[Blackfin] arch: Functional power management support: Add support for cpu frequency scaling

Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>

1 files changed, 194 insertions, 0 deletions

diff --git a/arch/blackfin/mach-common/cpufreq.c b/arch/blackfin/mach-common/cpufreq.c
new file mode 100644
index 00000000000..ed81e00d20e
--- /dev/null
+++ b/arch/blackfin/mach-common/cpufreq.c
@@ -0,0 +1,194 @@
+/*
+ * File:	 arch/blackfin/mach-common/cpufreq.c
+ * Based on:
+ * Author:
+ *
+ * Created:
+ * Description:	 Blackfin core clock scaling
+ *
+ * Modified:
+ *		 Copyright 2004-2008 Analog Devices Inc.
+ *
+ * Bugs:	 Enter bugs at http://blackfin.uclinux.org/
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see the file COPYING, or write
+ * to the Free Software Foundation, Inc.,
+ * 51 Franklin St, Fifth Floor, Boston, MA	02110-1301	USA
+ */
+
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/init.h>
+#include <linux/cpufreq.h>
+#include <linux/fs.h>
+#include <asm/blackfin.h>
+#include <asm/time.h>
+
+
+/* this is the table of CCLK frequencies, in Hz */
+/* .index is the entry in the auxillary dpm_state_table[] */
+static struct cpufreq_frequency_table bfin_freq_table[] = {
+	{
+		.frequency = CPUFREQ_TABLE_END,
+		.index = 0,
+	},
+	{
+		.frequency = CPUFREQ_TABLE_END,
+		.index = 1,
+	},
+	{
+		.frequency = CPUFREQ_TABLE_END,
+		.index = 2,
+	},
+	{
+		.frequency = CPUFREQ_TABLE_END,
+		.index = 0,
+	},
+};
+
+static struct bfin_dpm_state {
+	unsigned int csel; /* system clock divider */
+	unsigned int tscale; /* change the divider on the core timer interrupt */
+} dpm_state_table[3];
+
+/**************************************************************************/
+
+static unsigned int bfin_getfreq(unsigned int cpu)
+{
+	/* The driver only support single cpu */
+	if (cpu != 0)
+		return -1;
+
+	return get_cclk();
+}
+
+
+static int bfin_target(struct cpufreq_policy *policy,
+			unsigned int target_freq, unsigned int relation)
+{
+	unsigned int index, plldiv, tscale;
+	unsigned long flags, cclk_hz;
+	struct cpufreq_freqs freqs;
+
+	if (cpufreq_frequency_table_target(policy, bfin_freq_table,
+		 target_freq, relation, &index))
+		return -EINVAL;
+
+	cclk_hz = bfin_freq_table[index].frequency;
+
+	freqs.old = bfin_getfreq(0);
+	freqs.new = cclk_hz;
+	freqs.cpu = 0;
+
+	pr_debug("cpufreq: changing cclk to %lu; target = %u, oldfreq = %u\n",
+		 cclk_hz, target_freq, freqs.old);
+
+	cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
+	local_irq_save(flags);
+		plldiv = (bfin_read_PLL_DIV() & SSEL) | dpm_state_table[index].csel;
+		tscale = dpm_state_table[index].tscale;
+		bfin_write_PLL_DIV(plldiv);
+		/* we have to adjust the core timer, because it is using cclk */
+		bfin_write_TSCALE(tscale);
+		SSYNC();
+	local_irq_restore(flags);
+	cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
+
+	return 0;
+}
+
+static int bfin_verify_speed(struct cpufreq_policy *policy)
+{
+	return cpufreq_frequency_table_verify(policy, bfin_freq_table);
+}
+
+static int __init __bfin_cpu_init(struct cpufreq_policy *policy)
+{
+
+	unsigned long cclk, sclk, csel, min_cclk;
+	int index;
+
+#ifdef CONFIG_CYCLES_CLOCKSOURCE
+/*
+ * Clocksource CYCLES is still CONTINUOUS but not longer MONOTONIC in case we enable
+ * CPU frequency scaling, since CYCLES runs off Core Clock.
+ */
+	printk(KERN_WARNING "CPU frequency scaling not supported: Clocksource not suitable\n"
+		return -ENODEV;
+#endif
+
+	if (policy->cpu != 0)
+		return -EINVAL;
+
+	cclk = get_cclk();
+	sclk = get_sclk();
+
+#if ANOMALY_05000273
+	min_cclk = sclk * 2;
+#else
+	min_cclk = sclk;
+#endif
+	csel = ((bfin_read_PLL_DIV() & CSEL) >> 4);
+
+	for (index = 0;  (cclk >> index) >= min_cclk && csel <= 3; index++, csel++) {
+		bfin_freq_table[index].frequency = cclk >> index;
+		dpm_state_table[index].csel = csel << 4; /* Shift now into PLL_DIV bitpos */
+		dpm_state_table[index].tscale =  (TIME_SCALE / (1 << csel)) - 1;
+
+		pr_debug("cpufreq: freq:%d csel:%d tscale:%d\n",
+						 bfin_freq_table[index].frequency,
+						 dpm_state_table[index].csel,
+						 dpm_state_table[index].tscale);
+	}
+
+	policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
+
+	policy->cpuinfo.transition_latency = (bfin_read_PLL_LOCKCNT() / (sclk / 1000000)) * 1000;
+	/*Now ,only support one cpu */
+	policy->cur = cclk;
+	cpufreq_frequency_table_get_attr(bfin_freq_table, policy->cpu);
+	return cpufreq_frequency_table_cpuinfo(policy, bfin_freq_table);
+}
+
+static struct freq_attr *bfin_freq_attr[] = {
+	&cpufreq_freq_attr_scaling_available_freqs,
+	NULL,
+};
+
+static struct cpufreq_driver bfin_driver = {
+	.verify = bfin_verify_speed,
+	.target = bfin_target,
+	.get = bfin_getfreq,
+	.init = __bfin_cpu_init,
+	.name = "bfin cpufreq",
+	.owner = THIS_MODULE,
+	.attr = bfin_freq_attr,
+};
+
+static int __init bfin_cpu_init(void)
+{
+	return cpufreq_register_driver(&bfin_driver);
+}
+
+static void __exit bfin_cpu_exit(void)
+{
+	cpufreq_unregister_driver(&bfin_driver);
+}
+
+MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
+MODULE_DESCRIPTION("cpufreq driver for Blackfin");
+MODULE_LICENSE("GPL");
+
+module_init(bfin_cpu_init);
+module_exit(bfin_cpu_exit);