/* * Copyright (C) 2004-2007 Atmel Corporation * * Based on MIPS implementation arch/mips/kernel/time.c * Copyright 2001 MontaVista Software Inc. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ /*#define DEBUG*/ #include <linux/kernel.h> #include <linux/types.h> #include <linux/init.h> #include <linux/cpufreq.h> #include <linux/io.h> #include <linux/clk.h> #include <linux/err.h> #include <asm/system.h> static struct clk *cpuclk; static int at32_verify_speed(struct cpufreq_policy *policy) { if (policy->cpu != 0) return -EINVAL; cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq, policy->cpuinfo.max_freq); return 0; } static unsigned int at32_get_speed(unsigned int cpu) { /* No SMP support */ if (cpu) return 0; return (unsigned int)((clk_get_rate(cpuclk) + 500) / 1000); } static unsigned int ref_freq; static unsigned long loops_per_jiffy_ref; static int at32_set_target(struct cpufreq_policy *policy, unsigned int target_freq, unsigned int relation) { struct cpufreq_freqs freqs; long freq; /* Convert target_freq from kHz to Hz */ freq = clk_round_rate(cpuclk, target_freq * 1000); /* Check if policy->min <= new_freq <= policy->max */ if(freq < (policy->min * 1000) || freq > (policy->max * 1000)) return -EINVAL; pr_debug("cpufreq: requested frequency %u Hz\n", target_freq * 1000); freqs.old = at32_get_speed(0); freqs.new = (freq + 500) / 1000; freqs.cpu = 0; freqs.flags = 0; if (!ref_freq) { ref_freq = freqs.old; loops_per_jiffy_ref = boot_cpu_data.loops_per_jiffy; } cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE); if (freqs.old < freqs.new) boot_cpu_data.loops_per_jiffy = cpufreq_scale( loops_per_jiffy_ref, ref_freq, freqs.new); clk_set_rate(cpuclk, freq); if (freqs.new < freqs.old) boot_cpu_data.loops_per_jiffy = cpufreq_scale( loops_per_jiffy_ref, ref_freq, freqs.new); cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE); pr_debug("cpufreq: set frequency %lu Hz\n", freq); return 0; } static int __init at32_cpufreq_driver_init(struct cpufreq_policy *policy) { if (policy->cpu != 0) return -EINVAL; cpuclk = clk_get(NULL, "cpu"); if (IS_ERR(cpuclk)) { pr_debug("cpufreq: could not get CPU clk\n"); return PTR_ERR(cpuclk); } policy->cpuinfo.min_freq = (clk_round_rate(cpuclk, 1) + 500) / 1000; policy->cpuinfo.max_freq = (clk_round_rate(cpuclk, ~0UL) + 500) / 1000; policy->cpuinfo.transition_latency = 0; policy->cur = at32_get_speed(0); policy->min = policy->cpuinfo.min_freq; policy->max = policy->cpuinfo.max_freq; printk("cpufreq: AT32AP CPU frequency driver\n"); return 0; } static struct cpufreq_driver at32_driver = { .name = "at32ap", .owner = THIS_MODULE, .init = at32_cpufreq_driver_init, .verify = at32_verify_speed, .target = at32_set_target, .get = at32_get_speed, .flags = CPUFREQ_STICKY, }; static int __init at32_cpufreq_init(void) { return cpufreq_register_driver(&at32_driver); } late_initcall(at32_cpufreq_init);