[PATCH] 1/3 Dynamic cpufreq governor and updates to ACPI P-state driver

From: Pallipadi, Venkatesh
Date: Mon Oct 20 2003 - 21:59:25 EST


Patch 1/3: Changes to ACPI P-state driver, to handle MSR
based transitions frequency transitions and make the driver
SMP aware.


diffstat dbs1.patch
arch/i386/kernel/cpu/cpufreq/Kconfig | 4
arch/i386/kernel/cpu/cpufreq/acpi.c | 141
+++++++++++++++++++++++++++--------
include/acpi/processor.h | 1
3 files changed, 116 insertions(+), 30 deletions(-)



diff -purN linux-2.6.0-test7/arch/i386/kernel/cpu/cpufreq/acpi.c
linux-2.6.0-test7-dbs/arch/i386/kernel/cpu/cpufreq/acpi.c
--- linux-2.6.0-test7/arch/i386/kernel/cpu/cpufreq/acpi.c
2003-10-20 00:24:43.000000000 -0700
+++ linux-2.6.0-test7-dbs/arch/i386/kernel/cpu/cpufreq/acpi.c
2003-10-20 02:11:01.000000000 -0700
@@ -99,7 +99,9 @@ acpi_processor_get_performance_control (

reg = (struct acpi_pct_register *) (obj.buffer.pointer);

- if (reg->space_id != ACPI_ADR_SPACE_SYSTEM_IO) {
+ perf->space_id = (int) reg->space_id;
+ if (reg->space_id != ACPI_ADR_SPACE_SYSTEM_IO &&
+ reg->space_id != ACPI_ADR_SPACE_FIXED_HARDWARE)
{
ACPI_DEBUG_PRINT((ACPI_DB_ERROR,
"Unsupported address space [%d]
(control_register)\n",
(u32) reg->space_id));
@@ -126,7 +128,8 @@ acpi_processor_get_performance_control (

reg = (struct acpi_pct_register *) (obj.buffer.pointer);

- if (reg->space_id != ACPI_ADR_SPACE_SYSTEM_IO) {
+ if (reg->space_id != ACPI_ADR_SPACE_SYSTEM_IO &&
+ reg->space_id != ACPI_ADR_SPACE_FIXED_HARDWARE)
{
ACPI_DEBUG_PRINT((ACPI_DB_ERROR,
"Unsupported address space [%d]
(status_register)\n",
(u32) reg->space_id));
@@ -224,16 +227,100 @@ end:
return_VALUE(result);
}

+struct set_performance_param {
+ int cpu;
+ struct acpi_processor_performance *perf;
+ unsigned int state;
+ unsigned int async;
+ unsigned int retval;
+};
+
+static void
+target_cpu_set_performance(struct set_performance_param *param)
+{
+ struct acpi_processor_performance *perf = param->perf;
+ u16 port = 0;
+ int state = param->state;
+ unsigned int value = perf->states[state].control;
+ int i = 0;
+
+ ACPI_FUNCTION_TRACE("target_cpu_set_performance");
+ if (perf->space_id == ACPI_ADR_SPACE_FIXED_HARDWARE) {
+ ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Writing 0x%x to MSR
0x%x\n",
+ value, perf->control_register));
+ wrmsr(perf->control_register, value, 0);
+ } else {
+ port = perf->control_register;
+ ACPI_DEBUG_PRINT((ACPI_DB_INFO,
+ "Writing 0x%04x to port 0x%04x\n", value,
port));
+
+ outl(value, port);
+ }
+
+ if (param->async) {
+ /* We don't want to wait for the status change here, as
+ * that will affect performance, especially with
frequent
+ * frequency switches. We assume the tranisition
+ * gone through and continue.
+ */
+ param->retval = perf->states[state].status;
+ return_VOID;
+ }
+
+ if (perf->space_id == ACPI_ADR_SPACE_FIXED_HARDWARE) {
+ ACPI_DEBUG_PRINT((ACPI_DB_INFO,
+ "Looking for 0x%02x from MSR 0x%04x\n",
+ (u16) perf->states[state].status,
+ perf->status_register));
+
+ for (i = 0; i < 100; i++) {
+ unsigned long unused_hi;
+ rdmsr(perf->status_register, value, unused_hi);
+ if (value == perf->states[state].status)
+ break;
+ udelay(10);
+ }
+ } else {
+ port = perf->status_register;
+
+ ACPI_DEBUG_PRINT((ACPI_DB_INFO,
+ "Looking for 0x%04x from port 0x%04x\n",
+ (u16) perf->states[state].status, port));
+
+ for (i = 0; i < 100; i++) {
+ value = inl(port);
+ if (value == perf->states[state].status)
+ break;
+ udelay(10);
+ }
+ }
+ param->retval = value;
+ return_VOID;
+}
+
+#ifdef CONFIG_SMP
+static void
+target_cpu_set_performance_ipi(void *data)
+{
+ struct set_performance_param *param;
+
+ param = (struct set_performance_param *) data;
+ if (param->cpu != smp_processor_id())
+ return;
+
+ target_cpu_set_performance(param);
+}
+#endif

static int
acpi_processor_set_performance (
struct acpi_processor_performance *perf,
int state)
{
- u16 port = 0;
- u16 value = 0;
+ unsigned int value = 0;
int i = 0;
struct cpufreq_freqs cpufreq_freqs;
+ struct set_performance_param param;

ACPI_FUNCTION_TRACE("acpi_processor_set_performance");

@@ -267,8 +354,12 @@ acpi_processor_set_performance (

/* cpufreq frequency struct */
cpufreq_freqs.cpu = perf->pr->id;
- cpufreq_freqs.old = perf->states[perf->state].core_frequency;
- cpufreq_freqs.new = perf->states[state].core_frequency;
+ /*
+ * cpufreq_notifier needs to send the freq in KHz. But acpi
+ * data we have is in MHz
+ */
+ cpufreq_freqs.old = perf->states[perf->state].core_frequency *
1000;
+ cpufreq_freqs.new = perf->states[state].core_frequency * 1000;

/* notify cpufreq */
cpufreq_notify_transition(&cpufreq_freqs, CPUFREQ_PRECHANGE);
@@ -276,35 +367,27 @@ acpi_processor_set_performance (
/*
* First we write the target state's 'control' value to the
* control_register.
- */
-
- port = perf->control_register;
- value = (u16) perf->states[state].control;
-
- ACPI_DEBUG_PRINT((ACPI_DB_INFO,
- "Writing 0x%04x to port 0x%04x\n", value, port));
-
- outw(value, port);
-
- /*
* Then we read the 'status_register' and compare the value with
the
* target state's 'status' to make sure the transition was
successful.
* Note that we'll poll for up to 1ms (100 cycles of 10us)
before
* giving up.
*/

- port = perf->status_register;
-
- ACPI_DEBUG_PRINT((ACPI_DB_INFO,
- "Looking for 0x%04x from port 0x%04x\n",
- (u16) perf->states[state].status, port));
-
- for (i=0; i<100; i++) {
- value = inw(port);
- if (value == (u16) perf->states[state].status)
- break;
- udelay(10);
- }
+ param.cpu = perf - performance;
+ param.perf = perf;
+ param.state = state;
+#ifdef CONFIG_SMP
+ param.async = 1; /* We don't want to wait in IPI context */
+ if (param.cpu != smp_processor_id())
+ smp_call_function(target_cpu_set_performance_ipi,
+ (void *)&param, 1, 1);
+ else
+ target_cpu_set_performance(&param);
+#else
+ param.async = 0;
+ target_cpu_set_performance(&param);
+#endif
+ value = param.retval;

/* notify cpufreq */
cpufreq_notify_transition(&cpufreq_freqs, CPUFREQ_POSTCHANGE);
diff -purN linux-2.6.0-test7/arch/i386/kernel/cpu/cpufreq/Kconfig
linux-2.6.0-test7-dbs/arch/i386/kernel/cpu/cpufreq/Kconfig
--- linux-2.6.0-test7/arch/i386/kernel/cpu/cpufreq/Kconfig
2003-10-14 16:28:32.000000000 -0700
+++ linux-2.6.0-test7-dbs/arch/i386/kernel/cpu/cpufreq/Kconfig
2003-10-20 02:27:39.000000000 -0700
@@ -36,7 +36,9 @@ config X86_ACPI_CPUFREQ
depends on CPU_FREQ_TABLE && ACPI_PROCESSOR
help
This driver adds a CPUFreq driver which utilizes the ACPI
- Processor Performance States.
+ Processor Performance States. This can work with variety
+ of platforms and support both Intel Speedstep and Intel
Enhanced
+ Speedstep, as long as BIOS-ACPI provides the P-state
information.

For details, take a look at linux/Documentation/cpu-freq.

diff -purN linux-2.6.0-test7/include/acpi/processor.h
linux-2.6.0-test7-dbs/include/acpi/processor.h
--- linux-2.6.0-test7/include/acpi/processor.h 2003-10-20
00:24:43.000000000 -0700
+++ linux-2.6.0-test7-dbs/include/acpi/processor.h 2003-10-20
02:11:08.000000000 -0700
@@ -73,6 +73,7 @@ struct acpi_processor_performance {
u16 control_register;
u16 status_register;
int state_count;
+ int space_id;
struct acpi_processor_px states[ACPI_PROCESSOR_MAX_PERFORMANCE];
struct cpufreq_frequency_table
freq_table[ACPI_PROCESSOR_MAX_PERFORMANCE];
struct acpi_processor *pr;

Attachment: dbs1.patch
Description: dbs1.patch