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/a... [2] - https://web.archive.org/web/20130730091033/http://www.marvell.com/embedded-p... [3] - https://web.archive.org/web/20120620073511/http://www.marvell.com/embedded-p...
Fixes: 8ac303d49f89 ("arm: kirkwood: Do not overwrite CONFIG_SYS_TCLK") Signed-off-by: Pali Rohár pali@kernel.org --- Michael, please test this patch, if it fixes your boards. --- arch/arm/mach-kirkwood/include/mach/kw88f6281.h | 3 ++- arch/arm/mach-kirkwood/include/mach/soc.h | 2 ++ 2 files changed, 4 insertions(+), 1 deletion(-)
diff --git a/arch/arm/mach-kirkwood/include/mach/kw88f6281.h b/arch/arm/mach-kirkwood/include/mach/kw88f6281.h index 87406081cf54..f86cd0bb6013 100644 --- a/arch/arm/mach-kirkwood/include/mach/kw88f6281.h +++ b/arch/arm/mach-kirkwood/include/mach/kw88f6281.h @@ -15,6 +15,7 @@ #define KW_REGS_PHY_BASE KW88F6281_REGS_PHYS_BASE
/* TCLK Core Clock definition */ -#define CONFIG_SYS_TCLK 200000000 /* 200MHz */ +#define CONFIG_SYS_TCLK ((readl(CONFIG_SAR_REG) & BIT(21)) ? \ + 166666667 : 200000000)
#endif /* _ASM_ARCH_KW88F6281_H */ diff --git a/arch/arm/mach-kirkwood/include/mach/soc.h b/arch/arm/mach-kirkwood/include/mach/soc.h index 1d7f2828cd38..5f545c6f4349 100644 --- a/arch/arm/mach-kirkwood/include/mach/soc.h +++ b/arch/arm/mach-kirkwood/include/mach/soc.h @@ -62,6 +62,8 @@ #define MVCPU_WIN_ENABLE KWCPU_WIN_ENABLE #define MVCPU_WIN_DISABLE KWCPU_WIN_DISABLE
+#define CONFIG_SAR_REG (KW_MPP_BASE + 0x0030) + #if defined (CONFIG_KW88F6281) #include <asm/arch/kw88f6281.h> #elif defined (CONFIG_KW88F6192)