linux-kernel - Re: [PATCH 4/4] arm: mediatek: Add earlyprintk support for MT6589

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Message-ID: <5345B370.6060004@free-electrons.com>
Date:	Wed, 09 Apr 2014 20:54:08 +0000
From:	Gregory CLEMENT <gregory.clement@...e-electrons.com>
To:	Matthias Brugger <matthias.bgg@...il.com>,
	linux-kernel@...r.kernel.org
CC:	mark.rutland@....com, andrew@...n.ch, linux-doc@...r.kernel.org,
	thierry.reding@...il.com, heiko.stuebner@...com,
	linux@....linux.org.uk, daniel.lezcano@...aro.org,
	florian.vaussard@...l.ch, sebastian.hesselbarth@...il.com,
	devicetree@...r.kernel.org, jason@...edaemon.net,
	pawel.moll@....com, ijc+devicetree@...lion.org.uk,
	robh+dt@...nel.org, tglx@...utronix.de,
	linux-arm-kernel@...ts.infradead.org, rdunlap@...radead.org,
	silvio.fricke@...il.com, galak@...eaurora.org, olof@...om.net,
	jic23@...nel.org
Subject: Re: [PATCH 4/4] arm: mediatek: Add earlyprintk support for MT6589

Hi Matthias,

On 09/04/2014 19:45, Matthias Brugger wrote:
> Signed-off-by: Matthias Brugger <matthias.bgg@...il.com>
> ---
>  arch/arm/Kconfig.debug            |   49 +++++++++++++++++++++++++++++++++++--
>  arch/arm/include/debug/mediatek.S |   38 ++++++++++++++++++++++++++++
>  2 files changed, 85 insertions(+), 2 deletions(-)
>  create mode 100644 arch/arm/include/debug/mediatek.S
> 
> diff --git a/arch/arm/Kconfig.debug b/arch/arm/Kconfig.debug
> index 4a2fc0b..dc51495 100644
> --- a/arch/arm/Kconfig.debug
> +++ b/arch/arm/Kconfig.debug
> @@ -797,6 +797,38 @@ choice
>  		  Say Y here if you want kernel low-level debugging support
>  		  on Ux500 based platforms.
>  
> +	config DEBUG_MTK6589_UART0
> +		depends on ARCH_MEDIATEK
> +		bool "Mediatek mt6589 UART0"
> +		select DEBUG_UART_MEDIATEK
> +		help
> +		  Say Y here if you want kernel low-level debugging support
> +		  on Mediatek mt6589 based platforms.
> +
> +	config DEBUG_MTK6589_UART1
> +		depends on ARCH_MEDIATEK
> +		bool "Mediatek mt6589 UART1"
> +		select DEBUG_UART_MEDIATEK
> +		help
> +		  Say Y here if you want kernel low-level debugging support
> +		  on Mediatek mt6589 based platforms.
> +
> +	config DEBUG_MTK6589_UART2
> +		depends on ARCH_MEDIATEK
> +		bool "Mediatek mt6589 UART2"
> +		select DEBUG_UART_MEDIATEK
> +		help
> +		  Say Y here if you want kernel low-level debugging support
> +		  on Mediatek mt6589 based platforms.
> +
> +	config DEBUG_MTK6589_UART3
> +		depends on ARCH_MEDIATEK
> +		bool "Mediatek mt6589 UART3"
> +		select DEBUG_UART_MEDIATEK
> +		help
> +		  Say Y here if you want kernel low-level debugging support
> +		  on Mediatek mt6589 based platforms.
> +
>  	config DEBUG_VEXPRESS_UART0_DETECT
>  		bool "Autodetect UART0 on Versatile Express Cortex-A core tiles"
>  		depends on ARCH_VEXPRESS && CPU_CP15_MMU
> @@ -954,6 +986,10 @@ config DEBUG_MSM_UART
>  	bool
>  	depends on ARCH_MSM || ARCH_QCOM
>  
> +config DEBUG_UART_MEDIATEK
> +	bool
> +	depends on ARCH_MEDIATEK
> +
>  config DEBUG_LL_INCLUDE
>  	string
>  	default "debug/8250.S" if DEBUG_LL_UART_8250 || DEBUG_UART_8250
> @@ -971,6 +1007,7 @@ config DEBUG_LL_INCLUDE
>  				 DEBUG_IMX53_UART ||\
>  				 DEBUG_IMX6Q_UART || \
>  				 DEBUG_IMX6SL_UART
> +	default "debug/mediatek.S" if DEBUG_UART_MEDIATEK
>  	default "debug/msm.S" if DEBUG_MSM_UART
>  	default "debug/omap2plus.S" if DEBUG_OMAP2PLUS_UART
>  	default "debug/sirf.S" if DEBUG_SIRFPRIMA2_UART1 || DEBUG_SIRFMARCO_UART1
> @@ -1043,6 +1080,10 @@ config DEBUG_UART_PHYS
>  	default 0xd0012000 if DEBUG_MVEBU_UART
>  	default 0xd4017000 if DEBUG_MMP_UART2
>  	default 0xd4018000 if DEBUG_MMP_UART3

it seems that this symbol are sorted by address so your symbols
should go just after the line
default 0x101fb000 if DEBUG_NOMADIK_UART

> +	default 0x11006000 if DEBUG_MTK6589_UART0
> +	default 0x11007000 if DEBUG_MTK6589_UART1
> +	default 0x11008000 if DEBUG_MTK6589_UART2
> +	default 0x11009000 if DEBUG_MTK6589_UART3
>  	default 0xe0000000 if ARCH_SPEAR13XX
>  	default 0xf0000be0 if ARCH_EBSA110
>  	default 0xf1012000 if DEBUG_MVEBU_UART_ALTERNATE
> @@ -1058,7 +1099,7 @@ config DEBUG_UART_PHYS
>  	default 0xfffff700 if ARCH_IOP33X
>  	depends on DEBUG_LL_UART_8250 || DEBUG_LL_UART_PL01X || \
>  		DEBUG_LL_UART_EFM32 || \
> -		DEBUG_UART_8250 || DEBUG_UART_PL01X
> +		DEBUG_UART_8250 || DEBUG_UART_PL01X || DEBUG_UART_MEDIATEK
>  
>  config DEBUG_UART_VIRT
>  	hex "Virtual base address of debug UART"
> @@ -1087,6 +1128,10 @@ config DEBUG_UART_VIRT
>  	default 0xfe012000 if ARCH_ORION5X
>  	default 0xfe017000 if DEBUG_MMP_UART2
>  	default 0xfe018000 if DEBUG_MMP_UART3
> +	default 0xF1006000 if DEBUG_MTK6589_UART0
> +	default 0xF1007000 if DEBUG_MTK6589_UART1
> +	default 0xF1008000 if DEBUG_MTK6589_UART2
> +	default 0xF1009000 if DEBUG_MTK6589_UART3
>  	default 0xfe100000 if DEBUG_IMX23_UART || DEBUG_IMX28_UART
>  	default 0xfe230000 if DEBUG_PICOXCELL_UART
>  	default 0xfe300000 if DEBUG_BCM_KONA_UART
> @@ -1116,7 +1161,7 @@ config DEBUG_UART_VIRT
>  	default 0xff003000 if DEBUG_U300_UART
>  	default DEBUG_UART_PHYS if !MMU
>  	depends on DEBUG_LL_UART_8250 || DEBUG_LL_UART_PL01X || \
> -		DEBUG_UART_8250 || DEBUG_UART_PL01X
> +		DEBUG_UART_8250 || DEBUG_UART_PL01X || DEBUG_UART_MEDIATEK
>  
>  config DEBUG_UART_8250_SHIFT
>  	int "Register offset shift for the 8250 debug UART"
> diff --git a/arch/arm/include/debug/mediatek.S b/arch/arm/include/debug/mediatek.S
> new file mode 100644
> index 0000000..98e8414
> --- /dev/null
> +++ b/arch/arm/include/debug/mediatek.S
> @@ -0,0 +1,38 @@
> +/*
> + * Low-level debug macro for Mediatek SoCs
> + *
> + * Copyright (c) 2014 MundoReader S.L.
> + * Author: Matthias Brugger <matthias.bgg@...il.com>
> + *
> + * 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 <linux/serial_reg.h>
> +
> +	        .macro  addruart, rp, rv, tmp
> +	        ldr	\rp, =CONFIG_DEBUG_UART_PHYS
> +	        ldr	\rv, =CONFIG_DEBUG_UART_VIRT
> +	        .endm
> +
> +	        .macro  senduart,rd,rx
> +	        strb    \rd, [\rx, #0x0]
What about using a #define instead of numerical value?

> +	        .endm
> +
> +	        .macro  waituart,rd,rx
> +1001:   	ldr \rd, [\rx, #0x14]
ditto
> +	        tst \rd, #0x40
ditto
> +	        beq 1001b
> +	        .endm
> +
> +		.macro  busyuart,rd,rx
> +1002:   	ldr \rd, [\rx, #0x14]
ditto
> +	        tst \rd, #0x40
ditto
> +	        beq 1002b
> +	        .endm
> 

This file looks very similar to arch/arm/include/debug/pl01x.S,
the only difference is the value of some register offsets.
Should it be possible to make it configurable and then use the
same file?


Thanks,

Gregory



-- 
Gregory Clement, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com
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