GNU Linux-libre 5.19-rc6-gnu
[releases.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_device.h>
22 #include <linux/platform_device.h>
23 #include <linux/slab.h>
24 #include <linux/types.h>
25
26 /* SPEAr CPUFreq driver data structure */
27 static struct {
28         struct clk *clk;
29         unsigned int transition_latency;
30         struct cpufreq_frequency_table *freq_tbl;
31         u32 cnt;
32 } spear_cpufreq;
33
34 static struct clk *spear1340_cpu_get_possible_parent(unsigned long newfreq)
35 {
36         struct clk *sys_pclk;
37         int pclk;
38         /*
39          * In SPEAr1340, cpu clk's parent sys clk can take input from
40          * following sources
41          */
42         const char *sys_clk_src[] = {
43                 "sys_syn_clk",
44                 "pll1_clk",
45                 "pll2_clk",
46                 "pll3_clk",
47         };
48
49         /*
50          * As sys clk can have multiple source with their own range
51          * limitation so we choose possible sources accordingly
52          */
53         if (newfreq <= 300000000)
54                 pclk = 0; /* src is sys_syn_clk */
55         else if (newfreq > 300000000 && newfreq <= 500000000)
56                 pclk = 3; /* src is pll3_clk */
57         else if (newfreq == 600000000)
58                 pclk = 1; /* src is pll1_clk */
59         else
60                 return ERR_PTR(-EINVAL);
61
62         /* Get parent to sys clock */
63         sys_pclk = clk_get(NULL, sys_clk_src[pclk]);
64         if (IS_ERR(sys_pclk))
65                 pr_err("Failed to get %s clock\n", sys_clk_src[pclk]);
66
67         return sys_pclk;
68 }
69
70 /*
71  * In SPEAr1340, we cannot use newfreq directly because we need to actually
72  * access a source clock (clk) which might not be ancestor of cpu at present.
73  * Hence in SPEAr1340 we would operate on source clock directly before switching
74  * cpu clock to it.
75  */
76 static int spear1340_set_cpu_rate(struct clk *sys_pclk, unsigned long newfreq)
77 {
78         struct clk *sys_clk;
79         int ret = 0;
80
81         sys_clk = clk_get_parent(spear_cpufreq.clk);
82         if (IS_ERR(sys_clk)) {
83                 pr_err("failed to get cpu's parent (sys) clock\n");
84                 return PTR_ERR(sys_clk);
85         }
86
87         /* Set the rate of the source clock before changing the parent */
88         ret = clk_set_rate(sys_pclk, newfreq);
89         if (ret) {
90                 pr_err("Failed to set sys clk rate to %lu\n", newfreq);
91                 return ret;
92         }
93
94         ret = clk_set_parent(sys_clk, sys_pclk);
95         if (ret) {
96                 pr_err("Failed to set sys clk parent\n");
97                 return ret;
98         }
99
100         return 0;
101 }
102
103 static int spear_cpufreq_target(struct cpufreq_policy *policy,
104                 unsigned int index)
105 {
106         long newfreq;
107         struct clk *srcclk;
108         int ret, mult = 1;
109
110         newfreq = spear_cpufreq.freq_tbl[index].frequency * 1000;
111
112         if (of_machine_is_compatible("st,spear1340")) {
113                 /*
114                  * SPEAr1340 is special in the sense that due to the possibility
115                  * of multiple clock sources for cpu clk's parent we can have
116                  * different clock source for different frequency of cpu clk.
117                  * Hence we need to choose one from amongst these possible clock
118                  * sources.
119                  */
120                 srcclk = spear1340_cpu_get_possible_parent(newfreq);
121                 if (IS_ERR(srcclk)) {
122                         pr_err("Failed to get src clk\n");
123                         return PTR_ERR(srcclk);
124                 }
125
126                 /* SPEAr1340: src clk is always 2 * intended cpu clk */
127                 mult = 2;
128         } else {
129                 /*
130                  * src clock to be altered is ancestor of cpu clock. Hence we
131                  * can directly work on cpu clk
132                  */
133                 srcclk = spear_cpufreq.clk;
134         }
135
136         newfreq = clk_round_rate(srcclk, newfreq * mult);
137         if (newfreq <= 0) {
138                 pr_err("clk_round_rate failed for cpu src clock\n");
139                 return newfreq;
140         }
141
142         if (mult == 2)
143                 ret = spear1340_set_cpu_rate(srcclk, newfreq);
144         else
145                 ret = clk_set_rate(spear_cpufreq.clk, newfreq);
146
147         if (ret)
148                 pr_err("CPU Freq: cpu clk_set_rate failed: %d\n", ret);
149
150         return ret;
151 }
152
153 static int spear_cpufreq_init(struct cpufreq_policy *policy)
154 {
155         policy->clk = spear_cpufreq.clk;
156         cpufreq_generic_init(policy, spear_cpufreq.freq_tbl,
157                         spear_cpufreq.transition_latency);
158         return 0;
159 }
160
161 static struct cpufreq_driver spear_cpufreq_driver = {
162         .name           = "cpufreq-spear",
163         .flags          = CPUFREQ_NEED_INITIAL_FREQ_CHECK,
164         .verify         = cpufreq_generic_frequency_table_verify,
165         .target_index   = spear_cpufreq_target,
166         .get            = cpufreq_generic_get,
167         .init           = spear_cpufreq_init,
168         .attr           = cpufreq_generic_attr,
169 };
170
171 static int spear_cpufreq_probe(struct platform_device *pdev)
172 {
173         struct device_node *np;
174         const struct property *prop;
175         struct cpufreq_frequency_table *freq_tbl;
176         const __be32 *val;
177         int cnt, i, ret;
178
179         np = of_cpu_device_node_get(0);
180         if (!np) {
181                 pr_err("No cpu node found\n");
182                 return -ENODEV;
183         }
184
185         if (of_property_read_u32(np, "clock-latency",
186                                 &spear_cpufreq.transition_latency))
187                 spear_cpufreq.transition_latency = CPUFREQ_ETERNAL;
188
189         prop = of_find_property(np, "cpufreq_tbl", NULL);
190         if (!prop || !prop->value) {
191                 pr_err("Invalid cpufreq_tbl\n");
192                 ret = -ENODEV;
193                 goto out_put_node;
194         }
195
196         cnt = prop->length / sizeof(u32);
197         val = prop->value;
198
199         freq_tbl = kcalloc(cnt + 1, sizeof(*freq_tbl), GFP_KERNEL);
200         if (!freq_tbl) {
201                 ret = -ENOMEM;
202                 goto out_put_node;
203         }
204
205         for (i = 0; i < cnt; i++)
206                 freq_tbl[i].frequency = be32_to_cpup(val++);
207
208         freq_tbl[i].frequency = CPUFREQ_TABLE_END;
209
210         spear_cpufreq.freq_tbl = freq_tbl;
211
212         of_node_put(np);
213
214         spear_cpufreq.clk = clk_get(NULL, "cpu_clk");
215         if (IS_ERR(spear_cpufreq.clk)) {
216                 pr_err("Unable to get CPU clock\n");
217                 ret = PTR_ERR(spear_cpufreq.clk);
218                 goto out_put_mem;
219         }
220
221         ret = cpufreq_register_driver(&spear_cpufreq_driver);
222         if (!ret)
223                 return 0;
224
225         pr_err("failed register driver: %d\n", ret);
226         clk_put(spear_cpufreq.clk);
227
228 out_put_mem:
229         kfree(freq_tbl);
230         return ret;
231
232 out_put_node:
233         of_node_put(np);
234         return ret;
235 }
236
237 static struct platform_driver spear_cpufreq_platdrv = {
238         .driver = {
239                 .name   = "spear-cpufreq",
240         },
241         .probe          = spear_cpufreq_probe,
242 };
243 module_platform_driver(spear_cpufreq_platdrv);
244
245 MODULE_AUTHOR("Deepak Sikri <deepak.sikri@st.com>");
246 MODULE_DESCRIPTION("SPEAr CPUFreq driver");
247 MODULE_LICENSE("GPL");