LXR linux/drivers/cpufreq/highbank-cpufreq.c

   1/*
   2 * Copyright (C) 2012 Calxeda, Inc.
   3 *
   4 * This program is free software; you can redistribute it and/or modify
   5 * it under the terms of the GNU General Public License version 2 as
   6 * published by the Free Software Foundation.
   7 *
   8 * This driver provides the clk notifier callbacks that are used when
   9 * the cpufreq-cpu0 driver changes to frequency to alert the highbank
  10 * EnergyCore Management Engine (ECME) about the need to change
  11 * voltage. The ECME interfaces with the actual voltage regulators.
  12 */
  13
  14#define pr_fmt(fmt)     KBUILD_MODNAME ": " fmt
  15
  16#include <linux/kernel.h>
  17#include <linux/module.h>
  18#include <linux/clk.h>
  19#include <linux/cpu.h>
  20#include <linux/err.h>
  21#include <linux/of.h>
  22#include <linux/mailbox.h>
  23#include <linux/platform_device.h>
  24
  25#define HB_CPUFREQ_CHANGE_NOTE  0x80000001
  26#define HB_CPUFREQ_IPC_LEN      7
  27#define HB_CPUFREQ_VOLT_RETRIES 15
  28
  29static int hb_voltage_change(unsigned int freq)
  30{
  31        u32 msg[HB_CPUFREQ_IPC_LEN] = {HB_CPUFREQ_CHANGE_NOTE, freq / 1000000};
  32
  33        return pl320_ipc_transmit(msg);
  34}
  35
  36static int hb_cpufreq_clk_notify(struct notifier_block *nb,
  37                                unsigned long action, void *hclk)
  38{
  39        struct clk_notifier_data *clk_data = hclk;
  40        int i = 0;
  41
  42        if (action == PRE_RATE_CHANGE) {
  43                if (clk_data->new_rate > clk_data->old_rate)
  44                        while (hb_voltage_change(clk_data->new_rate))
  45                                if (i++ > HB_CPUFREQ_VOLT_RETRIES)
  46                                        return NOTIFY_BAD;
  47        } else if (action == POST_RATE_CHANGE) {
  48                if (clk_data->new_rate < clk_data->old_rate)
  49                        while (hb_voltage_change(clk_data->new_rate))
  50                                if (i++ > HB_CPUFREQ_VOLT_RETRIES)
  51                                        return NOTIFY_BAD;
  52        }
  53
  54        return NOTIFY_DONE;
  55}
  56
  57static struct notifier_block hb_cpufreq_clk_nb = {
  58        .notifier_call = hb_cpufreq_clk_notify,
  59};
  60
  61static int hb_cpufreq_driver_init(void)
  62{
  63        struct platform_device_info devinfo = { .name = "cpufreq-cpu0", };
  64        struct device *cpu_dev;
  65        struct clk *cpu_clk;
  66        struct device_node *np;
  67        int ret;
  68
  69        if (!of_machine_is_compatible("calxeda,highbank"))
  70                return -ENODEV;
  71
  72        for_each_child_of_node(of_find_node_by_path("/cpus"), np)
  73                if (of_get_property(np, "operating-points", NULL))
  74                        break;
  75
  76        if (!np) {
  77                pr_err("failed to find highbank cpufreq node\n");
  78                return -ENOENT;
  79        }
  80
  81        cpu_dev = get_cpu_device(0);
  82        if (!cpu_dev) {
  83                pr_err("failed to get highbank cpufreq device\n");
  84                ret = -ENODEV;
  85                goto out_put_node;
  86        }
  87
  88        cpu_dev->of_node = np;
  89
  90        cpu_clk = clk_get(cpu_dev, NULL);
  91        if (IS_ERR(cpu_clk)) {
  92                ret = PTR_ERR(cpu_clk);
  93                pr_err("failed to get cpu0 clock: %d\n", ret);
  94                goto out_put_node;
  95        }
  96
  97        ret = clk_notifier_register(cpu_clk, &hb_cpufreq_clk_nb);
  98        if (ret) {
  99                pr_err("failed to register clk notifier: %d\n", ret);
 100                goto out_put_node;
 101        }
 102
 103        /* Instantiate cpufreq-cpu0 */
 104        platform_device_register_full(&devinfo);
 105
 106out_put_node:
 107        of_node_put(np);
 108        return ret;
 109}
 110module_init(hb_cpufreq_driver_init);
 111
 112MODULE_AUTHOR("Mark Langsdorf <mark.langsdorf@calxeda.com>");
 113MODULE_DESCRIPTION("Calxeda Highbank cpufreq driver");
 114MODULE_LICENSE("GPL");
 115