linux/drivers/cpufreq/qoriq-cpufreq.c
Tang Yuantian 8a95c1441c cpufreq: qoriq: optimize the CPU frequency switching time
Each time the CPU switches its frequency, the clock nodes in
DTS are walked through to find proper clock source. This is
very time-consuming, for example, it is up to 500+ us on T4240.
Besides, switching time varies from clock to clock.
To optimize this, each input clock of CPU is buffered, so that
it can be picked up instantly when needed.

Since for each CPU each input clock is stored in a pointer
which takes 4 or 8 bytes memory and normally there are several
input clocks per CPU, that will not take much memory as well.

Signed-off-by: Tang Yuantian <Yuantian.Tang@freescale.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-06-15 15:47:28 +02:00

385 lines
8.4 KiB
C

/*
* Copyright 2013 Freescale Semiconductor, Inc.
*
* CPU Frequency Scaling driver for Freescale QorIQ SoCs.
*
* 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.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/clk.h>
#include <linux/cpufreq.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/of.h>
#include <linux/slab.h>
#include <linux/smp.h>
#if !defined(CONFIG_ARM)
#include <asm/smp.h> /* for get_hard_smp_processor_id() in UP configs */
#endif
/**
* struct cpu_data
* @pclk: the parent clock of cpu
* @table: frequency table
*/
struct cpu_data {
struct clk **pclk;
struct cpufreq_frequency_table *table;
};
/**
* struct soc_data - SoC specific data
* @freq_mask: mask the disallowed frequencies
* @flag: unique flags
*/
struct soc_data {
u32 freq_mask[4];
u32 flag;
};
#define FREQ_MASK 1
/* see hardware specification for the allowed frqeuencies */
static const struct soc_data sdata[] = {
{ /* used by p2041 and p3041 */
.freq_mask = {0x8, 0x8, 0x2, 0x2},
.flag = FREQ_MASK,
},
{ /* used by p5020 */
.freq_mask = {0x8, 0x2},
.flag = FREQ_MASK,
},
{ /* used by p4080, p5040 */
.freq_mask = {0},
.flag = 0,
},
};
/*
* the minimum allowed core frequency, in Hz
* for chassis v1.0, >= platform frequency
* for chassis v2.0, >= platform frequency / 2
*/
static u32 min_cpufreq;
static const u32 *fmask;
#if defined(CONFIG_ARM)
static int get_cpu_physical_id(int cpu)
{
return topology_core_id(cpu);
}
#else
static int get_cpu_physical_id(int cpu)
{
return get_hard_smp_processor_id(cpu);
}
#endif
static u32 get_bus_freq(void)
{
struct device_node *soc;
u32 sysfreq;
soc = of_find_node_by_type(NULL, "soc");
if (!soc)
return 0;
if (of_property_read_u32(soc, "bus-frequency", &sysfreq))
sysfreq = 0;
of_node_put(soc);
return sysfreq;
}
static struct device_node *cpu_to_clk_node(int cpu)
{
struct device_node *np, *clk_np;
if (!cpu_present(cpu))
return NULL;
np = of_get_cpu_node(cpu, NULL);
if (!np)
return NULL;
clk_np = of_parse_phandle(np, "clocks", 0);
if (!clk_np)
return NULL;
of_node_put(np);
return clk_np;
}
/* traverse cpu nodes to get cpu mask of sharing clock wire */
static void set_affected_cpus(struct cpufreq_policy *policy)
{
struct device_node *np, *clk_np;
struct cpumask *dstp = policy->cpus;
int i;
np = cpu_to_clk_node(policy->cpu);
if (!np)
return;
for_each_present_cpu(i) {
clk_np = cpu_to_clk_node(i);
if (!clk_np)
continue;
if (clk_np == np)
cpumask_set_cpu(i, dstp);
of_node_put(clk_np);
}
of_node_put(np);
}
/* reduce the duplicated frequencies in frequency table */
static void freq_table_redup(struct cpufreq_frequency_table *freq_table,
int count)
{
int i, j;
for (i = 1; i < count; i++) {
for (j = 0; j < i; j++) {
if (freq_table[j].frequency == CPUFREQ_ENTRY_INVALID ||
freq_table[j].frequency !=
freq_table[i].frequency)
continue;
freq_table[i].frequency = CPUFREQ_ENTRY_INVALID;
break;
}
}
}
/* sort the frequencies in frequency table in descenting order */
static void freq_table_sort(struct cpufreq_frequency_table *freq_table,
int count)
{
int i, j, ind;
unsigned int freq, max_freq;
struct cpufreq_frequency_table table;
for (i = 0; i < count - 1; i++) {
max_freq = freq_table[i].frequency;
ind = i;
for (j = i + 1; j < count; j++) {
freq = freq_table[j].frequency;
if (freq == CPUFREQ_ENTRY_INVALID ||
freq <= max_freq)
continue;
ind = j;
max_freq = freq;
}
if (ind != i) {
/* exchange the frequencies */
table.driver_data = freq_table[i].driver_data;
table.frequency = freq_table[i].frequency;
freq_table[i].driver_data = freq_table[ind].driver_data;
freq_table[i].frequency = freq_table[ind].frequency;
freq_table[ind].driver_data = table.driver_data;
freq_table[ind].frequency = table.frequency;
}
}
}
static int qoriq_cpufreq_cpu_init(struct cpufreq_policy *policy)
{
struct device_node *np, *pnode;
int i, count, ret;
u32 freq, mask;
struct clk *clk;
struct cpufreq_frequency_table *table;
struct cpu_data *data;
unsigned int cpu = policy->cpu;
u64 u64temp;
np = of_get_cpu_node(cpu, NULL);
if (!np)
return -ENODEV;
data = kzalloc(sizeof(*data), GFP_KERNEL);
if (!data)
goto err_np;
policy->clk = of_clk_get(np, 0);
if (IS_ERR(policy->clk)) {
pr_err("%s: no clock information\n", __func__);
goto err_nomem2;
}
pnode = of_parse_phandle(np, "clocks", 0);
if (!pnode) {
pr_err("%s: could not get clock information\n", __func__);
goto err_nomem2;
}
count = of_property_count_strings(pnode, "clock-names");
data->pclk = kcalloc(count, sizeof(struct clk *), GFP_KERNEL);
if (!data->pclk) {
pr_err("%s: no memory\n", __func__);
goto err_node;
}
table = kcalloc(count + 1, sizeof(*table), GFP_KERNEL);
if (!table) {
pr_err("%s: no memory\n", __func__);
goto err_pclk;
}
if (fmask)
mask = fmask[get_cpu_physical_id(cpu)];
else
mask = 0x0;
for (i = 0; i < count; i++) {
clk = of_clk_get(pnode, i);
data->pclk[i] = clk;
freq = clk_get_rate(clk);
/*
* the clock is valid if its frequency is not masked
* and large than minimum allowed frequency.
*/
if (freq < min_cpufreq || (mask & (1 << i)))
table[i].frequency = CPUFREQ_ENTRY_INVALID;
else
table[i].frequency = freq / 1000;
table[i].driver_data = i;
}
freq_table_redup(table, count);
freq_table_sort(table, count);
table[i].frequency = CPUFREQ_TABLE_END;
/* set the min and max frequency properly */
ret = cpufreq_table_validate_and_show(policy, table);
if (ret) {
pr_err("invalid frequency table: %d\n", ret);
goto err_nomem1;
}
data->table = table;
/* update ->cpus if we have cluster, no harm if not */
set_affected_cpus(policy);
policy->driver_data = data;
/* Minimum transition latency is 12 platform clocks */
u64temp = 12ULL * NSEC_PER_SEC;
do_div(u64temp, get_bus_freq());
policy->cpuinfo.transition_latency = u64temp + 1;
of_node_put(np);
of_node_put(pnode);
return 0;
err_nomem1:
kfree(table);
err_pclk:
kfree(data->pclk);
err_node:
of_node_put(pnode);
err_nomem2:
policy->driver_data = NULL;
kfree(data);
err_np:
of_node_put(np);
return -ENODEV;
}
static int __exit qoriq_cpufreq_cpu_exit(struct cpufreq_policy *policy)
{
struct cpu_data *data = policy->driver_data;
kfree(data->pclk);
kfree(data->table);
kfree(data);
policy->driver_data = NULL;
return 0;
}
static int qoriq_cpufreq_target(struct cpufreq_policy *policy,
unsigned int index)
{
struct clk *parent;
struct cpu_data *data = policy->driver_data;
parent = data->pclk[data->table[index].driver_data];
return clk_set_parent(policy->clk, parent);
}
static struct cpufreq_driver qoriq_cpufreq_driver = {
.name = "qoriq_cpufreq",
.flags = CPUFREQ_CONST_LOOPS,
.init = qoriq_cpufreq_cpu_init,
.exit = __exit_p(qoriq_cpufreq_cpu_exit),
.verify = cpufreq_generic_frequency_table_verify,
.target_index = qoriq_cpufreq_target,
.get = cpufreq_generic_get,
.attr = cpufreq_generic_attr,
};
static const struct of_device_id node_matches[] __initconst = {
{ .compatible = "fsl,p2041-clockgen", .data = &sdata[0], },
{ .compatible = "fsl,p3041-clockgen", .data = &sdata[0], },
{ .compatible = "fsl,p5020-clockgen", .data = &sdata[1], },
{ .compatible = "fsl,p4080-clockgen", .data = &sdata[2], },
{ .compatible = "fsl,p5040-clockgen", .data = &sdata[2], },
{ .compatible = "fsl,qoriq-clockgen-2.0", },
{}
};
static int __init qoriq_cpufreq_init(void)
{
int ret;
struct device_node *np;
const struct of_device_id *match;
const struct soc_data *data;
np = of_find_matching_node(NULL, node_matches);
if (!np)
return -ENODEV;
match = of_match_node(node_matches, np);
data = match->data;
if (data) {
if (data->flag)
fmask = data->freq_mask;
min_cpufreq = get_bus_freq();
} else {
min_cpufreq = get_bus_freq() / 2;
}
of_node_put(np);
ret = cpufreq_register_driver(&qoriq_cpufreq_driver);
if (!ret)
pr_info("Freescale QorIQ CPU frequency scaling driver\n");
return ret;
}
module_init(qoriq_cpufreq_init);
static void __exit qoriq_cpufreq_exit(void)
{
cpufreq_unregister_driver(&qoriq_cpufreq_driver);
}
module_exit(qoriq_cpufreq_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Tang Yuantian <Yuantian.Tang@freescale.com>");
MODULE_DESCRIPTION("cpufreq driver for Freescale QorIQ series SoCs");