cpufreq: SPEAr: Add CPUFreq driver
[linux-3.10.git] / drivers / cpufreq / spear-cpufreq.c
1 /*
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 */
26 static struct {
27         struct clk *clk;
28         unsigned int transition_latency;
29         struct cpufreq_frequency_table *freq_tbl;
30         u32 cnt;
31 } spear_cpufreq;
32
33 int spear_cpufreq_verify(struct cpufreq_policy *policy)
34 {
35         return cpufreq_frequency_table_verify(policy, spear_cpufreq.freq_tbl);
36 }
37
38 static unsigned int spear_cpufreq_get(unsigned int cpu)
39 {
40         return clk_get_rate(spear_cpufreq.clk) / 1000;
41 }
42
43 static 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  */
85 static 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
112 static 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
177 static 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
197 static int spear_cpufreq_exit(struct cpufreq_policy *policy)
198 {
199         cpufreq_frequency_table_put_attr(policy->cpu);
200         return 0;
201 }
202
203 static struct freq_attr *spear_cpufreq_attr[] = {
204          &cpufreq_freq_attr_scaling_available_freqs,
205          NULL,
206 };
207
208 static 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
219 static 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
279 out_put_mem:
280         kfree(freq_tbl);
281         return ret;
282
283 out_put_node:
284         of_node_put(np);
285         return ret;
286 }
287 late_initcall(spear_cpufreq_driver_init);
288
289 MODULE_AUTHOR("Deepak Sikri <deepak.sikri@st.com>");
290 MODULE_DESCRIPTION("SPEAr CPUFreq driver");
291 MODULE_LICENSE("GPL");