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 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
73 /*
74 * We treat unexpected efuse values as if the SoC was from
75 * the slowest bin. Expected efuse values are 1-3, slowest
76 * to fastest.
77 */
78 if (efuse_value >= 1 && efuse_value <= 3)
79 *versions = efuse_value - 1;
80 else
81 *versions = 0;
82
83 kfree(speedbin);
84 return 0;
85 };
86
sun50i_cpufreq_nvmem_probe(struct platform_device * pdev)87 static int sun50i_cpufreq_nvmem_probe(struct platform_device *pdev)
88 {
89 struct opp_table **opp_tables;
90 char name[MAX_NAME_LEN];
91 unsigned int cpu;
92 u32 speed = 0;
93 int ret;
94
95 opp_tables = kcalloc(num_possible_cpus(), sizeof(*opp_tables),
96 GFP_KERNEL);
97 if (!opp_tables)
98 return -ENOMEM;
99
100 ret = sun50i_cpufreq_get_efuse(&speed);
101 if (ret) {
102 kfree(opp_tables);
103 return ret;
104 }
105
106 snprintf(name, MAX_NAME_LEN, "speed%d", speed);
107
108 for_each_possible_cpu(cpu) {
109 struct device *cpu_dev = get_cpu_device(cpu);
110
111 if (!cpu_dev) {
112 ret = -ENODEV;
113 goto free_opp;
114 }
115
116 opp_tables[cpu] = dev_pm_opp_set_prop_name(cpu_dev, name);
117 if (IS_ERR(opp_tables[cpu])) {
118 ret = PTR_ERR(opp_tables[cpu]);
119 pr_err("Failed to set prop name\n");
120 goto free_opp;
121 }
122 }
123
124 cpufreq_dt_pdev = platform_device_register_simple("cpufreq-dt", -1,
125 NULL, 0);
126 if (!IS_ERR(cpufreq_dt_pdev)) {
127 platform_set_drvdata(pdev, opp_tables);
128 return 0;
129 }
130
131 ret = PTR_ERR(cpufreq_dt_pdev);
132 pr_err("Failed to register platform device\n");
133
134 free_opp:
135 for_each_possible_cpu(cpu) {
136 if (IS_ERR_OR_NULL(opp_tables[cpu]))
137 break;
138 dev_pm_opp_put_prop_name(opp_tables[cpu]);
139 }
140 kfree(opp_tables);
141
142 return ret;
143 }
144
sun50i_cpufreq_nvmem_remove(struct platform_device * pdev)145 static int sun50i_cpufreq_nvmem_remove(struct platform_device *pdev)
146 {
147 struct opp_table **opp_tables = platform_get_drvdata(pdev);
148 unsigned int cpu;
149
150 platform_device_unregister(cpufreq_dt_pdev);
151
152 for_each_possible_cpu(cpu)
153 dev_pm_opp_put_prop_name(opp_tables[cpu]);
154
155 kfree(opp_tables);
156
157 return 0;
158 }
159
160 static struct platform_driver sun50i_cpufreq_driver = {
161 .probe = sun50i_cpufreq_nvmem_probe,
162 .remove = sun50i_cpufreq_nvmem_remove,
163 .driver = {
164 .name = "sun50i-cpufreq-nvmem",
165 },
166 };
167
168 static const struct of_device_id sun50i_cpufreq_match_list[] = {
169 { .compatible = "allwinner,sun50i-h6" },
170 {}
171 };
172 MODULE_DEVICE_TABLE(of, sun50i_cpufreq_match_list);
173
sun50i_cpufreq_match_node(void)174 static const struct of_device_id *sun50i_cpufreq_match_node(void)
175 {
176 const struct of_device_id *match;
177 struct device_node *np;
178
179 np = of_find_node_by_path("/");
180 match = of_match_node(sun50i_cpufreq_match_list, np);
181 of_node_put(np);
182
183 return match;
184 }
185
186 /*
187 * Since the driver depends on nvmem drivers, which may return EPROBE_DEFER,
188 * all the real activity is done in the probe, which may be defered as well.
189 * The init here is only registering the driver and the platform device.
190 */
sun50i_cpufreq_init(void)191 static int __init sun50i_cpufreq_init(void)
192 {
193 const struct of_device_id *match;
194 int ret;
195
196 match = sun50i_cpufreq_match_node();
197 if (!match)
198 return -ENODEV;
199
200 ret = platform_driver_register(&sun50i_cpufreq_driver);
201 if (unlikely(ret < 0))
202 return ret;
203
204 sun50i_cpufreq_pdev =
205 platform_device_register_simple("sun50i-cpufreq-nvmem",
206 -1, NULL, 0);
207 ret = PTR_ERR_OR_ZERO(sun50i_cpufreq_pdev);
208 if (ret == 0)
209 return 0;
210
211 platform_driver_unregister(&sun50i_cpufreq_driver);
212 return ret;
213 }
214 module_init(sun50i_cpufreq_init);
215
sun50i_cpufreq_exit(void)216 static void __exit sun50i_cpufreq_exit(void)
217 {
218 platform_device_unregister(sun50i_cpufreq_pdev);
219 platform_driver_unregister(&sun50i_cpufreq_driver);
220 }
221 module_exit(sun50i_cpufreq_exit);
222
223 MODULE_DESCRIPTION("Sun50i-h6 cpufreq driver");
224 MODULE_LICENSE("GPL v2");
225