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