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/module.h>
14 #include <linux/nvmem-consumer.h>
15 #include <linux/of_device.h>
16 #include <linux/platform_device.h>
17 #include <linux/pm_opp.h>
18 #include <linux/slab.h>
19
20 #define MAX_NAME_LEN 7
21
22 #define NVMEM_MASK 0x7
23 #define NVMEM_SHIFT 5
24
25 static struct platform_device *cpufreq_dt_pdev, *sun50i_cpufreq_pdev;
26
27 /**
28 * sun50i_cpufreq_get_efuse() - Determine speed grade from efuse value
29 * @versions: Set to the value parsed from efuse
30 *
31 * Returns 0 if success.
32 */
sun50i_cpufreq_get_efuse(u32 * versions)33 static int sun50i_cpufreq_get_efuse(u32 *versions)
34 {
35 struct nvmem_cell *speedbin_nvmem;
36 struct device_node *np;
37 struct device *cpu_dev;
38 u32 *speedbin, efuse_value;
39 size_t len;
40 int ret;
41
42 cpu_dev = get_cpu_device(0);
43 if (!cpu_dev)
44 return -ENODEV;
45
46 np = dev_pm_opp_of_get_opp_desc_node(cpu_dev);
47 if (!np)
48 return -ENOENT;
49
50 ret = of_device_is_compatible(np,
51 "allwinner,sun50i-h6-operating-points");
52 if (!ret) {
53 of_node_put(np);
54 return -ENOENT;
55 }
56
57 speedbin_nvmem = of_nvmem_cell_get(np, NULL);
58 of_node_put(np);
59 if (IS_ERR(speedbin_nvmem))
60 return dev_err_probe(cpu_dev, PTR_ERR(speedbin_nvmem),
61 "Could not get nvmem cell\n");
62
63 speedbin = nvmem_cell_read(speedbin_nvmem, &len);
64 nvmem_cell_put(speedbin_nvmem);
65 if (IS_ERR(speedbin))
66 return PTR_ERR(speedbin);
67
68 efuse_value = (*speedbin >> NVMEM_SHIFT) & NVMEM_MASK;
69
70 /*
71 * We treat unexpected efuse values as if the SoC was from
72 * the slowest bin. Expected efuse values are 1-3, slowest
73 * to fastest.
74 */
75 if (efuse_value >= 1 && efuse_value <= 3)
76 *versions = efuse_value - 1;
77 else
78 *versions = 0;
79
80 kfree(speedbin);
81 return 0;
82 };
83
sun50i_cpufreq_nvmem_probe(struct platform_device * pdev)84 static int sun50i_cpufreq_nvmem_probe(struct platform_device *pdev)
85 {
86 int *opp_tokens;
87 char name[MAX_NAME_LEN];
88 unsigned int cpu;
89 u32 speed = 0;
90 int ret;
91
92 opp_tokens = kcalloc(num_possible_cpus(), sizeof(*opp_tokens),
93 GFP_KERNEL);
94 if (!opp_tokens)
95 return -ENOMEM;
96
97 ret = sun50i_cpufreq_get_efuse(&speed);
98 if (ret) {
99 kfree(opp_tokens);
100 return ret;
101 }
102
103 snprintf(name, MAX_NAME_LEN, "speed%d", speed);
104
105 for_each_possible_cpu(cpu) {
106 struct device *cpu_dev = get_cpu_device(cpu);
107
108 if (!cpu_dev) {
109 ret = -ENODEV;
110 goto free_opp;
111 }
112
113 opp_tokens[cpu] = dev_pm_opp_set_prop_name(cpu_dev, name);
114 if (opp_tokens[cpu] < 0) {
115 ret = opp_tokens[cpu];
116 pr_err("Failed to set prop name\n");
117 goto free_opp;
118 }
119 }
120
121 cpufreq_dt_pdev = platform_device_register_simple("cpufreq-dt", -1,
122 NULL, 0);
123 if (!IS_ERR(cpufreq_dt_pdev)) {
124 platform_set_drvdata(pdev, opp_tokens);
125 return 0;
126 }
127
128 ret = PTR_ERR(cpufreq_dt_pdev);
129 pr_err("Failed to register platform device\n");
130
131 free_opp:
132 for_each_possible_cpu(cpu)
133 dev_pm_opp_put_prop_name(opp_tokens[cpu]);
134 kfree(opp_tokens);
135
136 return ret;
137 }
138
sun50i_cpufreq_nvmem_remove(struct platform_device * pdev)139 static int sun50i_cpufreq_nvmem_remove(struct platform_device *pdev)
140 {
141 int *opp_tokens = platform_get_drvdata(pdev);
142 unsigned int cpu;
143
144 platform_device_unregister(cpufreq_dt_pdev);
145
146 for_each_possible_cpu(cpu)
147 dev_pm_opp_put_prop_name(opp_tokens[cpu]);
148
149 kfree(opp_tokens);
150
151 return 0;
152 }
153
154 static struct platform_driver sun50i_cpufreq_driver = {
155 .probe = sun50i_cpufreq_nvmem_probe,
156 .remove = sun50i_cpufreq_nvmem_remove,
157 .driver = {
158 .name = "sun50i-cpufreq-nvmem",
159 },
160 };
161
162 static const struct of_device_id sun50i_cpufreq_match_list[] = {
163 { .compatible = "allwinner,sun50i-h6" },
164 {}
165 };
166 MODULE_DEVICE_TABLE(of, sun50i_cpufreq_match_list);
167
sun50i_cpufreq_match_node(void)168 static const struct of_device_id *sun50i_cpufreq_match_node(void)
169 {
170 const struct of_device_id *match;
171 struct device_node *np;
172
173 np = of_find_node_by_path("/");
174 match = of_match_node(sun50i_cpufreq_match_list, np);
175 of_node_put(np);
176
177 return match;
178 }
179
180 /*
181 * Since the driver depends on nvmem drivers, which may return EPROBE_DEFER,
182 * all the real activity is done in the probe, which may be defered as well.
183 * The init here is only registering the driver and the platform device.
184 */
sun50i_cpufreq_init(void)185 static int __init sun50i_cpufreq_init(void)
186 {
187 const struct of_device_id *match;
188 int ret;
189
190 match = sun50i_cpufreq_match_node();
191 if (!match)
192 return -ENODEV;
193
194 ret = platform_driver_register(&sun50i_cpufreq_driver);
195 if (unlikely(ret < 0))
196 return ret;
197
198 sun50i_cpufreq_pdev =
199 platform_device_register_simple("sun50i-cpufreq-nvmem",
200 -1, NULL, 0);
201 ret = PTR_ERR_OR_ZERO(sun50i_cpufreq_pdev);
202 if (ret == 0)
203 return 0;
204
205 platform_driver_unregister(&sun50i_cpufreq_driver);
206 return ret;
207 }
208 module_init(sun50i_cpufreq_init);
209
sun50i_cpufreq_exit(void)210 static void __exit sun50i_cpufreq_exit(void)
211 {
212 platform_device_unregister(sun50i_cpufreq_pdev);
213 platform_driver_unregister(&sun50i_cpufreq_driver);
214 }
215 module_exit(sun50i_cpufreq_exit);
216
217 MODULE_DESCRIPTION("Sun50i-h6 cpufreq driver");
218 MODULE_LICENSE("GPL v2");
219
