diff options
Diffstat (limited to 'drivers/cpufreq/sc520_freq.c')
| -rw-r--r-- | drivers/cpufreq/sc520_freq.c | 192 |
1 files changed, 192 insertions, 0 deletions
diff --git a/drivers/cpufreq/sc520_freq.c b/drivers/cpufreq/sc520_freq.c new file mode 100644 index 00000000000..1e205e6b172 --- /dev/null +++ b/drivers/cpufreq/sc520_freq.c @@ -0,0 +1,192 @@ +/* + * 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); + |