External Memory Controller can gather various hardware statistics that
are intended to be used for debugging purposes and for dynamic frequency
scaling of memory bus.

Document the new mfd-simple compatible and EMC statistics sub-device.
The subdev contains EMC DFS OPP table and interconnect paths to be used
for dynamic scaling of system's memory bandwidth based on EMC utilization
statistics.

Signed-off-by: Dmitry Osipenko <dig...@gmail.com>
---
 .../memory-controllers/nvidia,tegra20-emc.txt | 43 +++++++++++++++++--
 1 file changed, 40 insertions(+), 3 deletions(-)

diff --git 
a/Documentation/devicetree/bindings/memory-controllers/nvidia,tegra20-emc.txt 
b/Documentation/devicetree/bindings/memory-controllers/nvidia,tegra20-emc.txt
index 8d09b228ac42..382aabcd6952 100644
--- 
a/Documentation/devicetree/bindings/memory-controllers/nvidia,tegra20-emc.txt
+++ 
b/Documentation/devicetree/bindings/memory-controllers/nvidia,tegra20-emc.txt
@@ -4,7 +4,7 @@ Properties:
 - name : Should be emc
 - #address-cells : Should be 1
 - #size-cells : Should be 0
-- compatible : Should contain "nvidia,tegra20-emc".
+- compatible : Should contain "nvidia,tegra20-emc" and "simple-mfd".
 - reg : Offset and length of the register set for the device
 - nvidia,use-ram-code : If present, the sub-nodes will be addressed
   and chosen using the ramcode board selector. If omitted, only one
@@ -17,7 +17,8 @@ Properties:
 - core-supply: Phandle of voltage regulator of the SoC "core" power domain.
 - operating-points-v2: See ../bindings/opp/opp.txt for details.
 
-Child device nodes describe the memory settings for different configurations 
and clock rates.
+Child device nodes describe the memory settings for different configurations 
and clock rates,
+as well as EMC activity statistics collection sub-device.
 
 Example:
 
@@ -31,17 +32,34 @@ Example:
                ...
        };
 
+       emc_bw_dfs_opp_table: emc_opp_table1 {
+               compatible = "operating-points-v2";
+
+               opp@36000000 {
+                       opp-hz = /bits/ 64 <36000000>;
+                       opp-peak-kBps = <144000>;
+               };
+               ...
+       };
+
        memory-controller@7000f400 {
                #address-cells = < 1 >;
                #size-cells = < 0 >;
                #interconnect-cells = < 0 >;
-               compatible = "nvidia,tegra20-emc";
+               compatible = "nvidia,tegra20-emc", "simple-mfd";
                reg = <0x7000f400 0x400>;
                interrupts = <0 78 0x04>;
                clocks = <&tegra_car TEGRA20_CLK_EMC>;
                nvidia,memory-controller = <&mc>;
                core-supply = <&core_vdd_reg>;
                operating-points-v2 = <&emc_icc_dvfs_opp_table>;
+
+               emc-stats {
+                       compatible = "nvidia,tegra20-emc-statistics";
+                       operating-points-v2 = <&emc_bw_dfs_opp_table>;
+                       interconnects = <&mc TEGRA20_MC_MPCORER &emc>;
+                       interconnect-names = "cpu";
+               };
        }
 
 
@@ -120,3 +138,22 @@ Properties:
                                                 0 0 0 0 0 0 0 0 0 0 0 0 0 0
                                                 0 0 0 0 >;
                };
+
+
+
+Embedded Memory Controller statistics gathering sub-device
+
+EMC statistics subdev gathers information about hardware utilization
+which is intended to be used for debugging purposes and for dynamic
+frequency scaling based on the collected stats.
+
+Properties:
+- name : Should be emc-stats.
+- compatible : Should contain "nvidia,tegra20-emc-statistics".
+- operating-points-v2: See ../bindings/opp/opp.txt for details.
+- interconnects: Should contain entries for memory clients sitting on
+                 MC->EMC memory interconnect path.
+- interconnect-names: Should include name of the interconnect path for each
+                      interconnect entry. Consult TRM documentation for
+                      information about available memory clients, see MEMORY
+                      CONTROLLER section.
-- 
2.27.0

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