* [PATCH] detect processor speed in p4-clockmod
@ 2003-11-04 19:38 Dominik Brodowski
0 siblings, 0 replies; only message in thread
From: Dominik Brodowski @ 2003-11-04 19:38 UTC (permalink / raw)
To: davej, cpufreq
[Note: probably too invasive for 2.6.0-testX]
Instead of relying on cpu_khz or user input, decode the appropriate MSR in
p4_clockmod to detect the maximum frequency of the CPU.
Dominik
diff -ruN linux-original/arch/i386/kernel/cpu/cpufreq/p4-clockmod.c linux/arch/i386/kernel/cpu/cpufreq/p4-clockmod.c
--- linux-original/arch/i386/kernel/cpu/cpufreq/p4-clockmod.c 2003-11-04 15:27:33.000000000 +0100
+++ linux/arch/i386/kernel/cpu/cpufreq/p4-clockmod.c 2003-11-04 20:23:07.384393904 +0100
@@ -48,8 +48,7 @@
static int has_N44_O17_errata[NR_CPUS];
-static int stock_freq;
-
+unsigned int stock_freq;
static int cpufreq_p4_setdc(unsigned int cpu, unsigned int newstate)
{
@@ -175,6 +174,54 @@
return cpufreq_frequency_table_verify(policy, &p4clockmod_table[0]);
}
+/* copied from speedstep_lib, made SMP-compatible */
+static unsigned int cpufreq_p4_get_frequency(struct cpuinfo_x86 *c)
+{
+ u32 msr_lo, msr_hi, mult;
+ unsigned int fsb = 0;
+
+ if (c->x86 != 0xF) {
+ printk(KERN_DEBUG PFX "Unknown P4. Please send an e-mail to <linux@brodo.de>\n");
+ return 0;
+ }
+
+ rdmsr(0x2c, msr_lo, msr_hi);
+
+ /* printk(KERN_DEBUG PFX "P4 - MSR_EBC_FREQUENCY_ID: 0x%x 0x%x\n", msr_lo, msr_hi); */
+ /* decode the FSB: see IA-32 Intel (C) Architecture Software
+ * Developer's Manual, Volume 3: System Prgramming Guide,
+ * revision #12 in Table B-1: MSRs in the Pentium 4 and
+ * Intel Xeon Processors, on page B-4 and B-5.
+ */
+ if (c->x86_model < 2)
+ fsb = 100 * 1000;
+ else {
+ u8 fsb_code = (msr_lo >> 16) & 0x7;
+ switch (fsb_code) {
+ case 0:
+ fsb = 100 * 1000;
+ break;
+ case 1:
+ fsb = 13333 * 10;
+ break;
+ case 2:
+ fsb = 200 * 1000;
+ break;
+ }
+ }
+
+ if (!fsb) {
+ printk(KERN_DEBUG PFX "couldn't detect FSB speed. Please send an e-mail to <linux@brodo.de>\n");
+ printk(KERN_DEBUG PFX "P4 - MSR_EBC_FREQUENCY_ID: 0x%x 0x%x\n", msr_lo, msr_hi);
+ }
+
+ /* Multiplier. */
+ mult = msr_lo >> 24;
+
+ return (fsb * mult);
+}
+
+
static int cpufreq_p4_cpu_init(struct cpufreq_policy *policy)
{
@@ -192,15 +239,10 @@
has_N44_O17_errata[policy->cpu] = 1;
}
- /* get frequency */
- if (!stock_freq) {
- if (cpu_khz)
- stock_freq = cpu_khz;
- else {
- printk(KERN_INFO PFX "unknown core frequency - please use module parameter 'stock_freq'\n");
- return -EINVAL;
- }
- }
+ /* get max frequency */
+ stock_freq = cpufreq_p4_get_frequency(c);
+ if (!stock_freq)
+ return -EINVAL;
/* table init */
for (i=1; (p4clockmod_table[i].frequency != CPUFREQ_TABLE_END); i++) {
@@ -269,8 +311,6 @@
}
-MODULE_PARM(stock_freq, "i");
-
MODULE_AUTHOR ("Zwane Mwaikambo <zwane@commfireservices.com>");
MODULE_DESCRIPTION ("cpufreq driver for Pentium(TM) 4/Xeon(TM)");
MODULE_LICENSE ("GPL");
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2003-11-04 19:38 [PATCH] detect processor speed in p4-clockmod Dominik Brodowski
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