Fully tested for aarch64 OS without a bus error

[meesokim]

aarch64 architecture is for 64bit OS.
It doesn't allow the 32bit compiler option like -marm -mabi=aapcs-linux -mhard-float -mfloat-abi=hard
So I've replaced them to 64bit compiler option.
Unfortunately BCM2835_TIMER_BASE is not an aligned 64bit address. Therefore we can use 64bit address directly.
It's fixed by calculating upper 32bit and lower 32bit value respectively.
There is no more any bus error after applying this patches.

[juj]

I wonder if instead of the above, it would work to do

#if __aarch64__
typedef uint64_t __attribute__((aligned(4))) timer_uint64_t;
#else
typedef uint64_t timer_uint64_t;
#endif

volatile timer_uint64_t *systemTimerRegister = 0;

This will tell the compiler that systemTimerRegister points to something that is only 32-bit aligned, and it should then automatically generate the appropriate 32-bit load and stores on its own.

After that, the other #ifdef __aarch64__s would not be necessary below?

[meesokim]

I've applied your patch on the following 64bit OS.
"Linux raspberrypi 5.15.84-v8+ #1613 SMP PREEMPT Thu Jan 5 12:03:08 GMT 2023 aarch64 GNU/Linux"

But it makes same bus error.

bcm_host_get_peripheral_address: 0x3f000000, bcm_host_get_peripheral_size: 16777216, bcm_host_get_sdram_address: 0xc0000000
BCM core speed: current: 400000000hz, max turbo: 400000000hz. SPI CDIV: 6, SPI max frequency: 66666667hz
Initializing display
bcm2835 library version: 10071 (0x00002757)
Creating SPI task thread
InitSPI done
Bus error

[juj]

Oh, bummer. That would have been sweet if that had worked.

[juj]

Looks like some unrelated commit slipped into the PR tree?

[juj]

Maybe

// On 32-bit Pi, we can perform an unaligned 64-bit pointer access to read the timer for a micro-optimization, but on 64-bit Pi reading in 32-bit parts is needed.
#if __aarch64__
  systemTimerRegister = (volatile uint32_t*)
#else
  systemTimerRegister = (volatile uint64_t*)
#endif
systemTimerRegister = (volatile uint32_t*)((uintptr_t)bcm2835 + BCM2835_TIMER_BASE + 0x04);

?

[juj]

Maybe

#define tick() (systemTimerRegister[0] | ((uint64_t)systemTimerRegister[1] << 32))

?

[lolax80]

Does a 64bit Version of rcp-ili9341 will come?

[samveen]

@meesokim would you please seperate out the kedei_trash stuff out into a seperate PR, so that we users can test this more easily?

[Keniis0712]

I cloned it and built, but it still caused a bus error:

bcm_host_get_peripheral_address: 0x3f000000, bcm_host_get_peripheral_size: 16777216, bcm_host_get_sdram_address: 0xc0000000
BCM core speed: current: 250000000hz, max turbo: 400000000hz. SPI CDIV: 6, SPI max frequency: 66666667hz
Allocated DMA channel 7
Allocated DMA channel 1
Enabling DMA channels Tx:7 and Rx:1
Bus error

I'm sure there wasn't any compile error and this was the only question

[maxgdn]

I cloned it and built as well, but also get a bus error:

sudo apt-get install libraspberrypi-dev raspberrypi-kernel-headers

lscpu
Architecture:            aarch64
  CPU op-mode(s):        32-bit, 64-bit
  Byte Order:            Little Endian
CPU(s):                  4

lsb_release -a
No LSB modules are available.
Distributor ID:	Debian
Description:	Debian GNU/Linux 12 (bookworm)
Release:	12
Codename:	bookworm

cmake -DWAVESHARE35B_ILI9486=ON -DSPI_BUS_CLOCK_DIVISOR=25 -DDMA_TX_CHANNEL=9 -DDMA_RX_CHANNEL=6 -DSTATISTICS=0 ..

bcm_host_get_peripheral_address: 0xfe000000, bcm_host_get_peripheral_size: 25165824, bcm_host_get_sdram_address: 0xc0000000
BCM core speed: current: 232527000hz, max turbo: 500000000hz. SPI CDIV: 25, SPI max frequency: 20000000hz
Allocated DMA channel 9
Allocated DMA channel 6
Enabling DMA channels Tx:9 and Rx:6
Bus error

This is off of the newest Raspbian Lite install.