projects / GitHub / mt8127 / android_kernel_alcatel_ttab.git / blame
| Commit | Line | Data |
|---|---|---|
| ce26c5bb MH |
1 | /* |
| 2 | * linux/drivers/devfreq/governor_simpleondemand.c | |
| 3 | * | |
| 4 | * Copyright (C) 2011 Samsung Electronics | |
| 5 | * MyungJoo Ham <myungjoo.ham@samsung.com> | |
| 6 | * | |
| 7 | * This program is free software; you can redistribute it and/or modify | |
| 8 | * it under the terms of the GNU General Public License version 2 as | |
| 9 | * published by the Free Software Foundation. | |
| 10 | */ | |
| 11 | ||
| 12 | #include <linux/errno.h> | |
| 13 | #include <linux/devfreq.h> | |
| 14 | #include <linux/math64.h> | |
| 15 | ||
| 16 | /* Default constants for DevFreq-Simple-Ondemand (DFSO) */ | |
| 17 | #define DFSO_UPTHRESHOLD (90) | |
| 18 | #define DFSO_DOWNDIFFERENCTIAL (5) | |
| 19 | static int devfreq_simple_ondemand_func(struct devfreq *df, | |
| 20 | unsigned long *freq) | |
| 21 | { | |
| 22 | struct devfreq_dev_status stat; | |
| 23 | int err = df->profile->get_dev_status(df->dev.parent, &stat); | |
| 24 | unsigned long long a, b; | |
| 25 | unsigned int dfso_upthreshold = DFSO_UPTHRESHOLD; | |
| 26 | unsigned int dfso_downdifferential = DFSO_DOWNDIFFERENCTIAL; | |
| 27 | struct devfreq_simple_ondemand_data *data = df->data; | |
| 28 | ||
| 29 | if (err) | |
| 30 | return err; | |
| 31 | ||
| 32 | if (data) { | |
| 33 | if (data->upthreshold) | |
| 34 | dfso_upthreshold = data->upthreshold; | |
| 35 | if (data->downdifferential) | |
| 36 | dfso_downdifferential = data->downdifferential; | |
| 37 | } | |
| 38 | if (dfso_upthreshold > 100 || | |
| 39 | dfso_upthreshold < dfso_downdifferential) | |
| 40 | return -EINVAL; | |
| 41 | ||
| 42 | /* Assume MAX if it is going to be divided by zero */ | |
| 43 | if (stat.total_time == 0) { | |
| 44 | *freq = UINT_MAX; | |
| 45 | return 0; | |
| 46 | } | |
| 47 | ||
| 48 | /* Prevent overflow */ | |
| 49 | if (stat.busy_time >= (1 << 24) || stat.total_time >= (1 << 24)) { | |
| 50 | stat.busy_time >>= 7; | |
| 51 | stat.total_time >>= 7; | |
| 52 | } | |
| 53 | ||
| 54 | /* Set MAX if it's busy enough */ | |
| 55 | if (stat.busy_time * 100 > | |
| 56 | stat.total_time * dfso_upthreshold) { | |
| 57 | *freq = UINT_MAX; | |
| 58 | return 0; | |
| 59 | } | |
| 60 | ||
| 61 | /* Set MAX if we do not know the initial frequency */ | |
| 62 | if (stat.current_frequency == 0) { | |
| 63 | *freq = UINT_MAX; | |
| 64 | return 0; | |
| 65 | } | |
| 66 | ||
| 67 | /* Keep the current frequency */ | |
| 68 | if (stat.busy_time * 100 > | |
| 69 | stat.total_time * (dfso_upthreshold - dfso_downdifferential)) { | |
| 70 | *freq = stat.current_frequency; | |
| 71 | return 0; | |
| 72 | } | |
| 73 | ||
| 74 | /* Set the desired frequency based on the load */ | |
| 75 | a = stat.busy_time; | |
| 76 | a *= stat.current_frequency; | |
| 77 | b = div_u64(a, stat.total_time); | |
| 78 | b *= 100; | |
| 79 | b = div_u64(b, (dfso_upthreshold - dfso_downdifferential / 2)); | |
| 80 | *freq = (unsigned long) b; | |
| 81 | ||
| 82 | return 0; | |
| 83 | } | |
| 84 | ||
| 85 | const struct devfreq_governor devfreq_simple_ondemand = { | |
| 86 | .name = "simple_ondemand", | |
| 87 | .get_target_freq = devfreq_simple_ondemand_func, | |
| 88 | }; |