1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * APM X-Gene SoC Hardware Monitoring Driver
4  *
5  * Copyright (c) 2016, Applied Micro Circuits Corporation
6  * Author: Loc Ho <lho@apm.com>
7  *         Hoan Tran <hotran@apm.com>
8  *
9  * This driver provides the following features:
10  *  - Retrieve CPU total power (uW)
11  *  - Retrieve IO total power (uW)
12  *  - Retrieve SoC temperature (milli-degree C) and alarm
13  */
14 #include <linux/acpi.h>
15 #include <linux/dma-mapping.h>
16 #include <linux/hwmon.h>
17 #include <linux/hwmon-sysfs.h>
18 #include <linux/io.h>
19 #include <linux/interrupt.h>
20 #include <linux/kfifo.h>
21 #include <linux/mailbox_controller.h>
22 #include <linux/mailbox_client.h>
23 #include <linux/module.h>
24 #include <linux/of.h>
25 #include <linux/platform_device.h>
26 
27 #include <acpi/pcc.h>
28 
29 /* SLIMpro message defines */
30 #define MSG_TYPE_DBG			0
31 #define MSG_TYPE_ERR			7
32 #define MSG_TYPE_PWRMGMT		9
33 
34 #define MSG_TYPE(v)			(((v) & 0xF0000000) >> 28)
35 #define MSG_TYPE_SET(v)			(((v) << 28) & 0xF0000000)
36 #define MSG_SUBTYPE(v)			(((v) & 0x0F000000) >> 24)
37 #define MSG_SUBTYPE_SET(v)		(((v) << 24) & 0x0F000000)
38 
39 #define DBG_SUBTYPE_SENSOR_READ		4
40 #define SENSOR_RD_MSG			0x04FFE902
41 #define SENSOR_RD_EN_ADDR(a)		((a) & 0x000FFFFF)
42 #define PMD_PWR_REG			0x20
43 #define PMD_PWR_MW_REG			0x26
44 #define SOC_PWR_REG			0x21
45 #define SOC_PWR_MW_REG			0x27
46 #define SOC_TEMP_REG			0x10
47 
48 #define TEMP_NEGATIVE_BIT		8
49 #define SENSOR_INVALID_DATA		BIT(15)
50 
51 #define PWRMGMT_SUBTYPE_TPC		1
52 #define TPC_ALARM			2
53 #define TPC_GET_ALARM			3
54 #define TPC_CMD(v)			(((v) & 0x00FF0000) >> 16)
55 #define TPC_CMD_SET(v)			(((v) << 16) & 0x00FF0000)
56 #define TPC_EN_MSG(hndl, cmd, type) \
57 	(MSG_TYPE_SET(MSG_TYPE_PWRMGMT) | \
58 	MSG_SUBTYPE_SET(hndl) | TPC_CMD_SET(cmd) | type)
59 
60 /*
61  * Arbitrary retries in case the remote processor is slow to respond
62  * to PCC commands
63  */
64 #define PCC_NUM_RETRIES			500
65 
66 #define ASYNC_MSG_FIFO_SIZE		16
67 #define MBOX_OP_TIMEOUTMS		1000
68 
69 #define WATT_TO_mWATT(x)		((x) * 1000)
70 #define mWATT_TO_uWATT(x)		((x) * 1000)
71 #define CELSIUS_TO_mCELSIUS(x)		((x) * 1000)
72 
73 #define to_xgene_hwmon_dev(cl)		\
74 	container_of(cl, struct xgene_hwmon_dev, mbox_client)
75 
76 enum xgene_hwmon_version {
77 	XGENE_HWMON_V1 = 0,
78 	XGENE_HWMON_V2 = 1,
79 };
80 
81 struct slimpro_resp_msg {
82 	u32 msg;
83 	u32 param1;
84 	u32 param2;
85 } __packed;
86 
87 struct xgene_hwmon_dev {
88 	struct device		*dev;
89 	struct mbox_chan	*mbox_chan;
90 	struct pcc_mbox_chan	*pcc_chan;
91 	struct mbox_client	mbox_client;
92 	int			mbox_idx;
93 
94 	spinlock_t		kfifo_lock;
95 	struct mutex		rd_mutex;
96 	struct completion	rd_complete;
97 	int			resp_pending;
98 	struct slimpro_resp_msg sync_msg;
99 
100 	struct work_struct	workq;
101 	struct kfifo_rec_ptr_1	async_msg_fifo;
102 
103 	struct device		*hwmon_dev;
104 	bool			temp_critical_alarm;
105 
106 	unsigned int		usecs_lat;
107 };
108 
109 /*
110  * This function tests and clears a bitmask then returns its old value
111  */
112 static u16 xgene_word_tst_and_clr(u16 *addr, u16 mask)
113 {
114 	u16 ret, val;
115 
116 	val = le16_to_cpu(READ_ONCE(*addr));
117 	ret = val & mask;
118 	val &= ~mask;
119 	WRITE_ONCE(*addr, cpu_to_le16(val));
120 
121 	return ret;
122 }
123 
124 static int xgene_hwmon_pcc_rd(struct xgene_hwmon_dev *ctx, u32 *msg)
125 {
126 	struct acpi_pcct_shared_memory __iomem *generic_comm_base =
127 							ctx->pcc_chan->shmem;
128 	u32 *ptr = (void *)(generic_comm_base + 1);
129 	int rc, i;
130 	u16 val;
131 
132 	mutex_lock(&ctx->rd_mutex);
133 	init_completion(&ctx->rd_complete);
134 	ctx->resp_pending = true;
135 
136 	/* Write signature for subspace */
137 	WRITE_ONCE(generic_comm_base->signature,
138 		   cpu_to_le32(PCC_SIGNATURE | ctx->mbox_idx));
139 
140 	/* Write to the shared command region */
141 	WRITE_ONCE(generic_comm_base->command,
142 		   cpu_to_le16(MSG_TYPE(msg[0]) | PCC_CMD_GENERATE_DB_INTR));
143 
144 	/* Flip CMD COMPLETE bit */
145 	val = le16_to_cpu(READ_ONCE(generic_comm_base->status));
146 	val &= ~PCC_STATUS_CMD_COMPLETE;
147 	WRITE_ONCE(generic_comm_base->status, cpu_to_le16(val));
148 
149 	/* Copy the message to the PCC comm space */
150 	for (i = 0; i < sizeof(struct slimpro_resp_msg) / 4; i++)
151 		WRITE_ONCE(ptr[i], cpu_to_le32(msg[i]));
152 
153 	/* Ring the doorbell */
154 	rc = mbox_send_message(ctx->mbox_chan, msg);
155 	if (rc < 0) {
156 		dev_err(ctx->dev, "Mailbox send error %d\n", rc);
157 		goto err;
158 	}
159 	if (!wait_for_completion_timeout(&ctx->rd_complete,
160 					 usecs_to_jiffies(ctx->usecs_lat))) {
161 		dev_err(ctx->dev, "Mailbox operation timed out\n");
162 		rc = -ETIMEDOUT;
163 		goto err;
164 	}
165 
166 	/* Check for error message */
167 	if (MSG_TYPE(ctx->sync_msg.msg) == MSG_TYPE_ERR) {
168 		rc = -EINVAL;
169 		goto err;
170 	}
171 
172 	msg[0] = ctx->sync_msg.msg;
173 	msg[1] = ctx->sync_msg.param1;
174 	msg[2] = ctx->sync_msg.param2;
175 
176 err:
177 	mbox_chan_txdone(ctx->mbox_chan, 0);
178 	ctx->resp_pending = false;
179 	mutex_unlock(&ctx->rd_mutex);
180 	return rc;
181 }
182 
183 static int xgene_hwmon_rd(struct xgene_hwmon_dev *ctx, u32 *msg)
184 {
185 	int rc;
186 
187 	mutex_lock(&ctx->rd_mutex);
188 	init_completion(&ctx->rd_complete);
189 	ctx->resp_pending = true;
190 
191 	rc = mbox_send_message(ctx->mbox_chan, msg);
192 	if (rc < 0) {
193 		dev_err(ctx->dev, "Mailbox send error %d\n", rc);
194 		goto err;
195 	}
196 
197 	if (!wait_for_completion_timeout(&ctx->rd_complete,
198 					 msecs_to_jiffies(MBOX_OP_TIMEOUTMS))) {
199 		dev_err(ctx->dev, "Mailbox operation timed out\n");
200 		rc = -ETIMEDOUT;
201 		goto err;
202 	}
203 
204 	/* Check for error message */
205 	if (MSG_TYPE(ctx->sync_msg.msg) == MSG_TYPE_ERR) {
206 		rc = -EINVAL;
207 		goto err;
208 	}
209 
210 	msg[0] = ctx->sync_msg.msg;
211 	msg[1] = ctx->sync_msg.param1;
212 	msg[2] = ctx->sync_msg.param2;
213 
214 err:
215 	ctx->resp_pending = false;
216 	mutex_unlock(&ctx->rd_mutex);
217 	return rc;
218 }
219 
220 static int xgene_hwmon_reg_map_rd(struct xgene_hwmon_dev *ctx, u32 addr,
221 				  u32 *data)
222 {
223 	u32 msg[3];
224 	int rc;
225 
226 	msg[0] = SENSOR_RD_MSG;
227 	msg[1] = SENSOR_RD_EN_ADDR(addr);
228 	msg[2] = 0;
229 
230 	if (acpi_disabled)
231 		rc = xgene_hwmon_rd(ctx, msg);
232 	else
233 		rc = xgene_hwmon_pcc_rd(ctx, msg);
234 
235 	if (rc < 0)
236 		return rc;
237 
238 	/*
239 	 * Check if sensor data is valid.
240 	 */
241 	if (msg[1] & SENSOR_INVALID_DATA)
242 		return -ENODATA;
243 
244 	*data = msg[1];
245 
246 	return rc;
247 }
248 
249 static int xgene_hwmon_get_notification_msg(struct xgene_hwmon_dev *ctx,
250 					    u32 *amsg)
251 {
252 	u32 msg[3];
253 	int rc;
254 
255 	msg[0] = TPC_EN_MSG(PWRMGMT_SUBTYPE_TPC, TPC_GET_ALARM, 0);
256 	msg[1] = 0;
257 	msg[2] = 0;
258 
259 	rc = xgene_hwmon_pcc_rd(ctx, msg);
260 	if (rc < 0)
261 		return rc;
262 
263 	amsg[0] = msg[0];
264 	amsg[1] = msg[1];
265 	amsg[2] = msg[2];
266 
267 	return rc;
268 }
269 
270 static int xgene_hwmon_get_cpu_pwr(struct xgene_hwmon_dev *ctx, u32 *val)
271 {
272 	u32 watt, mwatt;
273 	int rc;
274 
275 	rc = xgene_hwmon_reg_map_rd(ctx, PMD_PWR_REG, &watt);
276 	if (rc < 0)
277 		return rc;
278 
279 	rc = xgene_hwmon_reg_map_rd(ctx, PMD_PWR_MW_REG, &mwatt);
280 	if (rc < 0)
281 		return rc;
282 
283 	*val = WATT_TO_mWATT(watt) + mwatt;
284 	return 0;
285 }
286 
287 static int xgene_hwmon_get_io_pwr(struct xgene_hwmon_dev *ctx, u32 *val)
288 {
289 	u32 watt, mwatt;
290 	int rc;
291 
292 	rc = xgene_hwmon_reg_map_rd(ctx, SOC_PWR_REG, &watt);
293 	if (rc < 0)
294 		return rc;
295 
296 	rc = xgene_hwmon_reg_map_rd(ctx, SOC_PWR_MW_REG, &mwatt);
297 	if (rc < 0)
298 		return rc;
299 
300 	*val = WATT_TO_mWATT(watt) + mwatt;
301 	return 0;
302 }
303 
304 static int xgene_hwmon_get_temp(struct xgene_hwmon_dev *ctx, u32 *val)
305 {
306 	return xgene_hwmon_reg_map_rd(ctx, SOC_TEMP_REG, val);
307 }
308 
309 /*
310  * Sensor temperature/power functions
311  */
312 static ssize_t temp1_input_show(struct device *dev,
313 				struct device_attribute *attr,
314 				char *buf)
315 {
316 	struct xgene_hwmon_dev *ctx = dev_get_drvdata(dev);
317 	int rc, temp;
318 	u32 val;
319 
320 	rc = xgene_hwmon_get_temp(ctx, &val);
321 	if (rc < 0)
322 		return rc;
323 
324 	temp = sign_extend32(val, TEMP_NEGATIVE_BIT);
325 
326 	return sysfs_emit(buf, "%d\n", CELSIUS_TO_mCELSIUS(temp));
327 }
328 
329 static ssize_t temp1_label_show(struct device *dev,
330 				struct device_attribute *attr,
331 				char *buf)
332 {
333 	return sysfs_emit(buf, "SoC Temperature\n");
334 }
335 
336 static ssize_t temp1_critical_alarm_show(struct device *dev,
337 					 struct device_attribute *devattr,
338 					 char *buf)
339 {
340 	struct xgene_hwmon_dev *ctx = dev_get_drvdata(dev);
341 
342 	return sysfs_emit(buf, "%d\n", ctx->temp_critical_alarm);
343 }
344 
345 static ssize_t power1_label_show(struct device *dev,
346 				 struct device_attribute *attr,
347 				 char *buf)
348 {
349 	return sysfs_emit(buf, "CPU power\n");
350 }
351 
352 static ssize_t power2_label_show(struct device *dev,
353 				 struct device_attribute *attr,
354 				 char *buf)
355 {
356 	return sysfs_emit(buf, "IO power\n");
357 }
358 
359 static ssize_t power1_input_show(struct device *dev,
360 				 struct device_attribute *attr,
361 				 char *buf)
362 {
363 	struct xgene_hwmon_dev *ctx = dev_get_drvdata(dev);
364 	u32 val;
365 	int rc;
366 
367 	rc = xgene_hwmon_get_cpu_pwr(ctx, &val);
368 	if (rc < 0)
369 		return rc;
370 
371 	return sysfs_emit(buf, "%u\n", mWATT_TO_uWATT(val));
372 }
373 
374 static ssize_t power2_input_show(struct device *dev,
375 				 struct device_attribute *attr,
376 				 char *buf)
377 {
378 	struct xgene_hwmon_dev *ctx = dev_get_drvdata(dev);
379 	u32 val;
380 	int rc;
381 
382 	rc = xgene_hwmon_get_io_pwr(ctx, &val);
383 	if (rc < 0)
384 		return rc;
385 
386 	return sysfs_emit(buf, "%u\n", mWATT_TO_uWATT(val));
387 }
388 
389 static DEVICE_ATTR_RO(temp1_label);
390 static DEVICE_ATTR_RO(temp1_input);
391 static DEVICE_ATTR_RO(temp1_critical_alarm);
392 static DEVICE_ATTR_RO(power1_label);
393 static DEVICE_ATTR_RO(power1_input);
394 static DEVICE_ATTR_RO(power2_label);
395 static DEVICE_ATTR_RO(power2_input);
396 
397 static struct attribute *xgene_hwmon_attrs[] = {
398 	&dev_attr_temp1_label.attr,
399 	&dev_attr_temp1_input.attr,
400 	&dev_attr_temp1_critical_alarm.attr,
401 	&dev_attr_power1_label.attr,
402 	&dev_attr_power1_input.attr,
403 	&dev_attr_power2_label.attr,
404 	&dev_attr_power2_input.attr,
405 	NULL,
406 };
407 
408 ATTRIBUTE_GROUPS(xgene_hwmon);
409 
410 static int xgene_hwmon_tpc_alarm(struct xgene_hwmon_dev *ctx,
411 				 struct slimpro_resp_msg *amsg)
412 {
413 	ctx->temp_critical_alarm = !!amsg->param2;
414 	sysfs_notify(&ctx->dev->kobj, NULL, "temp1_critical_alarm");
415 
416 	return 0;
417 }
418 
419 static void xgene_hwmon_process_pwrmsg(struct xgene_hwmon_dev *ctx,
420 				       struct slimpro_resp_msg *amsg)
421 {
422 	if ((MSG_SUBTYPE(amsg->msg) == PWRMGMT_SUBTYPE_TPC) &&
423 	    (TPC_CMD(amsg->msg) == TPC_ALARM))
424 		xgene_hwmon_tpc_alarm(ctx, amsg);
425 }
426 
427 /*
428  * This function is called to process async work queue
429  */
430 static void xgene_hwmon_evt_work(struct work_struct *work)
431 {
432 	struct slimpro_resp_msg amsg;
433 	struct xgene_hwmon_dev *ctx;
434 	int ret;
435 
436 	ctx = container_of(work, struct xgene_hwmon_dev, workq);
437 	while (kfifo_out_spinlocked(&ctx->async_msg_fifo, &amsg,
438 				    sizeof(struct slimpro_resp_msg),
439 				    &ctx->kfifo_lock)) {
440 		/*
441 		 * If PCC, send a consumer command to Platform to get info
442 		 * If Slimpro Mailbox, get message from specific FIFO
443 		 */
444 		if (!acpi_disabled) {
445 			ret = xgene_hwmon_get_notification_msg(ctx,
446 							       (u32 *)&amsg);
447 			if (ret < 0)
448 				continue;
449 		}
450 
451 		if (MSG_TYPE(amsg.msg) == MSG_TYPE_PWRMGMT)
452 			xgene_hwmon_process_pwrmsg(ctx, &amsg);
453 	}
454 }
455 
456 static int xgene_hwmon_rx_ready(struct xgene_hwmon_dev *ctx, void *msg)
457 {
458 	if (IS_ERR_OR_NULL(ctx->hwmon_dev) && !ctx->resp_pending) {
459 		/* Enqueue to the FIFO */
460 		kfifo_in_spinlocked(&ctx->async_msg_fifo, msg,
461 				    sizeof(struct slimpro_resp_msg),
462 				    &ctx->kfifo_lock);
463 		return -ENODEV;
464 	}
465 
466 	return 0;
467 }
468 
469 /*
470  * This function is called when the SLIMpro Mailbox received a message
471  */
472 static void xgene_hwmon_rx_cb(struct mbox_client *cl, void *msg)
473 {
474 	struct xgene_hwmon_dev *ctx = to_xgene_hwmon_dev(cl);
475 
476 	/*
477 	 * While the driver registers with the mailbox framework, an interrupt
478 	 * can be pending before the probe function completes its
479 	 * initialization. If such condition occurs, just queue up the message
480 	 * as the driver is not ready for servicing the callback.
481 	 */
482 	if (xgene_hwmon_rx_ready(ctx, msg) < 0)
483 		return;
484 
485 	/*
486 	 * Response message format:
487 	 * msg[0] is the return code of the operation
488 	 * msg[1] is the first parameter word
489 	 * msg[2] is the second parameter word
490 	 *
491 	 * As message only supports dword size, just assign it.
492 	 */
493 
494 	/* Check for sync query */
495 	if (ctx->resp_pending &&
496 	    ((MSG_TYPE(((u32 *)msg)[0]) == MSG_TYPE_ERR) ||
497 	     (MSG_TYPE(((u32 *)msg)[0]) == MSG_TYPE_DBG &&
498 	      MSG_SUBTYPE(((u32 *)msg)[0]) == DBG_SUBTYPE_SENSOR_READ) ||
499 	     (MSG_TYPE(((u32 *)msg)[0]) == MSG_TYPE_PWRMGMT &&
500 	      MSG_SUBTYPE(((u32 *)msg)[0]) == PWRMGMT_SUBTYPE_TPC &&
501 	      TPC_CMD(((u32 *)msg)[0]) == TPC_ALARM))) {
502 		ctx->sync_msg.msg = ((u32 *)msg)[0];
503 		ctx->sync_msg.param1 = ((u32 *)msg)[1];
504 		ctx->sync_msg.param2 = ((u32 *)msg)[2];
505 
506 		/* Operation waiting for response */
507 		complete(&ctx->rd_complete);
508 
509 		return;
510 	}
511 
512 	/* Enqueue to the FIFO */
513 	kfifo_in_spinlocked(&ctx->async_msg_fifo, msg,
514 			    sizeof(struct slimpro_resp_msg), &ctx->kfifo_lock);
515 	/* Schedule the bottom handler */
516 	schedule_work(&ctx->workq);
517 }
518 
519 /*
520  * This function is called when the PCC Mailbox received a message
521  */
522 static void xgene_hwmon_pcc_rx_cb(struct mbox_client *cl, void *msg)
523 {
524 	struct xgene_hwmon_dev *ctx = to_xgene_hwmon_dev(cl);
525 	struct acpi_pcct_shared_memory __iomem *generic_comm_base =
526 							ctx->pcc_chan->shmem;
527 	struct slimpro_resp_msg amsg;
528 
529 	/*
530 	 * While the driver registers with the mailbox framework, an interrupt
531 	 * can be pending before the probe function completes its
532 	 * initialization. If such condition occurs, just queue up the message
533 	 * as the driver is not ready for servicing the callback.
534 	 */
535 	if (xgene_hwmon_rx_ready(ctx, &amsg) < 0)
536 		return;
537 
538 	msg = generic_comm_base + 1;
539 	/* Check if platform sends interrupt */
540 	if (!xgene_word_tst_and_clr(&generic_comm_base->status,
541 				    PCC_STATUS_SCI_DOORBELL))
542 		return;
543 
544 	/*
545 	 * Response message format:
546 	 * msg[0] is the return code of the operation
547 	 * msg[1] is the first parameter word
548 	 * msg[2] is the second parameter word
549 	 *
550 	 * As message only supports dword size, just assign it.
551 	 */
552 
553 	/* Check for sync query */
554 	if (ctx->resp_pending &&
555 	    ((MSG_TYPE(((u32 *)msg)[0]) == MSG_TYPE_ERR) ||
556 	     (MSG_TYPE(((u32 *)msg)[0]) == MSG_TYPE_DBG &&
557 	      MSG_SUBTYPE(((u32 *)msg)[0]) == DBG_SUBTYPE_SENSOR_READ) ||
558 	     (MSG_TYPE(((u32 *)msg)[0]) == MSG_TYPE_PWRMGMT &&
559 	      MSG_SUBTYPE(((u32 *)msg)[0]) == PWRMGMT_SUBTYPE_TPC &&
560 	      TPC_CMD(((u32 *)msg)[0]) == TPC_ALARM))) {
561 		/* Check if platform completes command */
562 		if (xgene_word_tst_and_clr(&generic_comm_base->status,
563 					   PCC_STATUS_CMD_COMPLETE)) {
564 			ctx->sync_msg.msg = ((u32 *)msg)[0];
565 			ctx->sync_msg.param1 = ((u32 *)msg)[1];
566 			ctx->sync_msg.param2 = ((u32 *)msg)[2];
567 
568 			/* Operation waiting for response */
569 			complete(&ctx->rd_complete);
570 
571 			return;
572 		}
573 	}
574 
575 	/*
576 	 * Platform notifies interrupt to OSPM.
577 	 * OPSM schedules a consumer command to get this information
578 	 * in a workqueue. Platform must wait until OSPM has issued
579 	 * a consumer command that serves this notification.
580 	 */
581 
582 	/* Enqueue to the FIFO */
583 	kfifo_in_spinlocked(&ctx->async_msg_fifo, &amsg,
584 			    sizeof(struct slimpro_resp_msg), &ctx->kfifo_lock);
585 	/* Schedule the bottom handler */
586 	schedule_work(&ctx->workq);
587 }
588 
589 static void xgene_hwmon_tx_done(struct mbox_client *cl, void *msg, int ret)
590 {
591 	if (ret) {
592 		dev_dbg(cl->dev, "TX did not complete: CMD sent:%x, ret:%d\n",
593 			*(u16 *)msg, ret);
594 	} else {
595 		dev_dbg(cl->dev, "TX completed. CMD sent:%x, ret:%d\n",
596 			*(u16 *)msg, ret);
597 	}
598 }
599 
600 #ifdef CONFIG_ACPI
601 static const struct acpi_device_id xgene_hwmon_acpi_match[] = {
602 	{"APMC0D29", XGENE_HWMON_V1},
603 	{"APMC0D8A", XGENE_HWMON_V2},
604 	{},
605 };
606 MODULE_DEVICE_TABLE(acpi, xgene_hwmon_acpi_match);
607 #endif
608 
609 static int xgene_hwmon_probe(struct platform_device *pdev)
610 {
611 	struct xgene_hwmon_dev *ctx;
612 	struct mbox_client *cl;
613 	int rc;
614 
615 	ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
616 	if (!ctx)
617 		return -ENOMEM;
618 
619 	ctx->dev = &pdev->dev;
620 	platform_set_drvdata(pdev, ctx);
621 	cl = &ctx->mbox_client;
622 
623 	spin_lock_init(&ctx->kfifo_lock);
624 	mutex_init(&ctx->rd_mutex);
625 
626 	rc = kfifo_alloc(&ctx->async_msg_fifo,
627 			 sizeof(struct slimpro_resp_msg) * ASYNC_MSG_FIFO_SIZE,
628 			 GFP_KERNEL);
629 	if (rc)
630 		return -ENOMEM;
631 
632 	INIT_WORK(&ctx->workq, xgene_hwmon_evt_work);
633 
634 	/* Request mailbox channel */
635 	cl->dev = &pdev->dev;
636 	cl->tx_done = xgene_hwmon_tx_done;
637 	cl->tx_block = false;
638 	cl->tx_tout = MBOX_OP_TIMEOUTMS;
639 	cl->knows_txdone = false;
640 	if (acpi_disabled) {
641 		cl->rx_callback = xgene_hwmon_rx_cb;
642 		ctx->mbox_chan = mbox_request_channel(cl, 0);
643 		if (IS_ERR(ctx->mbox_chan)) {
644 			dev_err(&pdev->dev,
645 				"SLIMpro mailbox channel request failed\n");
646 			rc = -ENODEV;
647 			goto out_mbox_free;
648 		}
649 	} else {
650 		struct pcc_mbox_chan *pcc_chan;
651 		const struct acpi_device_id *acpi_id;
652 
653 		acpi_id = acpi_match_device(pdev->dev.driver->acpi_match_table,
654 					    &pdev->dev);
655 		if (!acpi_id) {
656 			rc = -EINVAL;
657 			goto out_mbox_free;
658 		}
659 
660 		if (device_property_read_u32(&pdev->dev, "pcc-channel",
661 					     &ctx->mbox_idx)) {
662 			dev_err(&pdev->dev, "no pcc-channel property\n");
663 			rc = -ENODEV;
664 			goto out_mbox_free;
665 		}
666 
667 		cl->rx_callback = xgene_hwmon_pcc_rx_cb;
668 		pcc_chan = pcc_mbox_request_channel(cl, ctx->mbox_idx);
669 		if (IS_ERR(pcc_chan)) {
670 			dev_err(&pdev->dev,
671 				"PPC channel request failed\n");
672 			rc = -ENODEV;
673 			goto out_mbox_free;
674 		}
675 
676 		ctx->pcc_chan = pcc_chan;
677 		ctx->mbox_chan = pcc_chan->mchan;
678 
679 		if (!ctx->mbox_chan->mbox->txdone_irq) {
680 			dev_err(&pdev->dev, "PCC IRQ not supported\n");
681 			rc = -ENODEV;
682 			goto out;
683 		}
684 
685 		/*
686 		 * pcc_chan->latency is just a Nominal value. In reality
687 		 * the remote processor could be much slower to reply.
688 		 * So add an arbitrary amount of wait on top of Nominal.
689 		 */
690 		ctx->usecs_lat = PCC_NUM_RETRIES * pcc_chan->latency;
691 	}
692 
693 	ctx->hwmon_dev = hwmon_device_register_with_groups(ctx->dev,
694 							   "apm_xgene",
695 							   ctx,
696 							   xgene_hwmon_groups);
697 	if (IS_ERR(ctx->hwmon_dev)) {
698 		dev_err(&pdev->dev, "Failed to register HW monitor device\n");
699 		rc = PTR_ERR(ctx->hwmon_dev);
700 		goto out;
701 	}
702 
703 	/*
704 	 * Schedule the bottom handler if there is a pending message.
705 	 */
706 	schedule_work(&ctx->workq);
707 
708 	dev_info(&pdev->dev, "APM X-Gene SoC HW monitor driver registered\n");
709 
710 	return 0;
711 
712 out:
713 	if (acpi_disabled)
714 		mbox_free_channel(ctx->mbox_chan);
715 	else
716 		pcc_mbox_free_channel(ctx->pcc_chan);
717 out_mbox_free:
718 	kfifo_free(&ctx->async_msg_fifo);
719 
720 	return rc;
721 }
722 
723 static void xgene_hwmon_remove(struct platform_device *pdev)
724 {
725 	struct xgene_hwmon_dev *ctx = platform_get_drvdata(pdev);
726 
727 	cancel_work_sync(&ctx->workq);
728 	hwmon_device_unregister(ctx->hwmon_dev);
729 	kfifo_free(&ctx->async_msg_fifo);
730 	if (acpi_disabled)
731 		mbox_free_channel(ctx->mbox_chan);
732 	else
733 		pcc_mbox_free_channel(ctx->pcc_chan);
734 }
735 
736 static const struct of_device_id xgene_hwmon_of_match[] = {
737 	{.compatible = "apm,xgene-slimpro-hwmon"},
738 	{}
739 };
740 MODULE_DEVICE_TABLE(of, xgene_hwmon_of_match);
741 
742 static struct platform_driver xgene_hwmon_driver = {
743 	.probe = xgene_hwmon_probe,
744 	.remove = xgene_hwmon_remove,
745 	.driver = {
746 		.name = "xgene-slimpro-hwmon",
747 		.of_match_table = xgene_hwmon_of_match,
748 		.acpi_match_table = ACPI_PTR(xgene_hwmon_acpi_match),
749 	},
750 };
751 module_platform_driver(xgene_hwmon_driver);
752 
753 MODULE_DESCRIPTION("APM X-Gene SoC hardware monitor");
754 MODULE_LICENSE("GPL");
755