i.MX27: add cpu frequency scaling support

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

3 files changed, 155 insertions, 1 deletions

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 2599b277743..7014f50da6f 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1241,7 +1241,7 @@ endmenu
 
 menu "CPU Power Management"
 
-if (ARCH_SA1100 || ARCH_INTEGRATOR || ARCH_OMAP || ARCH_PXA || ARCH_S3C64XX)
+if (ARCH_SA1100 || ARCH_INTEGRATOR || ARCH_OMAP || ARCH_PXA || ARCH_S3C64XX || MACH_MX27)
 
 source "drivers/cpufreq/Kconfig"
 
diff --git a/arch/arm/mach-mx2/Makefile b/arch/arm/mach-mx2/Makefile
index b9b1cca4e9b..a7e2f5264bc 100644
--- a/arch/arm/mach-mx2/Makefile
+++ b/arch/arm/mach-mx2/Makefile
@@ -12,6 +12,11 @@ obj-$(CONFIG_MACH_MX27) += cpu_imx27.o
 obj-$(CONFIG_MACH_MX27) += clock_imx27.o
 
 obj-$(CONFIG_MACH_MX21ADS) += mx21ads.o
+
+ifeq ($(CONFIG_CPU_FREQ),y)
+obj-$(CONFIG_MACH_MX27) += cpufreq_imx27.o
+endif
+
 obj-$(CONFIG_MACH_MX27ADS) += mx27ads.o
 obj-$(CONFIG_MACH_PCM038) += pcm038.o
 obj-$(CONFIG_MACH_PCM970_BASEBOARD) += pcm970-baseboard.o
diff --git a/arch/arm/mach-mx2/cpufreq_imx27.c b/arch/arm/mach-mx2/cpufreq_imx27.c
new file mode 100644
index 00000000000..db6ad6b7577
--- /dev/null
+++ b/arch/arm/mach-mx2/cpufreq_imx27.c
@@ -0,0 +1,149 @@
+/*
+ *  linux/arch/arm/mach-mx2/cpufreq.c
+ *
+ *  Copyright (C) 2009 Sascha Hauer, Pengutronix
+ *
+ * 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, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/init.h>
+#include <linux/cpufreq.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <mach/hardware.h>
+
+static struct cpufreq_frequency_table mx27_freq_table[4 + 1];
+
+static struct clk *clk_cpu, *clk_mpll;
+static unsigned long mpll_rate;
+
+static int mx27_verify_policy(struct cpufreq_policy *policy)
+{	return cpufreq_frequency_table_verify(policy, mx27_freq_table);
+}
+
+static unsigned int mx27_cpufreq_get(unsigned int cpu)
+{
+	return clk_get_rate(clk_cpu) / 1000;
+}
+
+static unsigned char cpu_dividers[] = {2, 3, 6};
+
+static int mx27_set_target(struct cpufreq_policy *policy,
+			  unsigned int target_freq,
+			  unsigned int relation)
+{
+	struct cpufreq_freqs freqs;
+	unsigned int idx;
+
+	/* Lookup the next frequency */
+	if (cpufreq_frequency_table_target(policy, mx27_freq_table,
+					   target_freq, relation, &idx))
+		return -EINVAL;
+
+	freqs.old = policy->cur;
+	freqs.new = mx27_freq_table[idx].frequency;
+	freqs.cpu = policy->cpu;
+
+	/*
+	 * Tell everyone what we're about to do...
+	 * you should add a notify client with any platform specific
+	 * Vcc changing capability
+	 */
+	cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
+
+	clk_set_rate(clk_cpu, mpll_rate * 2 / cpu_dividers[idx]);
+
+	/*
+	 * Tell everyone what we've just done...
+	 * you should add a notify client with any platform specific
+	 * SDRAM refresh timer adjustments
+	 */
+	cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
+
+	return 0;
+}
+
+static __init int mx27_cpufreq_init(struct cpufreq_policy *policy)
+{
+	int ret, i;
+
+	clk_cpu = clk_get(NULL, "cpu");
+	if (IS_ERR(clk_cpu))
+		return PTR_ERR(clk_cpu);
+
+	clk_mpll = clk_get(NULL, "mpll");
+	if (IS_ERR(clk_mpll)) {
+		ret = PTR_ERR(clk_mpll);
+		goto out;
+	}
+
+	mpll_rate = clk_get_rate(clk_mpll);
+
+	/* set default policy and cpuinfo */
+	policy->cpuinfo.transition_latency = 10;
+	policy->cur = clk_get_rate(clk_cpu) / 1000;
+	policy->min = mpll_rate / 3;
+	policy->max = mpll_rate;
+
+	for (i = 0; i < ARRAY_SIZE(cpu_dividers); i++) {
+		mx27_freq_table[i].index = i;
+		mx27_freq_table[i].frequency = mpll_rate * 2 / cpu_dividers[i] / 1000;
+	}
+	mx27_freq_table[i].frequency = CPUFREQ_TABLE_END;
+
+	cpufreq_frequency_table_cpuinfo(policy, mx27_freq_table);
+
+	printk(KERN_INFO "i.MX27 CPU frequency change support initialized %d %d\n",
+			policy->min, policy->max);
+
+	return 0;
+out:
+	clk_put(clk_cpu);
+
+	return ret;
+}
+
+static struct cpufreq_driver mx27_cpufreq_driver = {
+	.verify	= mx27_verify_policy,
+	.target	= mx27_set_target,
+	.init	= mx27_cpufreq_init,
+	.get	= mx27_cpufreq_get,
+	.name	= "i.MX27",
+};
+
+static int __init mx27_cpu_init(void)
+{
+	if (!cpu_is_mx27())
+		return -ENODEV;
+
+	return cpufreq_register_driver(&mx27_cpufreq_driver);
+}
+
+static void __exit mx27_cpu_exit(void)
+{
+	cpufreq_unregister_driver(&mx27_cpufreq_driver);
+}
+
+
+MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>");
+MODULE_DESCRIPTION("CPU frequency changing driver for the i.MX27");
+MODULE_LICENSE("GPL");
+module_init(mx27_cpu_init);
+module_exit(mx27_cpu_exit);
+