summaryrefslogtreecommitdiffstats
path: root/tools/power/cpupower/debug/kernel/cpufreq-test_tsc.c
diff options
context:
space:
mode:
Diffstat (limited to 'tools/power/cpupower/debug/kernel/cpufreq-test_tsc.c')
-rw-r--r--tools/power/cpupower/debug/kernel/cpufreq-test_tsc.c113
1 files changed, 113 insertions, 0 deletions
diff --git a/tools/power/cpupower/debug/kernel/cpufreq-test_tsc.c b/tools/power/cpupower/debug/kernel/cpufreq-test_tsc.c
new file mode 100644
index 000000000000..66cace601e57
--- /dev/null
+++ b/tools/power/cpupower/debug/kernel/cpufreq-test_tsc.c
@@ -0,0 +1,113 @@
+/*
+ * test module to check whether the TSC-based delay routine continues
+ * to work properly after cpufreq transitions. Needs ACPI to work
+ * properly.
+ *
+ * Based partly on the Power Management Timer (PMTMR) code to be found
+ * in arch/i386/kernel/timers/timer_pm.c on recent 2.6. kernels, especially
+ * code written by John Stultz. The read_pmtmr function was copied verbatim
+ * from that file.
+ *
+ * (C) 2004 Dominik Brodowski
+ *
+ * To use:
+ * 1.) pass clock=tsc to the kernel on your bootloader
+ * 2.) modprobe this module (it'll fail)
+ * 3.) change CPU frequency
+ * 4.) modprobe this module again
+ * 5.) if the third value, "diff_pmtmr", changes between 2. and 4., the
+ * TSC-based delay routine on the Linux kernel does not correctly
+ * handle the cpufreq transition. Please report this to
+ * cpufreq@vger.kernel.org
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/delay.h>
+
+#include <asm/io.h>
+
+#include <acpi/acpi_bus.h>
+#include <acpi/acpi_drivers.h>
+
+static int pm_tmr_ioport = 0;
+
+/*helper function to safely read acpi pm timesource*/
+static u32 read_pmtmr(void)
+{
+ u32 v1=0,v2=0,v3=0;
+ /* It has been reported that because of various broken
+ * chipsets (ICH4, PIIX4 and PIIX4E) where the ACPI PM time
+ * source is not latched, so you must read it multiple
+ * times to insure a safe value is read.
+ */
+ do {
+ v1 = inl(pm_tmr_ioport);
+ v2 = inl(pm_tmr_ioport);
+ v3 = inl(pm_tmr_ioport);
+ } while ((v1 > v2 && v1 < v3) || (v2 > v3 && v2 < v1)
+ || (v3 > v1 && v3 < v2));
+
+ /* mask the output to 24 bits */
+ return (v2 & 0xFFFFFF);
+}
+
+static int __init cpufreq_test_tsc(void)
+{
+ u32 now, then, diff;
+ u64 now_tsc, then_tsc, diff_tsc;
+ int i;
+
+ /* the following code snipped is copied from arch/x86/kernel/acpi/boot.c
+ of Linux v2.6.25. */
+
+ /* detect the location of the ACPI PM Timer */
+ if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID) {
+ /* FADT rev. 2 */
+ if (acpi_gbl_FADT.xpm_timer_block.space_id !=
+ ACPI_ADR_SPACE_SYSTEM_IO)
+ return 0;
+
+ pm_tmr_ioport = acpi_gbl_FADT.xpm_timer_block.address;
+ /*
+ * "X" fields are optional extensions to the original V1.0
+ * fields, so we must selectively expand V1.0 fields if the
+ * corresponding X field is zero.
+ */
+ if (!pm_tmr_ioport)
+ pm_tmr_ioport = acpi_gbl_FADT.pm_timer_block;
+ } else {
+ /* FADT rev. 1 */
+ pm_tmr_ioport = acpi_gbl_FADT.pm_timer_block;
+ }
+
+ printk(KERN_DEBUG "start--> \n");
+ then = read_pmtmr();
+ rdtscll(then_tsc);
+ for (i=0;i<20;i++) {
+ mdelay(100);
+ now = read_pmtmr();
+ rdtscll(now_tsc);
+ diff = (now - then) & 0xFFFFFF;
+ diff_tsc = now_tsc - then_tsc;
+ printk(KERN_DEBUG "t1: %08u t2: %08u diff_pmtmr: %08u diff_tsc: %016llu\n", then, now, diff, diff_tsc);
+ then = now;
+ then_tsc = now_tsc;
+ }
+ printk(KERN_DEBUG "<-- end \n");
+ return -ENODEV;
+}
+
+static void __exit cpufreq_none(void)
+{
+ return;
+}
+
+module_init(cpufreq_test_tsc)
+module_exit(cpufreq_none)
+
+
+MODULE_AUTHOR("Dominik Brodowski");
+MODULE_DESCRIPTION("Verify the TSC cpufreq notifier working correctly -- needs ACPI-enabled system");
+MODULE_LICENSE ("GPL");