Add driver for ED060SC4 e-ink display panel

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diff --git a/drivers/gdisp/ED060SC4/readme.txt b/drivers/gdisp/ED060SC4/readme.txt
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+1. Introduction
+
+This is a driver for ED060SC4 800x600 e-ink display panel manufactured by
+Prime View. Note that this driver uses a direct connection to the panel from
+the processor; it does not use a separate controller chip between the processor
+and the panel.
+
+To use the driver, you need to be able to control the following signals from
+your processor:
+
+Gate driver: SPV, CKV, GMODE.
+Source driver: CL, LE, OE, SPH, D0-D7.
+Power supply: +-15V, +22V, -20V, digital Vdd
+
+The file "example_schematics.png" shows how to connect the signals to e.g. a
+STM32L151 microcontroller. It also includes an example circuit for providing
+the panel supply voltages.
+
+Note that the larger panels (such as the 800x600) consist of multiple segments
+with separate gate driver signals. These can be daisy chained as shown in the
+example schematic.
+
+
+
+
+2. Frame buffer emulation
+
+Because there is not enough memory to store a full frame buffer on the
+processor, this driver emulates a frame buffer by storing the display data in
+blocks. It will buffer up to EINK_NUMBUFFERS blocks and then write them to the
+screen. The following #defines control the buffering. Larger numbers will
+result in faster drawing, but also use more RAM on the processor:
+
+#define EINK_BLOCKWIDTH 20    // Width of a single block in buffer
+#define EINK_BLOCKHEIGHT 20   // Height of a single block in buffers
+#define EINK_NUMBUFFERS 40    // Number of blocks to buffer
+
+After drawing your images, you should flush the buffers using the following
+command:
+
+    #include <ed060sc4.h>
+    gdispControl(GDISP_CONTROL_FLUSH, 0);
+
+The buffers are also flushed whenever you turn the display off using:
+
+    gdispSetPowerMode(powerOff);
+
+
+
+3. Display clearing and writing waveforms
+
+This driver does not know the official Prime View waveforms for driving the
+display, mostly because those are trade secrets and not publicly available.
+Instead, it uses reverse engineered waveforms that are mostly functional.
+
+The following #defines control the waveforms:
+
+#define EINK_BLINKCLEAR TRUE      // Clear to opposite color first
+#define EINK_CLEARCOUNT 10        // Number of sweeps to clear the display
+#define EINK_WRITECOUNT 4         // Number of sweeps when writing to display
+
+Increasing the clearcount and writecount can improve contrast, but will also
+slow down the drawing and use more power.
+
+
+
+4. Clock speeds
+
+Because the driver bit bangs the display, the clock frequency of the processor
+is quite significant. This is controlled by EINK_CLOCKDELAY variable. Set it
+so that the delay is atleast 50 nanoseconds.
+
+
+
+5. Support for other kinds of panels
+
+Most of the Prime View panels should work using this driver, but only ED060SC4
+has been tested so far. Some points of consideration:
+
+- Some displays may use 4 bits per pixel. The driver currently assumes 2 bits
+  per pixel.
+- Larger displays may require some other way of daisy chaining than shown in
+  the example schematics.
+
+