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/*
* CPU frequency scaling for Broadcom BMIPS SoCs
*
* Copyright (c) 2017 Broadcom
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation version 2.
*
* This program is distributed "as is" WITHOUT ANY WARRANTY of any
* kind, whether express or implied; without even the implied warranty
* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <linux/cpufreq.h>
#include <linux/module.h>
#include <linux/of_address.h>
#include <linux/slab.h>
/* for mips_hpt_frequency */
#include <asm/time.h>
#define BMIPS_CPUFREQ_PREFIX "bmips"
#define BMIPS_CPUFREQ_NAME BMIPS_CPUFREQ_PREFIX "-cpufreq"
#define TRANSITION_LATENCY (25 * 1000) /* 25 us */
#define BMIPS5_CLK_DIV_SET_SHIFT 0x7
#define BMIPS5_CLK_DIV_SHIFT 0x4
#define BMIPS5_CLK_DIV_MASK 0xf
enum bmips_type {
BMIPS5000,
BMIPS5200,
};
struct cpufreq_compat {
const char *compatible;
unsigned int bmips_type;
unsigned int clk_mult;
unsigned int max_freqs;
};
#define BMIPS(c, t, m, f) { \
.compatible = c, \
.bmips_type = (t), \
.clk_mult = (m), \
.max_freqs = (f), \
}
static struct cpufreq_compat bmips_cpufreq_compat[] = {
BMIPS("brcm,bmips5000", BMIPS5000, 8, 4),
BMIPS("brcm,bmips5200", BMIPS5200, 8, 4),
{ }
};
static struct cpufreq_compat *priv;
static int htp_freq_to_cpu_freq(unsigned int clk_mult)
{
return mips_hpt_frequency * clk_mult / 1000;
}
static struct cpufreq_frequency_table *
bmips_cpufreq_get_freq_table(const struct cpufreq_policy *policy)
{
struct cpufreq_frequency_table *table;
unsigned long cpu_freq;
int i;
cpu_freq = htp_freq_to_cpu_freq(priv->clk_mult);
table = kmalloc_array(priv->max_freqs + 1, sizeof(*table), GFP_KERNEL);
if (!table)
return ERR_PTR(-ENOMEM);
for (i = 0; i < priv->max_freqs; i++) {
table[i].frequency = cpu_freq / (1 << i);
table[i].driver_data = i;
}
table[i].frequency = CPUFREQ_TABLE_END;
return table;
}
static unsigned int bmips_cpufreq_get(unsigned int cpu)
{
unsigned int div;
uint32_t mode;
switch (priv->bmips_type) {
case BMIPS5200:
case BMIPS5000:
mode = read_c0_brcm_mode();
div = ((mode >> BMIPS5_CLK_DIV_SHIFT) & BMIPS5_CLK_DIV_MASK);
break;
default:
div = 0;
}
return htp_freq_to_cpu_freq(priv->clk_mult) / (1 << div);
}
static int bmips_cpufreq_target_index(struct cpufreq_policy *policy,
unsigned int index)
{
unsigned int div = policy->freq_table[index].driver_data;
switch (priv->bmips_type) {
case BMIPS5200:
case BMIPS5000:
change_c0_brcm_mode(BMIPS5_CLK_DIV_MASK << BMIPS5_CLK_DIV_SHIFT,
(1 << BMIPS5_CLK_DIV_SET_SHIFT) |
(div << BMIPS5_CLK_DIV_SHIFT));
break;
default:
return -ENOTSUPP;
}
return 0;
}
static int bmips_cpufreq_exit(struct cpufreq_policy *policy)
{
kfree(policy->freq_table);
return 0;
}
static int bmips_cpufreq_init(struct cpufreq_policy *policy)
{
struct cpufreq_frequency_table *freq_table;
freq_table = bmips_cpufreq_get_freq_table(policy);
if (IS_ERR(freq_table)) {
pr_err("%s: couldn't determine frequency table (%ld).\n",
BMIPS_CPUFREQ_NAME, PTR_ERR(freq_table));
return PTR_ERR(freq_table);
}
cpufreq_generic_init(policy, freq_table, TRANSITION_LATENCY);
pr_info("%s: registered\n", BMIPS_CPUFREQ_NAME);
return 0;
}
static struct cpufreq_driver bmips_cpufreq_driver = {
.flags = CPUFREQ_NEED_INITIAL_FREQ_CHECK,
.verify = cpufreq_generic_frequency_table_verify,
.target_index = bmips_cpufreq_target_index,
.get = bmips_cpufreq_get,
.init = bmips_cpufreq_init,
.exit = bmips_cpufreq_exit,
.attr = cpufreq_generic_attr,
.name = BMIPS_CPUFREQ_PREFIX,
};
static int __init bmips_cpufreq_probe(void)
{
struct cpufreq_compat *cc;
struct device_node *np;
for (cc = bmips_cpufreq_compat; cc->compatible; cc++) {
np = of_find_compatible_node(NULL, "cpu", cc->compatible);
if (np) {
of_node_put(np);
priv = cc;
break;
}
}
/* We hit the guard element of the array. No compatible CPU found. */
if (!cc->compatible)
return -ENODEV;
return cpufreq_register_driver(&bmips_cpufreq_driver);
}
device_initcall(bmips_cpufreq_probe);
MODULE_AUTHOR("Markus Mayer <mmayer@broadcom.com>");
MODULE_DESCRIPTION("CPUfreq driver for Broadcom BMIPS SoCs");
MODULE_LICENSE("GPL");
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