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Diffstat (limited to 'kernel/drivers/cpufreq/at32ap-cpufreq.c')
-rw-r--r--kernel/drivers/cpufreq/at32ap-cpufreq.c127
1 files changed, 127 insertions, 0 deletions
diff --git a/kernel/drivers/cpufreq/at32ap-cpufreq.c b/kernel/drivers/cpufreq/at32ap-cpufreq.c
new file mode 100644
index 000000000..7b612c8bb
--- /dev/null
+++ b/kernel/drivers/cpufreq/at32ap-cpufreq.c
@@ -0,0 +1,127 @@
+/*
+ * 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 <linux/export.h>
+#include <linux/slab.h>
+
+static struct cpufreq_frequency_table *freq_table;
+
+static unsigned int ref_freq;
+static unsigned long loops_per_jiffy_ref;
+
+static int at32_set_target(struct cpufreq_policy *policy, unsigned int index)
+{
+ unsigned int old_freq, new_freq;
+
+ old_freq = policy->cur;
+ new_freq = freq_table[index].frequency;
+
+ if (!ref_freq) {
+ ref_freq = old_freq;
+ loops_per_jiffy_ref = boot_cpu_data.loops_per_jiffy;
+ }
+
+ if (old_freq < new_freq)
+ boot_cpu_data.loops_per_jiffy = cpufreq_scale(
+ loops_per_jiffy_ref, ref_freq, new_freq);
+ clk_set_rate(policy->clk, new_freq * 1000);
+ if (new_freq < old_freq)
+ boot_cpu_data.loops_per_jiffy = cpufreq_scale(
+ loops_per_jiffy_ref, ref_freq, new_freq);
+
+ return 0;
+}
+
+static int at32_cpufreq_driver_init(struct cpufreq_policy *policy)
+{
+ unsigned int frequency, rate, min_freq;
+ struct clk *cpuclk;
+ int retval, steps, i;
+
+ if (policy->cpu != 0)
+ return -EINVAL;
+
+ cpuclk = clk_get(NULL, "cpu");
+ if (IS_ERR(cpuclk)) {
+ pr_debug("cpufreq: could not get CPU clk\n");
+ retval = PTR_ERR(cpuclk);
+ goto out_err;
+ }
+
+ min_freq = (clk_round_rate(cpuclk, 1) + 500) / 1000;
+ frequency = (clk_round_rate(cpuclk, ~0UL) + 500) / 1000;
+ policy->cpuinfo.transition_latency = 0;
+
+ /*
+ * AVR32 CPU frequency rate scales in power of two between maximum and
+ * minimum, also add space for the table end marker.
+ *
+ * Further validate that the frequency is usable, and append it to the
+ * frequency table.
+ */
+ steps = fls(frequency / min_freq) + 1;
+ freq_table = kzalloc(steps * sizeof(struct cpufreq_frequency_table),
+ GFP_KERNEL);
+ if (!freq_table) {
+ retval = -ENOMEM;
+ goto out_err_put_clk;
+ }
+
+ for (i = 0; i < (steps - 1); i++) {
+ rate = clk_round_rate(cpuclk, frequency * 1000) / 1000;
+
+ if (rate != frequency)
+ freq_table[i].frequency = CPUFREQ_ENTRY_INVALID;
+ else
+ freq_table[i].frequency = frequency;
+
+ frequency /= 2;
+ }
+
+ policy->clk = cpuclk;
+ freq_table[steps - 1].frequency = CPUFREQ_TABLE_END;
+
+ retval = cpufreq_table_validate_and_show(policy, freq_table);
+ if (!retval) {
+ printk("cpufreq: AT32AP CPU frequency driver\n");
+ return 0;
+ }
+
+ kfree(freq_table);
+out_err_put_clk:
+ clk_put(cpuclk);
+out_err:
+ return retval;
+}
+
+static struct cpufreq_driver at32_driver = {
+ .name = "at32ap",
+ .init = at32_cpufreq_driver_init,
+ .verify = cpufreq_generic_frequency_table_verify,
+ .target_index = at32_set_target,
+ .get = cpufreq_generic_get,
+ .flags = CPUFREQ_STICKY,
+};
+
+static int __init at32_cpufreq_init(void)
+{
+ return cpufreq_register_driver(&at32_driver);
+}
+late_initcall(at32_cpufreq_init);