Re: [Xen-devel] [PATCH 2/5] xen/arm: add OMAP5432 UART support for early_printk

[Chen Baozi <baozich@xxxxxxxxx>]

On Aug 7, 2013, at 5:50 AM, Julien Grall <julien.grall@xxxxxxxxxx> wrote:

> Add Bamvor.
> 
> On 5 August 2013 12:49, Chen Baozi <baozich@xxxxxxxxx> wrote:
>> Signed-off-by: Chen Baozi <baozich@xxxxxxxxx>
>> ---
>> docs/misc/arm/early-printk.txt    |  1 +
>> xen/arch/arm/Rules.mk             |  4 ++++
>> xen/arch/arm/arm32/debug-8250.inc | 41 
>> +++++++++++++++++++++++++++++++++++++++
>> xen/include/xen/8250-uart.h       |  6 ++++++
>> 4 files changed, 52 insertions(+)
>> create mode 100644 xen/arch/arm/arm32/debug-8250.inc
>> 
>> diff --git a/docs/misc/arm/early-printk.txt b/docs/misc/arm/early-printk.txt
>> index fbc3208..874488f 100644
>> --- a/docs/misc/arm/early-printk.txt
>> +++ b/docs/misc/arm/early-printk.txt
>> @@ -13,6 +13,7 @@ where mach is the name of the machine:
>>   - exynos5250: printk with the second UART
>>   - midway: printk with the pl011 on Calxeda Midway processors
>>   - fastmodel: printk on ARM Fastmodel software emulators
>> +  - omap5432: printk with UART3 on TI OMAP5432 processors
> 
> This patch looks similar to
> http://lists.xen.org/archives/html/xen-devel/2013-07/msg00194.html.
> Could you also add suni6 support?

No problem.

Sorry, I forgot to cc to Bamvor. It is OK for me either using
Bamvor's patch with OMAP support or mine with suni6 support.

> 
>> 
>> The base address and baud rate is hardcoded in xen/arch/arm/Rules.mk,
>> see there when adding support for new machines.
>> diff --git a/xen/arch/arm/Rules.mk b/xen/arch/arm/Rules.mk
>> index a18e7fd..346c824 100644
>> --- a/xen/arch/arm/Rules.mk
>> +++ b/xen/arch/arm/Rules.mk
>> @@ -64,6 +64,10 @@ EARLY_PRINTK_INC := pl011
>> EARLY_PRINTK_BAUD := 115200
>> EARLY_UART_BASE_ADDRESS := 0xfff36000
>> endif
>> +ifeq ($(CONFIG_EARLY_PRINTK), omap5432)
>> +EARLY_PRINTK_INC := 8250
>> +EARLY_UART_BASE_ADDRESS := 0x48020000
>> +endif
>> 
>> ifneq ($(EARLY_PRINTK_INC),)
>> EARLY_PRINTK := y
>> diff --git a/xen/arch/arm/arm32/debug-8250.inc 
>> b/xen/arch/arm/arm32/debug-8250.inc
>> new file mode 100644
>> index 0000000..955d90c
>> --- /dev/null
>> +++ b/xen/arch/arm/arm32/debug-8250.inc
>> @@ -0,0 +1,41 @@
>> +/*
>> + * xen/arch/arm/arm32/debug-8250.inc
>> + *
>> + * 8250 specific debug code
>> + *
>> + * 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>
>> +
>> +/* OMAP UART wait UART to be ready to transmit
> s/OMAP/8250/
>> + * rb: register which contains the UART base address
>> + * rc: scratch register */
>> +.macro early_uart_ready rb rc
>> +1:
>> +       ldr     \rc, [\rb, #(UART_LSR << REG_SHIFT)] /* Read LSR */
>> +       tst     \rc, #UART_LSR_THRE   /* Check Xmit holding register flag */
>> +       beq     1b                    /* Wait for the UART to be ready */
>> +.endm
>> +
>> +/* OMAP UART transmit character
> Same here.
>> + * 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]      /* Write Transmit buffer */
>> +.endm
>> +
>> +/*
>> + * Local variables:
>> + * mode: ASM
>> + * indent-tabs-mode: nil
>> + * End:
>> + */
>> diff --git a/xen/include/xen/8250-uart.h b/xen/include/xen/8250-uart.h
>> index 7287364..0e6c6bd 100644
>> --- a/xen/include/xen/8250-uart.h
>> +++ b/xen/include/xen/8250-uart.h
>> @@ -22,6 +22,12 @@
>> #ifndef __XEN_8250_UART_H__
>> #define __XEN_8250_UART_H__
>> 
>> +#ifdef CONFIG_ARM
>> +#define REG_SHIFT         2
>> +#else
>> +#define REG_SHIFT         0
>> +#endif
> 
> If you don't use REG_SHIFT in other code than ARM, you can remove
> the #else.
> 
>> /* Register offsets */
>> #define UART_RBR          0x00    /* receive buffer       */
>> #define UART_THR          0x00    /* transmit holding     */
> 
> -- 
> Julien Grall


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