arch/arm/kernel/smp_scu.c

   1 /*
   2  *  linux/arch/arm/kernel/smp_scu.c
   3  *
   4  *  Copyright (C) 2002 ARM Ltd.
   5  *  All Rights Reserved
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  */
  11 #include <linux/init.h>
  12 #include <linux/io.h>
  13
  14 #include <asm/smp_plat.h>
  15 #include <asm/smp_scu.h>
  16 #include <asm/cacheflush.h>
  17 #include <asm/cputype.h>
  18
  19 #define SCU_CTRL                0x00
  20 #define SCU_ENABLE              (1 << 0)
  21 #define SCU_STANDBY_ENABLE      (1 << 5)
  22 #define SCU_CONFIG              0x04
  23 #define SCU_CPU_STATUS          0x08
  24 #define SCU_CPU_STATUS_MASK     GENMASK(1, 0)
  25 #define SCU_INVALIDATE          0x0c
  26 #define SCU_FPGA_REVISION       0x10
  27
  28 #ifdef CONFIG_SMP
  29 /*
  30  * Get the number of CPU cores from the SCU configuration
  31  */
  32 unsigned int __init scu_get_core_count(void __iomem *scu_base)
  33 {
  34         unsigned int ncores = readl_relaxed(scu_base + SCU_CONFIG);
  35         return (ncores & 0x03) + 1;
  36 }
  37
  38 /*
  39  * Enable the SCU
  40  */
  41 void scu_enable(void __iomem *scu_base)
  42 {
  43         u32 scu_ctrl;
  44
  45 #ifdef CONFIG_ARM_ERRATA_764369
  46         /* Cortex-A9 only */
  47         if ((read_cpuid_id() & 0xff0ffff0) == 0x410fc090) {
  48                 scu_ctrl = readl_relaxed(scu_base + 0x30);
  49                 if (!(scu_ctrl & 1))
  50                         writel_relaxed(scu_ctrl | 0x1, scu_base + 0x30);
  51         }
  52 #endif
  53
  54         scu_ctrl = readl_relaxed(scu_base + SCU_CTRL);
  55         /* already enabled? */
  56         if (scu_ctrl & SCU_ENABLE)
  57                 return;
  58
  59         scu_ctrl |= SCU_ENABLE;
  60
  61         /* Cortex-A9 earlier than r2p0 has no standby bit in SCU */
  62         if ((read_cpuid_id() & 0xff0ffff0) == 0x410fc090 &&
  63             (read_cpuid_id() & 0x00f0000f) >= 0x00200000)
  64                 scu_ctrl |= SCU_STANDBY_ENABLE;
  65
  66         writel_relaxed(scu_ctrl, scu_base + SCU_CTRL);
  67
  68         /*
  69          * Ensure that the data accessed by CPU0 before the SCU was
  70          * initialised is visible to the other CPUs.
  71          */
  72         flush_cache_all();
  73 }
  74 #endif
  75
  76 static int scu_set_power_mode_internal(void __iomem *scu_base,
  77                                        unsigned int logical_cpu,
  78                                        unsigned int mode)
  79 {
  80         unsigned int val;
  81         int cpu = MPIDR_AFFINITY_LEVEL(cpu_logical_map(logical_cpu), 0);
  82
  83         if (mode > 3 || mode == 1 || cpu > 3)
  84                 return -EINVAL;
  85
  86         val = readb_relaxed(scu_base + SCU_CPU_STATUS + cpu);
  87         val &= ~SCU_CPU_STATUS_MASK;
  88         val |= mode;
  89         writeb_relaxed(val, scu_base + SCU_CPU_STATUS + cpu);
  90
  91         return 0;
  92 }
  93
  94 /*
  95  * Set the executing CPUs power mode as defined.  This will be in
  96  * preparation for it executing a WFI instruction.
  97  *
  98  * This function must be called with preemption disabled, and as it
  99  * has the side effect of disabling coherency, caches must have been
 100  * flushed.  Interrupts must also have been disabled.
 101  */
 102 int scu_power_mode(void __iomem *scu_base, unsigned int mode)
 103 {
 104         return scu_set_power_mode_internal(scu_base, smp_processor_id(), mode);
 105 }
 106
 107 /*
 108  * Set the given (logical) CPU's power mode to SCU_PM_NORMAL.
 109  */
 110 int scu_cpu_power_enable(void __iomem *scu_base, unsigned int cpu)
 111 {
 112         return scu_set_power_mode_internal(scu_base, cpu, SCU_PM_NORMAL);
 113 }
 114
 115 int scu_get_cpu_power_mode(void __iomem *scu_base, unsigned int logical_cpu)
 116 {
 117         unsigned int val;
 118         int cpu = MPIDR_AFFINITY_LEVEL(cpu_logical_map(logical_cpu), 0);
 119
 120         if (cpu > 3)
 121                 return -EINVAL;
 122
 123         val = readb_relaxed(scu_base + SCU_CPU_STATUS + cpu);
 124         val &= SCU_CPU_STATUS_MASK;
 125
 126         return val;
 127 }