[CPUFREQ] Detect CPU speed without relying on cpu_khz

diff --git a/arch/i386/kernel/cpu/cpufreq/p4-clockmod.c b/arch/i386/kernel/cpu/cpufreq/p4-clockmod.c
index da3e11035e3a0ef73509b4df031bab1bf5653c1c..06cb5d7b4ba16ca4a875cdf72c6b7ec86adc6b32 100644 (file)
--- a/arch/i386/kernel/cpu/cpufreq/p4-clockmod.c
+++ b/arch/i386/kernel/cpu/cpufreq/p4-clockmod.c
@@ -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");
-                       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 @@ 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");