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>

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 {