From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dominik Brodowski Subject: [PATCH 5/8] p4_clockmod: detect speed without relying on cpu_khz or user input Date: Wed, 19 Nov 2003 19:32:28 +0100 Sender: cpufreq-bounces@www.linux.org.uk Message-ID: <20031119183228.GF20576@brodo.de> Mime-Version: 1.0 Return-path: Content-Disposition: inline List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: cpufreq-bounces@www.linux.org.uk Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: cpufreq@www.linux.org.uk, davej@codemonkey.org.uk Other cpufreq drivers don't rely on cpu_khz, but use the "decoded"/theoretical CPU frequency as base for all calculations. arch/i386/kernel/cpu/cpufreq/p4-clockmod.c | 66 +++++++++++++++++++++++------ 1 files changed, 53 insertions(+), 13 deletions(-) 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 2003-11-19 17:06:10.569869104 +0100 +++ linux/arch/i386/kernel/cpu/cpufreq/p4-clockmod.c 2003-11-19 18:18:53.114661488 +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 \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 \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 "); MODULE_DESCRIPTION ("cpufreq driver for Pentium(TM) 4/Xeon(TM)"); MODULE_LICENSE ("GPL");