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

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * Copyright (C) 2012 Calxeda, Inc.
   4 *
   5 * This driver provides the clk notifier callbacks that are used when
   6 * the cpufreq-dt driver changes to frequency to alert the highbank
   7 * EnergyCore Management Engine (ECME) about the need to change
   8 * voltage. The ECME interfaces with the actual voltage regulators.
   9 */
  10
  11#define pr_fmt(fmt)     KBUILD_MODNAME ": " fmt
  12
  13#include <linux/kernel.h>
  14#include <linux/module.h>
  15#include <linux/clk.h>
  16#include <linux/cpu.h>
  17#include <linux/err.h>
  18#include <linux/of.h>
  19#include <linux/pl320-ipc.h>
  20#include <linux/platform_device.h>
  21
  22#define HB_CPUFREQ_CHANGE_NOTE  0x80000001
  23#define HB_CPUFREQ_IPC_LEN      7
  24#define HB_CPUFREQ_VOLT_RETRIES 15
  25
  26static int hb_voltage_change(unsigned int freq)
  27{
  28        u32 msg[HB_CPUFREQ_IPC_LEN] = {HB_CPUFREQ_CHANGE_NOTE, freq / 1000000};
  29
  30        return pl320_ipc_transmit(msg);
  31}
  32
  33static int hb_cpufreq_clk_notify(struct notifier_block *nb,
  34                                unsigned long action, void *hclk)
  35{
  36        struct clk_notifier_data *clk_data = hclk;
  37        int i = 0;
  38
  39        if (action == PRE_RATE_CHANGE) {
  40                if (clk_data->new_rate > clk_data->old_rate)
  41                        while (hb_voltage_change(clk_data->new_rate))
  42                                if (i++ > HB_CPUFREQ_VOLT_RETRIES)
  43                                        return NOTIFY_BAD;
  44        } else if (action == POST_RATE_CHANGE) {
  45                if (clk_data->new_rate < clk_data->old_rate)
  46                        while (hb_voltage_change(clk_data->new_rate))
  47                                if (i++ > HB_CPUFREQ_VOLT_RETRIES)
  48                                        return NOTIFY_BAD;
  49        }
  50
  51        return NOTIFY_DONE;
  52}
  53
  54static struct notifier_block hb_cpufreq_clk_nb = {
  55        .notifier_call = hb_cpufreq_clk_notify,
  56};
  57
  58static int hb_cpufreq_driver_init(void)
  59{
  60        struct platform_device_info devinfo = { .name = "cpufreq-dt", };
  61        struct device *cpu_dev;
  62        struct clk *cpu_clk;
  63        struct device_node *np;
  64        int ret;
  65
  66        if ((!of_machine_is_compatible("calxeda,highbank")) &&
  67                (!of_machine_is_compatible("calxeda,ecx-2000")))
  68                return -ENODEV;
  69
  70        cpu_dev = get_cpu_device(0);
  71        if (!cpu_dev) {
  72                pr_err("failed to get highbank cpufreq device\n");
  73                return -ENODEV;
  74        }
  75
  76        np = of_node_get(cpu_dev->of_node);
  77        if (!np) {
  78                pr_err("failed to find highbank cpufreq node\n");
  79                return -ENOENT;
  80        }
  81
  82        cpu_clk = clk_get(cpu_dev, NULL);
  83        if (IS_ERR(cpu_clk)) {
  84                ret = PTR_ERR(cpu_clk);
  85                pr_err("failed to get cpu0 clock: %d\n", ret);
  86                goto out_put_node;
  87        }
  88
  89        ret = clk_notifier_register(cpu_clk, &hb_cpufreq_clk_nb);
  90        if (ret) {
  91                pr_err("failed to register clk notifier: %d\n", ret);
  92                goto out_put_node;
  93        }
  94
  95        /* Instantiate cpufreq-dt */
  96        platform_device_register_full(&devinfo);
  97
  98out_put_node:
  99        of_node_put(np);
 100        return ret;
 101}
 102module_init(hb_cpufreq_driver_init);
 103
 104static const struct of_device_id __maybe_unused hb_cpufreq_of_match[] = {
 105        { .compatible = "calxeda,highbank" },
 106        { .compatible = "calxeda,ecx-2000" },
 107        { },
 108};
 109MODULE_DEVICE_TABLE(of, hb_cpufreq_of_match);
 110
 111MODULE_AUTHOR("Mark Langsdorf <mark.langsdorf@calxeda.com>");
 112MODULE_DESCRIPTION("Calxeda Highbank cpufreq driver");
 113MODULE_LICENSE("GPL");
 114