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_NUM_CLK_ID,
37 };
38
39 static char *rpi_firmware_clk_names[] = {
40 [RPI_FIRMWARE_EMMC_CLK_ID] = "emmc",
41 [RPI_FIRMWARE_UART_CLK_ID] = "uart",
42 [RPI_FIRMWARE_ARM_CLK_ID] = "arm",
43 [RPI_FIRMWARE_CORE_CLK_ID] = "core",
44 [RPI_FIRMWARE_V3D_CLK_ID] = "v3d",
45 [RPI_FIRMWARE_H264_CLK_ID] = "h264",
46 [RPI_FIRMWARE_ISP_CLK_ID] = "isp",
47 [RPI_FIRMWARE_SDRAM_CLK_ID] = "sdram",
48 [RPI_FIRMWARE_PIXEL_CLK_ID] = "pixel",
49 [RPI_FIRMWARE_PWM_CLK_ID] = "pwm",
50 [RPI_FIRMWARE_HEVC_CLK_ID] = "hevc",
51 [RPI_FIRMWARE_EMMC2_CLK_ID] = "emmc2",
52 [RPI_FIRMWARE_M2MC_CLK_ID] = "m2mc",
53 [RPI_FIRMWARE_PIXEL_BVB_CLK_ID] = "pixel-bvb",
54 };
55
56 #define RPI_FIRMWARE_STATE_ENABLE_BIT BIT(0)
57 #define RPI_FIRMWARE_STATE_WAIT_BIT BIT(1)
58
59 struct raspberrypi_clk {
60 struct device *dev;
61 struct rpi_firmware *firmware;
62 struct platform_device *cpufreq;
63 };
64
65 struct raspberrypi_clk_data {
66 struct clk_hw hw;
67
68 unsigned int id;
69
70 struct raspberrypi_clk *rpi;
71 };
72
73 /*
74 * Structure of the message passed to Raspberry Pi's firmware in order to
75 * change clock rates. The 'disable_turbo' option is only available to the ARM
76 * clock (pllb) which we enable by default as turbo mode will alter multiple
77 * clocks at once.
78 *
79 * Even though we're able to access the clock registers directly we're bound to
80 * use the firmware interface as the firmware ultimately takes care of
81 * mitigating overheating/undervoltage situations and we would be changing
82 * frequencies behind his back.
83 *
84 * For more information on the firmware interface check:
85 * https://github.com/raspberrypi/firmware/wiki/Mailbox-property-interface
86 */
87 struct raspberrypi_firmware_prop {
88 __le32 id;
89 __le32 val;
90 __le32 disable_turbo;
91 } __packed;
92
raspberrypi_clock_property(struct rpi_firmware * firmware,const struct raspberrypi_clk_data * data,u32 tag,u32 * val)93 static int raspberrypi_clock_property(struct rpi_firmware *firmware,
94 const struct raspberrypi_clk_data *data,
95 u32 tag, u32 *val)
96 {
97 struct raspberrypi_firmware_prop msg = {
98 .id = cpu_to_le32(data->id),
99 .val = cpu_to_le32(*val),
100 .disable_turbo = cpu_to_le32(1),
101 };
102 int ret;
103
104 ret = rpi_firmware_property(firmware, tag, &msg, sizeof(msg));
105 if (ret)
106 return ret;
107
108 *val = le32_to_cpu(msg.val);
109
110 return 0;
111 }
112
raspberrypi_fw_is_prepared(struct clk_hw * hw)113 static int raspberrypi_fw_is_prepared(struct clk_hw *hw)
114 {
115 struct raspberrypi_clk_data *data =
116 container_of(hw, struct raspberrypi_clk_data, hw);
117 struct raspberrypi_clk *rpi = data->rpi;
118 u32 val = 0;
119 int ret;
120
121 ret = raspberrypi_clock_property(rpi->firmware, data,
122 RPI_FIRMWARE_GET_CLOCK_STATE, &val);
123 if (ret)
124 return 0;
125
126 return !!(val & RPI_FIRMWARE_STATE_ENABLE_BIT);
127 }
128
129
raspberrypi_fw_get_rate(struct clk_hw * hw,unsigned long parent_rate)130 static unsigned long raspberrypi_fw_get_rate(struct clk_hw *hw,
131 unsigned long parent_rate)
132 {
133 struct raspberrypi_clk_data *data =
134 container_of(hw, struct raspberrypi_clk_data, hw);
135 struct raspberrypi_clk *rpi = data->rpi;
136 u32 val = 0;
137 int ret;
138
139 ret = raspberrypi_clock_property(rpi->firmware, data,
140 RPI_FIRMWARE_GET_CLOCK_RATE, &val);
141 if (ret)
142 return 0;
143
144 return val;
145 }
146
raspberrypi_fw_set_rate(struct clk_hw * hw,unsigned long rate,unsigned long parent_rate)147 static int raspberrypi_fw_set_rate(struct clk_hw *hw, unsigned long rate,
148 unsigned long parent_rate)
149 {
150 struct raspberrypi_clk_data *data =
151 container_of(hw, struct raspberrypi_clk_data, hw);
152 struct raspberrypi_clk *rpi = data->rpi;
153 u32 _rate = rate;
154 int ret;
155
156 ret = raspberrypi_clock_property(rpi->firmware, data,
157 RPI_FIRMWARE_SET_CLOCK_RATE, &_rate);
158 if (ret)
159 dev_err_ratelimited(rpi->dev, "Failed to change %s frequency: %d\n",
160 clk_hw_get_name(hw), ret);
161
162 return ret;
163 }
164
raspberrypi_fw_dumb_determine_rate(struct clk_hw * hw,struct clk_rate_request * req)165 static int raspberrypi_fw_dumb_determine_rate(struct clk_hw *hw,
166 struct clk_rate_request *req)
167 {
168 /*
169 * The firmware will do the rounding but that isn't part of
170 * the interface with the firmware, so we just do our best
171 * here.
172 */
173 req->rate = clamp(req->rate, req->min_rate, req->max_rate);
174 return 0;
175 }
176
177 static const struct clk_ops raspberrypi_firmware_clk_ops = {
178 .is_prepared = raspberrypi_fw_is_prepared,
179 .recalc_rate = raspberrypi_fw_get_rate,
180 .determine_rate = raspberrypi_fw_dumb_determine_rate,
181 .set_rate = raspberrypi_fw_set_rate,
182 };
183
raspberrypi_clk_register(struct raspberrypi_clk * rpi,unsigned int parent,unsigned int id)184 static struct clk_hw *raspberrypi_clk_register(struct raspberrypi_clk *rpi,
185 unsigned int parent,
186 unsigned int id)
187 {
188 struct raspberrypi_clk_data *data;
189 struct clk_init_data init = {};
190 u32 min_rate, max_rate;
191 int ret;
192
193 data = devm_kzalloc(rpi->dev, sizeof(*data), GFP_KERNEL);
194 if (!data)
195 return ERR_PTR(-ENOMEM);
196 data->rpi = rpi;
197 data->id = id;
198
199 init.name = devm_kasprintf(rpi->dev, GFP_KERNEL,
200 "fw-clk-%s",
201 rpi_firmware_clk_names[id]);
202 init.ops = &raspberrypi_firmware_clk_ops;
203 init.flags = CLK_GET_RATE_NOCACHE;
204
205 data->hw.init = &init;
206
207 ret = raspberrypi_clock_property(rpi->firmware, data,
208 RPI_FIRMWARE_GET_MIN_CLOCK_RATE,
209 &min_rate);
210 if (ret) {
211 dev_err(rpi->dev, "Failed to get clock %d min freq: %d\n",
212 id, ret);
213 return ERR_PTR(ret);
214 }
215
216 ret = raspberrypi_clock_property(rpi->firmware, data,
217 RPI_FIRMWARE_GET_MAX_CLOCK_RATE,
218 &max_rate);
219 if (ret) {
220 dev_err(rpi->dev, "Failed to get clock %d max freq: %d\n",
221 id, ret);
222 return ERR_PTR(ret);
223 }
224
225 ret = devm_clk_hw_register(rpi->dev, &data->hw);
226 if (ret)
227 return ERR_PTR(ret);
228
229 clk_hw_set_rate_range(&data->hw, min_rate, max_rate);
230
231 if (id == RPI_FIRMWARE_ARM_CLK_ID) {
232 ret = devm_clk_hw_register_clkdev(rpi->dev, &data->hw,
233 NULL, "cpu0");
234 if (ret) {
235 dev_err(rpi->dev, "Failed to initialize clkdev\n");
236 return ERR_PTR(ret);
237 }
238 }
239
240 return &data->hw;
241 }
242
243 struct rpi_firmware_get_clocks_response {
244 u32 parent;
245 u32 id;
246 };
247
raspberrypi_discover_clocks(struct raspberrypi_clk * rpi,struct clk_hw_onecell_data * data)248 static int raspberrypi_discover_clocks(struct raspberrypi_clk *rpi,
249 struct clk_hw_onecell_data *data)
250 {
251 struct rpi_firmware_get_clocks_response *clks;
252 int ret;
253
254 /*
255 * The firmware doesn't guarantee that the last element of
256 * RPI_FIRMWARE_GET_CLOCKS is zeroed. So allocate an additional
257 * zero element as sentinel.
258 */
259 clks = devm_kcalloc(rpi->dev,
260 RPI_FIRMWARE_NUM_CLK_ID + 1, sizeof(*clks),
261 GFP_KERNEL);
262 if (!clks)
263 return -ENOMEM;
264
265 ret = rpi_firmware_property(rpi->firmware, RPI_FIRMWARE_GET_CLOCKS,
266 clks,
267 sizeof(*clks) * RPI_FIRMWARE_NUM_CLK_ID);
268 if (ret)
269 return ret;
270
271 while (clks->id) {
272 struct clk_hw *hw;
273
274 switch (clks->id) {
275 case RPI_FIRMWARE_ARM_CLK_ID:
276 case RPI_FIRMWARE_CORE_CLK_ID:
277 case RPI_FIRMWARE_M2MC_CLK_ID:
278 case RPI_FIRMWARE_V3D_CLK_ID:
279 case RPI_FIRMWARE_PIXEL_BVB_CLK_ID:
280 hw = raspberrypi_clk_register(rpi, clks->parent,
281 clks->id);
282 if (IS_ERR(hw))
283 return PTR_ERR(hw);
284
285 data->hws[clks->id] = hw;
286 data->num = clks->id + 1;
287 fallthrough;
288
289 default:
290 clks++;
291 break;
292 }
293 }
294
295 return 0;
296 }
297
raspberrypi_clk_probe(struct platform_device * pdev)298 static int raspberrypi_clk_probe(struct platform_device *pdev)
299 {
300 struct clk_hw_onecell_data *clk_data;
301 struct device_node *firmware_node;
302 struct device *dev = &pdev->dev;
303 struct rpi_firmware *firmware;
304 struct raspberrypi_clk *rpi;
305 int ret;
306
307 /*
308 * We can be probed either through the an old-fashioned
309 * platform device registration or through a DT node that is a
310 * child of the firmware node. Handle both cases.
311 */
312 if (dev->of_node)
313 firmware_node = of_get_parent(dev->of_node);
314 else
315 firmware_node = of_find_compatible_node(NULL, NULL,
316 "raspberrypi,bcm2835-firmware");
317 if (!firmware_node) {
318 dev_err(dev, "Missing firmware node\n");
319 return -ENOENT;
320 }
321
322 firmware = rpi_firmware_get(firmware_node);
323 of_node_put(firmware_node);
324 if (!firmware)
325 return -EPROBE_DEFER;
326
327 rpi = devm_kzalloc(dev, sizeof(*rpi), GFP_KERNEL);
328 if (!rpi)
329 return -ENOMEM;
330
331 rpi->dev = dev;
332 rpi->firmware = firmware;
333 platform_set_drvdata(pdev, rpi);
334
335 clk_data = devm_kzalloc(dev, struct_size(clk_data, hws,
336 RPI_FIRMWARE_NUM_CLK_ID),
337 GFP_KERNEL);
338 if (!clk_data)
339 return -ENOMEM;
340
341 ret = raspberrypi_discover_clocks(rpi, clk_data);
342 if (ret)
343 return ret;
344
345 ret = devm_of_clk_add_hw_provider(dev, of_clk_hw_onecell_get,
346 clk_data);
347 if (ret)
348 return ret;
349
350 rpi->cpufreq = platform_device_register_data(dev, "raspberrypi-cpufreq",
351 -1, NULL, 0);
352
353 return 0;
354 }
355
raspberrypi_clk_remove(struct platform_device * pdev)356 static int raspberrypi_clk_remove(struct platform_device *pdev)
357 {
358 struct raspberrypi_clk *rpi = platform_get_drvdata(pdev);
359
360 platform_device_unregister(rpi->cpufreq);
361
362 return 0;
363 }
364
365 static const struct of_device_id raspberrypi_clk_match[] = {
366 { .compatible = "raspberrypi,firmware-clocks" },
367 { },
368 };
369 MODULE_DEVICE_TABLE(of, raspberrypi_clk_match);
370
371 static struct platform_driver raspberrypi_clk_driver = {
372 .driver = {
373 .name = "raspberrypi-clk",
374 .of_match_table = raspberrypi_clk_match,
375 },
376 .probe = raspberrypi_clk_probe,
377 .remove = raspberrypi_clk_remove,
378 };
379 module_platform_driver(raspberrypi_clk_driver);
380
381 MODULE_AUTHOR("Nicolas Saenz Julienne <nsaenzjulienne@suse.de>");
382 MODULE_DESCRIPTION("Raspberry Pi firmware clock driver");
383 MODULE_LICENSE("GPL");
384 MODULE_ALIAS("platform:raspberrypi-clk");
385