The SPSR is used to store the current value of the CPSR when an exception
is taken so that it can be restored after handling the exception.
Each exception handling mode can access its own SPSR.
User mode and System mode do not have an SPSR because they are not
exception handling modes.
Signed-off-by: chao.an <anchao@xiaomi.com>
## Summary
To control the Data/Command Pin on ST7789 SPI Display, the SPI Driver flips the MISO Pin as though it was a GPIO.
To implement this on BL602, we reconfigure MISO from SPI Pin to GPIO Pin on the fly inside `bl602_spi_cmddata()`.
When the SPI Port is deselected (after the SPI operation), we revert MISO back from GPIO Pin to SPI Pin. We implement this inside `bl602_spi_select()`.
[More Details Here](https://github.com/lupyuen/st7789-nuttx#spi-cmddata)
## Impact
This change impacts 3 LCD drivers that call `SPI_CMDDATA()`: ST7735, ST7789, GC9A01.
Previously the BL602 SPI Driver would fail with "SPI cmddata not supported" when the above drivers are used.
After the change, the above drivers will set the LCD Data/Command Pin correctly.
## Testing
We tested this implementation of SPI Cmd/Data with NuttX ST7789 Driver and a Logic Analyser on PineCone BL602:
- [Testing with Logic Analyser](https://github.com/lupyuen/st7789-nuttx#spi-cmddata)
We also tested LVGL with ST7789 on PineCone BL602:
- [Testing with LVGL](https://github.com/lupyuen/st7789-nuttx#run-lvgl-demo)
As for regular SPI Devices that don't require SPI Cmd/Data, we tested `CONFIG_SPI_CMDDATA=y` with Semtech SX1262 SPI Transceiver on PineCone BL602:
- [Testing Cmd/Data](https://github.com/lupyuen/incubator-nuttx/releases/tag/release-2022-03-29)
As xtensa timer is common in all xtensa chips,
Use oneshot ops, implement a common xtensa oneshot timer.
Signed-off-by: zhuyanlin <zhuyanlin1@xiaomi.com>
## Summary
SPI Poll Send `bl602_spi_poll_send()` doesn't send any SPI Data because it doesn't enable SPI Master and it doesn't clear the SPI FIFO. Also it hangs because it loops forever waiting for the FIFO.
We fix this problem by moving the code that enables SPI Master and clears the FIFO, from SPI Poll Exchange `bl602_spi_poll_exchange()` to SPI Poll Send. (Note that SPI Poll Exchange calls SPI Poll Send)
[More Details Here](https://github.com/lupyuen/st7789-nuttx#fix-spi-send)
## Impact
This problem affects all NuttX Drivers that call `SPI_SEND()` on BL602, including the ST7789 Display Driver.
Previously `SPI_SEND()` didn't send any SPI Data and never returns, because it loops forever waiting to receive data.
Now `SPI_SEND()` sends data and returns correctly.
[More Details Here](https://github.com/lupyuen/st7789-nuttx#fix-spi-send)
## Testing
We tested the modified SPI Poll Send with NuttX ST7789 Driver and a Logic Analyser on PineCone BL602:
- [Testing with Logic Analyser](https://github.com/lupyuen/st7789-nuttx#fix-spi-send)
We also tested LVGL with ST7789 on PineCone BL602:
- [Testing with LVGL](https://github.com/lupyuen/st7789-nuttx#run-lvgl-demo)
As for the modified SPI Poll Exchange, we tested with Semtech SX1262 SPI Transceiver on PineCone BL602:
- [Testing SPI Poll Exchange](https://github.com/lupyuen/incubator-nuttx/releases/tag/release-2022-03-25)
since xcpt always point to the stack after the below change:
commit 7b9978883c
Author: chao.an <anchao@xiaomi.com>
Date: Tue Mar 1 01:06:24 2022 +0800
arch/arm: optimize context switch speed
The current context save implementation saves registers of each task
to xcp context, which is unnecessary because most of the arm registers are
already saved in the task stack, this commit replace the xcp context with
stack context to improve context switching performance and reduce the tcb
space occupation of tcb instance.
Signed-off-by: Xiang Xiao <xiaoxiang@xiaomi.com>
