1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Allwinner CPUFreq nvmem based driver
4 *
5 * The sun50i-cpufreq-nvmem driver reads the efuse value from the SoC to
6 * provide the OPP framework with required information.
7 *
8 * Copyright (C) 2019 Yangtao Li <tiny.windzz@gmail.com>
9 */
10
11 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
12
13 #include <linux/cpu.h>
14 #include <linux/module.h>
15 #include <linux/nvmem-consumer.h>
16 #include <linux/of.h>
17 #include <linux/platform_device.h>
18 #include <linux/pm_opp.h>
19 #include <linux/slab.h>
20
21 #define MAX_NAME_LEN 7
22
23 #define NVMEM_MASK 0x7
24 #define NVMEM_SHIFT 5
25
26 static struct platform_device *cpufreq_dt_pdev, *sun50i_cpufreq_pdev;
27
28 /**
29 * sun50i_cpufreq_get_efuse() - Determine speed grade from efuse value
30 * @versions: Set to the value parsed from efuse
31 *
32 * Returns 0 if success.
33 */
sun50i_cpufreq_get_efuse(u32 * versions)34 static int sun50i_cpufreq_get_efuse(u32 *versions)
35 {
36 struct nvmem_cell *speedbin_nvmem;
37 struct device_node *np;
38 struct device *cpu_dev;
39 u32 *speedbin, efuse_value;
40 size_t len;
41 int ret;
42
43 cpu_dev = get_cpu_device(0);
44 if (!cpu_dev)
45 return -ENODEV;
46
47 np = dev_pm_opp_of_get_opp_desc_node(cpu_dev);
48 if (!np)
49 return -ENOENT;
50
51 ret = of_device_is_compatible(np,
52 "allwinner,sun50i-h6-operating-points");
53 if (!ret) {
54 of_node_put(np);
55 return -ENOENT;
56 }
57
58 speedbin_nvmem = of_nvmem_cell_get(np, NULL);
59 of_node_put(np);
60 if (IS_ERR(speedbin_nvmem))
61 return dev_err_probe(cpu_dev, PTR_ERR(speedbin_nvmem),
62 "Could not get nvmem cell\n");
63
64 speedbin = nvmem_cell_read(speedbin_nvmem, &len);
65 nvmem_cell_put(speedbin_nvmem);
66 if (IS_ERR(speedbin))
67 return PTR_ERR(speedbin);
68
69 efuse_value = (*speedbin >> NVMEM_SHIFT) & NVMEM_MASK;
70
71 /*
72 * We treat unexpected efuse values as if the SoC was from
73 * the slowest bin. Expected efuse values are 1-3, slowest
74 * to fastest.
75 */
76 if (efuse_value >= 1 && efuse_value <= 3)
77 *versions = efuse_value - 1;
78 else
79 *versions = 0;
80
81 kfree(speedbin);
82 return 0;
83 };
84
sun50i_cpufreq_nvmem_probe(struct platform_device * pdev)85 static int sun50i_cpufreq_nvmem_probe(struct platform_device *pdev)
86 {
87 int *opp_tokens;
88 char name[MAX_NAME_LEN];
89 unsigned int cpu;
90 u32 speed = 0;
91 int ret;
92
93 opp_tokens = kcalloc(num_possible_cpus(), sizeof(*opp_tokens),
94 GFP_KERNEL);
95 if (!opp_tokens)
96 return -ENOMEM;
97
98 ret = sun50i_cpufreq_get_efuse(&speed);
99 if (ret) {
100 kfree(opp_tokens);
101 return ret;
102 }
103
104 snprintf(name, MAX_NAME_LEN, "speed%d", speed);
105
106 for_each_possible_cpu(cpu) {
107 struct device *cpu_dev = get_cpu_device(cpu);
108
109 if (!cpu_dev) {
110 ret = -ENODEV;
111 goto free_opp;
112 }
113
114 opp_tokens[cpu] = dev_pm_opp_set_prop_name(cpu_dev, name);
115 if (opp_tokens[cpu] < 0) {
116 ret = opp_tokens[cpu];
117 pr_err("Failed to set prop name\n");
118 goto free_opp;
119 }
120 }
121
122 cpufreq_dt_pdev = platform_device_register_simple("cpufreq-dt", -1,
123 NULL, 0);
124 if (!IS_ERR(cpufreq_dt_pdev)) {
125 platform_set_drvdata(pdev, opp_tokens);
126 return 0;
127 }
128
129 ret = PTR_ERR(cpufreq_dt_pdev);
130 pr_err("Failed to register platform device\n");
131
132 free_opp:
133 for_each_possible_cpu(cpu)
134 dev_pm_opp_put_prop_name(opp_tokens[cpu]);
135 kfree(opp_tokens);
136
137 return ret;
138 }
139
sun50i_cpufreq_nvmem_remove(struct platform_device * pdev)140 static void sun50i_cpufreq_nvmem_remove(struct platform_device *pdev)
141 {
142 int *opp_tokens = platform_get_drvdata(pdev);
143 unsigned int cpu;
144
145 platform_device_unregister(cpufreq_dt_pdev);
146
147 for_each_possible_cpu(cpu)
148 dev_pm_opp_put_prop_name(opp_tokens[cpu]);
149
150 kfree(opp_tokens);
151 }
152
153 static struct platform_driver sun50i_cpufreq_driver = {
154 .probe = sun50i_cpufreq_nvmem_probe,
155 .remove_new = sun50i_cpufreq_nvmem_remove,
156 .driver = {
157 .name = "sun50i-cpufreq-nvmem",
158 },
159 };
160
161 static const struct of_device_id sun50i_cpufreq_match_list[] = {
162 { .compatible = "allwinner,sun50i-h6" },
163 {}
164 };
165 MODULE_DEVICE_TABLE(of, sun50i_cpufreq_match_list);
166
sun50i_cpufreq_match_node(void)167 static const struct of_device_id *sun50i_cpufreq_match_node(void)
168 {
169 const struct of_device_id *match;
170 struct device_node *np;
171
172 np = of_find_node_by_path("/");
173 match = of_match_node(sun50i_cpufreq_match_list, np);
174 of_node_put(np);
175
176 return match;
177 }
178
179 /*
180 * Since the driver depends on nvmem drivers, which may return EPROBE_DEFER,
181 * all the real activity is done in the probe, which may be defered as well.
182 * The init here is only registering the driver and the platform device.
183 */
sun50i_cpufreq_init(void)184 static int __init sun50i_cpufreq_init(void)
185 {
186 const struct of_device_id *match;
187 int ret;
188
189 match = sun50i_cpufreq_match_node();
190 if (!match)
191 return -ENODEV;
192
193 ret = platform_driver_register(&sun50i_cpufreq_driver);
194 if (unlikely(ret < 0))
195 return ret;
196
197 sun50i_cpufreq_pdev =
198 platform_device_register_simple("sun50i-cpufreq-nvmem",
199 -1, NULL, 0);
200 ret = PTR_ERR_OR_ZERO(sun50i_cpufreq_pdev);
201 if (ret == 0)
202 return 0;
203
204 platform_driver_unregister(&sun50i_cpufreq_driver);
205 return ret;
206 }
207 module_init(sun50i_cpufreq_init);
208
sun50i_cpufreq_exit(void)209 static void __exit sun50i_cpufreq_exit(void)
210 {
211 platform_device_unregister(sun50i_cpufreq_pdev);
212 platform_driver_unregister(&sun50i_cpufreq_driver);
213 }
214 module_exit(sun50i_cpufreq_exit);
215
216 MODULE_DESCRIPTION("Sun50i-h6 cpufreq driver");
217 MODULE_LICENSE("GPL v2");
218