Re: [Xen-devel] [PATCH v2 01/15] xen: arm64: Add 8250 earlyprintk support

[Julien Grall <julien.grall@xxxxxxxxxx>]

On 11/22/2013 04:24 PM, Ian Campbell wrote:
> From: Pranavkumar Sawargaonkar <pranavkumar@xxxxxxxxxx>
>
> Extracted from "Basic Platform support for APM X-Gene Storm."
>
> Signed-off-by: Anup Patel <anup.patel@xxxxxxxxxx>
> Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar@xxxxxxxxxx>
>
> Reworked into generic 8250 driver, use EARLY_UART_REG_SHIFT.
>
> While there observe a missing shift in the arm32 version (UART_THR is zero so
> it doesn't really matter). Changed for consistency.
>
> Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
Acked-by: Julien Grall <julien.grall@xxxxxxxxxx>

> ---
> v2: Drop unused early_uart_init macro
> ---
>   xen/arch/arm/Rules.mk             |    6 +++++
>   xen/arch/arm/arm64/debug-8250.inc |   45 +++++++++++++++++++++++++++++++++++++
>   2 files changed, 51 insertions(+)
>   create mode 100644 xen/arch/arm/arm64/debug-8250.inc
>
> diff --git a/xen/arch/arm/Rules.mk b/xen/arch/arm/Rules.mk
> index c27c2eb..aaa203e 100644
> --- a/xen/arch/arm/Rules.mk
> +++ b/xen/arch/arm/Rules.mk
> @@ -82,6 +82,12 @@ EARLY_PRINTK_INC := 8250
>   EARLY_UART_BASE_ADDRESS := 0xF0406B00
>   EARLY_UART_REG_SHIFT := 2
>   endif
> +ifeq ($(CONFIG_EARLY_PRINTK), xgene-storm)
> +EARLY_PRINTK_INC := 8250
> +EARLY_PRINTK_BAUD := 115200
> +EARLY_UART_BASE_ADDRESS := 0x1c020000
> +EARLY_UART_REG_SHIFT := 2
> +endif
>
>   ifneq ($(EARLY_PRINTK_INC),)
>   EARLY_PRINTK := y
> diff --git a/xen/arch/arm/arm64/debug-8250.inc 
> b/xen/arch/arm/arm64/debug-8250.inc
> new file mode 100644
> index 0000000..158549a
> --- /dev/null
> +++ b/xen/arch/arm/arm64/debug-8250.inc
> @@ -0,0 +1,45 @@
> +/*
> + * xen/arch/arm/arm64/debug-8250.inc
> + *
> + * 8250 specific debug code
> + *
> + * Copyright (c) 2013 Applied Micro.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <xen/8250-uart.h>
> +
> +/* UART wait UART to be ready to transmit
> + * xb: register which contains the UART base address
> + * c: scratch register */
> +.macro early_uart_ready xb c
> +1:
> +       ldrb  w\c, [\xb, #UART_LSR << EARLY_UART_REG_SHIFT]
> +       and w\c, w\c, #UART_LSR_THRE
> +       cmp w\c, #UART_LSR_THRE
> +       b.ne 1b
> +.endm
> +
> +/* UART transmit character
> + * xb: register which contains the UART base address
> + * wt: register which contains the character to transmit */
> +.macro early_uart_transmit xb wt
> +        /* UART_THR  transmit holding */
> +        strb   \wt, [\xb, #UART_THR << EARLY_UART_REG_SHIFT]
> +.endm
> +
> +/*
> + * Local variables:
> + * mode: ASM
> + * indent-tabs-mode: nil
> + * End:
> + */
--
Julien Grall

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