GSOC2020 warmup Task

.gitignore

@@ -124,3 +124,7 @@ all.config
 
 # Kdevelop4
 *.kdev4
+
+# dtb objects
+*.dtb
+*.dtbo

Documentation/ABI/testing/debugfs-aufs

@@ -0,0 +1,55 @@
+What:		/debug/aufs/si_<id>/
+Date:		March 2009
+Contact:	J. R. Okajima <[email protected]>
+Description:
+		Under /debug/aufs, a directory named si_<id> is created
+		per aufs mount, where <id> is a unique id generated
+		internally.
+
+What:		/debug/aufs/si_<id>/plink
+Date:		Apr 2013
+Contact:	J. R. Okajima <[email protected]>
+Description:
+		It has three lines and shows the information about the
+		pseudo-link. The first line is a single number
+		representing a number of buckets. The second line is a
+		number of pseudo-links per buckets (separated by a
+		blank). The last line is a single number representing a
+		total number of psedo-links.
+		When the aufs mount option 'noplink' is specified, it
+		will show "1\n0\n0\n".
+
+What:		/debug/aufs/si_<id>/xib
+Date:		March 2009
+Contact:	J. R. Okajima <[email protected]>
+Description:
+		It shows the consumed blocks by xib (External Inode Number
+		Bitmap), its block size and file size.
+		When the aufs mount option 'noxino' is specified, it
+		will be empty. About XINO files, see the aufs manual.
+
+What:		/debug/aufs/si_<id>/xi0, xi1 ... xiN and xiN-N
+Date:		March 2009
+Contact:	J. R. Okajima <[email protected]>
+Description:
+		It shows the consumed blocks by xino (External Inode Number
+		Translation Table), its link count, block size and file
+		size.
+		Due to the file size limit, there may exist multiple
+		xino files per branch.  In this case, "-N" is added to
+		the filename and it corresponds to the index of the
+		internal xino array.  "-0" is omitted.
+		When the aufs mount option 'noxino' is specified, Those
+		entries won't exist.  About XINO files, see the aufs
+		manual.
+
+What:		/debug/aufs/si_<id>/xigen
+Date:		March 2009
+Contact:	J. R. Okajima <[email protected]>
+Description:
+		It shows the consumed blocks by xigen (External Inode
+		Generation Table), its block size and file size.
+		If CONFIG_AUFS_EXPORT is disabled, this entry will not
+		be created.
+		When the aufs mount option 'noxino' is specified, it
+		will be empty. About XINO files, see the aufs manual.

Documentation/ABI/testing/sysfs-aufs

@@ -0,0 +1,31 @@
+What:		/sys/fs/aufs/si_<id>/
+Date:		March 2009
+Contact:	J. R. Okajima <[email protected]>
+Description:
+		Under /sys/fs/aufs, a directory named si_<id> is created
+		per aufs mount, where <id> is a unique id generated
+		internally.
+
+What:		/sys/fs/aufs/si_<id>/br0, br1 ... brN
+Date:		March 2009
+Contact:	J. R. Okajima <[email protected]>
+Description:
+		It shows the abolute path of a member directory (which
+		is called branch) in aufs, and its permission.
+
+What:		/sys/fs/aufs/si_<id>/brid0, brid1 ... bridN
+Date:		July 2013
+Contact:	J. R. Okajima <[email protected]>
+Description:
+		It shows the id of a member directory (which is called
+		branch) in aufs.
+
+What:		/sys/fs/aufs/si_<id>/xi_path
+Date:		March 2009
+Contact:	J. R. Okajima <[email protected]>
+Description:
+		It shows the abolute path of XINO (External Inode Number
+		Bitmap, Translation Table and Generation Table) file
+		even if it is the default path.
+		When the aufs mount option 'noxino' is specified, it
+		will be empty. About XINO files, see the aufs manual.

Documentation/ABI/testing/sysfs-devices-platform-bone_capemgr

@@ -0,0 +1,63 @@
+What:		/sys/devices/platform/bone_capemgr/slots
+Date:		May 2015
+KernelVersion:	4.0
+Contact:	Pantelis Antoniou <[email protected]>
+Description:
+		READ:
+		  Describe the state of all the slots of the beaglebone capemgr.
+		  Each line of the output describes a slot:
+		  The slot format is as following:
+		  <slot-id>: [P-][F-][O-][l-][L-][D-] \
+			  <overlay-id> <board-name>,<version>,
+			  <manufacturer>,<part-number>
+
+		Where the flags are:
+		P: Slot has been probed
+		F: Slot has failed probing (i.e. no EEPROM detected)
+		O: Slot has been overridden by the user
+		l: Slot is current loading
+		L: Slot has completed loading and is ready
+		D: Slot has been disabled
+
+		Example:
+		0: P---L-  -1 BeagleBone RS232 CAPE,00A1,Beagleboardtoys,BB-BONE-SERL-03
+		1: PF----  -1
+		2: PF----  -1
+		3: PF----  -1
+
+		WRITE:
+		  Writing a string of the form <part-number>[:version] issues a request to
+		  load a firmware blob containing an overlay. The name of the firmware blob
+		  is <part-number>-[version|00A0].dtbo. This act is defined as a slot override.
+
+		  Writing a negative slot id removes the slot if it was an overridden one, or
+		  unloads a slot that was probed.
+
+What:		/sys/devices/platform/bone_capemgr/baseboard/<eeprom-field>
+Date:		May 2015
+KernelVersion:	4.0
+Contact:	Pantelis Antoniou <[email protected]>
+Description:	Contains the probed base board EEPROM field; one of:
+		board-name		- board-name as stored in cape EEPROM
+		dc-supplied		- whether the cape draws or supplies DC
+		eeprom-format-revision	- EEPROM format rev, only 00A0 supported
+		header			- header; should be 'aa 55 33 ee'
+		manufacturer		- manufacturer string
+		part-number		- part-number of the cape
+		serial-number		- serial number of the cape
+		version			- version of the cape, i.e. 00A0
+		number-of-pins		- displayed but ignored
+		pin-usage		- displayed but ignored
+		sys-5v			- displayed but ignored
+		vdd-3v3exp		- displayed but ignored
+		vdd-5v			- displayed but ignored
+What:		/sys/devices/platform/bone_capemgr/slot-<n>/<eeprom-field>
+Date:		May 2015
+KernelVersion:	4.0
+Contact:	Pantelis Antoniou <[email protected]>
+Description:	Contains the probed cape's EEPROM field; the field is one of:
+		board-name		- baseboard name i.e. A335BNLT
+		header			- header; should be 'aa 55 33 ee'
+		revision		- baseboard revision
+		serial-number		- baseboard serial number
+		config-option		- displayed but ignored

Documentation/ABI/testing/sysfs-firmware-devicetree-overlays

@@ -0,0 +1,52 @@
+What:		/sys/firmware/devicetree/overlays/
+Date:		October 2015
+Contact:	Pantelis Antoniou <[email protected]>
+Description:
+		This directory contains the applied device tree overlays of
+		the running system, as directories of the overlay id.
+
+What:		/sys/firmware/devicetree/overlays/enable
+Date:		October 2015
+Contact:	Pantelis Antoniou <[email protected]>
+Description:
+		The master enable switch, by default is 1, and when
+		set to 0 it cannot be re-enabled for security reasons.
+
+		The discussion about this switch takes place in:
+		http://comments.gmane.org/gmane.linux.drivers.devicetree/101871
+
+		Kees Cook:
+		"Coming from the perspective of drawing a bright line between
+		kernel and the root user (which tends to start with disabling
+		kernel module loading), I would say that there at least needs
+		to be a high-level one-way "off" switch for the interface so
+		that systems that have this interface can choose to turn it off
+		during initial boot, etc."
+
+What:		/sys/firmware/devicetree/overlays/<id>
+Date:		October 2015
+Contact:	Pantelis Antoniou <[email protected]>
+Description:
+		Each directory represents an applied overlay, containing
+		the following attribute files.
+
+What:		/sys/firmware/devicetree/overlays/<id>/can_remove
+Date:		October 2015
+Contact:	Pantelis Antoniou <[email protected]>
+Description:
+		The attribute set to 1 means that the overlay can be removed,
+		while 0 means that the overlay is being overlapped therefore
+		removal is prohibited.
+
+What:		/sys/firmware/devicetree/overlays/<id>/<fragment-name>/
+Date:		October 2015
+Contact:	Pantelis Antoniou <[email protected]>
+Description:
+		Each of these directories contain information about of the
+		particular overlay fragment.
+
+What:		/sys/firmware/devicetree/overlays/<id>/<fragment-name>/target
+Date:		October 2015
+Contact:	Pantelis Antoniou <[email protected]>
+Description:
+		The full-path of the target of the fragment

Documentation/admin-guide/kernel-parameters.txt

@@ -2883,6 +2883,8 @@
 			This can be set from sysctl after boot.
 			See Documentation/sysctl/vm.txt for details.
 
+	of_overlay_disable	[OF] Disable device tree overlays at boot time.
+
 	ohci1394_dma=early	[HW] enable debugging via the ohci1394 driver.
 			See Documentation/debugging-via-ohci1394.txt for more
 			info.

Documentation/devicetree/bindings/arm/omap/omap.txt

@@ -24,6 +24,8 @@ Optional properties:
 - ti,no-reset-on-init: When present, the module should not be reset at init
 - ti,no-idle-on-init: When present, the module should not be idled at init
 - ti,no-idle: When present, the module is never allowed to idle.
+- ti,deassert-hard-reset: list of hwmod and hardware reset line name pairs
+  (ascii strings) to be deasserted upon device instantiation.
 
 Example:
 

Documentation/devicetree/bindings/misc/bone_capemgr.txt

@@ -0,0 +1,111 @@
+* Beaglebone cape manager driver
+
+Required properties:
+- compatible: "ti,bone-capemgr"
+- eeprom: phandle to the EEPROM baseboard.
+          The EEPROM framework interface is use to obtain the data.
+
+Required children nodes:
+
+- baseboardmaps: Contains nodes, which each of the them defines a mapping from
+		 the baseboard EEPROM board-name ID to a DT friendly compatible
+		 string.
+
+  - board-name:      The baseboard EEPROM board name, i.e. A335BONE for the
+                     original beaglebone white.
+  - compatible-name: The DT friendly compatible string to be used for matching
+		     compatible capes, i.e. "ti,beaglebone"
+
+
+ - nvmem-cells: Defines the phandles of the nvmem cells of the baseboard and the
+                slots.
+ - nvmem-cells: Defines the names of the nvmem cells. Required to have at
+                least a baseboard cell name.
+
+ - #slots:	Defines how many slots are there.
+
+- Example of a beaglebone cape-manager:
+
+bone_capemgr {
+	compatible = "ti,bone-capemgr";
+	status = "okay";
+
+	nvmem-cell = <&baseboard_data
+		      &cape0_data &cape1_data &cape2_data &cape3_data>;
+	nvmem-cell-names = "baseboard", "slot0", "slot1", "slot2", "slot3";
+
+	#slots = <4>;
+
+	/* map board revisions to compatible definitions */
+	baseboardmaps {
+		baseboard_beaglebone: board@0 {
+			board-name = "A335BONE";
+			compatible-name = "ti,beaglebone";
+		};
+
+		baseboard_beaglebone_black: board@1 {
+			board-name = "A335BNLT";
+			compatible-name = "ti,beaglebone-black";
+		};
+	};
+};
+
+The format of the cape to be loaded is in a standard overlay format with
+the following root properties that are interpreted by the cape manager:
+
+Required properties:
+ - compatible: Should be compatible to the baseboard according to the
+               baseboard map value, i.e. "ti,beaglebone".
+ - part-numer: Should contain the part-number as stored in the EEPROM.
+ - version:    Should contain a list of all the version that are supported
+               by the single cape dtbo, i.e. "00A1".
+
+Optional properties:
+ - exclusive-use: A string list which state the resources this cape requires.
+                  No processing or matching to anything regarding the internal
+		  kernel state is performed; it's purpose is to guard against
+		  conflicts with other capes.
+ - priority:      A priority to be assigned when loading a cape. A lower value
+                  has higher priority. The purpose of the priority is to control
+		  which cape is loaded first in case of a conflict.
+
+- Example of a serial cape:
+
+/dts-v1/;
+/plugin/;
+/ {
+        compatible = "ti,beaglebone", "ti,beaglebone-black";
+
+        /* identification */
+        part-number = "BB-BONE-SERL-03";
+        version = "00A1";
+
+        /* state the resources this cape uses */
+        exclusive-use =
+                /* the pin header uses */
+                "P9.21",        /* uart2_txd */
+                "P9.22",        /* uart2_rxd */
+                /* the hardware ip uses */
+                "uart2";
+
+        fragment@0 {
+                target = <&am33xx_pinmux>;
+                __overlay__ {
+                        bb_uart2_pins: pinmux_bb_uart2_pins {
+                                pinctrl-single,pins = <
+                                        0x150 0x21      /* spi0_sclk.uart2_rxd | MODE1 */
+                                        0x154 0x01      /* spi0_d0.uart2_txd | MODE1 */
+                                >;
+                        };
+                };
+        };
+
+        fragment@1 {
+                target = <&uart2>;
+                __overlay__ {
+                        status = "okay";
+                        pinctrl-names = "default";
+                        pinctrl-0 = <&bb_uart2_pins>;
+                };
+        };
+};

Documentation/devicetree/configfs-overlays.txt

@@ -0,0 +1,31 @@
+Howto use the configfs overlay interface.
+
+A device-tree configfs entry is created in /config/device-tree/overlays
+and and it is manipulated using standard file system I/O.
+Note that this is a debug level interface, for use by developers and
+not necessarily something accessed by normal users due to the
+security implications of having direct access to the kernel's device tree.
+
+* To create an overlay you mkdir the directory:
+
+	# mkdir /config/device-tree/overlays/foo
+
+* Either you echo the overlay firmware file to the path property file.
+
+	# echo foo.dtbo >/config/device-tree/overlays/foo/path
+
+* Or you cat the contents of the overlay to the dtbo file
+
+	# cat foo.dtbo >/config/device-tree/overlays/foo/dtbo
+
+The overlay file will be applied, and devices will be created/destroyed
+as required.
+
+To remove it simply rmdir the directory.
+
+	# rmdir /config/device-tree/overlays/foo
+
+The rationalle of the dual interface (firmware & direct copy) is that each is
+better suited to different use patterns. The firmware interface is what's
+intended to be used by hardware managers in the kernel, while the copy interface
+make sense for developers (since it avoids problems with namespaces).