From: Russell King - ARM Linux <linux-lFZ/pmaqli7XmaaqVzeoHQ@public.gmane.org>
To: Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>
Cc: Peter De Schrijver
<pdeschrijver-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>,
Stephen Warren <swarren-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>,
Olof Johansson <olof-nZhT3qVonbNeoWH0uzbU5w@public.gmane.org>,
Arnd Bergmann <arnd-r2nGTMty4D4@public.gmane.org>,
Rob Herring <rob.herring-bsGFqQB8/DxBDgjK7y7TUQ@public.gmane.org>,
"linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org"
<linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org>,
"linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
Subject: Re: [PATCH V3 3/5] ARM: tegra: decouple uncompress.h and debug-macro.S
Date: Mon, 22 Oct 2012 23:13:07 +0100 [thread overview]
Message-ID: <20121022221307.GO21164@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <50857340.4010403-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>
On Mon, Oct 22, 2012 at 10:24:32AM -0600, Stephen Warren wrote:
> On 10/22/2012 02:18 AM, Peter De Schrijver wrote:
> >> +
> >> +#define checkuart(rp, rv, lhu, bit, uart) \
> >> + /* Load address of CLK_RST register */ \
> >> + movw rp, #TEGRA_CLK_RST_DEVICES_##lhu & 0xffff ; \
> >> + movt rp, #TEGRA_CLK_RST_DEVICES_##lhu >> 16 ; \
> >> + /* Load value from CLK_RST register */ \
> >> + ldr rp, [rp, #0] ; \
> >> + /* Test UART's reset bit */ \
> >> + tst rp, #(1 << bit) ; \
> >> + /* If set, can't use UART; jump to save no UART */ \
> >> + bne 90f ; \
> >> + /* Load address of CLK_OUT_ENB register */ \
> >> + movw rp, #TEGRA_CLK_OUT_ENB_##lhu & 0xffff ; \
> >> + movt rp, #TEGRA_CLK_OUT_ENB_##lhu >> 16 ; \
> >> + /* Load value from CLK_OUT_ENB register */ \
> >> + ldr rp, [rp, #0] ; \
> >> + /* Test UART's clock enable bit */ \
> >> + tst rp, #(1 << bit) ; \
> >> + /* If clear, can't use UART; jump to save no UART */ \
> >> + beq 90f ; \
> >> + /* Passed all tests, load address of UART registers */ \
> >> + movw rp, #TEGRA_UART##uart##_BASE & 0xffff ; \
> >> + movt rp, #TEGRA_UART##uart##_BASE >> 16 ; \
> >> + /* Jump to save UART address */ \
> >> + b 91f
> >>
> >
> > Maybe make this a subroutine?
>
> The addruart macro (which in turn uses the checkuart macro) is only
> allowed to use 3 registers; rp, rv, rtmp. I'm also not 100% sure if the
> stack is guaranteed to be set up when addruart is called either. So, I
> don't think making this a function is possible.
There's no stack. Remember, this stuff can be inserted as early as the
front of the kernel assembly code, where there is _nothing_ - the MMU
is off so virtual addresses are meaningless. etc.
WARNING: multiple messages have this Message-ID (diff)
From: linux@arm.linux.org.uk (Russell King - ARM Linux)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH V3 3/5] ARM: tegra: decouple uncompress.h and debug-macro.S
Date: Mon, 22 Oct 2012 23:13:07 +0100 [thread overview]
Message-ID: <20121022221307.GO21164@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <50857340.4010403@wwwdotorg.org>
On Mon, Oct 22, 2012 at 10:24:32AM -0600, Stephen Warren wrote:
> On 10/22/2012 02:18 AM, Peter De Schrijver wrote:
> >> +
> >> +#define checkuart(rp, rv, lhu, bit, uart) \
> >> + /* Load address of CLK_RST register */ \
> >> + movw rp, #TEGRA_CLK_RST_DEVICES_##lhu & 0xffff ; \
> >> + movt rp, #TEGRA_CLK_RST_DEVICES_##lhu >> 16 ; \
> >> + /* Load value from CLK_RST register */ \
> >> + ldr rp, [rp, #0] ; \
> >> + /* Test UART's reset bit */ \
> >> + tst rp, #(1 << bit) ; \
> >> + /* If set, can't use UART; jump to save no UART */ \
> >> + bne 90f ; \
> >> + /* Load address of CLK_OUT_ENB register */ \
> >> + movw rp, #TEGRA_CLK_OUT_ENB_##lhu & 0xffff ; \
> >> + movt rp, #TEGRA_CLK_OUT_ENB_##lhu >> 16 ; \
> >> + /* Load value from CLK_OUT_ENB register */ \
> >> + ldr rp, [rp, #0] ; \
> >> + /* Test UART's clock enable bit */ \
> >> + tst rp, #(1 << bit) ; \
> >> + /* If clear, can't use UART; jump to save no UART */ \
> >> + beq 90f ; \
> >> + /* Passed all tests, load address of UART registers */ \
> >> + movw rp, #TEGRA_UART##uart##_BASE & 0xffff ; \
> >> + movt rp, #TEGRA_UART##uart##_BASE >> 16 ; \
> >> + /* Jump to save UART address */ \
> >> + b 91f
> >>
> >
> > Maybe make this a subroutine?
>
> The addruart macro (which in turn uses the checkuart macro) is only
> allowed to use 3 registers; rp, rv, rtmp. I'm also not 100% sure if the
> stack is guaranteed to be set up when addruart is called either. So, I
> don't think making this a function is possible.
There's no stack. Remember, this stuff can be inserted as early as the
front of the kernel assembly code, where there is _nothing_ - the MMU
is off so virtual addresses are meaningless. etc.
next prev parent reply other threads:[~2012-10-22 22:13 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-19 22:41 [PATCH V3 1/5] ARM: implement debug_ll_io_init() Stephen Warren
2012-10-19 22:41 ` Stephen Warren
[not found] ` <1350686507-3022-1-git-send-email-swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>
2012-10-19 22:41 ` [PATCH V3 2/5] ARM: tegra: simplify DEBUG_LL UART selection options Stephen Warren
2012-10-19 22:41 ` Stephen Warren
2012-10-19 22:41 ` [PATCH V3 3/5] ARM: tegra: decouple uncompress.h and debug-macro.S Stephen Warren
2012-10-19 22:41 ` Stephen Warren
[not found] ` <1350686507-3022-3-git-send-email-swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>
2012-10-22 8:18 ` Peter De Schrijver
2012-10-22 8:18 ` Peter De Schrijver
[not found] ` <20121022081830.GH3196-Rysk9IDjsxmJz7etNGeUX8VPkgjIgRvpAL8bYrjMMd8@public.gmane.org>
2012-10-22 16:24 ` Stephen Warren
2012-10-22 16:24 ` Stephen Warren
[not found] ` <50857340.4010403-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>
2012-10-22 22:13 ` Russell King - ARM Linux [this message]
2012-10-22 22:13 ` Russell King - ARM Linux
2012-10-19 22:41 ` [PATCH V3 4/5] ARM: tegra: don't include iomap.h from debug-macro.S Stephen Warren
2012-10-19 22:41 ` Stephen Warren
2012-10-19 22:41 ` [PATCH V3 5/5] ARM: tegra: move debug-macro.S to include/debug Stephen Warren
2012-10-19 22:41 ` Stephen Warren
2012-10-20 13:36 ` [PATCH V3 1/5] ARM: implement debug_ll_io_init() Rob Herring
2012-10-20 13:36 ` Rob Herring
2012-11-05 19:03 ` Stephen Warren
2012-11-05 19:03 ` Stephen Warren
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