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/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
sun50i_h6_efuse_xlate(u32 speedbin)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
get_soc_id_revision(void)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 */
sun50i_h616_efuse_xlate(u32 speedbin)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 */
dt_has_supported_hw(void)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_property_present(opp, "opp-supported-hw")) {
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 */
sun50i_cpufreq_get_efuse(void)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
sun50i_cpufreq_nvmem_probe(struct platform_device * pdev)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
sun50i_cpufreq_nvmem_remove(struct platform_device * pdev)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
sun50i_cpufreq_match_node(void)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 */
sun50i_cpufreq_init(void)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
sun50i_cpufreq_exit(void)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");
347