diff options
Diffstat (limited to 'arch/arm/mach-davinci/cpufreq.c')
| -rw-r--r-- | arch/arm/mach-davinci/cpufreq.c | 226 |
1 files changed, 226 insertions, 0 deletions
diff --git a/arch/arm/mach-davinci/cpufreq.c b/arch/arm/mach-davinci/cpufreq.c new file mode 100644 index 000000000000..d3fa6de1e20f --- /dev/null +++ b/arch/arm/mach-davinci/cpufreq.c @@ -0,0 +1,226 @@ +/* + * CPU frequency scaling for DaVinci + * + * Copyright (C) 2009 Texas Instruments Incorporated - http://www.ti.com/ + * + * Based on linux/arch/arm/plat-omap/cpu-omap.c. Original Copyright follows: + * + * Copyright (C) 2005 Nokia Corporation + * Written by Tony Lindgren <tony@atomide.com> + * + * Based on cpu-sa1110.c, Copyright (C) 2001 Russell King + * + * Copyright (C) 2007-2008 Texas Instruments, Inc. + * Updated to support OMAP3 + * Rajendra Nayak <rnayak@ti.com> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ +#include <linux/types.h> +#include <linux/cpufreq.h> +#include <linux/init.h> +#include <linux/err.h> +#include <linux/clk.h> +#include <linux/platform_device.h> + +#include <mach/hardware.h> +#include <mach/cpufreq.h> +#include <mach/common.h> + +#include "clock.h" + +struct davinci_cpufreq { + struct device *dev; + struct clk *armclk; +}; +static struct davinci_cpufreq cpufreq; + +static int davinci_verify_speed(struct cpufreq_policy *policy) +{ + struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data; + struct cpufreq_frequency_table *freq_table = pdata->freq_table; + struct clk *armclk = cpufreq.armclk; + + if (freq_table) + return cpufreq_frequency_table_verify(policy, freq_table); + + if (policy->cpu) + return -EINVAL; + + cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq, + policy->cpuinfo.max_freq); + + policy->min = clk_round_rate(armclk, policy->min * 1000) / 1000; + policy->max = clk_round_rate(armclk, policy->max * 1000) / 1000; + cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq, + policy->cpuinfo.max_freq); + return 0; +} + +static unsigned int davinci_getspeed(unsigned int cpu) +{ + if (cpu) + return 0; + + return clk_get_rate(cpufreq.armclk) / 1000; +} + +static int davinci_target(struct cpufreq_policy *policy, + unsigned int target_freq, unsigned int relation) +{ + int ret = 0; + unsigned int idx; + struct cpufreq_freqs freqs; + struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data; + struct clk *armclk = cpufreq.armclk; + + /* + * Ensure desired rate is within allowed range. Some govenors + * (ondemand) will just pass target_freq=0 to get the minimum. + */ + if (target_freq < policy->cpuinfo.min_freq) + target_freq = policy->cpuinfo.min_freq; + if (target_freq > policy->cpuinfo.max_freq) + target_freq = policy->cpuinfo.max_freq; + + freqs.old = davinci_getspeed(0); + freqs.new = clk_round_rate(armclk, target_freq * 1000) / 1000; + freqs.cpu = 0; + + if (freqs.old == freqs.new) + return ret; + + cpufreq_debug_printk(CPUFREQ_DEBUG_DRIVER, + dev_driver_string(cpufreq.dev), + "transition: %u --> %u\n", freqs.old, freqs.new); + + ret = cpufreq_frequency_table_target(policy, pdata->freq_table, + freqs.new, relation, &idx); + if (ret) + return -EINVAL; + + cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE); + + /* if moving to higher frequency, up the voltage beforehand */ + if (pdata->set_voltage && freqs.new > freqs.old) + pdata->set_voltage(idx); + + ret = clk_set_rate(armclk, idx); + + /* if moving to lower freq, lower the voltage after lowering freq */ + if (pdata->set_voltage && freqs.new < freqs.old) + pdata->set_voltage(idx); + + cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE); + + return ret; +} + +static int __init davinci_cpu_init(struct cpufreq_policy *policy) +{ + int result = 0; + struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data; + struct cpufreq_frequency_table *freq_table = pdata->freq_table; + + if (policy->cpu != 0) + return -EINVAL; + + /* Finish platform specific initialization */ + if (pdata->init) { + result = pdata->init(); + if (result) + return result; + } + + policy->cur = policy->min = policy->max = davinci_getspeed(0); + + if (freq_table) { + result = cpufreq_frequency_table_cpuinfo(policy, freq_table); + if (!result) + cpufreq_frequency_table_get_attr(freq_table, + policy->cpu); + } else { + policy->cpuinfo.min_freq = policy->min; + policy->cpuinfo.max_freq = policy->max; + } + + policy->min = policy->cpuinfo.min_freq; + policy->max = policy->cpuinfo.max_freq; + policy->cur = davinci_getspeed(0); + + /* + * Time measurement across the target() function yields ~1500-1800us + * time taken with no drivers on notification list. + * Setting the latency to 2000 us to accomodate addition of drivers + * to pre/post change notification list. + */ + policy->cpuinfo.transition_latency = 2000 * 1000; + return 0; +} + +static int davinci_cpu_exit(struct cpufreq_policy *policy) +{ + cpufreq_frequency_table_put_attr(policy->cpu); + return 0; +} + +static struct freq_attr *davinci_cpufreq_attr[] = { + &cpufreq_freq_attr_scaling_available_freqs, + NULL, +}; + +static struct cpufreq_driver davinci_driver = { + .flags = CPUFREQ_STICKY, + .verify = davinci_verify_speed, + .target = davinci_target, + .get = davinci_getspeed, + .init = davinci_cpu_init, + .exit = davinci_cpu_exit, + .name = "davinci", + .attr = davinci_cpufreq_attr, +}; + +static int __init davinci_cpufreq_probe(struct platform_device *pdev) +{ + struct davinci_cpufreq_config *pdata = pdev->dev.platform_data; + + if (!pdata) + return -EINVAL; + if (!pdata->freq_table) + return -EINVAL; + + cpufreq.dev = &pdev->dev; + + cpufreq.armclk = clk_get(NULL, "arm"); + if (IS_ERR(cpufreq.armclk)) { + dev_err(cpufreq.dev, "Unable to get ARM clock\n"); + return PTR_ERR(cpufreq.armclk); + } + + return cpufreq_register_driver(&davinci_driver); +} + +static int __exit davinci_cpufreq_remove(struct platform_device *pdev) +{ + clk_put(cpufreq.armclk); + + return cpufreq_unregister_driver(&davinci_driver); +} + +static struct platform_driver davinci_cpufreq_driver = { + .driver = { + .name = "cpufreq-davinci", + .owner = THIS_MODULE, + }, + .remove = __exit_p(davinci_cpufreq_remove), +}; + +static int __init davinci_cpufreq_init(void) +{ + return platform_driver_probe(&davinci_cpufreq_driver, + davinci_cpufreq_probe); +} +late_initcall(davinci_cpufreq_init); + |