| /* |
| * 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"); |