[PATCH v2 1/3] input: cygnus-update touchscreen dt node document

[Raveendra Padasalagi]

In Cygnus SOC touch screen controller registers are shared
with ADC and flex timer. Using readl/writel could lead to
race condition. So touch screen driver is enhanced to support

1. If touchscreen register's are not shared. Register access
is handled through readl/writel if "brcm,iproc-touchscreen"
compatible is provided in touchscreen dt node. This will help
for future SOC's if comes with dedicated touchscreen IP register's.

2. If touchscreen register's are shared with other IP's, register
access is handled through syscon framework API's to take care of
mutually exclusive access. This feature can be enabled by selecting
"brcm,iproc-touchscreen-syscon" compatible string in the touchscreen
dt node.

Hence touchscreen dt node bindings document is updated to take care
of above changes in the touchscreen driver.

Signed-off-by: Raveendra Padasalagi <raveendra.padasalagi@xxxxxxxxxxxx>
Reviewed-by: Ray Jui <ray.jui@xxxxxxxxxxxx>
Reviewed-by: Scott Branden <scott.branden@xxxxxxxxxxxx>
---
 .../input/touchscreen/brcm,iproc-touchscreen.txt   | 57 +++++++++++++++++++---
 1 file changed, 51 insertions(+), 6 deletions(-)

diff --git a/Documentation/devicetree/bindings/input/touchscreen/brcm,iproc-touchscreen.txt b/Documentation/devicetree/bindings/input/touchscreen/brcm,iproc-touchscreen.txt
index 34e3382..f530c25 100644
--- a/Documentation/devicetree/bindings/input/touchscreen/brcm,iproc-touchscreen.txt
+++ b/Documentation/devicetree/bindings/input/touchscreen/brcm,iproc-touchscreen.txt
@@ -1,12 +1,30 @@
 * Broadcom's IPROC Touchscreen Controller
 
 Required properties:
-- compatible: must be "brcm,iproc-touchscreen"
-- reg: physical base address of the controller and length of memory mapped
-  region.
+- compatible: should be one of
+        "brcm,iproc-touchscreen"
+        "brcm,iproc-touchscreen-syscon"
+- ts_syscon: if "brcm,iproc-touchscreen-syscon" compatible string
+  is selected then "ts_syscon" is mandatory or else not required.
+  The "ts_syscon" is handler of syscon node defining physical base
+  address of the controller and length of memory mapped region.
+  If this property is selected please make sure MFD_SYSCON config
+  is enabled in the defconfig file.
+- reg: if "brcm,iproc-touchscreen" compatible string is selected
+  then "reg" property is mandatory or else not required.
+  The "reg" should be physical base address of the controller and
+  length of memory mapped region.
 - clocks:  The clock provided by the SOC to driver the tsc
 - clock-name:  name for the clock
 - interrupts: The touchscreen controller's interrupt
+- address-cells: Specify the number of u32 entries needed in child nodes.
+                 Should set to 1. This property is mandatory when
+                 "brcm,iproc-touchscreen-syscon" compatible string is selected
+                 or else not required.
+- size-cells: Specify number of u32 entries needed to specify child nodes size
+              in reg property. Should set to 1.This property is mandatory when
+              "brcm,iproc-touchscreen-syscon" compatible string is selected or
+              else not required.
 
 Optional properties:
 - scanning_period: Time between scans. Each step is 1024 us.  Valid 1-256.
@@ -53,13 +71,40 @@ Optional properties:
 - touchscreen-inverted-x: X axis is inverted (boolean)
 - touchscreen-inverted-y: Y axis is inverted (boolean)
 
-Example:
+Example 1: An example of touchscreen node with "brcm,iproc-touchscreen-syscon"
+           compatible string.
+
+	ts_adc_syscon: ts_adc_syscon@0x180a6000 {
+		compatible = "syscon";
+		reg = <0x180a6000 0xc30>;
+	};
 
 	touchscreen: tsc@0x180A6000 {
-		compatible = "brcm,iproc-touchscreen";
+		compatible = "brcm,iproc-touchscreen-syscon";
 		#address-cells = <1>;
 		#size-cells = <1>;
-		reg = <0x180A6000 0x40>;
+		ts_syscon = <&ts_adc_syscon>;
+		clocks = <&adc_clk>;
+		clock-names = "tsc_clk";
+		interrupts = <GIC_SPI 164 IRQ_TYPE_LEVEL_HIGH>;
+
+		scanning_period = <5>;
+		debounce_timeout = <40>;
+		settling_timeout = <7>;
+		touch_timeout = <10>;
+		average_data = <5>;
+		fifo_threshold = <1>;
+		/* Touchscreen is rotated 180 degrees. */
+		touchscreen-inverted-x;
+		touchscreen-inverted-y;
+	};
+
+Example 2: An example of touchscreen node with "brcm,iproc-touchscreen"
+          compatible string.
+
+	touchscreen: tsc@0x180A6000 {
+		compatible = "brcm,iproc-touchscreen";
+		reg = <0x180a6000 0x40>;
 		clocks = <&adc_clk>;
 		clock-names = "tsc_clk";
 		interrupts = <GIC_SPI 164 IRQ_TYPE_LEVEL_HIGH>;
-- 
1.9.1