arch/mips/kernel/mips-cpc.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright (C) 2013 Imagination Technologies
   4  * Author: Paul Burton <paul.burton@mips.com>
   5  */
   6
   7 #include <linux/bitfield.h>
   8 #include <linux/errno.h>
   9 #include <linux/percpu.h>
  10 #include <linux/of.h>
  11 #include <linux/of_address.h>
  12 #include <linux/spinlock.h>
  13
  14 #include <asm/mips-cps.h>
  15
  16 void __iomem *mips_cpc_base;
  17
  18 static DEFINE_PER_CPU_ALIGNED(spinlock_t, cpc_core_lock);
  19
  20 static DEFINE_PER_CPU_ALIGNED(unsigned long, cpc_core_lock_flags);
  21
  22 phys_addr_t __weak mips_cpc_default_phys_base(void)
  23 {
  24         struct device_node *cpc_node;
  25         struct resource res;
  26         int err;
  27
  28         cpc_node = of_find_compatible_node(of_root, NULL, "mti,mips-cpc");
  29         if (cpc_node) {
  30                 err = of_address_to_resource(cpc_node, 0, &res);
  31                 of_node_put(cpc_node);
  32                 if (!err)
  33                         return res.start;
  34         }
  35
  36         return 0;
  37 }
  38
  39 /**
  40  * mips_cpc_phys_base - retrieve the physical base address of the CPC
  41  *
  42  * This function returns the physical base address of the Cluster Power
  43  * Controller memory mapped registers, or 0 if no Cluster Power Controller
  44  * is present.
  45  */
  46 static phys_addr_t mips_cpc_phys_base(void)
  47 {
  48         unsigned long cpc_base;
  49
  50         if (!mips_cm_present())
  51                 return 0;
  52
  53         if (!(read_gcr_cpc_status() & CM_GCR_CPC_STATUS_EX))
  54                 return 0;
  55
  56         /* If the CPC is already enabled, leave it so */
  57         cpc_base = read_gcr_cpc_base();
  58         if (cpc_base & CM_GCR_CPC_BASE_CPCEN)
  59                 return cpc_base & CM_GCR_CPC_BASE_CPCBASE;
  60
  61         /* Otherwise, use the default address */
  62         cpc_base = mips_cpc_default_phys_base();
  63         if (!cpc_base)
  64                 return cpc_base;
  65
  66         /* Enable the CPC, mapped at the default address */
  67         write_gcr_cpc_base(cpc_base | CM_GCR_CPC_BASE_CPCEN);
  68         return cpc_base;
  69 }
  70
  71 int mips_cpc_probe(void)
  72 {
  73         phys_addr_t addr;
  74         unsigned int cpu;
  75
  76         for_each_possible_cpu(cpu)
  77                 spin_lock_init(&per_cpu(cpc_core_lock, cpu));
  78
  79         addr = mips_cpc_phys_base();
  80         if (!addr)
  81                 return -ENODEV;
  82
  83         mips_cpc_base = ioremap(addr, 0x8000);
  84         if (!mips_cpc_base)
  85                 return -ENXIO;
  86
  87         return 0;
  88 }
  89
  90 void mips_cpc_lock_other(unsigned int core)
  91 {
  92         unsigned int curr_core;
  93
  94         if (mips_cm_revision() >= CM_REV_CM3)
  95                 /* Systems with CM >= 3 lock the CPC via mips_cm_lock_other */
  96                 return;
  97
  98         preempt_disable();
  99         curr_core = cpu_core(&current_cpu_data);
 100         spin_lock_irqsave(&per_cpu(cpc_core_lock, curr_core),
 101                           per_cpu(cpc_core_lock_flags, curr_core));
 102         write_cpc_cl_other(FIELD_PREP(CPC_Cx_OTHER_CORENUM, core));
 103
 104         /*
 105          * Ensure the core-other region reflects the appropriate core &
 106          * VP before any accesses to it occur.
 107          */
 108         mb();
 109 }
 110
 111 void mips_cpc_unlock_other(void)
 112 {
 113         unsigned int curr_core;
 114
 115         if (mips_cm_revision() >= CM_REV_CM3)
 116                 /* Systems with CM >= 3 lock the CPC via mips_cm_lock_other */
 117                 return;
 118
 119         curr_core = cpu_core(&current_cpu_data);
 120         spin_unlock_irqrestore(&per_cpu(cpc_core_lock, curr_core),
 121                                per_cpu(cpc_core_lock_flags, curr_core));
 122         preempt_enable();
 123 }