| Zubair Lutfullah Kakakhel | ebf2b9e | 2016-07-29 15:11:20 +0100 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2016, Imagination Technologies Ltd. |
| 3 | * |
| 4 | * Zubair Lutfullah Kakakhel, Zubair.Kakakhel@imgtec.com |
| 5 | */ |
| 6 | |
| 7 | MIPSfpga |
| 8 | ======================================= |
| 9 | |
| 10 | MIPSfpga is an FPGA based development platform by Imagination Technologies |
| 11 | As we are dealing with a MIPS core instantiated on an FPGA, specifications |
| 12 | are fluid and can be varied in RTL. |
| 13 | |
| 14 | The example project provided by IMGTEC runs on the Nexys4DDR board by |
| 15 | Digilent powered by the ARTIX-7 FPGA by Xilinx. Relevant details about |
| 16 | the example project and the Nexys4DDR board: |
| 17 | |
| 18 | - microAptiv UP core m14Kc |
| 19 | - 50MHz clock speed |
| 20 | - 128Mbyte DDR RAM at 0x0000_0000 |
| 21 | - 8Kbyte RAM at 0x1000_0000 |
| 22 | - axi_intc at 0x1020_0000 |
| 23 | - axi_uart16550 at 0x1040_0000 |
| 24 | - axi_gpio at 0x1060_0000 |
| 25 | - axi_i2c at 0x10A0_0000 |
| 26 | - custom_gpio at 0x10C0_0000 |
| 27 | - axi_ethernetlite at 0x10E0_0000 |
| 28 | - 8Kbyte BootRAM at 0x1FC0_0000 |
| 29 | - 16Mbyte QPI at 0x1D00_0000 |
| 30 | |
| 31 | Boot protocol: |
| 32 | -------------- |
| 33 | |
| 34 | The BootRAM is a writeable "RAM" in FPGA at 0x1FC0_0000. |
| 35 | This is for easy reprogrammibility via JTAG. |
| 36 | |
| 37 | DDR initialization is already handled by a HW IP block. |
| 38 | |
| 39 | When the example project bitstream is loaded, the cpu_reset button |
| 40 | needs to be pressed. |
| 41 | |
| 42 | The bootram initializes the cache and axi_uart |
| 43 | Then checks if there is anything non 0xffff_ffff at location 0x1D40_0000 |
| 44 | |
| 45 | If there is, then that is considered as u-boot. u-boot is copied from |
| 46 | 0x1D40_0000 to memory and the bootram jumps into u-boot code. |
| 47 | |
| 48 | At this point, the board is ready to load the Linux kernel + buildroot initramfs |
| 49 | |
| 50 | This can be done in multiple ways: |
| 51 | |
| 52 | 1- JTAG load the binary and jump into it. |
| 53 | 2- Load kernel stored in the QSPI flash at 0x1D80_0000 |
| 54 | 3- Load uImage via tftp. Ethernet works in u-boot. |
| 55 | e.g. env set server ip 192.168.154.45; dhcp uImage; bootm |