138 lines
2.7 KiB
C
138 lines
2.7 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* sc520_freq.c: cpufreq driver for the AMD Elan sc520
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*
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* Copyright (C) 2005 Sean Young <sean@mess.org>
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*
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* Based on elanfreq.c
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*
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* 2005-03-30: - initial revision
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/delay.h>
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#include <linux/cpufreq.h>
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#include <linux/timex.h>
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#include <linux/io.h>
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#include <asm/cpu_device_id.h>
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#include <asm/msr.h>
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#define MMCR_BASE 0xfffef000 /* The default base address */
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#define OFFS_CPUCTL 0x2 /* CPU Control Register */
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static __u8 __iomem *cpuctl;
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static struct cpufreq_frequency_table sc520_freq_table[] = {
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{0, 0x01, 100000},
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{0, 0x02, 133000},
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{0, 0, CPUFREQ_TABLE_END},
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};
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static unsigned int sc520_freq_get_cpu_frequency(unsigned int cpu)
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{
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u8 clockspeed_reg = *cpuctl;
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switch (clockspeed_reg & 0x03) {
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default:
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pr_err("error: cpuctl register has unexpected value %02x\n",
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clockspeed_reg);
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case 0x01:
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return 100000;
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case 0x02:
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return 133000;
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}
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}
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static int sc520_freq_target(struct cpufreq_policy *policy, unsigned int state)
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{
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u8 clockspeed_reg;
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local_irq_disable();
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clockspeed_reg = *cpuctl & ~0x03;
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*cpuctl = clockspeed_reg | sc520_freq_table[state].driver_data;
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local_irq_enable();
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return 0;
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}
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/*
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* Module init and exit code
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*/
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static int sc520_freq_cpu_init(struct cpufreq_policy *policy)
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{
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struct cpuinfo_x86 *c = &cpu_data(0);
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/* capability check */
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if (c->x86_vendor != X86_VENDOR_AMD ||
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c->x86 != 4 || c->x86_model != 9)
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return -ENODEV;
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/* cpuinfo and default policy values */
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policy->cpuinfo.transition_latency = 1000000; /* 1ms */
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policy->freq_table = sc520_freq_table;
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return 0;
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}
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static struct cpufreq_driver sc520_freq_driver = {
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.get = sc520_freq_get_cpu_frequency,
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.verify = cpufreq_generic_frequency_table_verify,
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.target_index = sc520_freq_target,
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.init = sc520_freq_cpu_init,
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.name = "sc520_freq",
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.attr = cpufreq_generic_attr,
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};
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static const struct x86_cpu_id sc520_ids[] = {
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{ X86_VENDOR_AMD, 4, 9 },
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{}
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};
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MODULE_DEVICE_TABLE(x86cpu, sc520_ids);
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static int __init sc520_freq_init(void)
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{
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int err;
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if (!x86_match_cpu(sc520_ids))
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return -ENODEV;
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cpuctl = ioremap((unsigned long)(MMCR_BASE + OFFS_CPUCTL), 1);
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if (!cpuctl) {
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pr_err("sc520_freq: error: failed to remap memory\n");
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return -ENOMEM;
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}
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err = cpufreq_register_driver(&sc520_freq_driver);
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if (err)
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iounmap(cpuctl);
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return err;
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}
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static void __exit sc520_freq_exit(void)
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{
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cpufreq_unregister_driver(&sc520_freq_driver);
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iounmap(cpuctl);
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}
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Sean Young <sean@mess.org>");
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MODULE_DESCRIPTION("cpufreq driver for AMD's Elan sc520 CPU");
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module_init(sc520_freq_init);
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module_exit(sc520_freq_exit);
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