/* * sc520_freq.c: cpufreq driver for the AMD Elan sc520 * * Copyright (C) 2005 Sean Young <sean@mess.org> * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. * * Based on elanfreq.c * * 2005-03-30: - initial revision */ #include <linux/kernel.h> #include <linux/module.h> #include <linux/init.h> #include <linux/delay.h> #include <linux/cpufreq.h> #include <linux/timex.h> #include <linux/io.h> #include <asm/msr.h> #define MMCR_BASE 0xfffef000 /* The default base address */ #define OFFS_CPUCTL 0x2 /* CPU Control Register */ static __u8 __iomem *cpuctl; #define PFX "sc520_freq: " static struct cpufreq_frequency_table sc520_freq_table[] = { {0x01, 100000}, {0x02, 133000}, {0, CPUFREQ_TABLE_END}, }; static unsigned int sc520_freq_get_cpu_frequency(unsigned int cpu) { u8 clockspeed_reg = *cpuctl; switch (clockspeed_reg & 0x03) { default: printk(KERN_ERR PFX "error: cpuctl register has unexpected " "value %02x\n", clockspeed_reg); case 0x01: return 100000; case 0x02: return 133000; } } static void sc520_freq_set_cpu_state(unsigned int state) { struct cpufreq_freqs freqs; u8 clockspeed_reg; freqs.old = sc520_freq_get_cpu_frequency(0); freqs.new = sc520_freq_table[state].frequency; freqs.cpu = 0; /* AMD Elan is UP */ cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE); pr_debug("attempting to set frequency to %i kHz\n", sc520_freq_table[state].frequency); local_irq_disable(); clockspeed_reg = *cpuctl & ~0x03; *cpuctl = clockspeed_reg | sc520_freq_table[state].index; local_irq_enable(); cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE); }; static int sc520_freq_verify(struct cpufreq_policy *policy) { return cpufreq_frequency_table_verify(policy, &sc520_freq_table[0]); } static int sc520_freq_target(struct cpufreq_policy *policy, unsigned int target_freq, unsigned int relation) { unsigned int newstate = 0; if (cpufreq_frequency_table_target(policy, sc520_freq_table, target_freq, relation, &newstate)) return -EINVAL; sc520_freq_set_cpu_state(newstate); return 0; } /* * Module init and exit code */ static int sc520_freq_cpu_init(struct cpufreq_policy *policy) { struct cpuinfo_x86 *c = &cpu_data(0); int result; /* capability check */ if (c->x86_vendor != X86_VENDOR_AMD || c->x86 != 4 || c->x86_model != 9) return -ENODEV; /* cpuinfo and default policy values */ policy->cpuinfo.transition_latency = 1000000; /* 1ms */ policy->cur = sc520_freq_get_cpu_frequency(0); result = cpufreq_frequency_table_cpuinfo(policy, sc520_freq_table); if (result) return result; cpufreq_frequency_table_get_attr(sc520_freq_table, policy->cpu); return 0; } static int sc520_freq_cpu_exit(struct cpufreq_policy *policy) { cpufreq_frequency_table_put_attr(policy->cpu); return 0; } static struct freq_attr *sc520_freq_attr[] = { &cpufreq_freq_attr_scaling_available_freqs, NULL, }; static struct cpufreq_driver sc520_freq_driver = { .get = sc520_freq_get_cpu_frequency, .verify = sc520_freq_verify, .target = sc520_freq_target, .init = sc520_freq_cpu_init, .exit = sc520_freq_cpu_exit, .name = "sc520_freq", .owner = THIS_MODULE, .attr = sc520_freq_attr, }; static int __init sc520_freq_init(void) { struct cpuinfo_x86 *c = &cpu_data(0); int err; /* Test if we have the right hardware */ if (c->x86_vendor != X86_VENDOR_AMD || c->x86 != 4 || c->x86_model != 9) { pr_debug("no Elan SC520 processor found!\n"); return -ENODEV; } cpuctl = ioremap((unsigned long)(MMCR_BASE + OFFS_CPUCTL), 1); if (!cpuctl) { printk(KERN_ERR "sc520_freq: error: failed to remap memory\n"); return -ENOMEM; } err = cpufreq_register_driver(&sc520_freq_driver); if (err) iounmap(cpuctl); return err; } static void __exit sc520_freq_exit(void) { cpufreq_unregister_driver(&sc520_freq_driver); iounmap(cpuctl); } MODULE_LICENSE("GPL"); MODULE_AUTHOR("Sean Young <sean@mess.org>"); MODULE_DESCRIPTION("cpufreq driver for AMD's Elan sc520 CPU"); module_init(sc520_freq_init); module_exit(sc520_freq_exit);