From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001
From: André Fabian Silva Delgado <emulatorman@parabola.nu>
Date: Wed, 5 Aug 2015 17:04:01 -0300
Subject: Initial import

---
 .../power/cpupower/debug/kernel/cpufreq-test_tsc.c | 110 +++++++++++++++++++++
 1 file changed, 110 insertions(+)
 create mode 100644 tools/power/cpupower/debug/kernel/cpufreq-test_tsc.c

(limited to 'tools/power/cpupower/debug/kernel/cpufreq-test_tsc.c')

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..5224ee5b3
--- /dev/null
+++ b/tools/power/cpupower/debug/kernel/cpufreq-test_tsc.c
@@ -0,0 +1,110 @@
+/*
+ * 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();
+        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");
-- 
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