diff options
Diffstat (limited to 'drivers/cpufreq/cpufreq_opp.c')
| -rw-r--r-- | drivers/cpufreq/cpufreq_opp.c | 110 |
1 files changed, 110 insertions, 0 deletions
diff --git a/drivers/cpufreq/cpufreq_opp.c b/drivers/cpufreq/cpufreq_opp.c new file mode 100644 index 000000000000..c0c6f4a4eccf --- /dev/null +++ b/drivers/cpufreq/cpufreq_opp.c @@ -0,0 +1,110 @@ +/* + * Generic OPP helper interface for CPUFreq drivers + * + * Copyright (C) 2009-2014 Texas Instruments Incorporated. + * Nishanth Menon + * Romit Dasgupta + * Kevin Hilman + * + * 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/cpufreq.h> +#include <linux/device.h> +#include <linux/err.h> +#include <linux/errno.h> +#include <linux/export.h> +#include <linux/kernel.h> +#include <linux/pm_opp.h> +#include <linux/rcupdate.h> +#include <linux/slab.h> + +/** + * dev_pm_opp_init_cpufreq_table() - create a cpufreq table for a device + * @dev: device for which we do this operation + * @table: Cpufreq table returned back to caller + * + * Generate a cpufreq table for a provided device- this assumes that the + * opp list is already initialized and ready for usage. + * + * This function allocates required memory for the cpufreq table. It is + * expected that the caller does the required maintenance such as freeing + * the table as required. + * + * Returns -EINVAL for bad pointers, -ENODEV if the device is not found, -ENOMEM + * if no memory available for the operation (table is not populated), returns 0 + * if successful and table is populated. + * + * WARNING: It is important for the callers to ensure refreshing their copy of + * the table if any of the mentioned functions have been invoked in the interim. + * + * Locking: The internal device_opp and opp structures are RCU protected. + * Since we just use the regular accessor functions to access the internal data + * structures, we use RCU read lock inside this function. As a result, users of + * this function DONOT need to use explicit locks for invoking. + */ +int dev_pm_opp_init_cpufreq_table(struct device *dev, + struct cpufreq_frequency_table **table) +{ + struct dev_pm_opp *opp; + struct cpufreq_frequency_table *freq_table = NULL; + int i, max_opps, ret = 0; + unsigned long rate; + + rcu_read_lock(); + + max_opps = dev_pm_opp_get_opp_count(dev); + if (max_opps <= 0) { + ret = max_opps ? max_opps : -ENODATA; + goto out; + } + + freq_table = kzalloc(sizeof(*freq_table) * (max_opps + 1), GFP_KERNEL); + if (!freq_table) { + ret = -ENOMEM; + goto out; + } + + for (i = 0, rate = 0; i < max_opps; i++, rate++) { + /* find next rate */ + opp = dev_pm_opp_find_freq_ceil(dev, &rate); + if (IS_ERR(opp)) { + ret = PTR_ERR(opp); + goto out; + } + freq_table[i].driver_data = i; + freq_table[i].frequency = rate / 1000; + } + + freq_table[i].driver_data = i; + freq_table[i].frequency = CPUFREQ_TABLE_END; + + *table = &freq_table[0]; + +out: + rcu_read_unlock(); + if (ret) + kfree(freq_table); + + return ret; +} +EXPORT_SYMBOL_GPL(dev_pm_opp_init_cpufreq_table); + +/** + * dev_pm_opp_free_cpufreq_table() - free the cpufreq table + * @dev: device for which we do this operation + * @table: table to free + * + * Free up the table allocated by dev_pm_opp_init_cpufreq_table + */ +void dev_pm_opp_free_cpufreq_table(struct device *dev, + struct cpufreq_frequency_table **table) +{ + if (!table) + return; + + kfree(*table); + *table = NULL; +} +EXPORT_SYMBOL_GPL(dev_pm_opp_free_cpufreq_table); |
