summaryrefslogtreecommitdiffstats
path: root/arch/unicore32/kernel/cpu-ucv2.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/unicore32/kernel/cpu-ucv2.c')
-rw-r--r--arch/unicore32/kernel/cpu-ucv2.c93
1 files changed, 93 insertions, 0 deletions
diff --git a/arch/unicore32/kernel/cpu-ucv2.c b/arch/unicore32/kernel/cpu-ucv2.c
new file mode 100644
index 000000000000..4a99f62584c7
--- /dev/null
+++ b/arch/unicore32/kernel/cpu-ucv2.c
@@ -0,0 +1,93 @@
+/*
+ * linux/arch/unicore32/kernel/cpu-ucv2.c: clock scaling for the UniCore-II
+ *
+ * Code specific to PKUnity SoC and UniCore ISA
+ *
+ * Maintained by GUAN Xue-tao <gxt@mprc.pku.edu.cn>
+ * Copyright (C) 2001-2010 Guan Xuetao
+ *
+ * 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.
+ */
+
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/init.h>
+#include <linux/clk.h>
+#include <linux/cpufreq.h>
+
+#include <mach/hardware.h>
+
+static struct cpufreq_driver ucv2_driver;
+
+/* make sure that only the "userspace" governor is run
+ * -- anything else wouldn't make sense on this platform, anyway.
+ */
+int ucv2_verify_speed(struct cpufreq_policy *policy)
+{
+ if (policy->cpu)
+ return -EINVAL;
+
+ cpufreq_verify_within_limits(policy,
+ policy->cpuinfo.min_freq, policy->cpuinfo.max_freq);
+
+ return 0;
+}
+
+static unsigned int ucv2_getspeed(unsigned int cpu)
+{
+ struct clk *mclk = clk_get(NULL, "MAIN_CLK");
+
+ if (cpu)
+ return 0;
+ return clk_get_rate(mclk)/1000;
+}
+
+static int ucv2_target(struct cpufreq_policy *policy,
+ unsigned int target_freq,
+ unsigned int relation)
+{
+ unsigned int cur = ucv2_getspeed(0);
+ struct cpufreq_freqs freqs;
+ struct clk *mclk = clk_get(NULL, "MAIN_CLK");
+
+ cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
+
+ if (!clk_set_rate(mclk, target_freq * 1000)) {
+ freqs.old = cur;
+ freqs.new = target_freq;
+ freqs.cpu = 0;
+ }
+
+ cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
+
+ return 0;
+}
+
+static int __init ucv2_cpu_init(struct cpufreq_policy *policy)
+{
+ if (policy->cpu != 0)
+ return -EINVAL;
+ policy->cur = ucv2_getspeed(0);
+ policy->min = policy->cpuinfo.min_freq = 250000;
+ policy->max = policy->cpuinfo.max_freq = 1000000;
+ policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
+ return 0;
+}
+
+static struct cpufreq_driver ucv2_driver = {
+ .flags = CPUFREQ_STICKY,
+ .verify = ucv2_verify_speed,
+ .target = ucv2_target,
+ .get = ucv2_getspeed,
+ .init = ucv2_cpu_init,
+ .name = "UniCore-II",
+};
+
+static int __init ucv2_cpufreq_init(void)
+{
+ return cpufreq_register_driver(&ucv2_driver);
+}
+
+arch_initcall(ucv2_cpufreq_init);