diff options
Diffstat (limited to 'tools/power/cpupower/debug/kernel')
| -rw-r--r-- | tools/power/cpupower/debug/kernel/Makefile | 23 | ||||
| -rw-r--r-- | tools/power/cpupower/debug/kernel/cpufreq-test_tsc.c | 111 |
2 files changed, 134 insertions, 0 deletions
diff --git a/tools/power/cpupower/debug/kernel/Makefile b/tools/power/cpupower/debug/kernel/Makefile new file mode 100644 index 000000000..7b5c43684 --- /dev/null +++ b/tools/power/cpupower/debug/kernel/Makefile @@ -0,0 +1,23 @@ +# SPDX-License-Identifier: GPL-2.0 +obj-m := + +KDIR := /lib/modules/$(shell uname -r)/build +KMISC := /lib/modules/$(shell uname -r)/cpufrequtils/ + +ifeq ("$(CONFIG_X86_TSC)", "y") + obj-m += cpufreq-test_tsc.o +endif + +default: + $(MAKE) -C $(KDIR) M=$(CURDIR) + +clean: + - rm -rf *.o *.ko .*.cmd .*.mod.* *.mod.c + - rm -rf Module.symvers modules.order + +install: default + install -d $(KMISC) + install -m 644 -c *.ko $(KMISC) + /sbin/depmod -a + +all: default 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 000000000..e364b170b --- /dev/null +++ b/tools/power/cpupower/debug/kernel/cpufreq-test_tsc.c @@ -0,0 +1,111 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * 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"); |