[PATCH] arm: kirkwood: 88f6281: Detect CONFIG_SYS_TCLK from SAR register

[Michael Walle]

Am 2022-08-16 22:00, schrieb Pali Rohár:
> Bit 21 in SAR register specifies if TCLK is running at 166 MHz or 200 
> MHz.
> This information is undocumented in public Marvell Kirkwood Functional
> Specifications [2], but is available in Linux v3.15 kirkwood code [1].
> 
> Commit 8ac303d49f89 ("arm: kirkwood: Do not overwrite CONFIG_SYS_TCLK")
> broke support for Marvell 88F6281 SoCs because it was expected that all
> those SoCs have TCLK running at 200 MHz as specified in Marvell 88F6281
> Hardware Specifications [3].
> 
> Fix broken support for 88F6281 by detecting CONFIG_SYS_TCLK from SAR
> register, like it was doing Linux v3.15.
> 
> [1] -
> https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/arch/arm/mach-kirkwood/common.c?h=v3.15#n542
> [2] -
> https://web.archive.org/web/20130730091033/http://www.marvell.com/embedded-processors/kirkwood/assets/FS_88F6180_9x_6281_OpenSource.pdf
> [3] -
> https://web.archive.org/web/20120620073511/http://www.marvell.com/embedded-processors/kirkwood/assets/HW_88F6281_OpenSource.pdf
> 
> Fixes: 8ac303d49f89 ("arm: kirkwood: Do not overwrite CONFIG_SYS_TCLK")
> Signed-off-by: Pali Rohár <pali at kernel.org>
> ---
> Michael, please test this patch, if it fixes your boards.

Thanks, but this doesn't compile:

In file included from lib/time.c:19:
lib/time.c: In function ‘timer_get_boot_us’:
./arch/arm/include/asm/io.h:108:19: error: token "{" is not valid in 
preprocessor expressions
   108 | #define readl(c) ({ u32 __v = __arch_getl(c); __iormb(); __v; })
       |                   ^
./arch/arm/include/asm/arch/kw88f6281.h:18:29: note: in expansion of 
macro ‘readl’
    18 | #define CONFIG_SYS_TCLK   ((readl(CONFIG_SAR_REG) & BIT(21)) ? \
       |                             ^~~~~
./arch/arm/include/asm/arch/config.h:56:32: note: in expansion of macro 
‘CONFIG_SYS_TCLK’
    56 | #define CONFIG_SYS_TIMER_RATE  CONFIG_SYS_TCLK
       |                                ^~~~~~~~~~~~~~~
lib/time.c:50:5: note: in expansion of macro ‘CONFIG_SYS_TIMER_RATE’
    50 | #if CONFIG_SYS_TIMER_RATE == 1000000
       |     ^~~~~~~~~~~~~~~~~~~~~
./arch/arm/include/asm/io.h:108:19: error: token "{" is not valid in 
preprocessor expressions
   108 | #define readl(c) ({ u32 __v = __arch_getl(c); __iormb(); __v; })
       |                   ^
./arch/arm/include/asm/arch/kw88f6281.h:18:29: note: in expansion of 
macro ‘readl’
    18 | #define CONFIG_SYS_TCLK   ((readl(CONFIG_SAR_REG) & BIT(21)) ? \
       |                             ^~~~~
./arch/arm/include/asm/arch/config.h:56:32: note: in expansion of macro 
‘CONFIG_SYS_TCLK’
    56 | #define CONFIG_SYS_TIMER_RATE  CONFIG_SYS_TCLK
       |                                ^~~~~~~~~~~~~~~
lib/time.c:52:7: note: in expansion of macro ‘CONFIG_SYS_TIMER_RATE’
    52 | #elif CONFIG_SYS_TIMER_RATE > 1000000
       |       ^~~~~~~~~~~~~~~~~~~~~
make[1]: *** [scripts/Makefile.build:257: lib/time.o] Fehler 1

-michael