Re: [PATCH 1/1] cpufreq: eeepc 900 frequency scaling driver

[Tom Hughes <tom@compton.nu>]

Matthew Garrett wrote:

> It appears to be implemented in the 900 and 901 BIOSes as well, so some 
> kind of limitation is probably needed. The best approach would probably 
> to check whether the CPU has the EST flag. Just do something like:
> 
> struct cpuinfo_x86 *cpu = &cpu_data(policy->cpu);
> 
> if (cpu->x86_vendor != X86_VENDOR_INTEL || cpu_has(cpu, X86_FEATURE_EST))
> 	return -ENODEV
> 
> at the top of the cpufreq init code. That way you'll refuse to bind on 
> anything that implements speedstep and acpi-cpufreq can be used instead.

Sounds like a good idea - here's a new version with that check added:

--- kmod-eeepc-laptop-2.6.28rc5/eeepc-laptop.c	2008-11-20 09:24:41.000000000 +0000
+++ kmod-eeepc-laptop-cpufreq/eeepc-laptop.c	2008-12-07 15:54:07.000000000 +0000
@@ -25,6 +25,7 @@
 #include <linux/fb.h>
 #include <linux/hwmon.h>
 #include <linux/hwmon-sysfs.h>
+#include <linux/cpufreq.h>
 #include <acpi/acpi_drivers.h>
 #include <acpi/acpi_bus.h>
 #include <linux/uaccess.h>
@@ -731,6 +732,118 @@
 };
 
 /*
+ * Cpufreq
+ *
+ * Based on work by Cristiano P. <cris69@solnet.ch>
+ */
+static struct cpufreq_frequency_table eeepc_cpufreq_table[] = {
+       {0, 630000},
+       {1, 900000},
+       {0, CPUFREQ_TABLE_END}
+};
+
+static unsigned int eeepc_cpufreq_get(unsigned int cpu)
+{
+	switch (get_acpi(CM_ASL_CPUFV)) {
+	case 0x200:
+		return 900000;
+	case 0x201:
+		return 630000;
+	}
+
+	return 0;
+}
+
+static void eeepc_cpufreq_set(unsigned int frequency)
+{
+	struct cpufreq_freqs freqs;
+
+	freqs.cpu = 0;
+	freqs.old = eeepc_cpufreq_get(0);
+	freqs.new = frequency;
+
+	cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
+
+	switch (frequency) {
+	case 900000:
+		set_acpi(CM_ASL_CPUFV, 0);
+		break;
+	case 630000:
+		set_acpi(CM_ASL_CPUFV, 1);
+		break;
+	}
+
+	cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
+
+	return;
+}
+
+static int eeepc_cpufreq_verify(struct cpufreq_policy *policy)
+{
+	return cpufreq_frequency_table_verify(policy, eeepc_cpufreq_table);
+}
+
+static int eeepc_cpufreq_target (struct cpufreq_policy *policy,
+				 unsigned int target_freq,
+				 unsigned int relation)
+{
+	unsigned int newstate = 0;
+
+	if (cpufreq_frequency_table_target(policy, eeepc_cpufreq_table,
+					   target_freq, relation, &newstate))
+		return -EINVAL;
+
+	eeepc_cpufreq_set(eeepc_cpufreq_table[newstate].frequency);
+
+	return 0;
+}
+
+static int eeepc_cpufreq_cpu_init(struct cpufreq_policy *policy)
+{
+	struct cpuinfo_x86 *cpu = &cpu_data(policy->cpu);
+
+	/* Defer to acpi-cpufreq if this CPU has SpeedStep support */
+	if (cpu->x86_vendor != X86_VENDOR_INTEL || cpu_has(cpu, X86_FEATURE_EST))
+		return -ENODEV;
+
+	if (get_acpi(CM_ASL_CPUFV) < 0)
+		return -ENODEV;
+
+	policy->cpuinfo.transition_latency = 1000000;
+	policy->cur = eeepc_cpufreq_get(policy->cpu);
+
+	if (cpufreq_frequency_table_cpuinfo(policy, eeepc_cpufreq_table))
+		return -EINVAL;
+
+	cpufreq_frequency_table_get_attr(eeepc_cpufreq_table, policy->cpu);
+
+	return 0;
+}
+
+static int eeepc_cpufreq_cpu_exit(struct cpufreq_policy *policy)
+{
+	cpufreq_frequency_table_put_attr(policy->cpu);
+
+	return 0;
+}
+
+static struct freq_attr *eeepc_cpufreq_attr[] = {
+	&cpufreq_freq_attr_scaling_available_freqs,
+	NULL,
+};
+
+static struct cpufreq_driver eeepc_cpufreq_driver = {
+	.verify         = eeepc_cpufreq_verify,
+	.target         = eeepc_cpufreq_target,
+	.init           = eeepc_cpufreq_cpu_init,
+	.exit           = eeepc_cpufreq_cpu_exit,
+	.get            = eeepc_cpufreq_get,
+	.name           = "eeepc",
+	.owner          = THIS_MODULE,
+	.attr           = eeepc_cpufreq_attr,
+};
+
+/*
  * exit/init
  */
 static void eeepc_backlight_exit(void)
@@ -759,10 +872,16 @@
 	eeepc_hwmon_device = NULL;
 }
 
+static void eeepc_cpufreq_exit(void)
+{
+	cpufreq_unregister_driver(&eeepc_cpufreq_driver);
+}
+
 static void __exit eeepc_laptop_exit(void)
 {
 	eeepc_backlight_exit();
 	eeepc_hwmon_exit();
+	eeepc_cpufreq_exit();
 	acpi_bus_unregister_driver(&eeepc_hotk_driver);
 	sysfs_remove_group(&platform_device->dev.kobj,
 			   &platform_attribute_group);
@@ -810,6 +929,11 @@
 	return result;
 }
 
+static int eeepc_cpufreq_init(struct device *dev)
+{
+	return cpufreq_register_driver(&eeepc_cpufreq_driver);
+}
+
 static int __init eeepc_laptop_init(void)
 {
 	struct device *dev;
@@ -837,6 +961,9 @@
 	result = eeepc_hwmon_init(dev);
 	if (result)
 		goto fail_hwmon;
+	result = eeepc_cpufreq_init(dev);
+	if (result)
+		goto fail_cpufreq;
 	/* Register platform stuff */
 	result = platform_driver_register(&platform_driver);
 	if (result)
@@ -861,6 +988,8 @@
 fail_platform_device1:
 	platform_driver_unregister(&platform_driver);
 fail_platform_driver:
+	eeepc_cpufreq_exit();
+fail_cpufreq:
 	eeepc_hwmon_exit();
 fail_hwmon:
 	eeepc_backlight_exit();


Tom

-- 
Tom Hughes (tom@compton.nu)
http://www.compton.nu/