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authorPrathyush K <prathyush.k@samsung.com>2014-07-11 08:02:15 +0900
committerKukjin Kim <kgene.kim@samsung.com>2014-07-11 08:03:19 +0900
commitc760569d0e9c06b39dd19e82bff0b704d90a73b7 (patch)
treef0e69210b658804b75f39a650c36bb867f732cc0 /Documentation
parentbe0b420ad6123e587738a67a9eff3ec213a57604 (diff)
downloadlinux-c760569d0e9c06b39dd19e82bff0b704d90a73b7.tar.bz2
ARM: EXYNOS: Add support for clock handling in power domain
While powering on/off a local powerdomain in exynos5 chipsets, the input clocks to each device gets modified. This behaviour is based on the SYSCLK_SYS_PWR_REG registers. E.g. SYSCLK_MFC_SYS_PWR_REG = 0x0, the parent of input clock to MFC (aclk333) gets modified to oscclk = 0x1, no change in clocks. The recommended value of SYSCLK_SYS_PWR_REG before power gating any domain is 0x0. So we must also restore the clocks while powering on a domain everytime. This patch adds the framework for getting the required mux and parent clocks through a power domain device node. With this patch, while powering off a domain, parent is set to oscclk and while powering back on, its re-set to the correct parent which is as per the recommended pd on/off sequence. Signed-off-by: Prathyush K <prathyush.k@samsung.com> Signed-off-by: Andrew Bresticker <abrestic@chromium.org> Signed-off-by: Arun Kumar K <arun.kk@samsung.com> Signed-off-by: Shaik Ameer Basha <shaik.ameer@samsung.com> Reviewed-by: Tomasz Figa <t.figa@samsung.com> Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/devicetree/bindings/arm/exynos/power_domain.txt20
1 files changed, 20 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/arm/exynos/power_domain.txt b/Documentation/devicetree/bindings/arm/exynos/power_domain.txt
index 5216b419016a..8b4f7b7fe88b 100644
--- a/Documentation/devicetree/bindings/arm/exynos/power_domain.txt
+++ b/Documentation/devicetree/bindings/arm/exynos/power_domain.txt
@@ -9,6 +9,18 @@ Required Properties:
- reg: physical base address of the controller and length of memory mapped
region.
+Optional Properties:
+- clocks: List of clock handles. The parent clocks of the input clocks to the
+ devices in this power domain are set to oscclk before power gating
+ and restored back after powering on a domain. This is required for
+ all domains which are powered on and off and not required for unused
+ domains.
+- clock-names: The following clocks can be specified:
+ - oscclk: Oscillator clock.
+ - pclkN, clkN: Pairs of parent of input clock and input clock to the
+ devices in this power domain. Maximum of 4 pairs (N = 0 to 3)
+ are supported currently.
+
Node of a device using power domains must have a samsung,power-domain property
defined with a phandle to respective power domain.
@@ -19,6 +31,14 @@ Example:
reg = <0x10023C00 0x10>;
};
+ mfc_pd: power-domain@10044060 {
+ compatible = "samsung,exynos4210-pd";
+ reg = <0x10044060 0x20>;
+ clocks = <&clock CLK_FIN_PLL>, <&clock CLK_MOUT_SW_ACLK333>,
+ <&clock CLK_MOUT_USER_ACLK333>;
+ clock-names = "oscclk", "pclk0", "clk0";
+ };
+
Example of the node using power domain:
node {