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-rw-r--r--arch/arm/mach-imx/cpufreq.c206
1 files changed, 206 insertions, 0 deletions
diff --git a/arch/arm/mach-imx/cpufreq.c b/arch/arm/mach-imx/cpufreq.c
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+++ b/arch/arm/mach-imx/cpufreq.c
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+/*
+ * 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 controlling CPU frequency. It allows you to change
+ * the CPU clock speed on the fly.
+ */
+
+#include <linux/module.h>
+#include <linux/cpufreq.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+
+#include "hardware.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 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->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 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");