(Added more people in the To: and CC: list)
---------- Forwarded message ----------
From: Gang Liang <randomizedthinking@xxxxxxxxx>
Date: Wed, Jun 2, 2010 at 4:48 PM
Subject: [loongson2-PATCH] modification of the cpufreq module
To: linux-mips@xxxxxxxxxxxxxx, Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Cc: Zhangjin Wu <wuzhangjin@xxxxxxxxx>, Hua Yan <yanh@xxxxxxxxxx>
This patch updates some aspects of the current implementation of
cpufreq driver for Loongson2.
1) A default cpu_wait handler is installed such that the cpu will be
alive at the lowest possible power level when a cpu_wait call is made;
2) The number of frequency levels is reduced to 3, and the lowest
frequency is capped as a half of the full cpu speed. The "nowait" option
is removed.
Thanks!
---
arch/mips/include/asm/mach-loongson/loongson.h | 4 +-
arch/mips/kernel/cpu-probe.c | 21 +++++++++
arch/mips/kernel/cpufreq/loongson2_clock.c | 52 +++--------------------
arch/mips/kernel/cpufreq/loongson2_cpufreq.c | 54 +++++++++---------------
4 files changed, 50 insertions(+), 81 deletions(-)
diff --git a/arch/mips/include/asm/mach-loongson/loongson.h
b/arch/mips/include/asm/mach-loongson/loongson.h
index 53d0bef..33164b9 100644
--- a/arch/mips/include/asm/mach-loongson/loongson.h
+++ b/arch/mips/include/asm/mach-loongson/loongson.h
@@ -242,8 +242,8 @@ extern int mach_i8259_irq(void);
#ifdef CONFIG_CPU_SUPPORTS_CPUFREQ
#include <linux/cpufreq.h>
-extern void loongson2_cpu_wait(void);
-extern struct cpufreq_frequency_table loongson2_clockmod_table[];
+/* extern void loongson2_cpu_wait(void); */
+/* extern struct cpufreq_frequency_table loongson2_clockmod_table[]; */
/* Chip Config */
#define LOONGSON_CHIPCFG0 LOONGSON_REG(LOONGSON_REGBASE + 0x80)
diff --git a/arch/mips/kernel/cpu-probe.c b/arch/mips/kernel/cpu-probe.c
index be5bb16..5b3072c 100644
--- a/arch/mips/kernel/cpu-probe.c
+++ b/arch/mips/kernel/cpu-probe.c
@@ -25,6 +25,9 @@
#include <asm/system.h>
#include <asm/watch.h>
#include <asm/spram.h>
+
+#include <loongson.h>
+
/*
* Not all of the MIPS CPUs have the "wait" instruction available. Moreover,
* the implementation of the "wait" feature differs between CPU families. This
@@ -51,6 +54,21 @@ static void r39xx_wait(void)
extern void r4k_wait(void);
+DEFINE_SPINLOCK(loongson2_wait_lock);
+static void loongson2_cpu_wait(void)
+{
+ u32 cpu_freq;
+ unsigned long flags;
+
+ /* enter the lowest power mode available while still alive */
+ /* future work: check cpu freq -- do nothing if no change */
+ /* otherwise, change the frequency and propagate the clock rate */
+ spin_lock_irqsave(&loongson2_wait_lock, flags);
+ cpu_freq = LOONGSON_CHIPCFG0;
+ LOONGSON_CHIPCFG0 = (cpu_freq & ~0x7) | 1;
+ spin_unlock_irqrestore(&loongson2_wait_lock, flags);
+}
+
/*
* This variant is preferable as it allows testing need_resched and going to
* sleep depending on the outcome atomically. Unfortunately the "It is
@@ -212,6 +230,9 @@ void __init check_wait(void)
if ((c->processor_id & 0x00ff) >= 0x40)
cpu_wait = r4k_wait;
break;
+ case CPU_LOONGSON2:
+ cpu_wait = loongson2_cpu_wait;
+ break;
default:
break;
}
diff --git a/arch/mips/kernel/cpufreq/loongson2_clock.c
b/arch/mips/kernel/cpufreq/loongson2_clock.c
index cefc6e2..0b30fe9 100644
--- a/arch/mips/kernel/cpufreq/loongson2_clock.c
+++ b/arch/mips/kernel/cpufreq/loongson2_clock.c
@@ -18,25 +18,7 @@ static LIST_HEAD(clock_list);
static DEFINE_SPINLOCK(clock_lock);
static DEFINE_MUTEX(clock_list_sem);
-/* Minimum CLK support */
-enum {
- DC_ZERO, DC_25PT = 2, DC_37PT, DC_50PT, DC_62PT, DC_75PT,
- DC_87PT, DC_DISABLE, DC_RESV
-};
-
-struct cpufreq_frequency_table loongson2_clockmod_table[] = {
- {DC_RESV, CPUFREQ_ENTRY_INVALID},
- {DC_ZERO, CPUFREQ_ENTRY_INVALID},
- {DC_25PT, 0},
- {DC_37PT, 0},
- {DC_50PT, 0},
- {DC_62PT, 0},
- {DC_75PT, 0},
- {DC_87PT, 0},
- {DC_DISABLE, 0},
- {DC_RESV, CPUFREQ_TABLE_END},
-};
-EXPORT_SYMBOL_GPL(loongson2_clockmod_table);
+#define LS2_MAX_CPUFREQ_LEVEL 8
static struct clk cpu_clk = {
.name = "cpu_clk",
@@ -109,21 +91,15 @@ int clk_set_rate_ex(struct clk *clk, unsigned
long rate, int algo_id)
if (unlikely(clk->flags & CLK_RATE_PROPAGATES))
propagate_rate(clk);
- for (i = 0; loongson2_clockmod_table[i].frequency != CPUFREQ_TABLE_END;
- i++) {
- if (loongson2_clockmod_table[i].frequency ==
- CPUFREQ_ENTRY_INVALID)
- continue;
- if (rate == loongson2_clockmod_table[i].frequency)
- break;
- }
- if (rate != loongson2_clockmod_table[i].frequency)
- return -ENOTSUPP;
+ i = rate * LS2_MAX_CPUFREQ_LEVEL / cpu_clock_freq;
+ if ( i < 1 || i > LS2_MAX_CPUFREQ_LEVEL )
+ return -ENOTSUPP;
- clk->rate = rate;
+ /* indeed, a rounded rate is assigned */
+ clk->rate = i * (cpu_clock_freq / LS2_MAX_CPUFREQ_LEVEL);
regval = LOONGSON_CHIPCFG0;
- regval = (regval & ~0x7) | (loongson2_clockmod_table[i].index - 1);
+ regval = (regval & ~0x7) | i;
LOONGSON_CHIPCFG0 = regval;
return ret;
@@ -151,20 +127,6 @@ EXPORT_SYMBOL_GPL(clk_round_rate);
* interrupt disabled content
*/
-DEFINE_SPINLOCK(loongson2_wait_lock);
-void loongson2_cpu_wait(void)
-{
- u32 cpu_freq;
- unsigned long flags;
-
- spin_lock_irqsave(&loongson2_wait_lock, flags);
- cpu_freq = LOONGSON_CHIPCFG0;
- LOONGSON_CHIPCFG0 &= ~0x7; /* Put CPU into wait mode */
- LOONGSON_CHIPCFG0 = cpu_freq; /* Restore CPU state */
- spin_unlock_irqrestore(&loongson2_wait_lock, flags);
-}
-EXPORT_SYMBOL_GPL(loongson2_cpu_wait);
-
MODULE_AUTHOR("Yanhua <yanh@xxxxxxxxxx>");
MODULE_DESCRIPTION("cpufreq driver for Loongson 2F");
MODULE_LICENSE("GPL");
diff --git a/arch/mips/kernel/cpufreq/loongson2_cpufreq.c
b/arch/mips/kernel/cpufreq/loongson2_cpufreq.c
index 2f6a0b1..0488945 100644
--- a/arch/mips/kernel/cpufreq/loongson2_cpufreq.c
+++ b/arch/mips/kernel/cpufreq/loongson2_cpufreq.c
@@ -21,11 +21,16 @@
#include <loongson.h>
-static uint nowait;
+#define LS2_CPUFREQ_LEVEL 3
static struct clk *cpuclk;
-static void (*saved_cpu_wait) (void);
+struct cpufreq_frequency_table loongson2_clockmod_table[] = {
+ {0, 0},
+ {1, 0},
+ {2, 0},
+ { .frequency = CPUFREQ_TABLE_END },
+};
static int loongson2_cpu_freq_notifier(struct notifier_block *nb,
unsigned long val, void *data);
@@ -67,14 +72,11 @@ static int loongson2_cpufreq_target(struct
cpufreq_policy *policy,
cpus_allowed = current->cpus_allowed;
set_cpus_allowed(current, cpumask_of_cpu(cpu));
- if (cpufreq_frequency_table_target
- (policy, &loongson2_clockmod_table[0], target_freq, relation,
- &newstate))
+ if (cpufreq_frequency_table_target (policy,
+ &loongson2_clockmod_table[0], target_freq,
relation, &newstate))
return -EINVAL;
- freq =
- ((cpu_clock_freq / 1000) *
- loongson2_clockmod_table[newstate].index) / 8;
+ freq = loongson2_clockmod_table[newstate].frequency;
if (freq < policy->min || freq > policy->max)
return -EINVAL;
@@ -88,15 +90,10 @@ static int loongson2_cpufreq_target(struct
cpufreq_policy *policy,
if (freqs.new == freqs.old)
return 0;
- /* notifiers */
+ /* change cpu clock between notifier pairs */
cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
-
set_cpus_allowed(current, cpus_allowed);
-
- /* setting the cpu frequency */
clk_set_rate(cpuclk, freq);
-
- /* notifiers */
cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
pr_debug("cpufreq: set frequency %u kHz\n", freq);
@@ -121,11 +118,12 @@ static int loongson2_cpufreq_cpu_init(struct
cpufreq_policy *policy)
if (!cpuclk->rate)
return -EINVAL;
- /* clock table init */
- for (i = 2;
- (loongson2_clockmod_table[i].frequency != CPUFREQ_TABLE_END);
- i++)
- loongson2_clockmod_table[i].frequency = (cpuclk->rate * i) / 8;
+ /* initialize the clock table such that all frequencies */
+ /* evenly span within [cpu_clock_freq/2, cpu_clock_freq] */
+ for (i = 0; i < LS2_CPUFREQ_LEVEL; i++) {
+ loongson2_clockmod_table[i].frequency = cpuclk->rate *
+ (i+LS2_CPUFREQ_LEVEL-1) / (2*LS2_CPUFREQ_LEVEL-2);
+ }
policy->cur = loongson2_cpufreq_get(policy->cpu);
@@ -139,7 +137,7 @@ static int loongson2_cpufreq_cpu_init(struct
cpufreq_policy *policy)
static int loongson2_cpufreq_verify(struct cpufreq_policy *policy)
{
return cpufreq_frequency_table_verify(policy,
- &loongson2_clockmod_table[0]);
+ &loongson2_clockmod_table[0]);
}
static int loongson2_cpufreq_exit(struct cpufreq_policy *policy)
@@ -185,7 +183,7 @@ static int __init cpufreq_init(void)
{
int ret;
- /* Register platform stuff */
+ /* Register platform driver */
ret = platform_driver_register(&platform_driver);
if (ret)
return ret;
@@ -195,20 +193,11 @@ static int __init cpufreq_init(void)
cpufreq_register_notifier(&loongson2_cpufreq_notifier_block,
CPUFREQ_TRANSITION_NOTIFIER);
- ret = cpufreq_register_driver(&loongson2_cpufreq_driver);
-
- if (!ret && !nowait) {
- saved_cpu_wait = cpu_wait;
- cpu_wait = loongson2_cpu_wait;
- }
-
- return ret;
+ return cpufreq_register_driver(&loongson2_cpufreq_driver);
}
static void __exit cpufreq_exit(void)
{
- if (!nowait && saved_cpu_wait)
- cpu_wait = saved_cpu_wait;
cpufreq_unregister_driver(&loongson2_cpufreq_driver);
cpufreq_unregister_notifier(&loongson2_cpufreq_notifier_block,
CPUFREQ_TRANSITION_NOTIFIER);
@@ -219,9 +208,6 @@ static void __exit cpufreq_exit(void)
module_init(cpufreq_init);
module_exit(cpufreq_exit);
-module_param(nowait, uint, 0644);
-MODULE_PARM_DESC(nowait, "Disable Loongson-2F specific wait");
-
MODULE_AUTHOR("Yanhua <yanh@xxxxxxxxxx>");
MODULE_DESCRIPTION("cpufreq driver for Loongson2F");
MODULE_LICENSE("GPL");
--
Gang Liang
Life is beautiful!
