1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * Raspberry Pi driver for firmware controlled clocks
4 *
5 * Even though clk-bcm2835 provides an interface to the hardware registers for
6 * the system clocks we've had to factor out 'pllb' as the firmware 'owns' it.
7 * We're not allowed to change it directly as we might race with the
8 * over-temperature and under-voltage protections provided by the firmware.
9 *
10 * Copyright (C) 2019 Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
11 */
12
13 #include <linux/clkdev.h>
14 #include <linux/clk-provider.h>
15 #include <linux/io.h>
16 #include <linux/module.h>
17 #include <linux/platform_device.h>
18
19 #include <soc/bcm2835/raspberrypi-firmware.h>
20
21 enum rpi_firmware_clk_id {
22 RPI_FIRMWARE_EMMC_CLK_ID = 1,
23 RPI_FIRMWARE_UART_CLK_ID,
24 RPI_FIRMWARE_ARM_CLK_ID,
25 RPI_FIRMWARE_CORE_CLK_ID,
26 RPI_FIRMWARE_V3D_CLK_ID,
27 RPI_FIRMWARE_H264_CLK_ID,
28 RPI_FIRMWARE_ISP_CLK_ID,
29 RPI_FIRMWARE_SDRAM_CLK_ID,
30 RPI_FIRMWARE_PIXEL_CLK_ID,
31 RPI_FIRMWARE_PWM_CLK_ID,
32 RPI_FIRMWARE_HEVC_CLK_ID,
33 RPI_FIRMWARE_EMMC2_CLK_ID,
34 RPI_FIRMWARE_M2MC_CLK_ID,
35 RPI_FIRMWARE_PIXEL_BVB_CLK_ID,
36 RPI_FIRMWARE_VEC_CLK_ID,
37 RPI_FIRMWARE_NUM_CLK_ID,
38 };
39
40 static char *rpi_firmware_clk_names[] = {
41 [RPI_FIRMWARE_EMMC_CLK_ID] = "emmc",
42 [RPI_FIRMWARE_UART_CLK_ID] = "uart",
43 [RPI_FIRMWARE_ARM_CLK_ID] = "arm",
44 [RPI_FIRMWARE_CORE_CLK_ID] = "core",
45 [RPI_FIRMWARE_V3D_CLK_ID] = "v3d",
46 [RPI_FIRMWARE_H264_CLK_ID] = "h264",
47 [RPI_FIRMWARE_ISP_CLK_ID] = "isp",
48 [RPI_FIRMWARE_SDRAM_CLK_ID] = "sdram",
49 [RPI_FIRMWARE_PIXEL_CLK_ID] = "pixel",
50 [RPI_FIRMWARE_PWM_CLK_ID] = "pwm",
51 [RPI_FIRMWARE_HEVC_CLK_ID] = "hevc",
52 [RPI_FIRMWARE_EMMC2_CLK_ID] = "emmc2",
53 [RPI_FIRMWARE_M2MC_CLK_ID] = "m2mc",
54 [RPI_FIRMWARE_PIXEL_BVB_CLK_ID] = "pixel-bvb",
55 [RPI_FIRMWARE_VEC_CLK_ID] = "vec",
56 };
57
58 #define RPI_FIRMWARE_STATE_ENABLE_BIT BIT(0)
59 #define RPI_FIRMWARE_STATE_WAIT_BIT BIT(1)
60
61 struct raspberrypi_clk_variant;
62
63 struct raspberrypi_clk {
64 struct device *dev;
65 struct rpi_firmware *firmware;
66 struct platform_device *cpufreq;
67 };
68
69 struct raspberrypi_clk_data {
70 struct clk_hw hw;
71
72 unsigned int id;
73 struct raspberrypi_clk_variant *variant;
74
75 struct raspberrypi_clk *rpi;
76 };
77
78 struct raspberrypi_clk_variant {
79 bool export;
80 char *clkdev;
81 unsigned long min_rate;
82 bool minimize;
83 };
84
85 static struct raspberrypi_clk_variant
86 raspberrypi_clk_variants[RPI_FIRMWARE_NUM_CLK_ID] = {
87 [RPI_FIRMWARE_ARM_CLK_ID] = {
88 .export = true,
89 .clkdev = "cpu0",
90 },
91 [RPI_FIRMWARE_CORE_CLK_ID] = {
92 .export = true,
93
94 /*
95 * The clock is shared between the HVS and the CSI
96 * controllers, on the BCM2711 and will change depending
97 * on the pixels composited on the HVS and the capture
98 * resolution on Unicam.
99 *
100 * Since the rate can get quite large, and we need to
101 * coordinate between both driver instances, let's
102 * always use the minimum the drivers will let us.
103 */
104 .minimize = true,
105 },
106 [RPI_FIRMWARE_M2MC_CLK_ID] = {
107 .export = true,
108
109 /*
110 * If we boot without any cable connected to any of the
111 * HDMI connector, the firmware will skip the HSM
112 * initialization and leave it with a rate of 0,
113 * resulting in a bus lockup when we're accessing the
114 * registers even if it's enabled.
115 *
116 * Let's put a sensible default so that we don't end up
117 * in this situation.
118 */
119 .min_rate = 120000000,
120
121 /*
122 * The clock is shared between the two HDMI controllers
123 * on the BCM2711 and will change depending on the
124 * resolution output on each. Since the rate can get
125 * quite large, and we need to coordinate between both
126 * driver instances, let's always use the minimum the
127 * drivers will let us.
128 */
129 .minimize = true,
130 },
131 [RPI_FIRMWARE_V3D_CLK_ID] = {
132 .export = true,
133 },
134 [RPI_FIRMWARE_PIXEL_CLK_ID] = {
135 .export = true,
136 },
137 [RPI_FIRMWARE_HEVC_CLK_ID] = {
138 .export = true,
139 },
140 [RPI_FIRMWARE_PIXEL_BVB_CLK_ID] = {
141 .export = true,
142 },
143 [RPI_FIRMWARE_VEC_CLK_ID] = {
144 .export = true,
145 },
146 };
147
148 /*
149 * Structure of the message passed to Raspberry Pi's firmware in order to
150 * change clock rates. The 'disable_turbo' option is only available to the ARM
151 * clock (pllb) which we enable by default as turbo mode will alter multiple
152 * clocks at once.
153 *
154 * Even though we're able to access the clock registers directly we're bound to
155 * use the firmware interface as the firmware ultimately takes care of
156 * mitigating overheating/undervoltage situations and we would be changing
157 * frequencies behind his back.
158 *
159 * For more information on the firmware interface check:
160 * https://github.com/raspberrypi/firmware/wiki/Mailbox-property-interface
161 */
162 struct raspberrypi_firmware_prop {
163 __le32 id;
164 __le32 val;
165 __le32 disable_turbo;
166 } __packed;
167
raspberrypi_clock_property(struct rpi_firmware * firmware,const struct raspberrypi_clk_data * data,u32 tag,u32 * val)168 static int raspberrypi_clock_property(struct rpi_firmware *firmware,
169 const struct raspberrypi_clk_data *data,
170 u32 tag, u32 *val)
171 {
172 struct raspberrypi_firmware_prop msg = {
173 .id = cpu_to_le32(data->id),
174 .val = cpu_to_le32(*val),
175 .disable_turbo = cpu_to_le32(1),
176 };
177 int ret;
178
179 ret = rpi_firmware_property(firmware, tag, &msg, sizeof(msg));
180 if (ret)
181 return ret;
182
183 *val = le32_to_cpu(msg.val);
184
185 return 0;
186 }
187
raspberrypi_fw_is_prepared(struct clk_hw * hw)188 static int raspberrypi_fw_is_prepared(struct clk_hw *hw)
189 {
190 struct raspberrypi_clk_data *data =
191 container_of(hw, struct raspberrypi_clk_data, hw);
192 struct raspberrypi_clk *rpi = data->rpi;
193 u32 val = 0;
194 int ret;
195
196 ret = raspberrypi_clock_property(rpi->firmware, data,
197 RPI_FIRMWARE_GET_CLOCK_STATE, &val);
198 if (ret)
199 return 0;
200
201 return !!(val & RPI_FIRMWARE_STATE_ENABLE_BIT);
202 }
203
204
raspberrypi_fw_get_rate(struct clk_hw * hw,unsigned long parent_rate)205 static unsigned long raspberrypi_fw_get_rate(struct clk_hw *hw,
206 unsigned long parent_rate)
207 {
208 struct raspberrypi_clk_data *data =
209 container_of(hw, struct raspberrypi_clk_data, hw);
210 struct raspberrypi_clk *rpi = data->rpi;
211 u32 val = 0;
212 int ret;
213
214 ret = raspberrypi_clock_property(rpi->firmware, data,
215 RPI_FIRMWARE_GET_CLOCK_RATE, &val);
216 if (ret)
217 return 0;
218
219 return val;
220 }
221
raspberrypi_fw_set_rate(struct clk_hw * hw,unsigned long rate,unsigned long parent_rate)222 static int raspberrypi_fw_set_rate(struct clk_hw *hw, unsigned long rate,
223 unsigned long parent_rate)
224 {
225 struct raspberrypi_clk_data *data =
226 container_of(hw, struct raspberrypi_clk_data, hw);
227 struct raspberrypi_clk *rpi = data->rpi;
228 u32 _rate = rate;
229 int ret;
230
231 ret = raspberrypi_clock_property(rpi->firmware, data,
232 RPI_FIRMWARE_SET_CLOCK_RATE, &_rate);
233 if (ret)
234 dev_err_ratelimited(rpi->dev, "Failed to change %s frequency: %d\n",
235 clk_hw_get_name(hw), ret);
236
237 return ret;
238 }
239
raspberrypi_fw_dumb_determine_rate(struct clk_hw * hw,struct clk_rate_request * req)240 static int raspberrypi_fw_dumb_determine_rate(struct clk_hw *hw,
241 struct clk_rate_request *req)
242 {
243 struct raspberrypi_clk_data *data =
244 container_of(hw, struct raspberrypi_clk_data, hw);
245 struct raspberrypi_clk_variant *variant = data->variant;
246
247 /*
248 * The firmware will do the rounding but that isn't part of
249 * the interface with the firmware, so we just do our best
250 * here.
251 */
252
253 req->rate = clamp(req->rate, req->min_rate, req->max_rate);
254
255 /*
256 * We want to aggressively reduce the clock rate here, so let's
257 * just ignore the requested rate and return the bare minimum
258 * rate we can get away with.
259 */
260 if (variant->minimize && req->min_rate > 0)
261 req->rate = req->min_rate;
262
263 return 0;
264 }
265
266 static const struct clk_ops raspberrypi_firmware_clk_ops = {
267 .is_prepared = raspberrypi_fw_is_prepared,
268 .recalc_rate = raspberrypi_fw_get_rate,
269 .determine_rate = raspberrypi_fw_dumb_determine_rate,
270 .set_rate = raspberrypi_fw_set_rate,
271 };
272
raspberrypi_clk_register(struct raspberrypi_clk * rpi,unsigned int parent,unsigned int id,struct raspberrypi_clk_variant * variant)273 static struct clk_hw *raspberrypi_clk_register(struct raspberrypi_clk *rpi,
274 unsigned int parent,
275 unsigned int id,
276 struct raspberrypi_clk_variant *variant)
277 {
278 struct raspberrypi_clk_data *data;
279 struct clk_init_data init = {};
280 u32 min_rate, max_rate;
281 int ret;
282
283 data = devm_kzalloc(rpi->dev, sizeof(*data), GFP_KERNEL);
284 if (!data)
285 return ERR_PTR(-ENOMEM);
286 data->rpi = rpi;
287 data->id = id;
288 data->variant = variant;
289
290 init.name = devm_kasprintf(rpi->dev, GFP_KERNEL,
291 "fw-clk-%s",
292 rpi_firmware_clk_names[id]);
293 init.ops = &raspberrypi_firmware_clk_ops;
294 init.flags = CLK_GET_RATE_NOCACHE;
295
296 data->hw.init = &init;
297
298 ret = raspberrypi_clock_property(rpi->firmware, data,
299 RPI_FIRMWARE_GET_MIN_CLOCK_RATE,
300 &min_rate);
301 if (ret) {
302 dev_err(rpi->dev, "Failed to get clock %d min freq: %d\n",
303 id, ret);
304 return ERR_PTR(ret);
305 }
306
307 ret = raspberrypi_clock_property(rpi->firmware, data,
308 RPI_FIRMWARE_GET_MAX_CLOCK_RATE,
309 &max_rate);
310 if (ret) {
311 dev_err(rpi->dev, "Failed to get clock %d max freq: %d\n",
312 id, ret);
313 return ERR_PTR(ret);
314 }
315
316 ret = devm_clk_hw_register(rpi->dev, &data->hw);
317 if (ret)
318 return ERR_PTR(ret);
319
320 clk_hw_set_rate_range(&data->hw, min_rate, max_rate);
321
322 if (variant->clkdev) {
323 ret = devm_clk_hw_register_clkdev(rpi->dev, &data->hw,
324 NULL, variant->clkdev);
325 if (ret) {
326 dev_err(rpi->dev, "Failed to initialize clkdev\n");
327 return ERR_PTR(ret);
328 }
329 }
330
331 if (variant->min_rate) {
332 unsigned long rate;
333
334 clk_hw_set_rate_range(&data->hw, variant->min_rate, max_rate);
335
336 rate = raspberrypi_fw_get_rate(&data->hw, 0);
337 if (rate < variant->min_rate) {
338 ret = raspberrypi_fw_set_rate(&data->hw, variant->min_rate, 0);
339 if (ret)
340 return ERR_PTR(ret);
341 }
342 }
343
344 return &data->hw;
345 }
346
347 struct rpi_firmware_get_clocks_response {
348 u32 parent;
349 u32 id;
350 };
351
raspberrypi_discover_clocks(struct raspberrypi_clk * rpi,struct clk_hw_onecell_data * data)352 static int raspberrypi_discover_clocks(struct raspberrypi_clk *rpi,
353 struct clk_hw_onecell_data *data)
354 {
355 struct rpi_firmware_get_clocks_response *clks;
356 int ret;
357
358 /*
359 * The firmware doesn't guarantee that the last element of
360 * RPI_FIRMWARE_GET_CLOCKS is zeroed. So allocate an additional
361 * zero element as sentinel.
362 */
363 clks = devm_kcalloc(rpi->dev,
364 RPI_FIRMWARE_NUM_CLK_ID + 1, sizeof(*clks),
365 GFP_KERNEL);
366 if (!clks)
367 return -ENOMEM;
368
369 ret = rpi_firmware_property(rpi->firmware, RPI_FIRMWARE_GET_CLOCKS,
370 clks,
371 sizeof(*clks) * RPI_FIRMWARE_NUM_CLK_ID);
372 if (ret)
373 return ret;
374
375 while (clks->id) {
376 struct raspberrypi_clk_variant *variant;
377
378 if (clks->id > RPI_FIRMWARE_NUM_CLK_ID) {
379 dev_err(rpi->dev, "Unknown clock id: %u (max: %u)\n",
380 clks->id, RPI_FIRMWARE_NUM_CLK_ID);
381 return -EINVAL;
382 }
383
384 variant = &raspberrypi_clk_variants[clks->id];
385 if (variant->export) {
386 struct clk_hw *hw;
387
388 hw = raspberrypi_clk_register(rpi, clks->parent,
389 clks->id, variant);
390 if (IS_ERR(hw))
391 return PTR_ERR(hw);
392
393 data->hws[clks->id] = hw;
394 data->num = clks->id + 1;
395 }
396
397 clks++;
398 }
399
400 return 0;
401 }
402
raspberrypi_clk_probe(struct platform_device * pdev)403 static int raspberrypi_clk_probe(struct platform_device *pdev)
404 {
405 struct clk_hw_onecell_data *clk_data;
406 struct device_node *firmware_node;
407 struct device *dev = &pdev->dev;
408 struct rpi_firmware *firmware;
409 struct raspberrypi_clk *rpi;
410 int ret;
411
412 /*
413 * We can be probed either through the an old-fashioned
414 * platform device registration or through a DT node that is a
415 * child of the firmware node. Handle both cases.
416 */
417 if (dev->of_node)
418 firmware_node = of_get_parent(dev->of_node);
419 else
420 firmware_node = of_find_compatible_node(NULL, NULL,
421 "raspberrypi,bcm2835-firmware");
422 if (!firmware_node) {
423 dev_err(dev, "Missing firmware node\n");
424 return -ENOENT;
425 }
426
427 firmware = devm_rpi_firmware_get(&pdev->dev, firmware_node);
428 of_node_put(firmware_node);
429 if (!firmware)
430 return -EPROBE_DEFER;
431
432 rpi = devm_kzalloc(dev, sizeof(*rpi), GFP_KERNEL);
433 if (!rpi)
434 return -ENOMEM;
435
436 rpi->dev = dev;
437 rpi->firmware = firmware;
438 platform_set_drvdata(pdev, rpi);
439
440 clk_data = devm_kzalloc(dev, struct_size(clk_data, hws,
441 RPI_FIRMWARE_NUM_CLK_ID),
442 GFP_KERNEL);
443 if (!clk_data)
444 return -ENOMEM;
445
446 ret = raspberrypi_discover_clocks(rpi, clk_data);
447 if (ret)
448 return ret;
449
450 ret = devm_of_clk_add_hw_provider(dev, of_clk_hw_onecell_get,
451 clk_data);
452 if (ret)
453 return ret;
454
455 rpi->cpufreq = platform_device_register_data(dev, "raspberrypi-cpufreq",
456 -1, NULL, 0);
457
458 return 0;
459 }
460
raspberrypi_clk_remove(struct platform_device * pdev)461 static int raspberrypi_clk_remove(struct platform_device *pdev)
462 {
463 struct raspberrypi_clk *rpi = platform_get_drvdata(pdev);
464
465 platform_device_unregister(rpi->cpufreq);
466
467 return 0;
468 }
469
470 static const struct of_device_id raspberrypi_clk_match[] = {
471 { .compatible = "raspberrypi,firmware-clocks" },
472 { },
473 };
474 MODULE_DEVICE_TABLE(of, raspberrypi_clk_match);
475
476 static struct platform_driver raspberrypi_clk_driver = {
477 .driver = {
478 .name = "raspberrypi-clk",
479 .of_match_table = raspberrypi_clk_match,
480 },
481 .probe = raspberrypi_clk_probe,
482 .remove = raspberrypi_clk_remove,
483 };
484 module_platform_driver(raspberrypi_clk_driver);
485
486 MODULE_AUTHOR("Nicolas Saenz Julienne <nsaenzjulienne@suse.de>");
487 MODULE_DESCRIPTION("Raspberry Pi firmware clock driver");
488 MODULE_LICENSE("GPL");
489 MODULE_ALIAS("platform:raspberrypi-clk");
490
