diff options
Diffstat (limited to 'arch/arm/mach-imx/cpufreq.c')
| -rw-r--r-- | arch/arm/mach-imx/cpufreq.c | 206 |
1 files changed, 206 insertions, 0 deletions
diff --git a/arch/arm/mach-imx/cpufreq.c b/arch/arm/mach-imx/cpufreq.c new file mode 100644 index 000000000000..36e8b3994470 --- /dev/null +++ b/arch/arm/mach-imx/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 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 __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"); |