ramips: add hack to detect missing mt7621 cpu cores

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

diff --git a/target/linux/ramips/patches-4.4/100-mt7621-core-detect-hack.patch b/target/linux/ramips/patches-4.4/100-mt7621-core-detect-hack.patch
new file mode 100644 (file)
index 0000000..4049d13
--- /dev/null
+++ b/target/linux/ramips/patches-4.4/100-mt7621-core-detect-hack.patch
@@ -0,0 +1,61 @@
+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
+@@ -44,6 +44,11 @@ static unsigned core_vpe_count(unsigned
+       return (cfg >> CM_GCR_Cx_CONFIG_PVPE_SHF) + 1;
+ }
+ 
++bool __weak plat_cpu_core_present(int core)
++{
++      return true;
++}
++
+ static void __init cps_smp_setup(void)
+ {
+       unsigned int ncores, nvpes, core_vpes;
+@@ -53,6 +58,8 @@ static void __init cps_smp_setup(void)
+       ncores = mips_cm_numcores();
+       pr_info("VPE topology ");
+       for (c = nvpes = 0; c < ncores; c++) {
++              if (!plat_cpu_core_present(c))
++                      continue;
+               core_vpes = core_vpe_count(c);
+               pr_cont("%c%u", c ? ',' : '{', core_vpes);
+ 
+--- a/arch/mips/ralink/mt7621.c
++++ b/arch/mips/ralink/mt7621.c
+@@ -20,6 +20,7 @@
+ #include <asm/mips-cpc.h>
+ #include <asm/mach-ralink/ralink_regs.h>
+ #include <asm/mach-ralink/mt7621.h>
++#include <asm/mips-boards/launch.h>
+ 
+ #include <pinmux.h>
+ 
+@@ -163,6 +164,20 @@ 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);