diff options
Diffstat (limited to 'arch/arm/mach-mx2/cpufreq_imx27.c')
| -rw-r--r-- | arch/arm/mach-mx2/cpufreq_imx27.c | 149 |
1 files changed, 149 insertions, 0 deletions
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); + |