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1 | /* |
2 | * CPU frequency scaling for OMAP using OPP information |
3 | * |
4 | * Copyright (C) 2005 Nokia Corporation |
5 | * Written by Tony Lindgren <tony@atomide.com> |
6 | * |
7 | * Based on cpu-sa1110.c, Copyright (C) 2001 Russell King |
8 | * |
9 | * Copyright (C) 2007-2011 Texas Instruments, Inc. |
10 | * - OMAP3/4 support by Rajendra Nayak, Santosh Shilimkar |
11 | * |
12 | * This program is free software; you can redistribute it and/or modify |
13 | * it under the terms of the GNU General Public License version 2 as |
14 | * published by the Free Software Foundation. |
15 | */ |
16 | #include <linux/types.h> |
17 | #include <linux/kernel.h> |
18 | #include <linux/sched.h> |
19 | #include <linux/cpufreq.h> |
20 | #include <linux/delay.h> |
21 | #include <linux/init.h> |
22 | #include <linux/err.h> |
23 | #include <linux/clk.h> |
24 | #include <linux/io.h> |
25 | #include <linux/opp.h> |
26 | #include <linux/cpu.h> |
27 | #include <linux/module.h> |
28 | #include <linux/regulator/consumer.h> |
29 | |
30 | #include <asm/smp_plat.h> |
31 | #include <asm/cpu.h> |
32 | |
33 | /* OPP tolerance in percentage */ |
34 | #define OPP_TOLERANCE 4 |
35 | |
36 | static struct cpufreq_frequency_table *freq_table; |
37 | static atomic_t freq_table_users = ATOMIC_INIT(0); |
38 | static struct clk *mpu_clk; |
39 | static struct device *mpu_dev; |
40 | static struct regulator *mpu_reg; |
41 | |
42 | static int omap_verify_speed(struct cpufreq_policy *policy) |
43 | { |
44 | if (!freq_table) |
45 | return -EINVAL; |
46 | return cpufreq_frequency_table_verify(policy, freq_table); |
47 | } |
48 | |
49 | static unsigned int omap_getspeed(unsigned int cpu) |
50 | { |
51 | unsigned long rate; |
52 | |
53 | if (cpu >= NR_CPUS) |
54 | return 0; |
55 | |
56 | rate = clk_get_rate(mpu_clk) / 1000; |
57 | return rate; |
58 | } |
59 | |
60 | static int omap_target(struct cpufreq_policy *policy, |
61 | unsigned int target_freq, |
62 | unsigned int relation) |
63 | { |
64 | unsigned int i; |
65 | int r, ret = 0; |
66 | struct cpufreq_freqs freqs; |
67 | struct opp *opp; |
68 | unsigned long freq, volt = 0, volt_old = 0, tol = 0; |
69 | |
70 | if (!freq_table) { |
71 | dev_err(mpu_dev, "%s: cpu%d: no freq table!\n", __func__, |
72 | policy->cpu); |
73 | return -EINVAL; |
74 | } |
75 | |
76 | ret = cpufreq_frequency_table_target(policy, freq_table, target_freq, |
77 | relation, &i); |
78 | if (ret) { |
79 | dev_dbg(mpu_dev, "%s: cpu%d: no freq match for %d(ret=%d)\n", |
80 | __func__, policy->cpu, target_freq, ret); |
81 | return ret; |
82 | } |
83 | freqs.new = freq_table[i].frequency; |
84 | if (!freqs.new) { |
85 | dev_err(mpu_dev, "%s: cpu%d: no match for freq %d\n", __func__, |
86 | policy->cpu, target_freq); |
87 | return -EINVAL; |
88 | } |
89 | |
90 | freqs.old = omap_getspeed(policy->cpu); |
91 | freqs.cpu = policy->cpu; |
92 | |
93 | if (freqs.old == freqs.new && policy->cur == freqs.new) |
94 | return ret; |
95 | |
96 | /* notifiers */ |
97 | for_each_cpu(i, policy->cpus) { |
98 | freqs.cpu = i; |
99 | cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE); |
100 | } |
101 | |
102 | freq = freqs.new * 1000; |
103 | ret = clk_round_rate(mpu_clk, freq); |
104 | if (IS_ERR_VALUE(ret)) { |
105 | dev_warn(mpu_dev, |
106 | "CPUfreq: Cannot find matching frequency for %lu\n", |
107 | freq); |
108 | return ret; |
109 | } |
110 | freq = ret; |
111 | |
112 | if (mpu_reg) { |
113 | rcu_read_lock(); |
114 | opp = opp_find_freq_ceil(mpu_dev, &freq); |
115 | if (IS_ERR(opp)) { |
116 | rcu_read_unlock(); |
117 | dev_err(mpu_dev, "%s: unable to find MPU OPP for %d\n", |
118 | __func__, freqs.new); |
119 | return -EINVAL; |
120 | } |
121 | volt = opp_get_voltage(opp); |
122 | rcu_read_unlock(); |
123 | tol = volt * OPP_TOLERANCE / 100; |
124 | volt_old = regulator_get_voltage(mpu_reg); |
125 | } |
126 | |
127 | dev_dbg(mpu_dev, "cpufreq-omap: %u MHz, %ld mV --> %u MHz, %ld mV\n", |
128 | freqs.old / 1000, volt_old ? volt_old / 1000 : -1, |
129 | freqs.new / 1000, volt ? volt / 1000 : -1); |
130 | |
131 | /* scaling up? scale voltage before frequency */ |
132 | if (mpu_reg && (freqs.new > freqs.old)) { |
133 | r = regulator_set_voltage(mpu_reg, volt - tol, volt + tol); |
134 | if (r < 0) { |
135 | dev_warn(mpu_dev, "%s: unable to scale voltage up.\n", |
136 | __func__); |
137 | freqs.new = freqs.old; |
138 | goto done; |
139 | } |
140 | } |
141 | |
142 | ret = clk_set_rate(mpu_clk, freqs.new * 1000); |
143 | |
144 | /* scaling down? scale voltage after frequency */ |
145 | if (mpu_reg && (freqs.new < freqs.old)) { |
146 | r = regulator_set_voltage(mpu_reg, volt - tol, volt + tol); |
147 | if (r < 0) { |
148 | dev_warn(mpu_dev, "%s: unable to scale voltage down.\n", |
149 | __func__); |
150 | ret = clk_set_rate(mpu_clk, freqs.old * 1000); |
151 | freqs.new = freqs.old; |
152 | goto done; |
153 | } |
154 | } |
155 | |
156 | freqs.new = omap_getspeed(policy->cpu); |
157 | |
158 | done: |
159 | /* notifiers */ |
160 | for_each_cpu(i, policy->cpus) { |
161 | freqs.cpu = i; |
162 | cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE); |
163 | } |
164 | |
165 | return ret; |
166 | } |
167 | |
168 | static inline void freq_table_free(void) |
169 | { |
170 | if (atomic_dec_and_test(&freq_table_users)) |
171 | opp_free_cpufreq_table(mpu_dev, &freq_table); |
172 | } |
173 | |
174 | static int __cpuinit omap_cpu_init(struct cpufreq_policy *policy) |
175 | { |
176 | int result = 0; |
177 | |
178 | mpu_clk = clk_get(NULL, "cpufreq_ck"); |
179 | if (IS_ERR(mpu_clk)) |
180 | return PTR_ERR(mpu_clk); |
181 | |
182 | if (policy->cpu >= NR_CPUS) { |
183 | result = -EINVAL; |
184 | goto fail_ck; |
185 | } |
186 | |
187 | policy->cur = policy->min = policy->max = omap_getspeed(policy->cpu); |
188 | |
189 | if (!freq_table) |
190 | result = opp_init_cpufreq_table(mpu_dev, &freq_table); |
191 | |
192 | if (result) { |
193 | dev_err(mpu_dev, "%s: cpu%d: failed creating freq table[%d]\n", |
194 | __func__, policy->cpu, result); |
195 | goto fail_ck; |
196 | } |
197 | |
198 | atomic_inc_return(&freq_table_users); |
199 | |
200 | result = cpufreq_frequency_table_cpuinfo(policy, freq_table); |
201 | if (result) |
202 | goto fail_table; |
203 | |
204 | cpufreq_frequency_table_get_attr(freq_table, policy->cpu); |
205 | |
206 | policy->min = policy->cpuinfo.min_freq; |
207 | policy->max = policy->cpuinfo.max_freq; |
208 | policy->cur = omap_getspeed(policy->cpu); |
209 | |
210 | /* |
211 | * On OMAP SMP configuartion, both processors share the voltage |
212 | * and clock. So both CPUs needs to be scaled together and hence |
213 | * needs software co-ordination. Use cpufreq affected_cpus |
214 | * interface to handle this scenario. Additional is_smp() check |
215 | * is to keep SMP_ON_UP build working. |
216 | */ |
217 | if (is_smp()) |
218 | cpumask_setall(policy->cpus); |
219 | |
220 | /* FIXME: what's the actual transition time? */ |
221 | policy->cpuinfo.transition_latency = 300 * 1000; |
222 | |
223 | return 0; |
224 | |
225 | fail_table: |
226 | freq_table_free(); |
227 | fail_ck: |
228 | clk_put(mpu_clk); |
229 | return result; |
230 | } |
231 | |
232 | static int omap_cpu_exit(struct cpufreq_policy *policy) |
233 | { |
234 | freq_table_free(); |
235 | clk_put(mpu_clk); |
236 | return 0; |
237 | } |
238 | |
239 | static struct freq_attr *omap_cpufreq_attr[] = { |
240 | &cpufreq_freq_attr_scaling_available_freqs, |
241 | NULL, |
242 | }; |
243 | |
244 | static struct cpufreq_driver omap_driver = { |
245 | .flags = CPUFREQ_STICKY, |
246 | .verify = omap_verify_speed, |
247 | .target = omap_target, |
248 | .get = omap_getspeed, |
249 | .init = omap_cpu_init, |
250 | .exit = omap_cpu_exit, |
251 | .name = "omap", |
252 | .attr = omap_cpufreq_attr, |
253 | }; |
254 | |
255 | static int __init omap_cpufreq_init(void) |
256 | { |
257 | mpu_dev = get_cpu_device(0); |
258 | if (!mpu_dev) { |
259 | pr_warning("%s: unable to get the mpu device\n", __func__); |
260 | return -EINVAL; |
261 | } |
262 | |
263 | mpu_reg = regulator_get(mpu_dev, "vcc"); |
264 | if (IS_ERR(mpu_reg)) { |
265 | pr_warning("%s: unable to get MPU regulator\n", __func__); |
266 | mpu_reg = NULL; |
267 | } else { |
268 | /* |
269 | * Ensure physical regulator is present. |
270 | * (e.g. could be dummy regulator.) |
271 | */ |
272 | if (regulator_get_voltage(mpu_reg) < 0) { |
273 | pr_warn("%s: physical regulator not present for MPU\n", |
274 | __func__); |
275 | regulator_put(mpu_reg); |
276 | mpu_reg = NULL; |
277 | } |
278 | } |
279 | |
280 | return cpufreq_register_driver(&omap_driver); |
281 | } |
282 | |
283 | static void __exit omap_cpufreq_exit(void) |
284 | { |
285 | cpufreq_unregister_driver(&omap_driver); |
286 | } |
287 | |
288 | MODULE_DESCRIPTION("cpufreq driver for OMAP SoCs"); |
289 | MODULE_LICENSE("GPL"); |
290 | module_init(omap_cpufreq_init); |
291 | module_exit(omap_cpufreq_exit); |
292 |
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