diff options
Diffstat (limited to 'drivers/cpufreq/tegra-cpufreq.c')
| -rw-r--r-- | drivers/cpufreq/tegra-cpufreq.c | 292 |
1 files changed, 292 insertions, 0 deletions
diff --git a/drivers/cpufreq/tegra-cpufreq.c b/drivers/cpufreq/tegra-cpufreq.c new file mode 100644 index 00000000000..c74c0e130ef --- /dev/null +++ b/drivers/cpufreq/tegra-cpufreq.c @@ -0,0 +1,292 @@ +/* + * Copyright (C) 2010 Google, Inc. + * + * Author: + * Colin Cross <ccross@google.com> + * Based on arch/arm/plat-omap/cpu-omap.c, (C) 2005 Nokia Corporation + * + * This software is licensed under the terms of the GNU General Public + * License version 2, as published by the Free Software Foundation, and + * may be copied, distributed, and modified under those terms. + * + * 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. + * + */ + +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/types.h> +#include <linux/sched.h> +#include <linux/cpufreq.h> +#include <linux/delay.h> +#include <linux/init.h> +#include <linux/err.h> +#include <linux/clk.h> +#include <linux/io.h> +#include <linux/suspend.h> + +/* Frequency table index must be sequential starting at 0 */ +static struct cpufreq_frequency_table freq_table[] = { + { 0, 216000 }, + { 1, 312000 }, + { 2, 456000 }, + { 3, 608000 }, + { 4, 760000 }, + { 5, 816000 }, + { 6, 912000 }, + { 7, 1000000 }, + { 8, CPUFREQ_TABLE_END }, +}; + +#define NUM_CPUS 2 + +static struct clk *cpu_clk; +static struct clk *pll_x_clk; +static struct clk *pll_p_clk; +static struct clk *emc_clk; + +static unsigned long target_cpu_speed[NUM_CPUS]; +static DEFINE_MUTEX(tegra_cpu_lock); +static bool is_suspended; + +static int tegra_verify_speed(struct cpufreq_policy *policy) +{ + return cpufreq_frequency_table_verify(policy, freq_table); +} + +static unsigned int tegra_getspeed(unsigned int cpu) +{ + unsigned long rate; + + if (cpu >= NUM_CPUS) + return 0; + + rate = clk_get_rate(cpu_clk) / 1000; + return rate; +} + +static int tegra_cpu_clk_set_rate(unsigned long rate) +{ + int ret; + + /* + * Take an extra reference to the main pll so it doesn't turn + * off when we move the cpu off of it + */ + clk_prepare_enable(pll_x_clk); + + ret = clk_set_parent(cpu_clk, pll_p_clk); + if (ret) { + pr_err("Failed to switch cpu to clock pll_p\n"); + goto out; + } + + if (rate == clk_get_rate(pll_p_clk)) + goto out; + + ret = clk_set_rate(pll_x_clk, rate); + if (ret) { + pr_err("Failed to change pll_x to %lu\n", rate); + goto out; + } + + ret = clk_set_parent(cpu_clk, pll_x_clk); + if (ret) { + pr_err("Failed to switch cpu to clock pll_x\n"); + goto out; + } + +out: + clk_disable_unprepare(pll_x_clk); + return ret; +} + +static int tegra_update_cpu_speed(struct cpufreq_policy *policy, + unsigned long rate) +{ + int ret = 0; + struct cpufreq_freqs freqs; + + freqs.old = tegra_getspeed(0); + freqs.new = rate; + + if (freqs.old == freqs.new) + return ret; + + /* + * Vote on memory bus frequency based on cpu frequency + * This sets the minimum frequency, display or avp may request higher + */ + if (rate >= 816000) + clk_set_rate(emc_clk, 600000000); /* cpu 816 MHz, emc max */ + else if (rate >= 456000) + clk_set_rate(emc_clk, 300000000); /* cpu 456 MHz, emc 150Mhz */ + else + clk_set_rate(emc_clk, 100000000); /* emc 50Mhz */ + + cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE); + +#ifdef CONFIG_CPU_FREQ_DEBUG + printk(KERN_DEBUG "cpufreq-tegra: transition: %u --> %u\n", + freqs.old, freqs.new); +#endif + + ret = tegra_cpu_clk_set_rate(freqs.new * 1000); + if (ret) { + pr_err("cpu-tegra: Failed to set cpu frequency to %d kHz\n", + freqs.new); + return ret; + } + + cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE); + + return 0; +} + +static unsigned long tegra_cpu_highest_speed(void) +{ + unsigned long rate = 0; + int i; + + for_each_online_cpu(i) + rate = max(rate, target_cpu_speed[i]); + return rate; +} + +static int tegra_target(struct cpufreq_policy *policy, + unsigned int target_freq, + unsigned int relation) +{ + unsigned int idx; + unsigned int freq; + int ret = 0; + + mutex_lock(&tegra_cpu_lock); + + if (is_suspended) { + ret = -EBUSY; + goto out; + } + + cpufreq_frequency_table_target(policy, freq_table, target_freq, + relation, &idx); + + freq = freq_table[idx].frequency; + + target_cpu_speed[policy->cpu] = freq; + + ret = tegra_update_cpu_speed(policy, tegra_cpu_highest_speed()); + +out: + mutex_unlock(&tegra_cpu_lock); + return ret; +} + +static int tegra_pm_notify(struct notifier_block *nb, unsigned long event, + void *dummy) +{ + mutex_lock(&tegra_cpu_lock); + if (event == PM_SUSPEND_PREPARE) { + struct cpufreq_policy *policy = cpufreq_cpu_get(0); + is_suspended = true; + pr_info("Tegra cpufreq suspend: setting frequency to %d kHz\n", + freq_table[0].frequency); + tegra_update_cpu_speed(policy, freq_table[0].frequency); + cpufreq_cpu_put(policy); + } else if (event == PM_POST_SUSPEND) { + is_suspended = false; + } + mutex_unlock(&tegra_cpu_lock); + + return NOTIFY_OK; +} + +static struct notifier_block tegra_cpu_pm_notifier = { + .notifier_call = tegra_pm_notify, +}; + +static int tegra_cpu_init(struct cpufreq_policy *policy) +{ + if (policy->cpu >= NUM_CPUS) + return -EINVAL; + + clk_prepare_enable(emc_clk); + clk_prepare_enable(cpu_clk); + + cpufreq_frequency_table_cpuinfo(policy, freq_table); + cpufreq_frequency_table_get_attr(freq_table, policy->cpu); + policy->cur = tegra_getspeed(policy->cpu); + target_cpu_speed[policy->cpu] = policy->cur; + + /* FIXME: what's the actual transition time? */ + policy->cpuinfo.transition_latency = 300 * 1000; + + cpumask_copy(policy->cpus, cpu_possible_mask); + + if (policy->cpu == 0) + register_pm_notifier(&tegra_cpu_pm_notifier); + + return 0; +} + +static int tegra_cpu_exit(struct cpufreq_policy *policy) +{ + cpufreq_frequency_table_cpuinfo(policy, freq_table); + clk_disable_unprepare(emc_clk); + return 0; +} + +static struct freq_attr *tegra_cpufreq_attr[] = { + &cpufreq_freq_attr_scaling_available_freqs, + NULL, +}; + +static struct cpufreq_driver tegra_cpufreq_driver = { + .verify = tegra_verify_speed, + .target = tegra_target, + .get = tegra_getspeed, + .init = tegra_cpu_init, + .exit = tegra_cpu_exit, + .name = "tegra", + .attr = tegra_cpufreq_attr, +}; + +static int __init tegra_cpufreq_init(void) +{ + cpu_clk = clk_get_sys(NULL, "cpu"); + if (IS_ERR(cpu_clk)) + return PTR_ERR(cpu_clk); + + pll_x_clk = clk_get_sys(NULL, "pll_x"); + if (IS_ERR(pll_x_clk)) + return PTR_ERR(pll_x_clk); + + pll_p_clk = clk_get_sys(NULL, "pll_p_cclk"); + if (IS_ERR(pll_p_clk)) + return PTR_ERR(pll_p_clk); + + emc_clk = clk_get_sys("cpu", "emc"); + if (IS_ERR(emc_clk)) { + clk_put(cpu_clk); + return PTR_ERR(emc_clk); + } + + return cpufreq_register_driver(&tegra_cpufreq_driver); +} + +static void __exit tegra_cpufreq_exit(void) +{ + cpufreq_unregister_driver(&tegra_cpufreq_driver); + clk_put(emc_clk); + clk_put(cpu_clk); +} + + +MODULE_AUTHOR("Colin Cross <ccross@android.com>"); +MODULE_DESCRIPTION("cpufreq driver for Nvidia Tegra2"); +MODULE_LICENSE("GPL"); +module_init(tegra_cpufreq_init); +module_exit(tegra_cpufreq_exit); |