Re: [Xen-devel] [PATCH V2 28/33] xen/arm: Don't use pl011 UART by default for early printk

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2013-05-08 at 03:33 +0100, Julien Grall wrote:
> diff --git a/xen/arch/arm/arm32/Makefile b/xen/arch/arm/arm32/Makefile
> index 1ad3364..6af8ca3 100644
> --- a/xen/arch/arm/arm32/Makefile
> +++ b/xen/arch/arm/arm32/Makefile
> @@ -5,4 +5,7 @@ obj-y += mode_switch.o
>  obj-y += proc-ca15.o
> 
>  obj-y += traps.o
> -obj-y += domain.o
> \ No newline at end of file
> +obj-y += domain.o
> +
> +obj-$(EARLY_PRINTK) += debug.o
> +obj-$(CONFIG_EARLY_PL011) += debug-pl011.o

Is this correct now that you are using debug-pl011.inc?

>  /* Print a 32-bit number in hex.  Specific to the PL011 UART.
>   * r0: Number to print.
> - * clobbers r0-r3 */
> + * r11: Early UART base address
> + * clobbers r1-r3 */

This still clobbers r0, via the lsl below.

>  putn:
>          adr   r1, hex
>          mov   r3, #8
> -1:      ldr   r2, [r11, #0x18]       /* <- UARTFR (Flag register) */
> -        tst   r2, #0x8               /* Check BUSY bit */
> -        bne   1b                     /* Wait for the UART to be ready */
> +1:
> +        early_uart_ready r11, r2
>          and   r2, r0, #0xf0000000    /* Mask off the top nybble */
>          ldrb  r2, [r1, r2, lsr #28]  /* Convert to a char */
> -        str   r2, [r11]              /* -> UARTDR (Data Register) */
> +        early_uart_transmit r11, r2
>          lsl   r0, #4                 /* Roll it through one nybble at a time 
> */
>          subs  r3, r3, #1
>          bne   1b
> @@ -329,51 +329,44 @@ fail:   PRINT("- Boot failed -\r\n")
>  1:      wfe
>          b     1b
> 
> -#ifdef EARLY_UART_ADDRESS
> +#ifdef EARLY_PRINTK
> 
> -/* Bring up the UART. Specific to the PL011 UART.
> - * Clobbers r0-r2 */
> +/* Bring up the UART.
> + * x23: Early UART base address
> + * Clobbers x0-x1 */

Does it actually clobber x1?

>  init_uart:
> -        mov   x1, #0x0
> -        strh  w1, [x23, #0x24]       /* -> UARTIBRD (Baud divisor fraction) 
> */
> -        mov   x1, #0x4               /* 7.3728MHz / 0x4 == 16 * 115200 */
> -        strh  w1, [x23, #0x24]       /* -> UARTIBRD (Baud divisor integer) */
> -        mov   x1, #0x60              /* 8n1 */
> -        strh  w1, [x23, #0x24]       /* -> UARTLCR_H (Line control) */
> -        ldr   x1, =0x00000301        /* RXE | TXE | UARTEN */
> -        strh  w1, [x23, #0x30]       /* -> UARTCR (Control Register) */
> +        early_uart_init x23, 0
>          adr   x0, 1f
> -        b     puts
> +        b     puts                   /* Jump to puts */
>  1:      .asciz "- UART enabled -\r\n"
>          .align 4




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