123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110 |
- /*
- * 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
- * linux-pm@vger.kernel.org
- */
- #include <linux/kernel.h>
- #include <linux/module.h>
- #include <linux/init.h>
- #include <linux/delay.h>
- #include <linux/acpi.h>
- #include <asm/io.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();
- then_tsc = rdtsc();
- for (i=0;i<20;i++) {
- mdelay(100);
- now = read_pmtmr();
- now_tsc = rdtsc();
- 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");
|