Message-ID: <4936DD78.4090501@compton.nu>
Date: Wed, 03 Dec 2008 19:26:48 +0000
From: Tom Hughes <tom@compton.nu>
User-Agent: Thunderbird 2.0.0.18 (X11/20081119)
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To: Cristiano Prisciandaro <cristiano.p@solnet.ch>
CC: Dave Jones <davej@redhat.com>, cpufreq@vger.kernel.org,
       linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/1] cpufreq: eeepc 900 frequency scaling driver
References: <1227454026.7262.59.camel@localhost> <492A7632.4040106@compton.nu>
In-Reply-To: <492A7632.4040106@compton.nu>
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Tom Hughes wrote:
> Cristiano Prisciandaro wrote:
> 
>> From: Cristiano Prisciandaro <cristiano.p@solnet.ch>
>>
>> The bios of the eeepc 900 exposes an acpi method that allows clocking
>> the cpu to 630/900 MHz. This driver allows controlling the frequency
>> switch through the cpufreq subsystem.
> 
> I should perhaps add at this point that I have an alternative patch 
> based on Cristiano's code, which adds this cpufreq driver to the 
> existing eeepc-laptop module rather than creating a separate module for it.

For the record, and as this discussion seems to have ground to a halt a 
bit at the moment, here is my version of the eee 900 cpufreq driver:

--- kmod-eeepc-laptop-2.6.28rc5/eeepc-laptop.c	2008-11-20 09:24:41.000000000 +0000
+++ kmod-eeepc-laptop-cpufreq/eeepc-laptop.c	2008-12-03 18:59:14.000000000 +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 +732,112 @@
 };
 
 /*
+ * 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)
+{
+	if (get_acpi(CM_ASL_CPUFV) != -1)
+	{
+		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 +866,16 @@
 	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 +923,11 @@
 	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 +955,9 @@
 	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 +982,8 @@
 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/

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