davinci: add generic CPUFreq driver for DaVinci

Adds a basic CPUFreq driver for DaVinci devices registering with the
kernel CPUFreq infrastructure.

Support is added for both frequency and voltage regulation.

Signed-off-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>

1 files changed, 219 insertions, 0 deletions

diff --git a/arch/arm/mach-davinci/cpufreq.c b/arch/arm/mach-davinci/cpufreq.c
new file mode 100644
index 000000000000..8c8c07b12d87
--- /dev/null
+++ b/arch/arm/mach-davinci/cpufreq.c
@@ -0,0 +1,219 @@
+/*
+ * CPU frequency scaling for DaVinci
+ *
+ * Copyright (C) 2009 Texas Instruments Incorporated - http://www.ti.com/
+ *
+ * Based on linux/arch/arm/plat-omap/cpu-omap.c. Original Copyright follows:
+ *
+ *  Copyright (C) 2005 Nokia Corporation
+ *  Written by Tony Lindgren <tony@atomide.com>
+ *
+ *  Based on cpu-sa1110.c, Copyright (C) 2001 Russell King
+ *
+ * Copyright (C) 2007-2008 Texas Instruments, Inc.
+ * Updated to support OMAP3
+ * Rajendra Nayak <rnayak@ti.com>
+ *
+ * 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/types.h>
+#include <linux/cpufreq.h>
+#include <linux/init.h>
+#include <linux/err.h>
+#include <linux/clk.h>
+#include <linux/platform_device.h>
+
+#include <mach/hardware.h>
+#include <mach/cpufreq.h>
+#include <mach/common.h>
+
+#include "clock.h"
+
+struct davinci_cpufreq {
+	struct device *dev;
+	struct clk *armclk;
+};
+static struct davinci_cpufreq cpufreq;
+
+static int davinci_verify_speed(struct cpufreq_policy *policy)
+{
+	struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
+	struct cpufreq_frequency_table *freq_table = pdata->freq_table;
+	struct clk *armclk = cpufreq.armclk;
+
+	if (freq_table)
+		return cpufreq_frequency_table_verify(policy, freq_table);
+
+	if (policy->cpu)
+		return -EINVAL;
+
+	cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
+				     policy->cpuinfo.max_freq);
+
+	policy->min = clk_round_rate(armclk, policy->min * 1000) / 1000;
+	policy->max = clk_round_rate(armclk, policy->max * 1000) / 1000;
+	cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
+						policy->cpuinfo.max_freq);
+	return 0;
+}
+
+static unsigned int davinci_getspeed(unsigned int cpu)
+{
+	if (cpu)
+		return 0;
+
+	return clk_get_rate(cpufreq.armclk) / 1000;
+}
+
+static int davinci_target(struct cpufreq_policy *policy,
+				unsigned int target_freq, unsigned int relation)
+{
+	int ret = 0;
+	unsigned int idx;
+	struct cpufreq_freqs freqs;
+	struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
+	struct clk *armclk = cpufreq.armclk;
+
+	/*
+	 * Ensure desired rate is within allowed range.  Some govenors
+	 * (ondemand) will just pass target_freq=0 to get the minimum.
+	 */
+	if (target_freq < policy->cpuinfo.min_freq)
+		target_freq = policy->cpuinfo.min_freq;
+	if (target_freq > policy->cpuinfo.max_freq)
+		target_freq = policy->cpuinfo.max_freq;
+
+	freqs.old = davinci_getspeed(0);
+	freqs.new = clk_round_rate(armclk, target_freq * 1000) / 1000;
+	freqs.cpu = 0;
+
+	if (freqs.old == freqs.new)
+		return ret;
+
+	cpufreq_debug_printk(CPUFREQ_DEBUG_DRIVER,
+			dev_driver_string(cpufreq.dev),
+			"transition: %u --> %u\n", freqs.old, freqs.new);
+
+	ret = cpufreq_frequency_table_target(policy, pdata->freq_table,
+						freqs.new, relation, &idx);
+	if (ret)
+		return -EINVAL;
+
+	cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
+
+	/* if moving to higher frequency, up the voltage beforehand */
+	if (pdata->set_voltage && freqs.new > freqs.old)
+		pdata->set_voltage(idx);
+
+	ret = clk_set_rate(armclk, idx);
+
+	/* if moving to lower freq, lower the voltage after lowering freq */
+	if (pdata->set_voltage && freqs.new < freqs.old)
+		pdata->set_voltage(idx);
+
+	cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
+
+	return ret;
+}
+
+static int __init davinci_cpu_init(struct cpufreq_policy *policy)
+{
+	int result = 0;
+	struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
+	struct cpufreq_frequency_table *freq_table = pdata->freq_table;
+
+	if (policy->cpu != 0)
+		return -EINVAL;
+
+	policy->cur = policy->min = policy->max = davinci_getspeed(0);
+
+	if (freq_table) {
+		result = cpufreq_frequency_table_cpuinfo(policy, freq_table);
+		if (!result)
+			cpufreq_frequency_table_get_attr(freq_table,
+							policy->cpu);
+	} else {
+		policy->cpuinfo.min_freq = policy->min;
+		policy->cpuinfo.max_freq = policy->max;
+	}
+
+	policy->min = policy->cpuinfo.min_freq;
+	policy->max = policy->cpuinfo.max_freq;
+	policy->cur = davinci_getspeed(0);
+
+	/*
+	 * Time measurement across the target() function yields ~1500-1800us
+	 * time taken with no drivers on notification list.
+	 * Setting the latency to 2000 us to accomodate addition of drivers
+	 * to pre/post change notification list.
+	 */
+	policy->cpuinfo.transition_latency = 2000 * 1000;
+	return 0;
+}
+
+static int davinci_cpu_exit(struct cpufreq_policy *policy)
+{
+	cpufreq_frequency_table_put_attr(policy->cpu);
+	return 0;
+}
+
+static struct freq_attr *davinci_cpufreq_attr[] = {
+	&cpufreq_freq_attr_scaling_available_freqs,
+	NULL,
+};
+
+static struct cpufreq_driver davinci_driver = {
+	.flags		= CPUFREQ_STICKY,
+	.verify		= davinci_verify_speed,
+	.target		= davinci_target,
+	.get		= davinci_getspeed,
+	.init		= davinci_cpu_init,
+	.exit		= davinci_cpu_exit,
+	.name		= "davinci",
+	.attr		= davinci_cpufreq_attr,
+};
+
+static int __init davinci_cpufreq_probe(struct platform_device *pdev)
+{
+	struct davinci_cpufreq_config *pdata = pdev->dev.platform_data;
+
+	if (!pdata)
+		return -EINVAL;
+	if (!pdata->freq_table)
+		return -EINVAL;
+
+	cpufreq.dev = &pdev->dev;
+
+	cpufreq.armclk = clk_get(NULL, "arm");
+	if (IS_ERR(cpufreq.armclk)) {
+		dev_err(cpufreq.dev, "Unable to get ARM clock\n");
+		return PTR_ERR(cpufreq.armclk);
+	}
+
+	return cpufreq_register_driver(&davinci_driver);
+}
+
+static int __exit davinci_cpufreq_remove(struct platform_device *pdev)
+{
+	clk_put(cpufreq.armclk);
+
+	return cpufreq_unregister_driver(&davinci_driver);
+}
+
+static struct platform_driver davinci_cpufreq_driver = {
+	.driver = {
+		.name	 = "cpufreq-davinci",
+		.owner	 = THIS_MODULE,
+	},
+	.remove = __exit_p(davinci_cpufreq_remove),
+};
+
+static int __init davinci_cpufreq_init(void)
+{
+	return platform_driver_probe(&davinci_cpufreq_driver,
+							davinci_cpufreq_probe);
+}
+late_initcall(davinci_cpufreq_init);
+