This patch adds documentation for the Sipeed Maix bit, and more generally for the Kendryte K210 processor.
Signed-off-by: Sean Anderson seanga2@gmail.com ---
Changes in v9: - Mark dts code block as "none" explicitly Changes in v7: - Split off into its own patch - Fix size of clint
doc/board/index.rst | 1 + doc/board/sipeed/index.rst | 9 ++ doc/board/sipeed/maix.rst | 298 +++++++++++++++++++++++++++++++++++++ 3 files changed, 308 insertions(+) create mode 100644 doc/board/sipeed/index.rst create mode 100644 doc/board/sipeed/maix.rst
diff --git a/doc/board/index.rst b/doc/board/index.rst index 51a2ae6f28..dcc47c5a21 100644 --- a/doc/board/index.rst +++ b/doc/board/index.rst @@ -16,6 +16,7 @@ Board-specific doc renesas/index rockchip/index sifive/index + sipeed/index st/index toradex/index xilinx/index diff --git a/doc/board/sipeed/index.rst b/doc/board/sipeed/index.rst new file mode 100644 index 0000000000..3518e2d8f4 --- /dev/null +++ b/doc/board/sipeed/index.rst @@ -0,0 +1,9 @@ +.. SPDX-License-Identifier: GPL-2.0+ + +Sipeed +====== + +.. toctree:: + :maxdepth: 2 + + maix diff --git a/doc/board/sipeed/maix.rst b/doc/board/sipeed/maix.rst new file mode 100644 index 0000000000..06e0008b9f --- /dev/null +++ b/doc/board/sipeed/maix.rst @@ -0,0 +1,298 @@ +.. SPDX-License-Identifier: GPL-2.0+ +.. Copyright (C) 2020 Sean Anderson seanga2@gmail.com + +Maix Bit +======== + +Several of the Sipeed Maix series of boards cotain the Kendryte K210 processor, +a 64-bit RISC-V CPU. This processor contains several peripherals to accelerate +neural network processing and other "ai" tasks. This includes a "KPU" neural +network processor, an audio processor supporting beamforming reception, and a +digital video port supporting capture and output at VGA resolution. Other +peripherals include 8M of SRAM (accessible with and without caching); remappable +pins, including 40 GPIOs; AES, FFT, and SHA256 accelerators; a DMA controller; +and I2C, I2S, and SPI controllers. Maix peripherals vary, but include spi flash; +on-board usb-serial bridges; ports for cameras, displays, and sd cards; and +ESP32 chips. Currently, only the Sipeed Maix Bit V2.0 (bitm) is supported, but +the boards are fairly similar. + +Documentation for Maix boards is available from +`Sipeed's website http://dl.sipeed.com/MAIX/HDK/`_. +Documentation for the Kendryte K210 is available from +`Kendryte's website https://kendryte.com/downloads/`_. However, hardware +details are rather lacking, so most technical reference has been taken from the +`standalone sdk https://github.com/kendryte/kendryte-standalone-sdk`_. + +Build and boot steps +-------------------- + +To build u-boot, run + +.. code-block:: none + + make sipeed_maix_bitm_defconfig + make CROSS_COMPILE=<your cross compile prefix> + +To flash u-boot to a maix bit, run + +.. code-block:: none + + kflash -tp /dev/<your tty here> -B bit_mic u-boot-dtb.bin + +Boot output should look like the following: + +.. code-block:: none + + U-Boot 2020.04-rc2-00087-g2221cc09c1-dirty (Feb 28 2020 - 13:53:09 -0500) + + DRAM: 8 MiB + In: serial@38000000 + Out: serial@38000000 + Err: serial@38000000 + => + +Loading Images +^^^^^^^^^^^^^^ + +To load a kernel, transfer it over serial. + +.. code-block:: none + + => loady 80000000 1500000 + ## Switch baudrate to 1500000 bps and press ENTER ... + + *** baud: 1500000 + + *** baud: 1500000 *** + ## Ready for binary (ymodem) download to 0x80000000 at 1500000 bps... + C + *** file: loader.bin + $ sz -vv loader.bin + Sending: loader.bin + Bytes Sent:2478208 BPS:72937 + Sending: + Ymodem sectors/kbytes sent: 0/ 0k + Transfer complete + + *** exit status: 0 *** + ## Total Size = 0x0025d052 = 2478162 Bytes + ## Switch baudrate to 115200 bps and press ESC ... + + *** baud: 115200 + + *** baud: 115200 *** + => + +Running Programs +^^^^^^^^^^^^^^^^ + +Binaries +"""""""" + +To run a bare binary, use the ``go`` command: + +.. code-block:: none + + => loady + ## Ready for binary (ymodem) download to 0x80000000 at 115200 bps... + C + *** file: ./examples/standalone/hello_world.bin + $ sz -vv ./examples/standalone/hello_world.bin + Sending: hello_world.bin + Bytes Sent: 4864 BPS:649 + Sending: + Ymodem sectors/kbytes sent: 0/ 0k + Transfer complete + + *** exit status: 0 *** + (CAN) packets, 5 retries + ## Total Size = 0x000012f8 = 4856 Bytes + => go 80000000 + ## Starting application at 0x80000000 ... + Example expects ABI version 9 + Actual U-Boot ABI version 9 + Hello World + argc = 1 + argv[0] = "80000000" + argv[1] = "<NULL>" + Hit any key to exit ... + +Legacy Images +""""""""""""" + +To run legacy images, use the ``bootm`` command: + +.. code-block:: none + + $ tools/mkimage -A riscv -O u-boot -T standalone -C none -a 80000000 -e 80000000 -d examples/standalone/hello_world.bin hello_world.img + Image Name: + Created: Thu Mar 5 12:04:10 2020 + Image Type: RISC-V U-Boot Standalone Program (uncompressed) + Data Size: 4856 Bytes = 4.74 KiB = 0.00 MiB + Load Address: 80000000 + Entry Point: 80000000 + + $ picocom -b 115200 /dev/ttyUSB0i + => loady + ## Ready for binary (ymodem) download to 0x80000000 at 115200 bps... + C + *** file: hello_world.img + $ sz -vv hello_world.img + Sending: hello_world.img + Bytes Sent: 4992 BPS:665 + Sending: + Ymodem sectors/kbytes sent: 0/ 0k + Transfer complete + + *** exit status: 0 *** + CAN) packets, 3 retries + ## Total Size = 0x00001338 = 4920 Bytes + => bootm + ## Booting kernel from Legacy Image at 80000000 ... + Image Name: + Image Type: RISC-V U-Boot Standalone Program (uncompressed) + Data Size: 4856 Bytes = 4.7 KiB + Load Address: 80000000 + Entry Point: 80000000 + Verifying Checksum ... OK + Loading Standalone Program + Example expects ABI version 9 + Actual U-Boot ABI version 9 + Hello World + argc = 0 + argv[0] = "<NULL>" + Hit any key to exit ... + +Over- and Under-clocking +------------------------ + +To change the clock speed of the K210, you will need to enable +``CONFIG_CLK_K210_SET_RATE`` and edit the board's device tree. To do this, add a +section to ``arch/riscv/arch/riscv/dts/k210-maix-bit.dts`` like the following: + +.. code-block:: none + + &sysclk { + assigned-clocks = <&sysclk K210_CLK_PLL0>; + assigned-clock-rates = <800000000>; + }; + +There are three PLLs on the K210: PLL0 is the parent of most of the components, +including the CPU and RAM. PLL1 is the parent of the neural network coprocessor. +PLL2 is the parent of the sound processing devices. Note that child clocks of +PLL0 and PLL2 run at *half* the speed of the PLLs. For example, if PLL0 is +running at 800 MHz, then the CPU will run at 400 MHz. This is the example given +above. The CPU can be overclocked to around 600 MHz, and underclocked to 26 MHz. + +It is possible to set PLL2's parent to PLL0. The plls are more accurate when +converting between similar frequencies. This makes it easier to get an accurate +frequency for I2S. As an example, consider sampling an I2S device at 44.1 kHz. +On this device, the I2S serial clock runs at 64 times the sample rate. +Therefore, we would like to run PLL2 at an even multiple of 2.8224 MHz. If +PLL2's parent is IN0, we could use a frequency of 390 MHz (the same as the CPU's +default speed). Dividing by 138 yields a serial clock of about 2.8261 MHz. This +results in a sample rate of 44.158 kHz---around 50 Hz or .1% too fast. If, +instead, we set PLL2's parent to PLL1 running at 390 MHz, and request a rate of +2.8224 * 136 = 383.8464 MHz, the achieved rate is 383.90625 MHz. Dividing by 136 +yields a serial clock of about 2.8228 MHz. This results in a sample rate of +44.107 kHz---just 7 Hz or .02% too fast. This configuration is shown in the +following example: + +.. code-block:: none + + &sysclk { + assigned-clocks = <&sysclk K210_CLK_PLL1>, <&sysclk K210_CLK_PLL2>; + assigned-clock-parents = <0>, <&sysclk K210_CLK_PLL1>; + assigned-clock-rates = <390000000>, <383846400>; + }; + +There are a couple of quirks to the PLLs. First, there are more frequency ratios +just above and below 1.0, but there is a small gap around 1.0. To be explicit, +if the input frequency is 100 MHz, it would be impossible to have an output of +99 or 101 MHz. In addition, there is a maximum frequency for the internal VCO, +so higher input/output frequencies will be less accurate than lower ones. + +Technical Details +----------------- + +Boot Sequence +^^^^^^^^^^^^^ + +1. ``RESET`` pin is deasserted. +2. Both harts begin executing at ``0x00001000``. +3. Both harts jump to firmware at ``0x88000000``. +4. One hart is chosen as a boot hart. +5. Firmware reads value of pin ``IO_16`` (ISP). + + * If the pin is low, enter ISP mode. This mode allows loading data to ram, + writing it to flash, and booting from specific addresses. + * If the pin is high, continue boot. +6. Firmware reads the next stage from flash (SPI3) to address ``0x80000000``. + + * If byte 0 is 1, the next stage is decrypted using the built-in AES + accelerator and the one-time programmable, 128-bit AES key. + * Bytes 1 to 4 hold the length of the next stage. + * The SHA-256 sum of the next stage is automatically calculated, and verified + against the 32 bytes following the next stage. +7. The boot hart sends an IPI to the other hart telling it to jump to the next + stage. +8. The boot hart jumps to ``0x80000000``. + +Memory Map +^^^^^^^^^^ + +========== ========= =========== +Address Size Description +========== ========= =========== +0x00000000 0x1000 debug +0x00001000 0x1000 rom +0x02000000 0xC000 clint +0x0C000000 0x4000000 plic +0x38000000 0x1000 uarths +0x38001000 0x1000 gpiohs +0x40000000 0x400000 sram0 (non-cached) +0x40400000 0x200000 sram1 (non-cached) +0x40600000 0x200000 airam (non-cached) +0x40800000 0xC00000 kpu +0x42000000 0x400000 fft +0x50000000 0x1000 dmac +0x50200000 0x200000 apb0 +0x50200000 0x80 gpio +0x50210000 0x100 uart0 +0x50220000 0x100 uart1 +0x50230000 0x100 uart2 +0x50240000 0x100 spi slave +0x50250000 0x200 i2s0 +0x50250200 0x200 apu +0x50260000 0x200 i2s1 +0x50270000 0x200 i2s2 +0x50280000 0x100 i2c0 +0x50290000 0x100 i2c1 +0x502A0000 0x100 i2c2 +0x502B0000 0x100 fpioa +0x502C0000 0x100 sha256 +0x502D0000 0x100 timer0 +0x502E0000 0x100 timer1 +0x502F0000 0x100 timer2 +0x50400000 0x200000 apb1 +0x50400000 0x100 wdt0 +0x50410000 0x100 wdt1 +0x50420000 0x100 otp control +0x50430000 0x100 dvp +0x50440000 0x100 sysctl +0x50450000 0x100 aes +0x50460000 0x100 rtc +0x52000000 0x4000000 apb2 +0x52000000 0x100 spi0 +0x53000000 0x100 spi1 +0x54000000 0x200 spi3 +0x80000000 0x400000 sram0 (cached) +0x80400000 0x200000 sram1 (cached) +0x80600000 0x200000 airam (cached) +0x88000000 0x20000 otp +0x88000000 0xC200 firmware +0x8801C000 0x1000 riscv priv spec 1.9 config +0x8801D000 0x2000 flattened device tree (contains only addresses and + interrupts) +0x8801f000 0x1000 credits +========== ========= ===========