cpufreq for freescale mx51

Currently, only two operating points: 160Mhz and 800Mhz.
the operating points are tested on babbage 3.0

Signed-off-by: Yong Shen <yong.shen@linaro.org>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

1 files changed, 206 insertions, 0 deletions

diff --git a/arch/arm/plat-mxc/cpufreq.c b/arch/arm/plat-mxc/cpufreq.c
new file mode 100644
index 00000000000..039538e6879
--- /dev/null
+++ b/arch/arm/plat-mxc/cpufreq.c
@@ -0,0 +1,206 @@
+/*
+ * Copyright (C) 2010 Freescale Semiconductor, Inc. All Rights Reserved.
+ */
+
+/*
+ * The code contained herein is licensed under the GNU General Public
+ * License. You may obtain a copy of the GNU General Public License
+ * Version 2 or later at the following locations:
+ *
+ * http://www.opensource.org/licenses/gpl-license.html
+ * http://www.gnu.org/copyleft/gpl.html
+ */
+
+/*
+ * A driver for the Freescale Semiconductor i.MXC CPUfreq module.
+ * The CPUFREQ driver is for controling CPU frequency. It allows you to change
+ * the CPU clock speed on the fly.
+ */
+
+#include <linux/cpufreq.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <mach/hardware.h>
+#include <mach/clock.h>
+
+#define CLK32_FREQ	32768
+#define NANOSECOND	(1000 * 1000 * 1000)
+
+struct cpu_op *(*get_cpu_op)(int *op);
+
+static int cpu_freq_khz_min;
+static int cpu_freq_khz_max;
+
+static struct clk *cpu_clk;
+static struct cpufreq_frequency_table *imx_freq_table;
+
+static int cpu_op_nr;
+static struct cpu_op *cpu_op_tbl;
+
+static int set_cpu_freq(int freq)
+{
+	int ret = 0;
+	int org_cpu_rate;
+
+	org_cpu_rate = clk_get_rate(cpu_clk);
+	if (org_cpu_rate == freq)
+		return ret;
+
+	ret = clk_set_rate(cpu_clk, freq);
+	if (ret != 0) {
+		printk(KERN_DEBUG "cannot set CPU clock rate\n");
+		return ret;
+	}
+
+	return ret;
+}
+
+static int mxc_verify_speed(struct cpufreq_policy *policy)
+{
+	if (policy->cpu != 0)
+		return -EINVAL;
+
+	return cpufreq_frequency_table_verify(policy, imx_freq_table);
+}
+
+static unsigned int mxc_get_speed(unsigned int cpu)
+{
+	if (cpu)
+		return 0;
+
+	return clk_get_rate(cpu_clk) / 1000;
+}
+
+static int mxc_set_target(struct cpufreq_policy *policy,
+			  unsigned int target_freq, unsigned int relation)
+{
+	struct cpufreq_freqs freqs;
+	int freq_Hz;
+	int ret = 0;
+	unsigned int index;
+
+	cpufreq_frequency_table_target(policy, imx_freq_table,
+			target_freq, relation, &index);
+	freq_Hz = imx_freq_table[index].frequency * 1000;
+
+	freqs.old = clk_get_rate(cpu_clk) / 1000;
+	freqs.new = freq_Hz / 1000;
+	freqs.cpu = 0;
+	freqs.flags = 0;
+	cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
+
+	ret = set_cpu_freq(freq_Hz);
+
+	cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
+
+	return ret;
+}
+
+static int __init mxc_cpufreq_init(struct cpufreq_policy *policy)
+{
+	int ret;
+	int i;
+
+	printk(KERN_INFO "i.MXC CPU frequency driver\n");
+
+	if (policy->cpu != 0)
+		return -EINVAL;
+
+	if (!get_cpu_op)
+		return -EINVAL;
+
+	cpu_clk = clk_get(NULL, "cpu_clk");
+	if (IS_ERR(cpu_clk)) {
+		printk(KERN_ERR "%s: failed to get cpu clock\n", __func__);
+		return PTR_ERR(cpu_clk);
+	}
+
+	cpu_op_tbl = get_cpu_op(&cpu_op_nr);
+
+	cpu_freq_khz_min = cpu_op_tbl[0].cpu_rate / 1000;
+	cpu_freq_khz_max = cpu_op_tbl[0].cpu_rate / 1000;
+
+	imx_freq_table = kmalloc(
+		sizeof(struct cpufreq_frequency_table) * (cpu_op_nr + 1),
+			GFP_KERNEL);
+	if (!imx_freq_table) {
+		ret = -ENOMEM;
+		goto err1;
+	}
+
+	for (i = 0; i < cpu_op_nr; i++) {
+		imx_freq_table[i].index = i;
+		imx_freq_table[i].frequency = cpu_op_tbl[i].cpu_rate / 1000;
+
+		if ((cpu_op_tbl[i].cpu_rate / 1000) < cpu_freq_khz_min)
+			cpu_freq_khz_min = cpu_op_tbl[i].cpu_rate / 1000;
+
+		if ((cpu_op_tbl[i].cpu_rate / 1000) > cpu_freq_khz_max)
+			cpu_freq_khz_max = cpu_op_tbl[i].cpu_rate / 1000;
+	}
+
+	imx_freq_table[i].index = i;
+	imx_freq_table[i].frequency = CPUFREQ_TABLE_END;
+
+	policy->cur = clk_get_rate(cpu_clk) / 1000;
+	policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
+	policy->min = policy->cpuinfo.min_freq = cpu_freq_khz_min;
+	policy->max = policy->cpuinfo.max_freq = cpu_freq_khz_max;
+
+	/* Manual states, that PLL stabilizes in two CLK32 periods */
+	policy->cpuinfo.transition_latency = 2 * NANOSECOND / CLK32_FREQ;
+
+	ret = cpufreq_frequency_table_cpuinfo(policy, imx_freq_table);
+
+	if (ret < 0) {
+		printk(KERN_ERR "%s: failed to register i.MXC CPUfreq \
+				with error code %d\n", __func__, ret);
+		goto err;
+	}
+
+	cpufreq_frequency_table_get_attr(imx_freq_table, policy->cpu);
+	return 0;
+err:
+	kfree(imx_freq_table);
+err1:
+	clk_put(cpu_clk);
+	return ret;
+}
+
+static int mxc_cpufreq_exit(struct cpufreq_policy *policy)
+{
+	cpufreq_frequency_table_put_attr(policy->cpu);
+
+	set_cpu_freq(cpu_freq_khz_max * 1000);
+	clk_put(cpu_clk);
+	kfree(imx_freq_table);
+	return 0;
+}
+
+static struct cpufreq_driver mxc_driver = {
+	.flags = CPUFREQ_STICKY,
+	.verify = mxc_verify_speed,
+	.target = mxc_set_target,
+	.get = mxc_get_speed,
+	.init = mxc_cpufreq_init,
+	.exit = mxc_cpufreq_exit,
+	.name = "imx",
+};
+
+static int __devinit mxc_cpufreq_driver_init(void)
+{
+	return cpufreq_register_driver(&mxc_driver);
+}
+
+static void mxc_cpufreq_driver_exit(void)
+{
+	cpufreq_unregister_driver(&mxc_driver);
+}
+
+module_init(mxc_cpufreq_driver_init);
+module_exit(mxc_cpufreq_driver_exit);
+
+MODULE_AUTHOR("Freescale Semiconductor Inc. Yong Shen <yong.shen@linaro.org>");
+MODULE_DESCRIPTION("CPUfreq driver for i.MX");
+MODULE_LICENSE("GPL");