diff options
Diffstat (limited to 'drivers/cpufreq/omap-cpufreq.c')
| -rw-r--r-- | drivers/cpufreq/omap-cpufreq.c | 205 |
1 files changed, 205 insertions, 0 deletions
diff --git a/drivers/cpufreq/omap-cpufreq.c b/drivers/cpufreq/omap-cpufreq.c new file mode 100644 index 000000000..e3866e0d5 --- /dev/null +++ b/drivers/cpufreq/omap-cpufreq.c @@ -0,0 +1,205 @@ +/* + * CPU frequency scaling for OMAP using OPP information + * + * Copyright (C) 2005 Nokia Corporation + * Written by Tony Lindgren <tony@atomide.com> + * + * Based on cpu-sa1110.c, Copyright (C) 2001 Russell King + * + * Copyright (C) 2007-2011 Texas Instruments, Inc. + * - OMAP3/4 support by Rajendra Nayak, Santosh Shilimkar + * + * 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/kernel.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/pm_opp.h> +#include <linux/cpu.h> +#include <linux/module.h> +#include <linux/platform_device.h> +#include <linux/regulator/consumer.h> + +#include <asm/smp_plat.h> +#include <asm/cpu.h> + +/* OPP tolerance in percentage */ +#define OPP_TOLERANCE 4 + +static struct cpufreq_frequency_table *freq_table; +static atomic_t freq_table_users = ATOMIC_INIT(0); +static struct device *mpu_dev; +static struct regulator *mpu_reg; + +static int omap_target(struct cpufreq_policy *policy, unsigned int index) +{ + int r, ret; + struct dev_pm_opp *opp; + unsigned long freq, volt = 0, volt_old = 0, tol = 0; + unsigned int old_freq, new_freq; + + old_freq = policy->cur; + new_freq = freq_table[index].frequency; + + freq = new_freq * 1000; + ret = clk_round_rate(policy->clk, freq); + if (IS_ERR_VALUE(ret)) { + dev_warn(mpu_dev, + "CPUfreq: Cannot find matching frequency for %lu\n", + freq); + return ret; + } + freq = ret; + + if (mpu_reg) { + rcu_read_lock(); + opp = dev_pm_opp_find_freq_ceil(mpu_dev, &freq); + if (IS_ERR(opp)) { + rcu_read_unlock(); + dev_err(mpu_dev, "%s: unable to find MPU OPP for %d\n", + __func__, new_freq); + return -EINVAL; + } + volt = dev_pm_opp_get_voltage(opp); + rcu_read_unlock(); + tol = volt * OPP_TOLERANCE / 100; + volt_old = regulator_get_voltage(mpu_reg); + } + + dev_dbg(mpu_dev, "cpufreq-omap: %u MHz, %ld mV --> %u MHz, %ld mV\n", + old_freq / 1000, volt_old ? volt_old / 1000 : -1, + new_freq / 1000, volt ? volt / 1000 : -1); + + /* scaling up? scale voltage before frequency */ + if (mpu_reg && (new_freq > old_freq)) { + r = regulator_set_voltage(mpu_reg, volt - tol, volt + tol); + if (r < 0) { + dev_warn(mpu_dev, "%s: unable to scale voltage up.\n", + __func__); + return r; + } + } + + ret = clk_set_rate(policy->clk, new_freq * 1000); + + /* scaling down? scale voltage after frequency */ + if (mpu_reg && (new_freq < old_freq)) { + r = regulator_set_voltage(mpu_reg, volt - tol, volt + tol); + if (r < 0) { + dev_warn(mpu_dev, "%s: unable to scale voltage down.\n", + __func__); + clk_set_rate(policy->clk, old_freq * 1000); + return r; + } + } + + return ret; +} + +static inline void freq_table_free(void) +{ + if (atomic_dec_and_test(&freq_table_users)) + dev_pm_opp_free_cpufreq_table(mpu_dev, &freq_table); +} + +static int omap_cpu_init(struct cpufreq_policy *policy) +{ + int result; + + policy->clk = clk_get(NULL, "cpufreq_ck"); + if (IS_ERR(policy->clk)) + return PTR_ERR(policy->clk); + + if (!freq_table) { + result = dev_pm_opp_init_cpufreq_table(mpu_dev, &freq_table); + if (result) { + dev_err(mpu_dev, + "%s: cpu%d: failed creating freq table[%d]\n", + __func__, policy->cpu, result); + goto fail; + } + } + + atomic_inc_return(&freq_table_users); + + /* FIXME: what's the actual transition time? */ + result = cpufreq_generic_init(policy, freq_table, 300 * 1000); + if (!result) + return 0; + + freq_table_free(); +fail: + clk_put(policy->clk); + return result; +} + +static int omap_cpu_exit(struct cpufreq_policy *policy) +{ + freq_table_free(); + clk_put(policy->clk); + return 0; +} + +static struct cpufreq_driver omap_driver = { + .flags = CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK, + .verify = cpufreq_generic_frequency_table_verify, + .target_index = omap_target, + .get = cpufreq_generic_get, + .init = omap_cpu_init, + .exit = omap_cpu_exit, + .name = "omap", + .attr = cpufreq_generic_attr, +}; + +static int omap_cpufreq_probe(struct platform_device *pdev) +{ + mpu_dev = get_cpu_device(0); + if (!mpu_dev) { + pr_warning("%s: unable to get the mpu device\n", __func__); + return -EINVAL; + } + + mpu_reg = regulator_get(mpu_dev, "vcc"); + if (IS_ERR(mpu_reg)) { + pr_warning("%s: unable to get MPU regulator\n", __func__); + mpu_reg = NULL; + } else { + /* + * Ensure physical regulator is present. + * (e.g. could be dummy regulator.) + */ + if (regulator_get_voltage(mpu_reg) < 0) { + pr_warn("%s: physical regulator not present for MPU\n", + __func__); + regulator_put(mpu_reg); + mpu_reg = NULL; + } + } + + return cpufreq_register_driver(&omap_driver); +} + +static int omap_cpufreq_remove(struct platform_device *pdev) +{ + return cpufreq_unregister_driver(&omap_driver); +} + +static struct platform_driver omap_cpufreq_platdrv = { + .driver = { + .name = "omap-cpufreq", + }, + .probe = omap_cpufreq_probe, + .remove = omap_cpufreq_remove, +}; +module_platform_driver(omap_cpufreq_platdrv); + +MODULE_DESCRIPTION("cpufreq driver for OMAP SoCs"); +MODULE_LICENSE("GPL"); |