1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * CPUFreq support for Armada 8K
4 *
5 * Copyright (C) 2018 Marvell
6 *
7 * Omri Itach <omrii@marvell.com>
8 * Gregory Clement <gregory.clement@bootlin.com>
9 */
10
11 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
12
13 #include <linux/clk.h>
14 #include <linux/cpu.h>
15 #include <linux/err.h>
16 #include <linux/init.h>
17 #include <linux/kernel.h>
18 #include <linux/module.h>
19 #include <linux/of.h>
20 #include <linux/platform_device.h>
21 #include <linux/pm_opp.h>
22 #include <linux/slab.h>
23
24 static const struct of_device_id __maybe_unused armada_8k_cpufreq_of_match[] = {
25 { .compatible = "marvell,ap806-cpu-clock" },
26 { .compatible = "marvell,ap807-cpu-clock" },
27 { },
28 };
29 MODULE_DEVICE_TABLE(of, armada_8k_cpufreq_of_match);
30
31 /*
32 * Setup the opps list with the divider for the max frequency, that
33 * will be filled at runtime.
34 */
35 static const int opps_div[] __initconst = {1, 2, 3, 4};
36
37 static struct platform_device *armada_8k_pdev;
38
39 struct freq_table {
40 struct device *cpu_dev;
41 unsigned int freq[ARRAY_SIZE(opps_div)];
42 };
43
44 /* If the CPUs share the same clock, then they are in the same cluster. */
armada_8k_get_sharing_cpus(struct clk * cur_clk,struct cpumask * cpumask)45 static void __init armada_8k_get_sharing_cpus(struct clk *cur_clk,
46 struct cpumask *cpumask)
47 {
48 int cpu;
49
50 for_each_possible_cpu(cpu) {
51 struct device *cpu_dev;
52 struct clk *clk;
53
54 cpu_dev = get_cpu_device(cpu);
55 if (!cpu_dev) {
56 pr_warn("Failed to get cpu%d device\n", cpu);
57 continue;
58 }
59
60 clk = clk_get(cpu_dev, NULL);
61 if (IS_ERR(clk)) {
62 pr_warn("Cannot get clock for CPU %d\n", cpu);
63 } else {
64 if (clk_is_match(clk, cur_clk))
65 cpumask_set_cpu(cpu, cpumask);
66
67 clk_put(clk);
68 }
69 }
70 }
71
armada_8k_add_opp(struct clk * clk,struct device * cpu_dev,struct freq_table * freq_tables,int opps_index)72 static int __init armada_8k_add_opp(struct clk *clk, struct device *cpu_dev,
73 struct freq_table *freq_tables,
74 int opps_index)
75 {
76 unsigned int cur_frequency;
77 unsigned int freq;
78 int i, ret;
79
80 /* Get nominal (current) CPU frequency. */
81 cur_frequency = clk_get_rate(clk);
82 if (!cur_frequency) {
83 dev_err(cpu_dev, "Failed to get clock rate for this CPU\n");
84 return -EINVAL;
85 }
86
87 freq_tables[opps_index].cpu_dev = cpu_dev;
88
89 for (i = 0; i < ARRAY_SIZE(opps_div); i++) {
90 freq = cur_frequency / opps_div[i];
91
92 ret = dev_pm_opp_add(cpu_dev, freq, 0);
93 if (ret)
94 return ret;
95
96 freq_tables[opps_index].freq[i] = freq;
97 }
98
99 return 0;
100 }
101
armada_8k_cpufreq_free_table(struct freq_table * freq_tables)102 static void armada_8k_cpufreq_free_table(struct freq_table *freq_tables)
103 {
104 int opps_index, nb_cpus = num_possible_cpus();
105
106 for (opps_index = 0 ; opps_index <= nb_cpus; opps_index++) {
107 int i;
108
109 /* If cpu_dev is NULL then we reached the end of the array */
110 if (!freq_tables[opps_index].cpu_dev)
111 break;
112
113 for (i = 0; i < ARRAY_SIZE(opps_div); i++) {
114 /*
115 * A 0Hz frequency is not valid, this meant
116 * that it was not yet initialized so there is
117 * no more opp to free
118 */
119 if (freq_tables[opps_index].freq[i] == 0)
120 break;
121
122 dev_pm_opp_remove(freq_tables[opps_index].cpu_dev,
123 freq_tables[opps_index].freq[i]);
124 }
125 }
126
127 kfree(freq_tables);
128 }
129
armada_8k_cpufreq_init(void)130 static int __init armada_8k_cpufreq_init(void)
131 {
132 int ret = 0, opps_index = 0, cpu, nb_cpus;
133 struct freq_table *freq_tables;
134 struct device_node *node;
135 static struct cpumask cpus;
136
137 node = of_find_matching_node_and_match(NULL, armada_8k_cpufreq_of_match,
138 NULL);
139 if (!node || !of_device_is_available(node)) {
140 of_node_put(node);
141 return -ENODEV;
142 }
143 of_node_put(node);
144
145 nb_cpus = num_possible_cpus();
146 freq_tables = kcalloc(nb_cpus, sizeof(*freq_tables), GFP_KERNEL);
147 if (!freq_tables)
148 return -ENOMEM;
149 cpumask_copy(&cpus, cpu_possible_mask);
150
151 /*
152 * For each CPU, this loop registers the operating points
153 * supported (which are the nominal CPU frequency and full integer
154 * divisions of it).
155 */
156 for_each_cpu(cpu, &cpus) {
157 struct cpumask shared_cpus;
158 struct device *cpu_dev;
159 struct clk *clk;
160
161 cpu_dev = get_cpu_device(cpu);
162
163 if (!cpu_dev) {
164 pr_err("Cannot get CPU %d\n", cpu);
165 continue;
166 }
167
168 clk = clk_get(cpu_dev, NULL);
169
170 if (IS_ERR(clk)) {
171 pr_err("Cannot get clock for CPU %d\n", cpu);
172 ret = PTR_ERR(clk);
173 goto remove_opp;
174 }
175
176 ret = armada_8k_add_opp(clk, cpu_dev, freq_tables, opps_index);
177 if (ret) {
178 clk_put(clk);
179 goto remove_opp;
180 }
181
182 opps_index++;
183 cpumask_clear(&shared_cpus);
184 armada_8k_get_sharing_cpus(clk, &shared_cpus);
185 dev_pm_opp_set_sharing_cpus(cpu_dev, &shared_cpus);
186 cpumask_andnot(&cpus, &cpus, &shared_cpus);
187 clk_put(clk);
188 }
189
190 armada_8k_pdev = platform_device_register_simple("cpufreq-dt", -1,
191 NULL, 0);
192 ret = PTR_ERR_OR_ZERO(armada_8k_pdev);
193 if (ret)
194 goto remove_opp;
195
196 platform_set_drvdata(armada_8k_pdev, freq_tables);
197
198 return 0;
199
200 remove_opp:
201 armada_8k_cpufreq_free_table(freq_tables);
202 return ret;
203 }
204 module_init(armada_8k_cpufreq_init);
205
armada_8k_cpufreq_exit(void)206 static void __exit armada_8k_cpufreq_exit(void)
207 {
208 struct freq_table *freq_tables = platform_get_drvdata(armada_8k_pdev);
209
210 platform_device_unregister(armada_8k_pdev);
211 armada_8k_cpufreq_free_table(freq_tables);
212 }
213 module_exit(armada_8k_cpufreq_exit);
214
215 MODULE_AUTHOR("Gregory Clement <gregory.clement@bootlin.com>");
216 MODULE_DESCRIPTION("Armada 8K cpufreq driver");
217 MODULE_LICENSE("GPL");
218