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1 | /* |
2 | * File: arch/blackfin/mach-common/cpufreq.c | |
3 | * Based on: | |
4 | * Author: | |
5 | * | |
6 | * Created: | |
7 | * Description: Blackfin core clock scaling | |
8 | * | |
9 | * Modified: | |
10 | * Copyright 2004-2008 Analog Devices Inc. | |
11 | * | |
12 | * Bugs: Enter bugs at http://blackfin.uclinux.org/ | |
13 | * | |
14 | * This program is free software; you can redistribute it and/or modify | |
15 | * it under the terms of the GNU General Public License as published by | |
16 | * the Free Software Foundation; either version 2 of the License, or | |
17 | * (at your option) any later version. | |
18 | * | |
19 | * This program is distributed in the hope that it will be useful, | |
20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
22 | * GNU General Public License for more details. | |
23 | * | |
24 | * You should have received a copy of the GNU General Public License | |
25 | * along with this program; if not, see the file COPYING, or write | |
26 | * to the Free Software Foundation, Inc., | |
27 | * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA | |
28 | */ | |
29 | ||
30 | #include <linux/kernel.h> | |
31 | #include <linux/types.h> | |
32 | #include <linux/init.h> | |
33 | #include <linux/cpufreq.h> | |
34 | #include <linux/fs.h> | |
35 | #include <asm/blackfin.h> | |
36 | #include <asm/time.h> | |
37 | ||
38 | ||
39 | /* this is the table of CCLK frequencies, in Hz */ | |
40 | /* .index is the entry in the auxillary dpm_state_table[] */ | |
41 | static struct cpufreq_frequency_table bfin_freq_table[] = { | |
42 | { | |
43 | .frequency = CPUFREQ_TABLE_END, | |
44 | .index = 0, | |
45 | }, | |
46 | { | |
47 | .frequency = CPUFREQ_TABLE_END, | |
48 | .index = 1, | |
49 | }, | |
50 | { | |
51 | .frequency = CPUFREQ_TABLE_END, | |
52 | .index = 2, | |
53 | }, | |
54 | { | |
55 | .frequency = CPUFREQ_TABLE_END, | |
56 | .index = 0, | |
57 | }, | |
58 | }; | |
59 | ||
60 | static struct bfin_dpm_state { | |
61 | unsigned int csel; /* system clock divider */ | |
62 | unsigned int tscale; /* change the divider on the core timer interrupt */ | |
63 | } dpm_state_table[3]; | |
64 | ||
65 | /**************************************************************************/ | |
66 | ||
67 | static unsigned int bfin_getfreq(unsigned int cpu) | |
68 | { | |
69 | /* The driver only support single cpu */ | |
70 | if (cpu != 0) | |
71 | return -1; | |
72 | ||
73 | return get_cclk(); | |
74 | } | |
75 | ||
76 | ||
77 | static int bfin_target(struct cpufreq_policy *policy, | |
78 | unsigned int target_freq, unsigned int relation) | |
79 | { | |
80 | unsigned int index, plldiv, tscale; | |
81 | unsigned long flags, cclk_hz; | |
82 | struct cpufreq_freqs freqs; | |
83 | ||
84 | if (cpufreq_frequency_table_target(policy, bfin_freq_table, | |
85 | target_freq, relation, &index)) | |
86 | return -EINVAL; | |
87 | ||
88 | cclk_hz = bfin_freq_table[index].frequency; | |
89 | ||
90 | freqs.old = bfin_getfreq(0); | |
91 | freqs.new = cclk_hz; | |
92 | freqs.cpu = 0; | |
93 | ||
94 | pr_debug("cpufreq: changing cclk to %lu; target = %u, oldfreq = %u\n", | |
95 | cclk_hz, target_freq, freqs.old); | |
96 | ||
97 | cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE); | |
98 | local_irq_save(flags); | |
99 | plldiv = (bfin_read_PLL_DIV() & SSEL) | dpm_state_table[index].csel; | |
100 | tscale = dpm_state_table[index].tscale; | |
101 | bfin_write_PLL_DIV(plldiv); | |
102 | /* we have to adjust the core timer, because it is using cclk */ | |
103 | bfin_write_TSCALE(tscale); | |
104 | SSYNC(); | |
105 | local_irq_restore(flags); | |
106 | cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE); | |
107 | ||
108 | return 0; | |
109 | } | |
110 | ||
111 | static int bfin_verify_speed(struct cpufreq_policy *policy) | |
112 | { | |
113 | return cpufreq_frequency_table_verify(policy, bfin_freq_table); | |
114 | } | |
115 | ||
116 | static int __init __bfin_cpu_init(struct cpufreq_policy *policy) | |
117 | { | |
118 | ||
119 | unsigned long cclk, sclk, csel, min_cclk; | |
120 | int index; | |
121 | ||
122 | #ifdef CONFIG_CYCLES_CLOCKSOURCE | |
123 | /* | |
124 | * Clocksource CYCLES is still CONTINUOUS but not longer MONOTONIC in case we enable | |
125 | * CPU frequency scaling, since CYCLES runs off Core Clock. | |
126 | */ | |
127 | printk(KERN_WARNING "CPU frequency scaling not supported: Clocksource not suitable\n" | |
128 | return -ENODEV; | |
129 | #endif | |
130 | ||
131 | if (policy->cpu != 0) | |
132 | return -EINVAL; | |
133 | ||
134 | cclk = get_cclk(); | |
135 | sclk = get_sclk(); | |
136 | ||
137 | #if ANOMALY_05000273 | |
138 | min_cclk = sclk * 2; | |
139 | #else | |
140 | min_cclk = sclk; | |
141 | #endif | |
142 | csel = ((bfin_read_PLL_DIV() & CSEL) >> 4); | |
143 | ||
144 | for (index = 0; (cclk >> index) >= min_cclk && csel <= 3; index++, csel++) { | |
145 | bfin_freq_table[index].frequency = cclk >> index; | |
146 | dpm_state_table[index].csel = csel << 4; /* Shift now into PLL_DIV bitpos */ | |
147 | dpm_state_table[index].tscale = (TIME_SCALE / (1 << csel)) - 1; | |
148 | ||
149 | pr_debug("cpufreq: freq:%d csel:%d tscale:%d\n", | |
150 | bfin_freq_table[index].frequency, | |
151 | dpm_state_table[index].csel, | |
152 | dpm_state_table[index].tscale); | |
153 | } | |
154 | ||
155 | policy->governor = CPUFREQ_DEFAULT_GOVERNOR; | |
156 | ||
157 | policy->cpuinfo.transition_latency = (bfin_read_PLL_LOCKCNT() / (sclk / 1000000)) * 1000; | |
158 | /*Now ,only support one cpu */ | |
159 | policy->cur = cclk; | |
160 | cpufreq_frequency_table_get_attr(bfin_freq_table, policy->cpu); | |
161 | return cpufreq_frequency_table_cpuinfo(policy, bfin_freq_table); | |
162 | } | |
163 | ||
164 | static struct freq_attr *bfin_freq_attr[] = { | |
165 | &cpufreq_freq_attr_scaling_available_freqs, | |
166 | NULL, | |
167 | }; | |
168 | ||
169 | static struct cpufreq_driver bfin_driver = { | |
170 | .verify = bfin_verify_speed, | |
171 | .target = bfin_target, | |
172 | .get = bfin_getfreq, | |
173 | .init = __bfin_cpu_init, | |
174 | .name = "bfin cpufreq", | |
175 | .owner = THIS_MODULE, | |
176 | .attr = bfin_freq_attr, | |
177 | }; | |
178 | ||
179 | static int __init bfin_cpu_init(void) | |
180 | { | |
181 | return cpufreq_register_driver(&bfin_driver); | |
182 | } | |
183 | ||
184 | static void __exit bfin_cpu_exit(void) | |
185 | { | |
186 | cpufreq_unregister_driver(&bfin_driver); | |
187 | } | |
188 | ||
189 | MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>"); | |
190 | MODULE_DESCRIPTION("cpufreq driver for Blackfin"); | |
191 | MODULE_LICENSE("GPL"); | |
192 | ||
193 | module_init(bfin_cpu_init); | |
194 | module_exit(bfin_cpu_exit); |