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/*
* Copyright (C) 2012 Calxeda, Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This driver provides the clk notifier callbacks that are used when
* the cpufreq-cpu0 driver changes to frequency to alert the highbank
* EnergyCore Management Engine (ECME) about the need to change
* voltage. The ECME interfaces with the actual voltage regulators.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/clk.h>
#include <linux/cpu.h>
#include <linux/err.h>
#include <linux/of.h>
#include <linux/mailbox.h>
#define HB_CPUFREQ_CHANGE_NOTE 0x80000001
#define HB_CPUFREQ_IPC_LEN 7
#define HB_CPUFREQ_VOLT_RETRIES 15
static int hb_voltage_change(unsigned int freq)
{
int i;
u32 msg[HB_CPUFREQ_IPC_LEN];
msg[0] = HB_CPUFREQ_CHANGE_NOTE;
msg[1] = freq / 1000000;
for (i = 2; i < HB_CPUFREQ_IPC_LEN; i++)
msg[i] = 0;
return pl320_ipc_transmit(msg);
}
static int hb_cpufreq_clk_notify(struct notifier_block *nb,
unsigned long action, void *hclk)
{
struct clk_notifier_data *clk_data = hclk;
int i = 0;
if (action == PRE_RATE_CHANGE) {
if (clk_data->new_rate > clk_data->old_rate)
while (hb_voltage_change(clk_data->new_rate))
if (i++ > HB_CPUFREQ_VOLT_RETRIES)
return NOTIFY_BAD;
} else if (action == POST_RATE_CHANGE) {
if (clk_data->new_rate < clk_data->old_rate)
while (hb_voltage_change(clk_data->new_rate))
if (i++ > HB_CPUFREQ_VOLT_RETRIES)
return NOTIFY_BAD;
}
return NOTIFY_DONE;
}
static struct notifier_block hb_cpufreq_clk_nb = {
.notifier_call = hb_cpufreq_clk_notify,
};
static int hb_cpufreq_driver_init(void)
{
struct device *cpu_dev;
struct clk *cpu_clk;
struct device_node *np;
int ret;
if (!of_machine_is_compatible("calxeda,highbank"))
return -ENODEV;
for_each_child_of_node(of_find_node_by_path("/cpus"), np)
if (of_get_property(np, "operating-points", NULL))
break;
if (!np) {
pr_err("failed to find highbank cpufreq node\n");
return -ENOENT;
}
cpu_dev = get_cpu_device(0);
if (!cpu_dev) {
pr_err("failed to get highbank cpufreq device\n");
ret = -ENODEV;
goto out_put_node;
}
cpu_dev->of_node = np;
cpu_clk = clk_get(cpu_dev, NULL);
if (IS_ERR(cpu_clk)) {
ret = PTR_ERR(cpu_clk);
pr_err("failed to get cpu0 clock: %d\n", ret);
goto out_put_node;
}
ret = clk_notifier_register(cpu_clk, &hb_cpufreq_clk_nb);
if (ret) {
pr_err("failed to register clk notifier: %d\n", ret);
goto out_put_node;
}
out_put_node:
of_node_put(np);
return ret;
}
module_init(hb_cpufreq_driver_init);
MODULE_AUTHOR("Mark Langsdorf <mark.langsdorf@calxeda.com>");
MODULE_DESCRIPTION("Calxeda Highbank cpufreq driver");
MODULE_LICENSE("GPL");
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