1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Defines interfaces for interacting with the Raspberry Pi firmware's
4  * property channel.
5  *
6  * Copyright © 2015 Broadcom
7  */
8 
9 #include <linux/dma-mapping.h>
10 #include <linux/kref.h>
11 #include <linux/mailbox_client.h>
12 #include <linux/module.h>
13 #include <linux/of_platform.h>
14 #include <linux/platform_device.h>
15 #include <linux/slab.h>
16 #include <soc/bcm2835/raspberrypi-firmware.h>
17 
18 #define MBOX_MSG(chan, data28)		(((data28) & ~0xf) | ((chan) & 0xf))
19 #define MBOX_CHAN(msg)			((msg) & 0xf)
20 #define MBOX_DATA28(msg)		((msg) & ~0xf)
21 #define MBOX_CHAN_PROPERTY		8
22 
23 static struct platform_device *rpi_hwmon;
24 static struct platform_device *rpi_clk;
25 
26 struct rpi_firmware {
27 	struct mbox_client cl;
28 	struct mbox_chan *chan; /* The property channel. */
29 	struct completion c;
30 	u32 enabled;
31 
32 	struct kref consumers;
33 };
34 
35 static DEFINE_MUTEX(transaction_lock);
36 
37 static void response_callback(struct mbox_client *cl, void *msg)
38 {
39 	struct rpi_firmware *fw = container_of(cl, struct rpi_firmware, cl);
40 	complete(&fw->c);
41 }
42 
43 /*
44  * Sends a request to the firmware through the BCM2835 mailbox driver,
45  * and synchronously waits for the reply.
46  */
47 static int
48 rpi_firmware_transaction(struct rpi_firmware *fw, u32 chan, u32 data)
49 {
50 	u32 message = MBOX_MSG(chan, data);
51 	int ret;
52 
53 	WARN_ON(data & 0xf);
54 
55 	mutex_lock(&transaction_lock);
56 	reinit_completion(&fw->c);
57 	ret = mbox_send_message(fw->chan, &message);
58 	if (ret >= 0) {
59 		if (wait_for_completion_timeout(&fw->c, HZ)) {
60 			ret = 0;
61 		} else {
62 			ret = -ETIMEDOUT;
63 			WARN_ONCE(1, "Firmware transaction timeout");
64 		}
65 	} else {
66 		dev_err(fw->cl.dev, "mbox_send_message returned %d\n", ret);
67 	}
68 	mutex_unlock(&transaction_lock);
69 
70 	return ret;
71 }
72 
73 /**
74  * rpi_firmware_property_list - Submit firmware property list
75  * @fw:		Pointer to firmware structure from rpi_firmware_get().
76  * @data:	Buffer holding tags.
77  * @tag_size:	Size of tags buffer.
78  *
79  * Submits a set of concatenated tags to the VPU firmware through the
80  * mailbox property interface.
81  *
82  * The buffer header and the ending tag are added by this function and
83  * don't need to be supplied, just the actual tags for your operation.
84  * See struct rpi_firmware_property_tag_header for the per-tag
85  * structure.
86  */
87 int rpi_firmware_property_list(struct rpi_firmware *fw,
88 			       void *data, size_t tag_size)
89 {
90 	size_t size = tag_size + 12;
91 	u32 *buf;
92 	dma_addr_t bus_addr;
93 	int ret;
94 
95 	/* Packets are processed a dword at a time. */
96 	if (size & 3)
97 		return -EINVAL;
98 
99 	buf = dma_alloc_coherent(fw->cl.dev, PAGE_ALIGN(size), &bus_addr,
100 				 GFP_ATOMIC);
101 	if (!buf)
102 		return -ENOMEM;
103 
104 	/* The firmware will error out without parsing in this case. */
105 	WARN_ON(size >= 1024 * 1024);
106 
107 	buf[0] = size;
108 	buf[1] = RPI_FIRMWARE_STATUS_REQUEST;
109 	memcpy(&buf[2], data, tag_size);
110 	buf[size / 4 - 1] = RPI_FIRMWARE_PROPERTY_END;
111 	wmb();
112 
113 	ret = rpi_firmware_transaction(fw, MBOX_CHAN_PROPERTY, bus_addr);
114 
115 	rmb();
116 	memcpy(data, &buf[2], tag_size);
117 	if (ret == 0 && buf[1] != RPI_FIRMWARE_STATUS_SUCCESS) {
118 		/*
119 		 * The tag name here might not be the one causing the
120 		 * error, if there were multiple tags in the request.
121 		 * But single-tag is the most common, so go with it.
122 		 */
123 		dev_err(fw->cl.dev, "Request 0x%08x returned status 0x%08x\n",
124 			buf[2], buf[1]);
125 		ret = -EINVAL;
126 	}
127 
128 	dma_free_coherent(fw->cl.dev, PAGE_ALIGN(size), buf, bus_addr);
129 
130 	return ret;
131 }
132 EXPORT_SYMBOL_GPL(rpi_firmware_property_list);
133 
134 /**
135  * rpi_firmware_property - Submit single firmware property
136  * @fw:		Pointer to firmware structure from rpi_firmware_get().
137  * @tag:	One of enum_mbox_property_tag.
138  * @tag_data:	Tag data buffer.
139  * @buf_size:	Buffer size.
140  *
141  * Submits a single tag to the VPU firmware through the mailbox
142  * property interface.
143  *
144  * This is a convenience wrapper around
145  * rpi_firmware_property_list() to avoid some of the
146  * boilerplate in property calls.
147  */
148 int rpi_firmware_property(struct rpi_firmware *fw,
149 			  u32 tag, void *tag_data, size_t buf_size)
150 {
151 	struct rpi_firmware_property_tag_header *header;
152 	int ret;
153 
154 	/* Some mailboxes can use over 1k bytes. Rather than checking
155 	 * size and using stack or kmalloc depending on requirements,
156 	 * just use kmalloc. Mailboxes don't get called enough to worry
157 	 * too much about the time taken in the allocation.
158 	 */
159 	void *data = kmalloc(sizeof(*header) + buf_size, GFP_KERNEL);
160 
161 	if (!data)
162 		return -ENOMEM;
163 
164 	header = data;
165 	header->tag = tag;
166 	header->buf_size = buf_size;
167 	header->req_resp_size = 0;
168 	memcpy(data + sizeof(*header), tag_data, buf_size);
169 
170 	ret = rpi_firmware_property_list(fw, data, buf_size + sizeof(*header));
171 
172 	memcpy(tag_data, data + sizeof(*header), buf_size);
173 
174 	kfree(data);
175 
176 	return ret;
177 }
178 EXPORT_SYMBOL_GPL(rpi_firmware_property);
179 
180 static void
181 rpi_firmware_print_firmware_revision(struct rpi_firmware *fw)
182 {
183 	time64_t date_and_time;
184 	u32 packet;
185 	int ret = rpi_firmware_property(fw,
186 					RPI_FIRMWARE_GET_FIRMWARE_REVISION,
187 					&packet, sizeof(packet));
188 
189 	if (ret)
190 		return;
191 
192 	/* This is not compatible with y2038 */
193 	date_and_time = packet;
194 	dev_info(fw->cl.dev, "Attached to firmware from %ptT\n", &date_and_time);
195 }
196 
197 static void
198 rpi_register_hwmon_driver(struct device *dev, struct rpi_firmware *fw)
199 {
200 	u32 packet;
201 	int ret = rpi_firmware_property(fw, RPI_FIRMWARE_GET_THROTTLED,
202 					&packet, sizeof(packet));
203 
204 	if (ret)
205 		return;
206 
207 	rpi_hwmon = platform_device_register_data(dev, "raspberrypi-hwmon",
208 						  -1, NULL, 0);
209 }
210 
211 static void rpi_register_clk_driver(struct device *dev)
212 {
213 	struct device_node *firmware;
214 
215 	/*
216 	 * Earlier DTs don't have a node for the firmware clocks but
217 	 * rely on us creating a platform device by hand. If we do
218 	 * have a node for the firmware clocks, just bail out here.
219 	 */
220 	firmware = of_get_compatible_child(dev->of_node,
221 					   "raspberrypi,firmware-clocks");
222 	if (firmware) {
223 		of_node_put(firmware);
224 		return;
225 	}
226 
227 	rpi_clk = platform_device_register_data(dev, "raspberrypi-clk",
228 						-1, NULL, 0);
229 }
230 
231 static void rpi_firmware_delete(struct kref *kref)
232 {
233 	struct rpi_firmware *fw = container_of(kref, struct rpi_firmware,
234 					       consumers);
235 
236 	mbox_free_channel(fw->chan);
237 	kfree(fw);
238 }
239 
240 void rpi_firmware_put(struct rpi_firmware *fw)
241 {
242 	kref_put(&fw->consumers, rpi_firmware_delete);
243 }
244 EXPORT_SYMBOL_GPL(rpi_firmware_put);
245 
246 static void devm_rpi_firmware_put(void *data)
247 {
248 	struct rpi_firmware *fw = data;
249 
250 	rpi_firmware_put(fw);
251 }
252 
253 static int rpi_firmware_probe(struct platform_device *pdev)
254 {
255 	struct device *dev = &pdev->dev;
256 	struct rpi_firmware *fw;
257 
258 	/*
259 	 * Memory will be freed by rpi_firmware_delete() once all users have
260 	 * released their firmware handles. Don't use devm_kzalloc() here.
261 	 */
262 	fw = kzalloc(sizeof(*fw), GFP_KERNEL);
263 	if (!fw)
264 		return -ENOMEM;
265 
266 	fw->cl.dev = dev;
267 	fw->cl.rx_callback = response_callback;
268 	fw->cl.tx_block = true;
269 
270 	fw->chan = mbox_request_channel(&fw->cl, 0);
271 	if (IS_ERR(fw->chan)) {
272 		int ret = PTR_ERR(fw->chan);
273 		if (ret != -EPROBE_DEFER)
274 			dev_err(dev, "Failed to get mbox channel: %d\n", ret);
275 		return ret;
276 	}
277 
278 	init_completion(&fw->c);
279 	kref_init(&fw->consumers);
280 
281 	platform_set_drvdata(pdev, fw);
282 
283 	rpi_firmware_print_firmware_revision(fw);
284 	rpi_register_hwmon_driver(dev, fw);
285 	rpi_register_clk_driver(dev);
286 
287 	return 0;
288 }
289 
290 static void rpi_firmware_shutdown(struct platform_device *pdev)
291 {
292 	struct rpi_firmware *fw = platform_get_drvdata(pdev);
293 
294 	if (!fw)
295 		return;
296 
297 	rpi_firmware_property(fw, RPI_FIRMWARE_NOTIFY_REBOOT, NULL, 0);
298 }
299 
300 static int rpi_firmware_remove(struct platform_device *pdev)
301 {
302 	struct rpi_firmware *fw = platform_get_drvdata(pdev);
303 
304 	platform_device_unregister(rpi_hwmon);
305 	rpi_hwmon = NULL;
306 	platform_device_unregister(rpi_clk);
307 	rpi_clk = NULL;
308 
309 	rpi_firmware_put(fw);
310 
311 	return 0;
312 }
313 
314 /**
315  * rpi_firmware_get - Get pointer to rpi_firmware structure.
316  * @firmware_node:    Pointer to the firmware Device Tree node.
317  *
318  * The reference to rpi_firmware has to be released with rpi_firmware_put().
319  *
320  * Returns NULL is the firmware device is not ready.
321  */
322 struct rpi_firmware *rpi_firmware_get(struct device_node *firmware_node)
323 {
324 	struct platform_device *pdev = of_find_device_by_node(firmware_node);
325 	struct rpi_firmware *fw;
326 
327 	if (!pdev)
328 		return NULL;
329 
330 	fw = platform_get_drvdata(pdev);
331 	if (!fw)
332 		return NULL;
333 
334 	if (!kref_get_unless_zero(&fw->consumers))
335 		return NULL;
336 
337 	return fw;
338 }
339 EXPORT_SYMBOL_GPL(rpi_firmware_get);
340 
341 /**
342  * devm_rpi_firmware_get - Get pointer to rpi_firmware structure.
343  * @firmware_node:    Pointer to the firmware Device Tree node.
344  *
345  * Returns NULL is the firmware device is not ready.
346  */
347 struct rpi_firmware *devm_rpi_firmware_get(struct device *dev,
348 					   struct device_node *firmware_node)
349 {
350 	struct rpi_firmware *fw;
351 
352 	fw = rpi_firmware_get(firmware_node);
353 	if (!fw)
354 		return NULL;
355 
356 	if (devm_add_action_or_reset(dev, devm_rpi_firmware_put, fw))
357 		return NULL;
358 
359 	return fw;
360 }
361 EXPORT_SYMBOL_GPL(devm_rpi_firmware_get);
362 
363 static const struct of_device_id rpi_firmware_of_match[] = {
364 	{ .compatible = "raspberrypi,bcm2835-firmware", },
365 	{},
366 };
367 MODULE_DEVICE_TABLE(of, rpi_firmware_of_match);
368 
369 static struct platform_driver rpi_firmware_driver = {
370 	.driver = {
371 		.name = "raspberrypi-firmware",
372 		.of_match_table = rpi_firmware_of_match,
373 	},
374 	.probe		= rpi_firmware_probe,
375 	.shutdown	= rpi_firmware_shutdown,
376 	.remove		= rpi_firmware_remove,
377 };
378 module_platform_driver(rpi_firmware_driver);
379 
380 MODULE_AUTHOR("Eric Anholt <eric@anholt.net>");
381 MODULE_DESCRIPTION("Raspberry Pi firmware driver");
382 MODULE_LICENSE("GPL v2");
383