[PATCHv3 2/2] bsps/riscv: HTIF - Use 32-bit HTIF syscalls on RV32

[Sebastian Huber]

On 09/04/2019 11:23, Hesham Almatary wrote:
> HTIF devices are not supported on RV32, so proxy a write system call
>
> This syncs HTIF Console with riscv-pk (proxy kernel) to use 32-bit
> HTIF syscalls on RV32 instead of 64-bit commands that are not atomic.
> ---
>   bsps/riscv/riscv/console/htif.c | 59 +++++++++++++++++++++++++++++----
>   1 file changed, 53 insertions(+), 6 deletions(-)
>
> diff --git a/bsps/riscv/riscv/console/htif.c b/bsps/riscv/riscv/console/htif.c
> index bcfe6a5db5..34d36d0b52 100644
> --- a/bsps/riscv/riscv/console/htif.c
> +++ b/bsps/riscv/riscv/console/htif.c
> @@ -31,8 +31,8 @@
>   
>   #if RISCV_ENABLE_HTIF_SUPPORT != 0
>   
> +#include <bsp/irq-generic.h>

For the interrupt locks, you have to include <rtems.h>.

>   #include <dev/serial/htif.h>
> -
>   #include <assert.h>
>   
>   /* Most of the code below is copied from riscv-pk project */
> @@ -43,11 +43,15 @@
>   #define FROMHOST_CMD(fromhost_value) ((uint64_t)(fromhost_value) << 8 >> 56)
>   #define FROMHOST_DATA(fromhost_value) ((uint64_t)(fromhost_value) << 16 >> 16)
>   
> +#define SYS_write 64
> +
>   volatile uint64_t tohost __attribute__((section(".htif")));
>   volatile uint64_t fromhost __attribute__((section(".htif")));
>   volatile uint64_t riscv_fill_up_htif_section[510] __attribute__((section(".htif")));
>   volatile int htif_console_buf;
>   
> +RTEMS_INTERRUPT_LOCK_DEFINE( static, htif_lock, "htif_lock");

Superfluous pace after (.

> +
>   static void __check_fromhost(void)
>   {
>     uint64_t fh = fromhost;
> @@ -77,23 +81,66 @@ static void __set_tohost(uintptr_t dev, uintptr_t cmd, uintptr_t data)
>     tohost = TOHOST_CMD(dev, cmd, data);
>   }
>   
> +static void do_tohost_fromhost(uintptr_t dev, uintptr_t cmd, uintptr_t data)
> +{
> +  rtems_interrupt_lock_context htif_lock_context;
> +
> +  rtems_interrupt_lock_acquire(&htif_lock, &htif_lock_context);
> +  __set_tohost(dev, cmd, data);
> +
> +    while (1) {
> +      uint64_t fh = fromhost;
> +      if (fh) {
> +        if (FROMHOST_DEV(fh) == dev && FROMHOST_CMD(fh) == cmd) {
> +          fromhost = 0;
> +          break;
> +        }
> +        __check_fromhost();
> +      }
> +    }

Superfluous indent.

> +  rtems_interrupt_lock_release(&htif_lock, &htif_lock_context);
> +}
> +
> +void htif_syscall(uintptr_t arg)
> +{
> +  do_tohost_fromhost(0, 0, arg);
> +}
> +
> +void htif_console_putchar(rtems_termios_device_context *base, char ch)
> +{
> +#if __riscv_xlen == 32
> +  // HTIF devices are not supported on RV32, so proxy a write system call

C++ comment.

> +  volatile uint64_t magic_mem[8];
> +  magic_mem[0] = SYS_write;
> +  magic_mem[1] = 1;
> +  magic_mem[2] = (uintptr_t)&ch;
> +  magic_mem[3] = 1;
> +  do_tohost_fromhost(0, 0, (uintptr_t)magic_mem);
> +#else
> +  rtems_interrupt_lock_context htif_lock_context;
> +
> +  rtems_interrupt_lock_acquire(&htif_lock, &htif_lock_context);
> +  __set_tohost(1, 1, ch);
> +  rtems_interrupt_lock_release(&htif_lock, &htif_lock_context);
> +#endif
> +}
> +
>   int htif_console_getchar(rtems_termios_device_context *base)
>   {
> +  rtems_interrupt_lock_context htif_lock_context;
> +
> +  rtems_interrupt_lock_acquire(&htif_lock, &htif_lock_context);
>     __check_fromhost();
>     int ch = htif_console_buf;
>     if (ch >= 0) {
>       htif_console_buf = -1;
>       __set_tohost(1, 0, 0);
>     }
> +  rtems_interrupt_lock_release(&htif_lock, &htif_lock_context);
>   
>     return ch - 1;
>   }
>   
> -void htif_console_putchar(rtems_termios_device_context *base, char c)
> -{
> -  __set_tohost(1, 1, c);
> -}
> -
>   static void htif_console_write_polled(
>     rtems_termios_device_context *base,
>     const char *buf,

-- 
Sebastian Huber, embedded brains GmbH

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