1/*
  2 * Copyright (C) 2004-2007 Atmel Corporation
  3 *
  4 * Based on MIPS implementation arch/mips/kernel/time.c
  5 *   Copyright 2001 MontaVista Software Inc.
  6 *
  7 * This program is free software; you can redistribute it and/or modify
  8 * it under the terms of the GNU General Public License version 2 as
  9 * published by the Free Software Foundation.
 10 */
 11
 12/*#define DEBUG*/
 13
 14#include <linux/kernel.h>
 15#include <linux/types.h>
 16#include <linux/init.h>
 17#include <linux/cpufreq.h>
 18#include <linux/io.h>
 19#include <linux/clk.h>
 20#include <linux/err.h>
 21#include <linux/export.h>
 22#include <linux/slab.h>
 23
 24static struct cpufreq_frequency_table *freq_table;
 25
 26static unsigned int	ref_freq;
 27static unsigned long	loops_per_jiffy_ref;
 28
 29static int at32_set_target(struct cpufreq_policy *policy, unsigned int index)
 30{
 31	unsigned int old_freq, new_freq;
 32
 33	old_freq = policy->cur;
 34	new_freq = freq_table[index].frequency;
 35
 36	if (!ref_freq) {
 37		ref_freq = old_freq;
 38		loops_per_jiffy_ref = boot_cpu_data.loops_per_jiffy;
 39	}
 40
 41	if (old_freq < new_freq)
 42		boot_cpu_data.loops_per_jiffy = cpufreq_scale(
 43				loops_per_jiffy_ref, ref_freq, new_freq);
 44	clk_set_rate(policy->clk, new_freq * 1000);
 45	if (new_freq < old_freq)
 46		boot_cpu_data.loops_per_jiffy = cpufreq_scale(
 47				loops_per_jiffy_ref, ref_freq, new_freq);
 48
 49	return 0;
 50}
 51
 52static int at32_cpufreq_driver_init(struct cpufreq_policy *policy)
 53{
 54	unsigned int frequency, rate, min_freq;
 55	struct clk *cpuclk;
 56	int retval, steps, i;
 57
 58	if (policy->cpu != 0)
 59		return -EINVAL;
 60
 61	cpuclk = clk_get(NULL, "cpu");
 62	if (IS_ERR(cpuclk)) {
 63		pr_debug("cpufreq: could not get CPU clk\n");
 64		retval = PTR_ERR(cpuclk);
 65		goto out_err;
 66	}
 67
 68	min_freq = (clk_round_rate(cpuclk, 1) + 500) / 1000;
 69	frequency = (clk_round_rate(cpuclk, ~0UL) + 500) / 1000;
 70	policy->cpuinfo.transition_latency = 0;
 71
 72	/*
 73	 * AVR32 CPU frequency rate scales in power of two between maximum and
 74	 * minimum, also add space for the table end marker.
 75	 *
 76	 * Further validate that the frequency is usable, and append it to the
 77	 * frequency table.
 78	 */
 79	steps = fls(frequency / min_freq) + 1;
 80	freq_table = kzalloc(steps * sizeof(struct cpufreq_frequency_table),
 81			GFP_KERNEL);
 82	if (!freq_table) {
 83		retval = -ENOMEM;
 84		goto out_err_put_clk;
 85	}
 86
 87	for (i = 0; i < (steps - 1); i++) {
 88		rate = clk_round_rate(cpuclk, frequency * 1000) / 1000;
 89
 90		if (rate != frequency)
 91			freq_table[i].frequency = CPUFREQ_ENTRY_INVALID;
 92		else
 93			freq_table[i].frequency = frequency;
 94
 95		frequency /= 2;
 96	}
 97
 98	policy->clk = cpuclk;
 99	freq_table[steps - 1].frequency = CPUFREQ_TABLE_END;
100
101	retval = cpufreq_table_validate_and_show(policy, freq_table);
102	if (!retval) {
103		printk("cpufreq: AT32AP CPU frequency driver\n");
104		return 0;
105	}
106
107	kfree(freq_table);
108out_err_put_clk:
109	clk_put(cpuclk);
110out_err:
111	return retval;
112}
113
114static struct cpufreq_driver at32_driver = {
115	.name		= "at32ap",
116	.init		= at32_cpufreq_driver_init,
117	.verify		= cpufreq_generic_frequency_table_verify,
118	.target_index	= at32_set_target,
119	.get		= cpufreq_generic_get,
120	.flags		= CPUFREQ_STICKY,
121};
122
123static int __init at32_cpufreq_init(void)
124{
125	return cpufreq_register_driver(&at32_driver);
126}
127late_initcall(at32_cpufreq_init);