From mboxrd@z Thu Jan 1 00:00:00 1970 From: Palmer Dabbelt Subject: [PATCH v2] dt-bindings: Add an enable method to RISC-V Date: Thu, 7 Dec 2017 15:05:23 -0800 Message-ID: <20171207230523.29798-1-palmer@sifive.com> Return-path: Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, mark.rutland-5wv7dgnIgG8@public.gmane.org Cc: devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, patches-q3qR2WxjNRFS9aJRtSZj7A@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Palmer Dabbelt List-Id: devicetree@vger.kernel.org RISC-V doesn't currently specify a mechanism for enabling or disabling CPUs. Instead, we assume that all CPUs are enabled on boot, and if someone wants to save power we instead put a CPU to sleep via a WFI loop. Future systems may have an explicit mechanism for putting a CPU to sleep, so we're standardizing the device tree entry for when that happens. We're not defining a spin-table based interface to the firmware, as the plan is to handle this entirely within the kernel instead. CC: Mark Rutland Signed-off-by: Palmer Dabbelt --- Documentation/devicetree/bindings/riscv/cpus.txt | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/Documentation/devicetree/bindings/riscv/cpus.txt b/Documentation/devicetree/bindings/riscv/cpus.txt index adf7b7af5dc3..68f88eacc594 100644 --- a/Documentation/devicetree/bindings/riscv/cpus.txt +++ b/Documentation/devicetree/bindings/riscv/cpus.txt @@ -82,6 +82,15 @@ described below. Value type: Definition: Contains the RISC-V ISA string of this hart. These ISA strings are defined by the RISC-V ISA manual. + - cpu-enable-method: + Usage: optional + Value type: + Definition: When absent, default is either "always-disabled" + "always-enabled", depending on the current state + of the CPU. + Must be one of: + * "always-disabled": This CPU cannot be enabled. + * "always-enabled": This CPU cannot be disabled. Example: SiFive Freedom U540G Development Kit --------------------------------------------- -- 2.13.6 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html