drivers: bus: add a new driver for WEIM

The WEIM(Wireless External Interface Module) works like a bus.
You can attach many different devices on it, such as NOR, onenand.

In the case of i.MX6q-sabreauto, the NOR is connected to WEIM.

This patch also adds the devicetree binding document.
The driver only works when the devicetree is enabled.

Signed-off-by: Huang Shijie <b32955@freescale.com>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

1 files changed, 49 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/bus/imx-weim.txt b/Documentation/devicetree/bindings/bus/imx-weim.txt
new file mode 100644
index 000000000000..cedc2a9c4785
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+++ b/Documentation/devicetree/bindings/bus/imx-weim.txt
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+Device tree bindings for i.MX Wireless External Interface Module (WEIM)
+
+The term "wireless" does not imply that the WEIM is literally an interface
+without wires. It simply means that this module was originally designed for
+wireless and mobile applications that use low-power technology.
+
+The actual devices are instantiated from the child nodes of a WEIM node.
+
+Required properties:
+
+ - compatible:          Should be set to "fsl,imx6q-weim"
+ - reg:                 A resource specifier for the register space
+                        (see the example below)
+ - clocks:              the clock, see the example below.
+ - #address-cells:      Must be set to 2 to allow memory address translation
+ - #size-cells:         Must be set to 1 to allow CS address passing
+ - ranges:              Must be set up to reflect the memory layout with four
+                        integer values for each chip-select line in use:
+
+                           <cs-number> 0 <physical address of mapping> <size>
+
+Timing property for child nodes. It is mandatory, not optional.
+
+ - fsl,weim-cs-timing:  The timing array, contains 6 timing values for the
+                        child node. We can get the CS index from the child
+                        node's "reg" property. This property contains the values
+                        for the registers EIM_CSnGCR1, EIM_CSnGCR2, EIM_CSnRCR1,
+                        EIM_CSnRCR2, EIM_CSnWCR1, EIM_CSnWCR2 in this order.
+
+Example for an imx6q-sabreauto board, the NOR flash connected to the WEIM:
+
+        weim: weim@021b8000 {
+                compatible = "fsl,imx6q-weim";
+                reg = <0x021b8000 0x4000>;
+                clocks = <&clks 196>;
+                #address-cells = <2>;
+                #size-cells = <1>;
+                ranges = <0 0 0x08000000 0x08000000>;
+
+                nor@0,0 {
+                        compatible = "cfi-flash";
+                        reg = <0 0 0x02000000>;
+                        #address-cells = <1>;
+                        #size-cells = <1>;
+                        bank-width = <2>;
+                        fsl,weim-cs-timing = <0x00620081 0x00000001 0x1c022000
+                                        0x0000c000 0x1404a38e 0x00000000>;
+                };
+        };