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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Copyright (C) 2012 Calxeda, Inc.4 *5 * This driver provides the clk notifier callbacks that are used when6 * the cpufreq-dt driver changes to frequency to alert the highbank7 * EnergyCore Management Engine (ECME) about the need to change8 * voltage. The ECME interfaces with the actual voltage regulators.9 */10 11#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt12 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 0x8000000123#define HB_CPUFREQ_IPC_LEN 724#define HB_CPUFREQ_VOLT_RETRIES 1525 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 __init 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