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Diffstat (limited to 'arch/sh/kernel/cpufreq.c')
| -rw-r--r-- | arch/sh/kernel/cpufreq.c | 218 |
1 files changed, 218 insertions, 0 deletions
diff --git a/arch/sh/kernel/cpufreq.c b/arch/sh/kernel/cpufreq.c new file mode 100644 index 00000000000..e0b384bef55 --- /dev/null +++ b/arch/sh/kernel/cpufreq.c @@ -0,0 +1,218 @@ +/* + * arch/sh/kernel/cpufreq.c + * + * cpufreq driver for the SuperH processors. + * + * Copyright (C) 2002, 2003, 2004, 2005 Paul Mundt + * Copyright (C) 2002 M. R. Brown + * + * 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. + */ +#include <linux/types.h> +#include <linux/cpufreq.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/slab.h> +#include <linux/init.h> +#include <linux/delay.h> +#include <linux/cpumask.h> +#include <linux/smp.h> + +#include <asm/processor.h> +#include <asm/watchdog.h> +#include <asm/freq.h> +#include <asm/io.h> + +/* + * For SuperH, each policy change requires that we change the IFC, BFC, and + * PFC at the same time. Here we define sane values that won't trash the + * system. + * + * Note the max set is computed at runtime, we use the divisors that we booted + * with to setup our maximum operating frequencies. + */ +struct clock_set { + unsigned int ifc; + unsigned int bfc; + unsigned int pfc; +} clock_sets[] = { +#if defined(CONFIG_CPU_SH3) || defined(CONFIG_CPU_SH2) + { 0, 0, 0 }, /* not implemented yet */ +#elif defined(CONFIG_CPU_SH4) + { 4, 8, 8 }, /* min - IFC: 1/4, BFC: 1/8, PFC: 1/8 */ + { 1, 2, 2 }, /* max - IFC: 1, BFC: 1/2, PFC: 1/2 */ +#endif +}; + +#define MIN_CLOCK_SET 0 +#define MAX_CLOCK_SET (ARRAY_SIZE(clock_sets) - 1) + +/* + * For the time being, we only support two frequencies, which in turn are + * aimed at the POWERSAVE and PERFORMANCE policies, which in turn are derived + * directly from the respective min/max clock sets. Technically we could + * support a wider range of frequencies, but these vary far too much for each + * CPU subtype (and we'd have to construct a frequency table for each subtype). + * + * Maybe something to implement in the future.. + */ +#define SH_FREQ_MAX 0 +#define SH_FREQ_MIN 1 + +static struct cpufreq_frequency_table sh_freqs[] = { + { SH_FREQ_MAX, 0 }, + { SH_FREQ_MIN, 0 }, + { 0, CPUFREQ_TABLE_END }, +}; + +static void sh_cpufreq_update_clocks(unsigned int set) +{ + current_cpu_data.cpu_clock = current_cpu_data.master_clock / clock_sets[set].ifc; + current_cpu_data.bus_clock = current_cpu_data.master_clock / clock_sets[set].bfc; + current_cpu_data.module_clock = current_cpu_data.master_clock / clock_sets[set].pfc; + current_cpu_data.loops_per_jiffy = loops_per_jiffy; +} + +/* XXX: This needs to be split out per CPU and CPU subtype. */ +/* + * Here we notify other drivers of the proposed change and the final change. + */ +static int sh_cpufreq_setstate(unsigned int cpu, unsigned int set) +{ + unsigned short frqcr = ctrl_inw(FRQCR); + cpumask_t cpus_allowed; + struct cpufreq_freqs freqs; + + if (!cpu_online(cpu)) + return -ENODEV; + + cpus_allowed = current->cpus_allowed; + set_cpus_allowed(current, cpumask_of_cpu(cpu)); + + BUG_ON(smp_processor_id() != cpu); + + freqs.cpu = cpu; + freqs.old = current_cpu_data.cpu_clock / 1000; + freqs.new = (current_cpu_data.master_clock / clock_sets[set].ifc) / 1000; + + cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE); +#if defined(CONFIG_CPU_SH3) + frqcr |= (newstate & 0x4000) << 14; + frqcr |= (newstate & 0x000c) << 2; +#elif defined(CONFIG_CPU_SH4) + /* + * FRQCR.PLL2EN is 1, we need to allow the PLL to stabilize by + * initializing the WDT. + */ + if (frqcr & (1 << 9)) { + __u8 csr; + + /* + * Set the overflow period to the highest available, + * in this case a 1/4096 division ratio yields a 5.25ms + * overflow period. See asm-sh/watchdog.h for more + * information and a range of other divisors. + */ + csr = sh_wdt_read_csr(); + csr |= WTCSR_CKS_4096; + sh_wdt_write_csr(csr); + + sh_wdt_write_cnt(0); + } + frqcr &= 0x0e00; /* Clear ifc, bfc, pfc */ + frqcr |= get_ifc_value(clock_sets[set].ifc) << 6; + frqcr |= get_bfc_value(clock_sets[set].bfc) << 3; + frqcr |= get_pfc_value(clock_sets[set].pfc); +#endif + ctrl_outw(frqcr, FRQCR); + sh_cpufreq_update_clocks(set); + + set_cpus_allowed(current, cpus_allowed); + cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE); + + return 0; +} + +static int sh_cpufreq_cpu_init(struct cpufreq_policy *policy) +{ + unsigned int min_freq, max_freq; + unsigned int ifc, bfc, pfc; + + if (!cpu_online(policy->cpu)) + return -ENODEV; + + /* Update our maximum clock set */ + get_current_frequency_divisors(&ifc, &bfc, &pfc); + clock_sets[MAX_CLOCK_SET].ifc = ifc; + clock_sets[MAX_CLOCK_SET].bfc = bfc; + clock_sets[MAX_CLOCK_SET].pfc = pfc; + + /* Convert from Hz to kHz */ + max_freq = current_cpu_data.cpu_clock / 1000; + min_freq = (current_cpu_data.master_clock / clock_sets[MIN_CLOCK_SET].ifc) / 1000; + + sh_freqs[SH_FREQ_MAX].frequency = max_freq; + sh_freqs[SH_FREQ_MIN].frequency = min_freq; + + /* cpuinfo and default policy values */ + policy->governor = CPUFREQ_DEFAULT_GOVERNOR; + policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL; + policy->cur = max_freq; + + return cpufreq_frequency_table_cpuinfo(policy, &sh_freqs[0]); +} + +static int sh_cpufreq_verify(struct cpufreq_policy *policy) +{ + return cpufreq_frequency_table_verify(policy, &sh_freqs[0]); +} + +static int sh_cpufreq_target(struct cpufreq_policy *policy, + unsigned int target_freq, + unsigned int relation) +{ + unsigned int set, idx = 0; + + if (cpufreq_frequency_table_target(policy, &sh_freqs[0], target_freq, relation, &idx)) + return -EINVAL; + + set = (idx == SH_FREQ_MIN) ? MIN_CLOCK_SET : MAX_CLOCK_SET; + + sh_cpufreq_setstate(policy->cpu, set); + + return 0; +} + +static struct cpufreq_driver sh_cpufreq_driver = { + .owner = THIS_MODULE, + .name = "SH cpufreq", + .init = sh_cpufreq_cpu_init, + .verify = sh_cpufreq_verify, + .target = sh_cpufreq_target, +}; + +static int __init sh_cpufreq_init(void) +{ + if (!current_cpu_data.cpu_clock) + return -EINVAL; + if (cpufreq_register_driver(&sh_cpufreq_driver)) + return -EINVAL; + + return 0; +} + +static void __exit sh_cpufreq_exit(void) +{ + cpufreq_unregister_driver(&sh_cpufreq_driver); +} + +module_init(sh_cpufreq_init); +module_exit(sh_cpufreq_exit); + +MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>"); +MODULE_DESCRIPTION("cpufreq driver for SuperH"); +MODULE_LICENSE("GPL"); + |