libswitchhw: added Readme file

ed889612 · Tomasz Wlostowski · Alessandro Rubini · 69e157a3 · ed889612
Commit ed889612 authored Oct 12, 2011 by Tomasz Wlostowski Committed by Alessandro Rubini Oct 23, 2011
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README userspace/libswitchhw/README +21 -0

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--- a/userspace/libswitchhw/README
+++ b/userspace/libswitchhw/README
+Switch V2 Hardware Library (libswitchhw)
+-------------------------------
+
+Libswitchhw is a collection of low-level userspace drivers for various 
+peripherals in the switch, which do not need kernel modules. These are:
+- Main FPGA (fpga_io.c) and CPU GPIO ports (pio.c), pin definitions (pio_pins.c)
+- AD9516 PLL and clock distribution chip (ad9516.c)
+- SPI master for communication with the timing FPGA (clkb_io.c)
+- DMTD phase shifter PLL (dmpll.c, main clock recovery PLL - obsolete in V3, 
+  to be replaced by the SoftPLL)
+- Helper PLL (hpll.c, producing the "slightly offset" frequency for the DMTDs - 
+  obsolete in V3, to be replaced by the SoftPLL)
+- PPS generator (pps_gen.c, adjustment of time)
+- Watchdog SPI link (watchdog.c)
+- PHY calibrators (phy_calibration.c, xpoint.c, DS90LVxx buffers in the 
+  MiniBackplane V2, ADN4600 crosspoint for clock feedback) and the calibration DMTDs
+- Altera FPGA bootloader & revision management (mblaster.c, fpgaboot.c)
+
+
+Libswitchhw also provides a single routine to initialize all that stuff (see init.c)
+and some utility/tracing functions (trace.c, util.c)