + DEVICE=+acpi:PNP0A03:00 + 6,339,5140900;NET: Registered protocol family 10 + 30,340,5690716;udevd[80]: starting version 181 + + The DEVICE= key uniquely identifies devices the following way: + b12:8 - block dev_t + c127:3 - char dev_t + n8 - netdev ifindex + +sound:card0 - subsystem:devname + +Users: dmesg(1), userspace kernel log consumers diff --git a/Documentation/ABI/testing/sysfs-class-extcon b/Documentation/ABI/testing/sysfs-class-extcon new file mode 100644 index 000000000000..20ab361bd8c6 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-class-extcon @@ -0,0 +1,97 @@ +What: /sys/class/extcon/.../ +Date: February 2012 +Contact: MyungJoo Ham <myungjoo.ham@samsung.com> +Description: + Provide a place in sysfs for the extcon objects. + This allows accessing extcon specific variables. + The name of extcon object denoted as ... is the name given + with extcon_dev_register. + + One extcon device denotes a single external connector + port. An external connector may have multiple cables + attached simultaneously. Many of docks, cradles, and + accessory cables have such capability. For example, + the 30-pin port of Nuri board (/arch/arm/mach-exynos) + may have both HDMI and Charger attached, or analog audio, + video, and USB cables attached simulteneously. + + If there are cables mutually exclusive with each other, + such binary relations may be expressed with extcon_dev's + mutually_exclusive array. + +What: /sys/class/extcon/.../name +Date: February 2012 +Contact: MyungJoo Ham <myungjoo.ham@samsung.com> +Description: + The /sys/class/extcon/.../name shows the name of the extcon + object. If the extcon object has an optional callback + "show_name" defined, the callback will provide the name with + this sysfs node. + +What: /sys/class/extcon/.../state +Date: February 2012 +Contact: MyungJoo Ham <myungjoo.ham@samsung.com> +Description: + The /sys/class/extcon/.../state shows and stores the cable + attach/detach information of the corresponding extcon object. + If the extcon object has an optional callback "show_state" + defined, the showing function is overriden with the optional + callback. + + If the default callback for showing function is used, the + format is like this: + # cat state + USB_OTG=1 + HDMI=0 + TA=1 + EAR_JACK=0 + # + In this example, the extcon device have USB_OTG and TA + cables attached and HDMI and EAR_JACK cables detached. + + In order to update the state of an extcon device, enter a hex + state number starting with 0x. + echo 0xHEX > state + + This updates the whole state of the extcon dev. + Inputs of all the methods are required to meet the + mutually_exclusive contidions if they exist. + + It is recommended to use this "global" state interface if + you need to enter the value atomically. The later state + interface associated with each cable cannot update + multiple cable states of an extcon device simultaneously. + +What: /sys/class/extcon/.../cable.x/name +Date: February 2012 +Contact: MyungJoo Ham <myungjoo.ham@samsung.com> +Description: + The /sys/class/extcon/.../cable.x/name shows the name of cable + "x" (integer between 0 and 31) of an extcon device. + +What: /sys/class/extcon/.../cable.x/state +Date: February 2012 +Contact: MyungJoo Ham <myungjoo.ham@samsung.com> +Description: + The /sys/class/extcon/.../cable.x/name shows and stores the + state of cable "x" (integer between 0 and 31) of an extcon + device. The state value is either 0 (detached) or 1 + (attached). + +What: /sys/class/extcon/.../mutually_exclusive/... +Date: December 2011 +Contact: MyungJoo Ham <myungjoo.ham@samsung.com> +Description: + Shows the relations of mutually exclusiveness. For example, + if the mutually_exclusive array of extcon_dev is + {0x3, 0x5, 0xC, 0x0}, the, the output is: + # ls mutually_exclusive/ + 0x3 + 0x5 + 0xc + # + + Note that mutually_exclusive is a sub-directory of the extcon + device and the file names under the mutually_exclusive + directory show the mutually-exclusive sets, not the contents + of the files. |