target/linux/mvebu/patches-3.10/0024-arm-mvebu-remove-dependency-of-SMP-init-on-static-I-.patch

   1 From 9398729313b826469fede3acda5fedd1eb21cb3e Mon Sep 17 00:00:00 2001
   2 From: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
   3 Date: Wed, 5 Jun 2013 09:04:54 +0200
   4 Subject: [PATCH 024/203] arm: mvebu: remove dependency of SMP init on static
   5  I/O mapping
   6
   7 The ->smp_init_cpus() function is called very early during boot, at a
   8 point where dynamic I/O mappings are not yet possible. However, in the
   9 Armada 370/XP implementation of this function, we have to get the
  10 number of CPUs. We used to do that by accessing a hardware register,
  11 which requires relying on a static I/O mapping set up by
  12 ->map_io(). Not only this requires hardcoding a virtual address, but
  13 it also prevents us from removing the static I/O mapping.
  14
  15 So this commit changes the way used to get the number of CPUs: we now
  16 use the Device Tree, which is a representation of the hardware, and
  17 provides us the number of available CPUs. This is also more accurate,
  18 because it potentially allows to boot the Linux kernel on only a
  19 number of CPUs given by the Device Tree, instead of unconditionally on
  20 all CPUs.
  21
  22 As a consequence, the coherency_get_cpu_count() function becomes no
  23 longer used, so we remove it.
  24
  25 Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
  26 Acked-by: Arnd Bergmann <arnd@arndb.de>
  27 Signed-off-by: Jason Cooper <jason@lakedaemon.net>
  28 ---
  29  arch/arm/mach-mvebu/coherency.c | 12 ------------
  30  arch/arm/mach-mvebu/coherency.h |  4 ----
  31  arch/arm/mach-mvebu/common.h    |  2 ++
  32  arch/arm/mach-mvebu/platsmp.c   | 10 +++++++++-
  33  4 files changed, 11 insertions(+), 17 deletions(-)
  34
  35 --- a/arch/arm/mach-mvebu/coherency.c
  36 +++ b/arch/arm/mach-mvebu/coherency.c
  37 @@ -47,18 +47,6 @@ static struct of_device_id of_coherency_
  38         { /* end of list */ },
  39  };
  40
  41 -#ifdef CONFIG_SMP
  42 -int coherency_get_cpu_count(void)
  43 -{
  44 -       int reg, cnt;
  45 -
  46 -       reg = readl(coherency_base + COHERENCY_FABRIC_CFG_OFFSET);
  47 -       cnt = (reg & 0xF) + 1;
  48 -
  49 -       return cnt;
  50 -}
  51 -#endif
  52 -
  53  /* Function defined in coherency_ll.S */
  54  int ll_set_cpu_coherent(void __iomem *base_addr, unsigned int hw_cpu_id);
  55
  56 --- a/arch/arm/mach-mvebu/coherency.h
  57 +++ b/arch/arm/mach-mvebu/coherency.h
  58 @@ -14,10 +14,6 @@
  59  #ifndef __MACH_370_XP_COHERENCY_H
  60  #define __MACH_370_XP_COHERENCY_H
  61
  62 -#ifdef CONFIG_SMP
  63 -int coherency_get_cpu_count(void);
  64 -#endif
  65 -
  66  int set_cpu_coherent(int cpu_id, int smp_group_id);
  67  int coherency_init(void);
  68
  69 --- a/arch/arm/mach-mvebu/common.h
  70 +++ b/arch/arm/mach-mvebu/common.h
  71 @@ -15,6 +15,8 @@
  72  #ifndef __ARCH_MVEBU_COMMON_H
  73  #define __ARCH_MVEBU_COMMON_H
  74
  75 +#define ARMADA_XP_MAX_CPUS 4
  76 +
  77  void mvebu_restart(char mode, const char *cmd);
  78
  79  void armada_370_xp_init_irq(void);
  80 --- a/arch/arm/mach-mvebu/platsmp.c
  81 +++ b/arch/arm/mach-mvebu/platsmp.c
  82 @@ -88,8 +88,16 @@ static int __cpuinit armada_xp_boot_seco
  83
  84  static void __init armada_xp_smp_init_cpus(void)
  85  {
  86 +       struct device_node *np;
  87         unsigned int i, ncores;
  88 -       ncores = coherency_get_cpu_count();
  89 +
  90 +       np = of_find_node_by_name(NULL, "cpus");
  91 +       if (!np)
  92 +               panic("No 'cpus' node found\n");
  93 +
  94 +       ncores = of_get_child_count(np);
  95 +       if (ncores == 0 || ncores > ARMADA_XP_MAX_CPUS)
  96 +               panic("Invalid number of CPUs in DT\n");
  97
  98         /* Limit possible CPUs to defconfig */
  99         if (ncores > nr_cpu_ids) {