Merge tag 'docs/v5.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media

Pull rst conversion of docs from Mauro Carvalho Chehab:
 "As agreed with Jon, I'm sending this big series directly to you, c/c
  him, as this series required a special care, in order to avoid
  conflicts with other trees"

* tag 'docs/v5.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media: (77 commits)
  docs: kbuild: fix build with pdf and fix some minor issues
  docs: block: fix pdf output
  docs: arm: fix a breakage with pdf output
  docs: don't use nested tables
  docs: gpio: add sysfs interface to the admin-guide
  docs: locking: add it to the main index
  docs: add some directories to the main documentation index
  docs: add SPDX tags to new index files
  docs: add a memory-devices subdir to driver-api
  docs: phy: place documentation under driver-api
  docs: serial: move it to the driver-api
  docs: driver-api: add remaining converted dirs to it
  docs: driver-api: add xilinx driver API documentation
  docs: driver-api: add a series of orphaned documents
  docs: admin-guide: add a series of orphaned documents
  docs: cgroup-v1: add it to the admin-guide book
  docs: aoe: add it to the driver-api book
  docs: add some documentation dirs to the driver-api book
  docs: driver-model: move it to the driver-api book
  docs: lp855x-driver.rst: add it to the driver-api book
  ...

1 files changed, 31 insertions, 0 deletions

diff --git a/Documentation/ioctl/ioctl-decoding.rst b/Documentation/ioctl/ioctl-decoding.rst
new file mode 100644
index 000000000000..380d6bb3e3ea
--- /dev/null
+++ b/Documentation/ioctl/ioctl-decoding.rst
@@ -0,0 +1,31 @@
+==============================
+Decoding an IOCTL Magic Number
+==============================
+
+To decode a hex IOCTL code:
+
+Most architectures use this generic format, but check
+include/ARCH/ioctl.h for specifics, e.g. powerpc
+uses 3 bits to encode read/write and 13 bits for size.
+
+ ====== ==================================
+ bits   meaning
+ ====== ==================================
+ 31-30	00 - no parameters: uses _IO macro
+	10 - read: _IOR
+	01 - write: _IOW
+	11 - read/write: _IOWR
+
+ 29-16	size of arguments
+
+ 15-8	ascii character supposedly
+	unique to each driver
+
+ 7-0	function #
+ ====== ==================================
+
+
+So for example 0x82187201 is a read with arg length of 0x218,
+character 'r' function 1. Grepping the source reveals this is::
+
+	#define VFAT_IOCTL_READDIR_BOTH         _IOR('r', 1, struct dirent [2])