Commit f162ed11 authored by Dave Jones's avatar Dave Jones Committed by Dave Jones

[CPUFREQ] Detect CPU speed without relying on cpu_khz

parent b8030f26
......@@ -48,8 +48,7 @@ enum {
static int has_N44_O17_errata[NR_CPUS];
static int stock_freq;
static unsigned int stock_freq;
static int cpufreq_p4_setdc(unsigned int cpu, unsigned int newstate)
{
......@@ -175,6 +174,54 @@ static int cpufreq_p4_verify(struct cpufreq_policy *policy)
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 @@ static int cpufreq_p4_cpu_init(struct cpufreq_policy *policy)
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");
/* 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 @@ static void __exit cpufreq_p4_exit(void)
}
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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