1 files changed, 112 insertions, 0 deletions
diff --git a/tools/power/cpupower/debug/i386/centrino-decode.c b/tools/power/cpupower/debug/i386/centrino-decode.c
new file mode 100644
index 000000000..700cd31a7
--- /dev/null
+++ b/tools/power/cpupower/debug/i386/centrino-decode.c
@@ -0,0 +1,112 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  (C) 2003 - 2004  Dominik Brodowski <linux@dominikbrodowski.de>
+ *
+ * Based on code found in
+ * linux/arch/i386/kernel/cpu/cpufreq/speedstep-centrino.c
+ * and originally developed by Jeremy Fitzhardinge.
+ *
+ * USAGE: simply run it to decode the current settings on CPU 0,
+ *	  or pass the CPU number as argument, or pass the MSR content
+ *	  as argument.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <unistd.h>
+#include <errno.h>
+#include <fcntl.h>
+
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#define MCPU	32
+
+#define MSR_IA32_PERF_STATUS	0x198
+
+static int rdmsr(unsigned int cpu, unsigned int msr,
+		 unsigned int *lo, unsigned int *hi)
+{
+	int fd;
+	char file[20];
+	unsigned long long val;
+	int retval = -1;
+
+	*lo = *hi = 0;
+
+	if (cpu > MCPU)
+		goto err1;
+
+	sprintf(file, "/dev/cpu/%d/msr", cpu);
+	fd = open(file, O_RDONLY);
+
+	if (fd < 0)
+		goto err1;
+
+	if (lseek(fd, msr, SEEK_CUR) == -1)
+		goto err2;
+
+	if (read(fd, &val, 8) != 8)
+		goto err2;
+
+	*lo = (uint32_t )(val & 0xffffffffull);
+	*hi = (uint32_t )(val>>32 & 0xffffffffull);
+
+	retval = 0;
+err2:
+	close(fd);
+err1:
+	return retval;
+}
+
+static void decode (unsigned int msr)
+{
+	unsigned int multiplier;
+	unsigned int mv;
+
+	multiplier = ((msr >> 8) & 0xFF);
+
+	mv = (((msr & 0xFF) * 16) + 700);
+
+	printf("0x%x means multiplier %d @ %d mV\n", msr, multiplier, mv);
+}
+
+static int decode_live(unsigned int cpu)
+{
+	unsigned int lo, hi;
+	int err;
+
+	err = rdmsr(cpu, MSR_IA32_PERF_STATUS, &lo, &hi);
+
+	if (err) {
+		printf("can't get MSR_IA32_PERF_STATUS for cpu %d\n", cpu);
+		printf("Possible trouble: you don't run an Enhanced SpeedStep capable cpu\n");
+		printf("or you are not root, or the msr driver is not present\n");
+		return 1;
+	}
+
+	decode(lo);
+
+	return 0;
+}
+
+int main (int argc, char **argv)
+{
+	unsigned int cpu, mode = 0;
+
+	if (argc < 2)
+		cpu = 0;
+	else {
+		cpu = strtoul(argv[1], NULL, 0);
+		if (cpu >= MCPU)
+			mode = 1;
+	}
+
+	if (mode)
+		decode(cpu);
+	else
+		decode_live(cpu);
+
+	return 0;
+}