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() - Parse and return efuse value present on SoC
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 if (PTR_ERR(speedbin_nvmem) != -EPROBE_DEFER)
61 pr_err("Could not get nvmem cell: %ld\n",
62 PTR_ERR(speedbin_nvmem));
63 return PTR_ERR(speedbin_nvmem);
64 }
65
66 speedbin = nvmem_cell_read(speedbin_nvmem, &len);
67 nvmem_cell_put(speedbin_nvmem);
68 if (IS_ERR(speedbin))
69 return PTR_ERR(speedbin);
70
71 efuse_value = (*speedbin >> NVMEM_SHIFT) & NVMEM_MASK;
72 switch (efuse_value) {
73 case 0b0001:
74 *versions = 1;
75 break;
76 case 0b0011:
77 *versions = 2;
78 break;
79 default:
80 /*
81 * For other situations, we treat it as bin0.
82 * This vf table can be run for any good cpu.
83 */
84 *versions = 0;
85 break;
86 }
87
88 kfree(speedbin);
89 return 0;
90 };
91
sun50i_cpufreq_nvmem_probe(struct platform_device * pdev)92 static int sun50i_cpufreq_nvmem_probe(struct platform_device *pdev)
93 {
94 struct opp_table **opp_tables;
95 char name[MAX_NAME_LEN];
96 unsigned int cpu;
97 u32 speed = 0;
98 int ret;
99
100 opp_tables = kcalloc(num_possible_cpus(), sizeof(*opp_tables),
101 GFP_KERNEL);
102 if (!opp_tables)
103 return -ENOMEM;
104
105 ret = sun50i_cpufreq_get_efuse(&speed);
106 if (ret)
107 return ret;
108
109 snprintf(name, MAX_NAME_LEN, "speed%d", speed);
110
111 for_each_possible_cpu(cpu) {
112 struct device *cpu_dev = get_cpu_device(cpu);
113
114 if (!cpu_dev) {
115 ret = -ENODEV;
116 goto free_opp;
117 }
118
119 opp_tables[cpu] = dev_pm_opp_set_prop_name(cpu_dev, name);
120 if (IS_ERR(opp_tables[cpu])) {
121 ret = PTR_ERR(opp_tables[cpu]);
122 pr_err("Failed to set prop name\n");
123 goto free_opp;
124 }
125 }
126
127 cpufreq_dt_pdev = platform_device_register_simple("cpufreq-dt", -1,
128 NULL, 0);
129 if (!IS_ERR(cpufreq_dt_pdev)) {
130 platform_set_drvdata(pdev, opp_tables);
131 return 0;
132 }
133
134 ret = PTR_ERR(cpufreq_dt_pdev);
135 pr_err("Failed to register platform device\n");
136
137 free_opp:
138 for_each_possible_cpu(cpu) {
139 if (IS_ERR_OR_NULL(opp_tables[cpu]))
140 break;
141 dev_pm_opp_put_prop_name(opp_tables[cpu]);
142 }
143 kfree(opp_tables);
144
145 return ret;
146 }
147
sun50i_cpufreq_nvmem_remove(struct platform_device * pdev)148 static int sun50i_cpufreq_nvmem_remove(struct platform_device *pdev)
149 {
150 struct opp_table **opp_tables = platform_get_drvdata(pdev);
151 unsigned int cpu;
152
153 platform_device_unregister(cpufreq_dt_pdev);
154
155 for_each_possible_cpu(cpu)
156 dev_pm_opp_put_prop_name(opp_tables[cpu]);
157
158 kfree(opp_tables);
159
160 return 0;
161 }
162
163 static struct platform_driver sun50i_cpufreq_driver = {
164 .probe = sun50i_cpufreq_nvmem_probe,
165 .remove = sun50i_cpufreq_nvmem_remove,
166 .driver = {
167 .name = "sun50i-cpufreq-nvmem",
168 },
169 };
170
171 static const struct of_device_id sun50i_cpufreq_match_list[] = {
172 { .compatible = "allwinner,sun50i-h6" },
173 {}
174 };
175
sun50i_cpufreq_match_node(void)176 static const struct of_device_id *sun50i_cpufreq_match_node(void)
177 {
178 const struct of_device_id *match;
179 struct device_node *np;
180
181 np = of_find_node_by_path("/");
182 match = of_match_node(sun50i_cpufreq_match_list, np);
183 of_node_put(np);
184
185 return match;
186 }
187
188 /*
189 * Since the driver depends on nvmem drivers, which may return EPROBE_DEFER,
190 * all the real activity is done in the probe, which may be defered as well.
191 * The init here is only registering the driver and the platform device.
192 */
sun50i_cpufreq_init(void)193 static int __init sun50i_cpufreq_init(void)
194 {
195 const struct of_device_id *match;
196 int ret;
197
198 match = sun50i_cpufreq_match_node();
199 if (!match)
200 return -ENODEV;
201
202 ret = platform_driver_register(&sun50i_cpufreq_driver);
203 if (unlikely(ret < 0))
204 return ret;
205
206 sun50i_cpufreq_pdev =
207 platform_device_register_simple("sun50i-cpufreq-nvmem",
208 -1, NULL, 0);
209 ret = PTR_ERR_OR_ZERO(sun50i_cpufreq_pdev);
210 if (ret == 0)
211 return 0;
212
213 platform_driver_unregister(&sun50i_cpufreq_driver);
214 return ret;
215 }
216 module_init(sun50i_cpufreq_init);
217
sun50i_cpufreq_exit(void)218 static void __exit sun50i_cpufreq_exit(void)
219 {
220 platform_device_unregister(sun50i_cpufreq_pdev);
221 platform_driver_unregister(&sun50i_cpufreq_driver);
222 }
223 module_exit(sun50i_cpufreq_exit);
224
225 MODULE_DESCRIPTION("Sun50i-h6 cpufreq driver");
226 MODULE_LICENSE("GPL v2");
227
