forked from Minki/linux
6754f55610
Highbank processors depend on the external ECME to perform voltage management based on a requested frequency. Communication between the A9 cores and the ECME happens over the pl320 IPC channel. Signed-off-by: Mark Langsdorf <mark.langsdorf@calxeda.com> Reviewed-by: Shawn Guo <shawn.guo@linaro.org> Reviewed-by: Mike Turquette <mturquette@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
116 lines
2.8 KiB
C
116 lines
2.8 KiB
C
/*
|
|
* 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");
|