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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 <[email protected]>
9  */
10
11 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
12
13 #include <linux/arm-smccc.h>
14 #include <linux/cpu.h>
15 #include <linux/module.h>
16 #include <linux/nvmem-consumer.h>
17 #include <linux/of.h>
18 #include <linux/platform_device.h>
19 #include <linux/pm_opp.h>
20 #include <linux/slab.h>
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 struct sunxi_cpufreq_data {
28         u32 (*efuse_xlate)(u32 speedbin);
29 };
30
31 static u32 sun50i_h6_efuse_xlate(u32 speedbin)
32 {
33         u32 efuse_value;
34
35         efuse_value = (speedbin >> NVMEM_SHIFT) & NVMEM_MASK;
36
37         /*
38          * We treat unexpected efuse values as if the SoC was from
39          * the slowest bin. Expected efuse values are 1-3, slowest
40          * to fastest.
41          */
42         if (efuse_value >= 1 && efuse_value <= 3)
43                 return efuse_value - 1;
44         else
45                 return 0;
46 }
47
48 static int get_soc_id_revision(void)
49 {
50 #ifdef CONFIG_HAVE_ARM_SMCCC_DISCOVERY
51         return arm_smccc_get_soc_id_revision();
52 #else
53         return SMCCC_RET_NOT_SUPPORTED;
54 #endif
55 }
56
57 /*
58  * Judging by the OPP tables in the vendor BSP, the quality order of the
59  * returned speedbin index is 4 -> 0/2 -> 3 -> 1, from worst to best.
60  * 0 and 2 seem identical from the OPP tables' point of view.
61  */
62 static u32 sun50i_h616_efuse_xlate(u32 speedbin)
63 {
64         int ver_bits = get_soc_id_revision();
65         u32 value = 0;
66
67         switch (speedbin & 0xffff) {
68         case 0x2000:
69                 value = 0;
70                 break;
71         case 0x2400:
72         case 0x7400:
73         case 0x2c00:
74         case 0x7c00:
75                 if (ver_bits != SMCCC_RET_NOT_SUPPORTED && ver_bits <= 1) {
76                         /* ic version A/B */
77                         value = 1;
78                 } else {
79                         /* ic version C and later version */
80                         value = 2;
81                 }
82                 break;
83         case 0x5000:
84         case 0x5400:
85         case 0x6000:
86                 value = 3;
87                 break;
88         case 0x5c00:
89                 value = 4;
90                 break;
91         case 0x5d00:
92                 value = 0;
93                 break;
94         case 0x6c00:
95                 value = 5;
96                 break;
97         default:
98                 pr_warn("sun50i-cpufreq-nvmem: unknown speed bin 0x%x, using default bin 0\n",
99                         speedbin & 0xffff);
100                 value = 0;
101                 break;
102         }
103
104         return value;
105 }
106
107 static struct sunxi_cpufreq_data sun50i_h6_cpufreq_data = {
108         .efuse_xlate = sun50i_h6_efuse_xlate,
109 };
110
111 static struct sunxi_cpufreq_data sun50i_h616_cpufreq_data = {
112         .efuse_xlate = sun50i_h616_efuse_xlate,
113 };
114
115 static const struct of_device_id cpu_opp_match_list[] = {
116         { .compatible = "allwinner,sun50i-h6-operating-points",
117           .data = &sun50i_h6_cpufreq_data,
118         },
119         { .compatible = "allwinner,sun50i-h616-operating-points",
120           .data = &sun50i_h616_cpufreq_data,
121         },
122         {}
123 };
124
125 /**
126  * dt_has_supported_hw() - Check if any OPPs use opp-supported-hw
127  *
128  * If we ask the cpufreq framework to use the opp-supported-hw feature, it
129  * will ignore every OPP node without that DT property. If none of the OPPs
130  * have it, the driver will fail probing, due to the lack of OPPs.
131  *
132  * Returns true if we have at least one OPP with the opp-supported-hw property.
133  */
134 static bool dt_has_supported_hw(void)
135 {
136         bool has_opp_supported_hw = false;
137         struct device *cpu_dev;
138
139         cpu_dev = get_cpu_device(0);
140         if (!cpu_dev)
141                 return false;
142
143         struct device_node *np __free(device_node) =
144                 dev_pm_opp_of_get_opp_desc_node(cpu_dev);
145         if (!np)
146                 return false;
147
148         for_each_child_of_node_scoped(np, opp) {
149                 if (of_find_property(opp, "opp-supported-hw", NULL)) {
150                         has_opp_supported_hw = true;
151                         break;
152                 }
153         }
154
155         return has_opp_supported_hw;
156 }
157
158 /**
159  * sun50i_cpufreq_get_efuse() - Determine speed grade from efuse value
160  *
161  * Returns non-negative speed bin index on success, a negative error
162  * value otherwise.
163  */
164 static int sun50i_cpufreq_get_efuse(void)
165 {
166         const struct sunxi_cpufreq_data *opp_data;
167         struct nvmem_cell *speedbin_nvmem;
168         const struct of_device_id *match;
169         struct device *cpu_dev;
170         u32 *speedbin;
171         int ret;
172
173         cpu_dev = get_cpu_device(0);
174         if (!cpu_dev)
175                 return -ENODEV;
176
177         struct device_node *np __free(device_node) =
178                 dev_pm_opp_of_get_opp_desc_node(cpu_dev);
179         if (!np)
180                 return -ENOENT;
181
182         match = of_match_node(cpu_opp_match_list, np);
183         if (!match)
184                 return -ENOENT;
185
186         opp_data = match->data;
187
188         speedbin_nvmem = of_nvmem_cell_get(np, NULL);
189         if (IS_ERR(speedbin_nvmem))
190                 return dev_err_probe(cpu_dev, PTR_ERR(speedbin_nvmem),
191                                      "Could not get nvmem cell\n");
192
193         speedbin = nvmem_cell_read(speedbin_nvmem, NULL);
194         nvmem_cell_put(speedbin_nvmem);
195         if (IS_ERR(speedbin))
196                 return PTR_ERR(speedbin);
197
198         ret = opp_data->efuse_xlate(*speedbin);
199
200         kfree(speedbin);
201
202         return ret;
203 };
204
205 static int sun50i_cpufreq_nvmem_probe(struct platform_device *pdev)
206 {
207         int *opp_tokens;
208         char name[] = "speedXXXXXXXXXXX"; /* Integers can take 11 chars max */
209         unsigned int cpu, supported_hw;
210         struct dev_pm_opp_config config = {};
211         int speed;
212         int ret;
213
214         opp_tokens = kcalloc(num_possible_cpus(), sizeof(*opp_tokens),
215                              GFP_KERNEL);
216         if (!opp_tokens)
217                 return -ENOMEM;
218
219         speed = sun50i_cpufreq_get_efuse();
220         if (speed < 0) {
221                 kfree(opp_tokens);
222                 return speed;
223         }
224
225         /*
226          * We need at least one OPP with the "opp-supported-hw" property,
227          * or else the upper layers will ignore every OPP and will bail out.
228          */
229         if (dt_has_supported_hw()) {
230                 supported_hw = 1U << speed;
231                 config.supported_hw = &supported_hw;
232                 config.supported_hw_count = 1;
233         }
234
235         snprintf(name, sizeof(name), "speed%d", speed);
236         config.prop_name = name;
237
238         for_each_possible_cpu(cpu) {
239                 struct device *cpu_dev = get_cpu_device(cpu);
240
241                 if (!cpu_dev) {
242                         ret = -ENODEV;
243                         goto free_opp;
244                 }
245
246                 ret = dev_pm_opp_set_config(cpu_dev, &config);
247                 if (ret < 0)
248                         goto free_opp;
249
250                 opp_tokens[cpu] = ret;
251         }
252
253         cpufreq_dt_pdev = platform_device_register_simple("cpufreq-dt", -1,
254                                                           NULL, 0);
255         if (!IS_ERR(cpufreq_dt_pdev)) {
256                 platform_set_drvdata(pdev, opp_tokens);
257                 return 0;
258         }
259
260         ret = PTR_ERR(cpufreq_dt_pdev);
261         pr_err("Failed to register platform device\n");
262
263 free_opp:
264         for_each_possible_cpu(cpu)
265                 dev_pm_opp_clear_config(opp_tokens[cpu]);
266         kfree(opp_tokens);
267
268         return ret;
269 }
270
271 static void sun50i_cpufreq_nvmem_remove(struct platform_device *pdev)
272 {
273         int *opp_tokens = platform_get_drvdata(pdev);
274         unsigned int cpu;
275
276         platform_device_unregister(cpufreq_dt_pdev);
277
278         for_each_possible_cpu(cpu)
279                 dev_pm_opp_clear_config(opp_tokens[cpu]);
280
281         kfree(opp_tokens);
282 }
283
284 static struct platform_driver sun50i_cpufreq_driver = {
285         .probe = sun50i_cpufreq_nvmem_probe,
286         .remove_new = sun50i_cpufreq_nvmem_remove,
287         .driver = {
288                 .name = "sun50i-cpufreq-nvmem",
289         },
290 };
291
292 static const struct of_device_id sun50i_cpufreq_match_list[] = {
293         { .compatible = "allwinner,sun50i-h6" },
294         { .compatible = "allwinner,sun50i-h616" },
295         { .compatible = "allwinner,sun50i-h618" },
296         { .compatible = "allwinner,sun50i-h700" },
297         {}
298 };
299 MODULE_DEVICE_TABLE(of, sun50i_cpufreq_match_list);
300
301 static const struct of_device_id *sun50i_cpufreq_match_node(void)
302 {
303         struct device_node *np __free(device_node) = of_find_node_by_path("/");
304
305         return of_match_node(sun50i_cpufreq_match_list, np);
306 }
307
308 /*
309  * Since the driver depends on nvmem drivers, which may return EPROBE_DEFER,
310  * all the real activity is done in the probe, which may be defered as well.
311  * The init here is only registering the driver and the platform device.
312  */
313 static int __init sun50i_cpufreq_init(void)
314 {
315         const struct of_device_id *match;
316         int ret;
317
318         match = sun50i_cpufreq_match_node();
319         if (!match)
320                 return -ENODEV;
321
322         ret = platform_driver_register(&sun50i_cpufreq_driver);
323         if (unlikely(ret < 0))
324                 return ret;
325
326         sun50i_cpufreq_pdev =
327                 platform_device_register_simple("sun50i-cpufreq-nvmem",
328                                                 -1, NULL, 0);
329         ret = PTR_ERR_OR_ZERO(sun50i_cpufreq_pdev);
330         if (ret == 0)
331                 return 0;
332
333         platform_driver_unregister(&sun50i_cpufreq_driver);
334         return ret;
335 }
336 module_init(sun50i_cpufreq_init);
337
338 static void __exit sun50i_cpufreq_exit(void)
339 {
340         platform_device_unregister(sun50i_cpufreq_pdev);
341         platform_driver_unregister(&sun50i_cpufreq_driver);
342 }
343 module_exit(sun50i_cpufreq_exit);
344
345 MODULE_DESCRIPTION("Sun50i-h6 cpufreq driver");
346 MODULE_LICENSE("GPL v2");
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