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authorOlof Johansson <olof@lixom.net>2015-12-22 23:54:03 +0100
committerOlof Johansson <olof@lixom.net>2015-12-22 23:54:03 +0100
commitf625cb8c6d9753e99eb4f7a3d52de5a705c88637 (patch)
tree27a7f27ec834dbf39296a874e5c6353036833332 /Documentation
parentMerge tag 'v4.4-next-soc' of https://github.com/mbgg/linux-mediatek into next... (diff)
parentsoc: ti: Add wkup_m3_ipc driver (diff)
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Merge tag 'omap-for-v4.5/wakeup-m3' of git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap into next/drivers
TI wakeup M3 IPC device driver for v4.5 merge window. This driver will eventually allow am33xx and am437x to support PM with their Cortex-M3 power management processor. This driver has been waiting to get merged for quite a while but has had dependencies to the remoteproc that are now out of the way. * tag 'omap-for-v4.5/wakeup-m3' of git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap: soc: ti: Add wkup_m3_ipc driver Documentation: dt: add bindings for TI Wakeup M3 IPC device Signed-off-by: Olof Johansson <olof@lixom.net>
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+Wakeup M3 IPC Driver
+=====================
+
+The TI AM33xx and AM43xx family of devices use a small Cortex M3 co-processor
+(commonly referred to as Wakeup M3 or CM3) to help with various low power tasks
+that cannot be controlled from the MPU, like suspend/resume and certain deep
+C-states for CPU Idle. Once the wkup_m3_ipc driver uses the wkup_m3_rproc driver
+to boot the wkup_m3, it handles communication with the CM3 using IPC registers
+present in the SoC's control module and a mailbox. The wkup_m3_ipc exposes an
+API to allow the SoC PM code to execute specific PM tasks.
+
+Wkup M3 Device Node:
+====================
+A wkup_m3_ipc device node is used to represent the IPC registers within an
+SoC.
+
+Required properties:
+--------------------
+- compatible: Should be,
+ "ti,am3352-wkup-m3-ipc" for AM33xx SoCs
+ "ti,am4372-wkup-m3-ipc" for AM43xx SoCs
+- reg: Contains the IPC register address space to communicate
+ with the Wakeup M3 processor
+- interrupts: Contains the interrupt information for the wkup_m3
+ interrupt that signals the MPU.
+- ti,rproc: phandle to the wkup_m3 rproc node so the IPC driver
+ can boot it.
+- mboxes: phandles used by IPC framework to get correct mbox
+ channel for communication. Must point to appropriate
+ mbox_wkupm3 child node.
+
+Example:
+--------
+/* AM33xx */
+ l4_wkup: l4_wkup@44c00000 {
+ ...
+
+ scm: scm@210000 {
+ compatible = "ti,am3-scm", "simple-bus";
+ reg = <0x210000 0x2000>;
+ #address-cells = <1>;
+ #size-cells = <1>;
+ ranges = <0 0x210000 0x2000>;
+
+ ...
+
+ wkup_m3_ipc: wkup_m3_ipc@1324 {
+ compatible = "ti,am3352-wkup-m3-ipc";
+ reg = <0x1324 0x24>;
+ interrupts = <78>;
+ ti,rproc = <&wkup_m3>;
+ mboxes = <&mailbox &mbox_wkupm3>;
+ };
+
+ ...
+ };
+ };