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Deepak Sikri42099322012-11-27 14:05:26 +01001/*
2 * drivers/cpufreq/spear-cpufreq.c
3 *
4 * CPU Frequency Scaling for SPEAr platform
5 *
6 * Copyright (C) 2012 ST Microelectronics
7 * Deepak Sikri <deepak.sikri@st.com>
8 *
9 * This file is licensed under the terms of the GNU General Public
10 * License version 2. This program is licensed "as is" without any
11 * warranty of any kind, whether express or implied.
12 */
13
14#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
15
16#include <linux/clk.h>
17#include <linux/cpufreq.h>
18#include <linux/err.h>
19#include <linux/init.h>
20#include <linux/module.h>
21#include <linux/of.h>
22#include <linux/slab.h>
23#include <linux/types.h>
24
25/* SPEAr CPUFreq driver data structure */
26static struct {
27 struct clk *clk;
28 unsigned int transition_latency;
29 struct cpufreq_frequency_table *freq_tbl;
30 u32 cnt;
31} spear_cpufreq;
32
33int spear_cpufreq_verify(struct cpufreq_policy *policy)
34{
35 return cpufreq_frequency_table_verify(policy, spear_cpufreq.freq_tbl);
36}
37
38static unsigned int spear_cpufreq_get(unsigned int cpu)
39{
40 return clk_get_rate(spear_cpufreq.clk) / 1000;
41}
42
43static struct clk *spear1340_cpu_get_possible_parent(unsigned long newfreq)
44{
45 struct clk *sys_pclk;
46 int pclk;
47 /*
48 * In SPEAr1340, cpu clk's parent sys clk can take input from
49 * following sources
50 */
51 const char *sys_clk_src[] = {
52 "sys_syn_clk",
53 "pll1_clk",
54 "pll2_clk",
55 "pll3_clk",
56 };
57
58 /*
59 * As sys clk can have multiple source with their own range
60 * limitation so we choose possible sources accordingly
61 */
62 if (newfreq <= 300000000)
63 pclk = 0; /* src is sys_syn_clk */
64 else if (newfreq > 300000000 && newfreq <= 500000000)
65 pclk = 3; /* src is pll3_clk */
66 else if (newfreq == 600000000)
67 pclk = 1; /* src is pll1_clk */
68 else
69 return ERR_PTR(-EINVAL);
70
71 /* Get parent to sys clock */
72 sys_pclk = clk_get(NULL, sys_clk_src[pclk]);
73 if (IS_ERR(sys_pclk))
74 pr_err("Failed to get %s clock\n", sys_clk_src[pclk]);
75
76 return sys_pclk;
77}
78
79/*
80 * In SPEAr1340, we cannot use newfreq directly because we need to actually
81 * access a source clock (clk) which might not be ancestor of cpu at present.
82 * Hence in SPEAr1340 we would operate on source clock directly before switching
83 * cpu clock to it.
84 */
85static int spear1340_set_cpu_rate(struct clk *sys_pclk, unsigned long newfreq)
86{
87 struct clk *sys_clk;
88 int ret = 0;
89
90 sys_clk = clk_get_parent(spear_cpufreq.clk);
91 if (IS_ERR(sys_clk)) {
92 pr_err("failed to get cpu's parent (sys) clock\n");
93 return PTR_ERR(sys_clk);
94 }
95
96 /* Set the rate of the source clock before changing the parent */
97 ret = clk_set_rate(sys_pclk, newfreq);
98 if (ret) {
99 pr_err("Failed to set sys clk rate to %lu\n", newfreq);
100 return ret;
101 }
102
103 ret = clk_set_parent(sys_clk, sys_pclk);
104 if (ret) {
105 pr_err("Failed to set sys clk parent\n");
106 return ret;
107 }
108
109 return 0;
110}
111
112static int spear_cpufreq_target(struct cpufreq_policy *policy,
113 unsigned int target_freq, unsigned int relation)
114{
115 struct cpufreq_freqs freqs;
116 unsigned long newfreq;
117 struct clk *srcclk;
118 int index, ret, mult = 1;
119
120 if (cpufreq_frequency_table_target(policy, spear_cpufreq.freq_tbl,
121 target_freq, relation, &index))
122 return -EINVAL;
123
124 freqs.cpu = policy->cpu;
125 freqs.old = spear_cpufreq_get(0);
126
127 newfreq = spear_cpufreq.freq_tbl[index].frequency * 1000;
128 if (of_machine_is_compatible("st,spear1340")) {
129 /*
130 * SPEAr1340 is special in the sense that due to the possibility
131 * of multiple clock sources for cpu clk's parent we can have
132 * different clock source for different frequency of cpu clk.
133 * Hence we need to choose one from amongst these possible clock
134 * sources.
135 */
136 srcclk = spear1340_cpu_get_possible_parent(newfreq);
137 if (IS_ERR(srcclk)) {
138 pr_err("Failed to get src clk\n");
139 return PTR_ERR(srcclk);
140 }
141
142 /* SPEAr1340: src clk is always 2 * intended cpu clk */
143 mult = 2;
144 } else {
145 /*
146 * src clock to be altered is ancestor of cpu clock. Hence we
147 * can directly work on cpu clk
148 */
149 srcclk = spear_cpufreq.clk;
150 }
151
152 newfreq = clk_round_rate(srcclk, newfreq * mult);
153 if (newfreq < 0) {
154 pr_err("clk_round_rate failed for cpu src clock\n");
155 return newfreq;
156 }
157
158 freqs.new = newfreq / 1000;
159 freqs.new /= mult;
160 cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
161
162 if (mult == 2)
163 ret = spear1340_set_cpu_rate(srcclk, newfreq);
164 else
165 ret = clk_set_rate(spear_cpufreq.clk, newfreq);
166
167 /* Get current rate after clk_set_rate, in case of failure */
168 if (ret) {
169 pr_err("CPU Freq: cpu clk_set_rate failed: %d\n", ret);
170 freqs.new = clk_get_rate(spear_cpufreq.clk) / 1000;
171 }
172
173 cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
174 return ret;
175}
176
177static int spear_cpufreq_init(struct cpufreq_policy *policy)
178{
179 int ret;
180
181 ret = cpufreq_frequency_table_cpuinfo(policy, spear_cpufreq.freq_tbl);
182 if (ret) {
183 pr_err("cpufreq_frequency_table_cpuinfo() failed");
184 return ret;
185 }
186
187 cpufreq_frequency_table_get_attr(spear_cpufreq.freq_tbl, policy->cpu);
188 policy->cpuinfo.transition_latency = spear_cpufreq.transition_latency;
189 policy->cur = spear_cpufreq_get(0);
190
191 cpumask_copy(policy->cpus, topology_core_cpumask(policy->cpu));
192 cpumask_copy(policy->related_cpus, policy->cpus);
193
194 return 0;
195}
196
197static int spear_cpufreq_exit(struct cpufreq_policy *policy)
198{
199 cpufreq_frequency_table_put_attr(policy->cpu);
200 return 0;
201}
202
203static struct freq_attr *spear_cpufreq_attr[] = {
204 &cpufreq_freq_attr_scaling_available_freqs,
205 NULL,
206};
207
208static struct cpufreq_driver spear_cpufreq_driver = {
209 .name = "cpufreq-spear",
210 .flags = CPUFREQ_STICKY,
211 .verify = spear_cpufreq_verify,
212 .target = spear_cpufreq_target,
213 .get = spear_cpufreq_get,
214 .init = spear_cpufreq_init,
215 .exit = spear_cpufreq_exit,
216 .attr = spear_cpufreq_attr,
217};
218
219static int spear_cpufreq_driver_init(void)
220{
221 struct device_node *np;
222 const struct property *prop;
223 struct cpufreq_frequency_table *freq_tbl;
224 const __be32 *val;
225 int cnt, i, ret;
226
227 np = of_find_node_by_path("/cpus/cpu@0");
228 if (!np) {
229 pr_err("No cpu node found");
230 return -ENODEV;
231 }
232
233 if (of_property_read_u32(np, "clock-latency",
234 &spear_cpufreq.transition_latency))
235 spear_cpufreq.transition_latency = CPUFREQ_ETERNAL;
236
237 prop = of_find_property(np, "cpufreq_tbl", NULL);
238 if (!prop || !prop->value) {
239 pr_err("Invalid cpufreq_tbl");
240 ret = -ENODEV;
241 goto out_put_node;
242 }
243
244 cnt = prop->length / sizeof(u32);
245 val = prop->value;
246
247 freq_tbl = kmalloc(sizeof(*freq_tbl) * (cnt + 1), GFP_KERNEL);
248 if (!freq_tbl) {
249 ret = -ENOMEM;
250 goto out_put_node;
251 }
252
253 for (i = 0; i < cnt; i++) {
254 freq_tbl[i].index = i;
255 freq_tbl[i].frequency = be32_to_cpup(val++);
256 }
257
258 freq_tbl[i].index = i;
259 freq_tbl[i].frequency = CPUFREQ_TABLE_END;
260
261 spear_cpufreq.freq_tbl = freq_tbl;
262
263 of_node_put(np);
264
265 spear_cpufreq.clk = clk_get(NULL, "cpu_clk");
266 if (IS_ERR(spear_cpufreq.clk)) {
267 pr_err("Unable to get CPU clock\n");
268 ret = PTR_ERR(spear_cpufreq.clk);
269 goto out_put_mem;
270 }
271
272 ret = cpufreq_register_driver(&spear_cpufreq_driver);
273 if (!ret)
274 return 0;
275
276 pr_err("failed register driver: %d\n", ret);
277 clk_put(spear_cpufreq.clk);
278
279out_put_mem:
280 kfree(freq_tbl);
281 return ret;
282
283out_put_node:
284 of_node_put(np);
285 return ret;
286}
287late_initcall(spear_cpufreq_driver_init);
288
289MODULE_AUTHOR("Deepak Sikri <deepak.sikri@st.com>");
290MODULE_DESCRIPTION("SPEAr CPUFreq driver");
291MODULE_LICENSE("GPL");