cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
Log | Files | Refs | README | LICENSE | sfeed.txt

highbank-cpufreq.c (2932B)

      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");