// SPDX-License-Identifier: GPL-2.0-or-later /* * sc520_freq.c: cpufreq driver for the AMD Elan sc520 * * Copyright (C) 2005 Sean Young <sean@mess.org> * * Based on elanfreq.c * * 2005-03-30: - initial revision */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #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/cpu_device_id.h> #include <asm/msr.h> #define MMCR_BASE 0xfffef000 /* The default base address */ #define OFFS_CPUCTL 0x2 /* CPU Control Register */ static __u8 __iomem *cpuctl; static struct cpufreq_frequency_table sc520_freq_table[] = { {0, 0x01, 100000}, {0, 0x02, 133000}, {0, 0, CPUFREQ_TABLE_END}, }; static unsigned int sc520_freq_get_cpu_frequency(unsigned int cpu) { u8 clockspeed_reg = *cpuctl; switch (clockspeed_reg & 0x03) { default: pr_err("error: cpuctl register has unexpected value %02x\n", clockspeed_reg); case 0x01: return 100000; case 0x02: return 133000; } } static int sc520_freq_target(struct cpufreq_policy *policy, unsigned int state) { u8 clockspeed_reg; local_irq_disable(); clockspeed_reg = *cpuctl & ~0x03; *cpuctl = clockspeed_reg | sc520_freq_table[state].driver_data; local_irq_enable(); return 0; } /* * Module init and exit code */ static int sc520_freq_cpu_init(struct cpufreq_policy *policy) { struct cpuinfo_x86 *c = &cpu_data(0); /* 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->freq_table = sc520_freq_table; return 0; } static struct cpufreq_driver sc520_freq_driver = { .get = sc520_freq_get_cpu_frequency, .verify = cpufreq_generic_frequency_table_verify, .target_index = sc520_freq_target, .init = sc520_freq_cpu_init, .name = "sc520_freq", .attr = cpufreq_generic_attr, }; static const struct x86_cpu_id sc520_ids[] = { X86_MATCH_VENDOR_FAM_MODEL(AMD, 4, 9, NULL), {} }; MODULE_DEVICE_TABLE(x86cpu, sc520_ids); static int __init sc520_freq_init(void) { int err; if (!x86_match_cpu(sc520_ids)) return -ENODEV; cpuctl = ioremap((unsigned long)(MMCR_BASE + OFFS_CPUCTL), 1); if (!cpuctl) { pr_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);