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

["Bamvor Jian Zhang" <bjzhang@xxxxxxxx>]

Ian Campbell wrote:
> 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?
sun4i, sun5i use the Synopsys DesignWare 8250 IP. and sun6i is also the
8250 compatiblity one. how about i create a debug-8250.inc and update
it when other 8250 device add.
>
> 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.
yes. I saw Andre' patch. when i write this piece of code Andre's patch is
not commit. i will modify this in next version.
>
>> +
>> +/* 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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