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-rw-r--r--arch/sh/kernel/cpufreq.c218
1 files changed, 218 insertions, 0 deletions
diff --git a/arch/sh/kernel/cpufreq.c b/arch/sh/kernel/cpufreq.c
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+/*
+ * 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");
+