Re: [Xen-devel] [PATCH 2/4] xen/arm: introduce Allwinner sun6i SOC basic support

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Fri, 2013-05-31 at 20:53 +0800, Bamvor Jian Zhang wrote:
> Allwinner A31(code name sun6i) is a quad-core Cortex-A7 SOC. Allwinner has
> released the source code in http://git.rhombus-tech.net.
> 
> This patch define registers and macros for early printk and mode switch.
> kick cpu is not implemneted yet. because the secondary cpu boot up
> sequence is a little bit different from exynos5.
> 
> Signed-off-by: Bamvor Jian Zhang <bjzhang@xxxxxxxx>
> ---
>  xen/arch/arm/arm32/debug-sun6i.inc    | 50 
> +++++++++++++++++++++++++++++++++++
>  xen/include/asm-arm/platforms/sun6i.h | 28 ++++++++++++++++++++
>  2 files changed, 78 insertions(+)
>  create mode 100644 xen/arch/arm/arm32/debug-sun6i.inc
>  create mode 100644 xen/include/asm-arm/platforms/sun6i.h
> 
> diff --git a/xen/arch/arm/arm32/debug-sun6i.inc 
> b/xen/arch/arm/arm32/debug-sun6i.inc
> new file mode 100644
> index 0000000..eaa1197
> --- /dev/null
> +++ b/xen/arch/arm/arm32/debug-sun6i.inc
> @@ -0,0 +1,50 @@
> +/*
> + * xen/arch/arm/arm32/debug-sun6i.inc
> + *
> + * Allwinner sun6i specific debug code
> + *
> + * Bamvor Jian Zhang <bjzhang@xxxxxxxx>
> + * Copyright (c) 2013 SUSE
> + *
> + * 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.
> + */
> +
> +/* sun6i UART initialization

This does appear to use a distinct set of registers from either the
existing pl011 or exynos4xxx UART driver so it should be a separate
driver. Do you know if this particular logic block is specific to sn6i
or is it used elsewhere (e.g. in all sun*i)? Do you know if there is a
more generic name for the part?

Not a big deal -- we can always rename to be more generic as we see
other examples of the same UART.

> + * rb: register which contains the UART base address
> + * rc: scratch register 1 (unused here)
> + * rd: scratch register 2 (unused here) */
> +.macro early_uart_init rb, rc, rd
> +/* assume the uart already init by bootloader */
> +.endm

I think Andre's refactoring of the UART init stuff in and around commit
130645eee340608c12b632535d3f983508348ba1 lets you avoid this by just not
setting EARLY_PRINTK_INIT_UART.

> +
> +/* sun6i UART wait UART to be ready to transmit
> + * rb: register which contains the UART base address
> + * rc: scratch register */
> +.macro early_uart_ready rb, rc
> +1:
> +        ldr   \rc, [\rb, #0x7c]     /* <- UART_USR (Status Register) */
> +        tst   \rc, #0x2             /* Check BUSY bit */
> +        beq   1b                    /* Wait for the UART to be ready */
> +.endm
> +
> +/* sun6i UART transmit character
> + * rb: register which contains the UART base address
> + * rt: register which contains the character to transmit */
> +.macro early_uart_transmit rb, rt
> +        str   \rt, [\rb]            /* -> UART_THR (Transmit Holding 
> Register) */
> +.endm
> +
> +/*
> + * Local variables:
> + * mode: ASM
> + * indent-tabs-mode: nil
> + * End:
> + */
> diff --git a/xen/include/asm-arm/platforms/sun6i.h 
> b/xen/include/asm-arm/platforms/sun6i.h
> new file mode 100644
> index 0000000..f910ad6
> --- /dev/null
> +++ b/xen/include/asm-arm/platforms/sun6i.h
> @@ -0,0 +1,28 @@
> +#ifndef __ASM_ARM_PLATFORMS_SUN6I_H
> +#define __ASM_ASM_PLATFORMS_SUN6I_H
> +
> +/* Constants below is only used in assembly because the DTS is not yet 
> parsed */
> +#ifdef __ASSEMBLY__
> +
> +/* GIC Base Address */
> +#define SUN6I_GIC_BASE_ADDRESS       0x01c82000
> +
> +/* Timer's frequency */
> +/* \TODO I do not know yet, assume it 24MHz. check it later */
> +#define SUN6I_TIMER_FREQUENCY       (24 * 1000 * 1000) /* 24 MHz */
> +
> +/* Arndale machine ID */

Comment is out of date, but I hope we can avoid needing to know machine
numbers entirely some where down the line. (I expect this will be
clearer after my reply to #4)

> +/* XXX 3894 is downstream number for sun6i. 4137 is upstream number for 
> sun6i */
> +#define MACH_TYPE_SUN6I             4137
> +
> +#endif /* __ASSEMBLY__ */
> +
> +#endif /* __ASM_ARM_PLATFORMS_SUN6I_H */
> +/*
> + * Local variables:
> + * mode: C
> + * c-file-style: "BSD"
> + * c-basic-offset: 4
> + * indent-tabs-mode: nil
> + * End:
> + */



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