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

Tom Hughes
2008-12-07T15:55:47Z

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)