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                 of_node_put(cpc_node);
  31                 if (!err)
  32                         return res.start;
  33         }
  34
  35         return 0;
  36 }
  37
  38 /**
  39  * mips_cpc_phys_base - retrieve the physical base address of the CPC
  40  *
  41  * This function returns the physical base address of the Cluster Power
  42  * Controller memory mapped registers, or 0 if no Cluster Power Controller
  43  * is present.
  44  */
  45 static phys_addr_t mips_cpc_phys_base(void)
  46 {
  47         unsigned long cpc_base;
  48
  49         if (!mips_cm_present())
  50                 return 0;
  51
  52         if (!(read_gcr_cpc_status() & CM_GCR_CPC_STATUS_EX))
  53                 return 0;
  54
  55         /* If the CPC is already enabled, leave it so */
  56         cpc_base = read_gcr_cpc_base();
  57         if (cpc_base & CM_GCR_CPC_BASE_CPCEN)
  58                 return cpc_base & CM_GCR_CPC_BASE_CPCBASE;
  59
  60         /* Otherwise, use the default address */
  61         cpc_base = mips_cpc_default_phys_base();
  62         if (!cpc_base)
  63                 return cpc_base;
  64
  65         /* Enable the CPC, mapped at the default address */
  66         write_gcr_cpc_base(cpc_base | CM_GCR_CPC_BASE_CPCEN);
  67         return cpc_base;
  68 }
  69
  70 int mips_cpc_probe(void)
  71 {
  72         phys_addr_t addr;
  73         unsigned int cpu;
  74
  75         for_each_possible_cpu(cpu)
  76                 spin_lock_init(&per_cpu(cpc_core_lock, cpu));
  77
  78         addr = mips_cpc_phys_base();
  79         if (!addr)
  80                 return -ENODEV;
  81
  82         mips_cpc_base = ioremap(addr, 0x8000);
  83         if (!mips_cpc_base)
  84                 return -ENXIO;
  85
  86         return 0;
  87 }
  88
  89 void mips_cpc_lock_other(unsigned int core)
  90 {
  91         unsigned int curr_core;
  92
  93         if (mips_cm_revision() >= CM_REV_CM3)
  94                 /* Systems with CM >= 3 lock the CPC via mips_cm_lock_other */
  95                 return;
  96
  97         preempt_disable();
  98         curr_core = cpu_core(&current_cpu_data);
  99         spin_lock_irqsave(&per_cpu(cpc_core_lock, curr_core),
 100                           per_cpu(cpc_core_lock_flags, curr_core));
 101         write_cpc_cl_other(core << __ffs(CPC_Cx_OTHER_CORENUM));
 102
 103         /*
 104          * Ensure the core-other region reflects the appropriate core &
 105          * VP before any accesses to it occur.
 106          */
 107         mb();
 108 }
 109
 110 void mips_cpc_unlock_other(void)
 111 {
 112         unsigned int curr_core;
 113
 114         if (mips_cm_revision() >= CM_REV_CM3)
 115                 /* Systems with CM >= 3 lock the CPC via mips_cm_lock_other */
 116                 return;
 117
 118         curr_core = cpu_core(&current_cpu_data);
 119         spin_unlock_irqrestore(&per_cpu(cpc_core_lock, curr_core),
 120                                per_cpu(cpc_core_lock_flags, curr_core));
 121         preempt_enable();
 122 }