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 return ret;
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_tables[cpu] = dev_pm_opp_set_prop_name(cpu_dev, name);
115 if (IS_ERR(opp_tables[cpu])) {
116 ret = PTR_ERR(opp_tables[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_tables);
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 if (IS_ERR_OR_NULL(opp_tables[cpu]))
135 break;
136 dev_pm_opp_put_prop_name(opp_tables[cpu]);
137 }
138 kfree(opp_tables);
139
140 return ret;
141 }
142
sun50i_cpufreq_nvmem_remove(struct platform_device * pdev)143 static int sun50i_cpufreq_nvmem_remove(struct platform_device *pdev)
144 {
145 struct opp_table **opp_tables = platform_get_drvdata(pdev);
146 unsigned int cpu;
147
148 platform_device_unregister(cpufreq_dt_pdev);
149
150 for_each_possible_cpu(cpu)
151 dev_pm_opp_put_prop_name(opp_tables[cpu]);
152
153 kfree(opp_tables);
154
155 return 0;
156 }
157
158 static struct platform_driver sun50i_cpufreq_driver = {
159 .probe = sun50i_cpufreq_nvmem_probe,
160 .remove = sun50i_cpufreq_nvmem_remove,
161 .driver = {
162 .name = "sun50i-cpufreq-nvmem",
163 },
164 };
165
166 static const struct of_device_id sun50i_cpufreq_match_list[] = {
167 { .compatible = "allwinner,sun50i-h6" },
168 {}
169 };
170 MODULE_DEVICE_TABLE(of, sun50i_cpufreq_match_list);
171
sun50i_cpufreq_match_node(void)172 static const struct of_device_id *sun50i_cpufreq_match_node(void)
173 {
174 const struct of_device_id *match;
175 struct device_node *np;
176
177 np = of_find_node_by_path("/");
178 match = of_match_node(sun50i_cpufreq_match_list, np);
179 of_node_put(np);
180
181 return match;
182 }
183
184 /*
185 * Since the driver depends on nvmem drivers, which may return EPROBE_DEFER,
186 * all the real activity is done in the probe, which may be defered as well.
187 * The init here is only registering the driver and the platform device.
188 */
sun50i_cpufreq_init(void)189 static int __init sun50i_cpufreq_init(void)
190 {
191 const struct of_device_id *match;
192 int ret;
193
194 match = sun50i_cpufreq_match_node();
195 if (!match)
196 return -ENODEV;
197
198 ret = platform_driver_register(&sun50i_cpufreq_driver);
199 if (unlikely(ret < 0))
200 return ret;
201
202 sun50i_cpufreq_pdev =
203 platform_device_register_simple("sun50i-cpufreq-nvmem",
204 -1, NULL, 0);
205 ret = PTR_ERR_OR_ZERO(sun50i_cpufreq_pdev);
206 if (ret == 0)
207 return 0;
208
209 platform_driver_unregister(&sun50i_cpufreq_driver);
210 return ret;
211 }
212 module_init(sun50i_cpufreq_init);
213
sun50i_cpufreq_exit(void)214 static void __exit sun50i_cpufreq_exit(void)
215 {
216 platform_device_unregister(sun50i_cpufreq_pdev);
217 platform_driver_unregister(&sun50i_cpufreq_driver);
218 }
219 module_exit(sun50i_cpufreq_exit);
220
221 MODULE_DESCRIPTION("Sun50i-h6 cpufreq driver");
222 MODULE_LICENSE("GPL v2");
223
