MIPS: ath79: Store the SoC revision in a global variable

Knowing the exact revision of the SoC is required to make runtime decisions
in various code paths.  We have determined the SoC revision already, so we
only need to store that in a global variable.
Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Cc: Imre Kaloz <kaloz@openwrt.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/3027/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/ath79/common.c

@@ -30,6 +30,7 @@ u32 ath79_ddr_freq;
 EXPORT_SYMBOL_GPL(ath79_ddr_freq);
 
 enum ath79_soc_type ath79_soc;
+unsigned int ath79_soc_rev;
 
 void __iomem *ath79_pll_base;
 void __iomem *ath79_reset_base;

arch/mips/ath79/setup.c

@@ -149,6 +149,8 @@ static void __init ath79_detect_sys_type(void)
 		panic("ath79: unknown SoC, id:0x%08x\n", id);
 	}
 
+	ath79_soc_rev = rev;
+
 	sprintf(ath79_sys_type, "Atheros AR%s rev %u", chip, rev);
 	pr_info("SoC: %s\n", ath79_sys_type);
 }

arch/mips/include/asm/mach-ath79/ath79.h

@@ -32,6 +32,7 @@ enum ath79_soc_type {
 };
 
 extern enum ath79_soc_type ath79_soc;
+extern unsigned int ath79_soc_rev;
 
 static inline int soc_is_ar71xx(void)
 {