OpenWrt – Rev 4

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There is a variant of MT7621 which contains only one CPU core instead of 2.
This is not reflected in the config register, so the kernel detects more
physical cores, which leads to a hang on SMP bringup.
Add a hack to detect missing cores.

Signed-off-by: Felix Fietkau <nbd@nbd.name>

--- a/arch/mips/kernel/smp-cps.c
+++ b/arch/mips/kernel/smp-cps.c
@@ -47,6 +47,11 @@ static unsigned core_vpe_count(unsigned
        return mips_cps_numvps(cluster, core);
 }
 
+bool __weak plat_cpu_core_present(int core)
+{
+       return true;
+}
+
 static void __init cps_smp_setup(void)
 {
        unsigned int nclusters, ncores, nvpes, core_vpes;
@@ -64,6 +69,8 @@ static void __init cps_smp_setup(void)
 
                ncores = mips_cps_numcores(cl);
                for (c = 0; c < ncores; c++) {
+                       if (!plat_cpu_core_present(c))
+                               continue;
                        core_vpes = core_vpe_count(cl, c);
 
                        if (c > 0)
--- a/arch/mips/ralink/mt7621.c
+++ b/arch/mips/ralink/mt7621.c
@@ -15,6 +15,7 @@
 #include <asm/mips-cps.h>
 #include <asm/mach-ralink/ralink_regs.h>
 #include <asm/mach-ralink/mt7621.h>
+#include <asm/mips-boards/launch.h>
 
 #include <pinmux.h>
 
@@ -162,6 +163,20 @@ void __init ralink_of_remap(void)
                panic("Failed to remap core resources");
 }
 
+bool plat_cpu_core_present(int core)
+{
+       struct cpulaunch *launch = (struct cpulaunch *)CKSEG0ADDR(CPULAUNCH);
+
+       if (!core)
+               return true;
+       launch += core * 2; /* 2 VPEs per core */
+       if (!(launch->flags & LAUNCH_FREADY))
+               return false;
+       if (launch->flags & (LAUNCH_FGO | LAUNCH_FGONE))
+               return false;
+       return true;
+}
+
 void prom_soc_init(struct ralink_soc_info *soc_info)
 {
        void __iomem *sysc = (void __iomem *) KSEG1ADDR(MT7621_SYSC_BASE);