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
spear1340_cpu_get_possible_parent(unsigned long newfreq)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 */
spear1340_set_cpu_rate(struct clk * sys_pclk,unsigned long newfreq)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
spear_cpufreq_target(struct cpufreq_policy * policy,unsigned int index)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
spear_cpufreq_init(struct cpufreq_policy * policy)153 static int spear_cpufreq_init(struct cpufreq_policy *policy)
154 {
155 policy->clk = spear_cpufreq.clk;
156 return cpufreq_generic_init(policy, spear_cpufreq.freq_tbl,
157 spear_cpufreq.transition_latency);
158 }
159
160 static struct cpufreq_driver spear_cpufreq_driver = {
161 .name = "cpufreq-spear",
162 .flags = CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
163 .verify = cpufreq_generic_frequency_table_verify,
164 .target_index = spear_cpufreq_target,
165 .get = cpufreq_generic_get,
166 .init = spear_cpufreq_init,
167 .attr = cpufreq_generic_attr,
168 };
169
spear_cpufreq_probe(struct platform_device * pdev)170 static int spear_cpufreq_probe(struct platform_device *pdev)
171 {
172 struct device_node *np;
173 const struct property *prop;
174 struct cpufreq_frequency_table *freq_tbl;
175 const __be32 *val;
176 int cnt, i, ret;
177
178 np = of_cpu_device_node_get(0);
179 if (!np) {
180 pr_err("No cpu node found");
181 return -ENODEV;
182 }
183
184 if (of_property_read_u32(np, "clock-latency",
185 &spear_cpufreq.transition_latency))
186 spear_cpufreq.transition_latency = CPUFREQ_ETERNAL;
187
188 prop = of_find_property(np, "cpufreq_tbl", NULL);
189 if (!prop || !prop->value) {
190 pr_err("Invalid cpufreq_tbl");
191 ret = -ENODEV;
192 goto out_put_node;
193 }
194
195 cnt = prop->length / sizeof(u32);
196 val = prop->value;
197
198 freq_tbl = kzalloc(sizeof(*freq_tbl) * (cnt + 1), GFP_KERNEL);
199 if (!freq_tbl) {
200 ret = -ENOMEM;
201 goto out_put_node;
202 }
203
204 for (i = 0; i < cnt; i++)
205 freq_tbl[i].frequency = be32_to_cpup(val++);
206
207 freq_tbl[i].frequency = CPUFREQ_TABLE_END;
208
209 spear_cpufreq.freq_tbl = freq_tbl;
210
211 of_node_put(np);
212
213 spear_cpufreq.clk = clk_get(NULL, "cpu_clk");
214 if (IS_ERR(spear_cpufreq.clk)) {
215 pr_err("Unable to get CPU clock\n");
216 ret = PTR_ERR(spear_cpufreq.clk);
217 goto out_put_mem;
218 }
219
220 ret = cpufreq_register_driver(&spear_cpufreq_driver);
221 if (!ret)
222 return 0;
223
224 pr_err("failed register driver: %d\n", ret);
225 clk_put(spear_cpufreq.clk);
226
227 out_put_mem:
228 kfree(freq_tbl);
229 return ret;
230
231 out_put_node:
232 of_node_put(np);
233 return ret;
234 }
235
236 static struct platform_driver spear_cpufreq_platdrv = {
237 .driver = {
238 .name = "spear-cpufreq",
239 },
240 .probe = spear_cpufreq_probe,
241 };
242 module_platform_driver(spear_cpufreq_platdrv);
243
244 MODULE_AUTHOR("Deepak Sikri <deepak.sikri@st.com>");
245 MODULE_DESCRIPTION("SPEAr CPUFreq driver");
246 MODULE_LICENSE("GPL");
247