package/boot/uboot-d1/patches/0026-sunxi-psci-Avoid-hanging-when-CPU-0-is-hot-unplugged.patch

   1 From ca1e6f4491981432c3e88441131c8e25067da95e Mon Sep 17 00:00:00 2001
   2 From: Samuel Holland <samuel@sholland.org>
   3 Date: Sat, 9 Oct 2021 22:00:22 -0500
   4 Subject: [PATCH 26/90] sunxi: psci: Avoid hanging when CPU 0 is hot-unplugged
   5
   6 Do not try to send an SGI from CPU 0 to itself. Since FIQs are masked
   7 when entering monitor mode, this will hang. Plus, CPU 0 cannot fully
   8 power itself off anyway. Instead, have it turn FIQs back on and continue
   9 servicing SGIs from other cores.
  10
  11 Signed-off-by: Samuel Holland <samuel@sholland.org>
  12 ---
  13  arch/arm/cpu/armv7/sunxi/psci.c | 20 +++++++++++++++++---
  14  1 file changed, 17 insertions(+), 3 deletions(-)
  15
  16 --- a/arch/arm/cpu/armv7/sunxi/psci.c
  17 +++ b/arch/arm/cpu/armv7/sunxi/psci.c
  18 @@ -38,6 +38,15 @@
  19  #define SUN8I_R40_PWR_CLAMP(cpu)               (0x120 + (cpu) * 0x4)
  20  #define SUN8I_R40_SRAMC_SOFT_ENTRY_REG0                (0xbc)
  21
  22 +static inline u32 __secure cp15_read_mpidr(void)
  23 +{
  24 +       u32 val;
  25 +
  26 +       asm volatile ("mrc p15, 0, %0, c0, c0, 5" : "=r" (val));
  27 +
  28 +       return val;
  29 +}
  30 +
  31  static void __secure cp15_write_cntp_tval(u32 tval)
  32  {
  33         asm volatile ("mcr p15, 0, %0, c14, c2, 0" : : "r" (tval));
  34 @@ -281,9 +290,14 @@ s32 __secure psci_cpu_off(void)
  35  {
  36         psci_cpu_off_common();
  37
  38 -       /* Ask CPU0 via SGI15 to pull the rug... */
  39 -       writel(BIT(16) | 15, GICD_BASE + GICD_SGIR);
  40 -       dsb();
  41 +       if (cp15_read_mpidr() & 3) {
  42 +               /* Ask CPU0 via SGI15 to pull the rug... */
  43 +               writel(BIT(16) | 15, GICD_BASE + GICD_SGIR);
  44 +               dsb();
  45 +       } else {
  46 +               /* Unmask FIQs to service SGI15. */
  47 +               asm volatile ("cpsie f");
  48 +       }
  49
  50         /* Wait to be turned off */
  51         while (1)