dt-bindings: mediatek: Add binding for mt8183 IOMMU and SMI

This patch adds decriptions for mt8183 IOMMU and SMI.

mt8183 has only one M4U like mt8173 and is also MTK IOMMU gen2 which
uses ARM Short-Descriptor translation table format.

The mt8183 M4U-SMI HW diagram is as below:

                          EMI
                           |
                          M4U
                           |
                       ----------
                       |        |
                   gals0-rx   gals1-rx
                       |        |
                       |        |
                   gals0-tx   gals1-tx
                       |        |
                      ------------
                       SMI Common
                      ------------
                           |
  +-----+-----+--------+-----+-----+-------+-------+
  |     |     |        |     |     |       |       |
  |     |  gals-rx  gals-rx  |   gals-rx gals-rx gals-rx
  |     |     |        |     |     |       |       |
  |     |     |        |     |     |       |       |
  |     |  gals-tx  gals-tx  |   gals-tx gals-tx gals-tx
  |     |     |        |     |     |       |       |
larb0 larb1  IPU0    IPU1  larb4  larb5  larb6    CCU
disp  vdec   img     cam    venc   img    cam

All the connections are HW fixed, SW can NOT adjust it.

Compared with mt8173, we add a GALS(Global Async Local Sync) module
between SMI-common and M4U, and additional GALS between larb2/3/5/6
and SMI-common. GALS can help synchronize for the modules in different
clock frequency, it can be seen as a "asynchronous fifo".

GALS can only help transfer the command/data while it doesn't have
the configuring register, thus it has the special "smi" clock and it
doesn't have the "apb" clock. From the diagram above, we add "gals0"
and "gals1" clocks for smi-common and add a "gals" clock for smi-larb.

>From the diagram above, IPU0/IPU1(Image Processor Unit) and CCU(Camera
Control Unit) is connected with smi-common directly, we can take them
as "larb2", "larb3" and "larb7", and their register spaces are
different with the normal larb.

Signed-off-by: Yong Wu <yong.wu@mediatek.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Evan Green <evgreen@chromium.org>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

1 files changed, 27 insertions, 3 deletions

diff --git a/Documentation/devicetree/bindings/iommu/mediatek,iommu.txt b/Documentation/devicetree/bindings/iommu/mediatek,iommu.txt
index 6922db598def..ce59a505f5a4 100644
--- a/Documentation/devicetree/bindings/iommu/mediatek,iommu.txt
+++ b/Documentation/devicetree/bindings/iommu/mediatek,iommu.txt
@@ -11,10 +11,23 @@ ARM Short-Descriptor translation table format for address translation.
                |
               m4u (Multimedia Memory Management Unit)
                |
+          +--------+
+          |        |
+      gals0-rx   gals1-rx    (Global Async Local Sync rx)
+          |        |
+          |        |
+      gals0-tx   gals1-tx    (Global Async Local Sync tx)
+          |        |          Some SoCs may have GALS.
+          +--------+
+               |
            SMI Common(Smart Multimedia Interface Common)
                |
        +----------------+-------
        |                |
+       |             gals-rx        There may be GALS in some larbs.
+       |                |
+       |                |
+       |             gals-tx
        |                |
    SMI larb0        SMI larb1   ... SoCs have several SMI local arbiter(larb).
    (display)         (vdec)
@@ -36,6 +49,10 @@ each local arbiter.
 like display, video decode, and camera. And there are different ports
 in each larb. Take a example, There are many ports like MC, PP, VLD in the
 video decode local arbiter, all these ports are according to the video HW.
+  In some SoCs, there may be a GALS(Global Async Local Sync) module between
+smi-common and m4u, and additional GALS module between smi-larb and
+smi-common. GALS can been seen as a "asynchronous fifo" which could help
+synchronize for the modules in different clock frequency.
 
 Required properties:
 - compatible : must be one of the following string:
@@ -44,18 +61,25 @@ Required properties:
 	"mediatek,mt7623-m4u", "mediatek,mt2701-m4u" for mt7623 which uses
 						     generation one m4u HW.
 	"mediatek,mt8173-m4u" for mt8173 which uses generation two m4u HW.
+	"mediatek,mt8183-m4u" for mt8183 which uses generation two m4u HW.
 - reg : m4u register base and size.
 - interrupts : the interrupt of m4u.
 - clocks : must contain one entry for each clock-names.
-- clock-names : must be "bclk", It is the block clock of m4u.
+- clock-names : Only 1 optional clock:
+  - "bclk": the block clock of m4u.
+  Here is the list which require this "bclk":
+  - mt2701, mt2712, mt7623 and mt8173.
+  Note that m4u use the EMI clock which always has been enabled before kernel
+  if there is no this "bclk".
 - mediatek,larbs : List of phandle to the local arbiters in the current Socs.
 	Refer to bindings/memory-controllers/mediatek,smi-larb.txt. It must sort
 	according to the local arbiter index, like larb0, larb1, larb2...
 - iommu-cells : must be 1. This is the mtk_m4u_id according to the HW.
 	Specifies the mtk_m4u_id as defined in
 	dt-binding/memory/mt2701-larb-port.h for mt2701, mt7623
-	dt-binding/memory/mt2712-larb-port.h for mt2712, and
-	dt-binding/memory/mt8173-larb-port.h for mt8173.
+	dt-binding/memory/mt2712-larb-port.h for mt2712,
+	dt-binding/memory/mt8173-larb-port.h for mt8173, and
+	dt-binding/memory/mt8183-larb-port.h for mt8183.
 
 Example:
 	iommu: iommu@10205000 {