drivers/cpufreq/ppc_cbe_cpufreq_pmi.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * pmi backend for the cbe_cpufreq driver
   4  *
   5  * (C) Copyright IBM Deutschland Entwicklung GmbH 2005-2007
   6  *
   7  * Author: Christian Krafft <krafft@de.ibm.com>
   8  */
   9
  10 #include <linux/kernel.h>
  11 #include <linux/types.h>
  12 #include <linux/timer.h>
  13 #include <linux/init.h>
  14 #include <linux/of_platform.h>
  15
  16 #include <asm/processor.h>
  17 #include <asm/prom.h>
  18 #include <asm/pmi.h>
  19 #include <asm/cell-regs.h>
  20
  21 #ifdef DEBUG
  22 #include <asm/time.h>
  23 #endif
  24
  25 #include "ppc_cbe_cpufreq.h"
  26
  27 static u8 pmi_slow_mode_limit[MAX_CBE];
  28
  29 bool cbe_cpufreq_has_pmi = false;
  30 EXPORT_SYMBOL_GPL(cbe_cpufreq_has_pmi);
  31
  32 /*
  33  * hardware specific functions
  34  */
  35
  36 int cbe_cpufreq_set_pmode_pmi(int cpu, unsigned int pmode)
  37 {
  38         int ret;
  39         pmi_message_t pmi_msg;
  40 #ifdef DEBUG
  41         long time;
  42 #endif
  43         pmi_msg.type = PMI_TYPE_FREQ_CHANGE;
  44         pmi_msg.data1 = cbe_cpu_to_node(cpu);
  45         pmi_msg.data2 = pmode;
  46
  47 #ifdef DEBUG
  48         time = jiffies;
  49 #endif
  50         pmi_send_message(pmi_msg);
  51
  52 #ifdef DEBUG
  53         time = jiffies  - time;
  54         time = jiffies_to_msecs(time);
  55         pr_debug("had to wait %lu ms for a transition using " \
  56                  "PMI\n", time);
  57 #endif
  58         ret = pmi_msg.data2;
  59         pr_debug("PMI returned slow mode %d\n", ret);
  60
  61         return ret;
  62 }
  63 EXPORT_SYMBOL_GPL(cbe_cpufreq_set_pmode_pmi);
  64
  65
  66 static void cbe_cpufreq_handle_pmi(pmi_message_t pmi_msg)
  67 {
  68         u8 node, slow_mode;
  69
  70         BUG_ON(pmi_msg.type != PMI_TYPE_FREQ_CHANGE);
  71
  72         node = pmi_msg.data1;
  73         slow_mode = pmi_msg.data2;
  74
  75         pmi_slow_mode_limit[node] = slow_mode;
  76
  77         pr_debug("cbe_handle_pmi: node: %d max_freq: %d\n", node, slow_mode);
  78 }
  79
  80 static int pmi_notifier(struct notifier_block *nb,
  81                                        unsigned long event, void *data)
  82 {
  83         struct cpufreq_policy *policy = data;
  84         struct cpufreq_frequency_table *cbe_freqs = policy->freq_table;
  85         u8 node;
  86
  87         /* Should this really be called for CPUFREQ_ADJUST and CPUFREQ_NOTIFY
  88          * policy events?)
  89          */
  90         node = cbe_cpu_to_node(policy->cpu);
  91
  92         pr_debug("got notified, event=%lu, node=%u\n", event, node);
  93
  94         if (pmi_slow_mode_limit[node] != 0) {
  95                 pr_debug("limiting node %d to slow mode %d\n",
  96                          node, pmi_slow_mode_limit[node]);
  97
  98                 cpufreq_verify_within_limits(policy, 0,
  99
 100                         cbe_freqs[pmi_slow_mode_limit[node]].frequency);
 101         }
 102
 103         return 0;
 104 }
 105
 106 static struct notifier_block pmi_notifier_block = {
 107         .notifier_call = pmi_notifier,
 108 };
 109
 110 static struct pmi_handler cbe_pmi_handler = {
 111         .type                   = PMI_TYPE_FREQ_CHANGE,
 112         .handle_pmi_message     = cbe_cpufreq_handle_pmi,
 113 };
 114
 115
 116
 117 static int __init cbe_cpufreq_pmi_init(void)
 118 {
 119         cbe_cpufreq_has_pmi = pmi_register_handler(&cbe_pmi_handler) == 0;
 120
 121         if (!cbe_cpufreq_has_pmi)
 122                 return -ENODEV;
 123
 124         cpufreq_register_notifier(&pmi_notifier_block, CPUFREQ_POLICY_NOTIFIER);
 125
 126         return 0;
 127 }
 128 device_initcall(cbe_cpufreq_pmi_init);