1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * STi Mailbox
4 *
5 * Copyright (C) 2015 ST Microelectronics
6 *
7 * Author: Lee Jones <lee.jones@linaro.org> for ST Microelectronics
8 *
9 * Based on the original driver written by;
10 *   Alexandre Torgue, Olivier Lebreton and Loic Pallardy
11 */
12
13#include <linux/err.h>
14#include <linux/interrupt.h>
15#include <linux/io.h>
16#include <linux/kernel.h>
17#include <linux/mailbox_controller.h>
18#include <linux/module.h>
19#include <linux/of.h>
20#include <linux/platform_device.h>
21#include <linux/property.h>
22#include <linux/slab.h>
23
24#include "mailbox.h"
25
26#define STI_MBOX_INST_MAX	4      /* RAM saving: Max supported instances */
27#define STI_MBOX_CHAN_MAX	20     /* RAM saving: Max supported channels  */
28
29#define STI_IRQ_VAL_OFFSET	0x04   /* Read interrupt status	              */
30#define STI_IRQ_SET_OFFSET	0x24   /* Generate a Tx channel interrupt     */
31#define STI_IRQ_CLR_OFFSET	0x44   /* Clear pending Rx interrupts	      */
32#define STI_ENA_VAL_OFFSET	0x64   /* Read enable status		      */
33#define STI_ENA_SET_OFFSET	0x84   /* Enable a channel		      */
34#define STI_ENA_CLR_OFFSET	0xa4   /* Disable a channel		      */
35
36#define MBOX_BASE(mdev, inst)   ((mdev)->base + ((inst) * 4))
37
38/**
39 * struct sti_mbox_device - STi Mailbox device data
40 *
41 * @dev:	Device to which it is attached
42 * @mbox:	Representation of a communication channel controller
43 * @base:	Base address of the register mapping region
44 * @name:	Name of the mailbox
45 * @enabled:	Local copy of enabled channels
46 * @lock:	Mutex protecting enabled status
47 *
48 * An IP Mailbox is currently composed of 4 instances
49 * Each instance is currently composed of 32 channels
50 * This means that we have 128 channels per Mailbox
51 * A channel an be used for TX or RX
52 */
53struct sti_mbox_device {
54	struct device		*dev;
55	struct mbox_controller	*mbox;
56	void __iomem		*base;
57	const char		*name;
58	u32			enabled[STI_MBOX_INST_MAX];
59	spinlock_t		lock;
60};
61
62/**
63 * struct sti_mbox_pdata - STi Mailbox platform specific configuration
64 *
65 * @num_inst:	Maximum number of instances in one HW Mailbox
66 * @num_chan:	Maximum number of channel per instance
67 */
68struct sti_mbox_pdata {
69	unsigned int		num_inst;
70	unsigned int		num_chan;
71};
72
73/**
74 * struct sti_channel - STi Mailbox allocated channel information
75 *
76 * @mdev:	Pointer to parent Mailbox device
77 * @instance:	Instance number channel resides in
78 * @channel:	Channel number pertaining to this container
79 */
80struct sti_channel {
81	struct sti_mbox_device	*mdev;
82	unsigned int		instance;
83	unsigned int		channel;
84};
85
86static inline bool sti_mbox_channel_is_enabled(struct mbox_chan *chan)
87{
88	struct sti_channel *chan_info = chan->con_priv;
89	struct sti_mbox_device *mdev = chan_info->mdev;
90	unsigned int instance = chan_info->instance;
91	unsigned int channel = chan_info->channel;
92
93	return mdev->enabled[instance] & BIT(channel);
94}
95
96static inline
97struct mbox_chan *sti_mbox_to_channel(struct mbox_controller *mbox,
98				      unsigned int instance,
99				      unsigned int channel)
100{
101	struct sti_channel *chan_info;
102	int i;
103
104	for (i = 0; i < mbox->num_chans; i++) {
105		chan_info = mbox->chans[i].con_priv;
106		if (chan_info &&
107		    chan_info->instance == instance &&
108		    chan_info->channel == channel)
109			return &mbox->chans[i];
110	}
111
112	dev_err(mbox->dev,
113		"Channel not registered: instance: %d channel: %d\n",
114		instance, channel);
115
116	return NULL;
117}
118
119static void sti_mbox_enable_channel(struct mbox_chan *chan)
120{
121	struct sti_channel *chan_info = chan->con_priv;
122	struct sti_mbox_device *mdev = chan_info->mdev;
123	unsigned int instance = chan_info->instance;
124	unsigned int channel = chan_info->channel;
125	unsigned long flags;
126	void __iomem *base = MBOX_BASE(mdev, instance);
127
128	spin_lock_irqsave(&mdev->lock, flags);
129	mdev->enabled[instance] |= BIT(channel);
130	writel_relaxed(BIT(channel), base + STI_ENA_SET_OFFSET);
131	spin_unlock_irqrestore(&mdev->lock, flags);
132}
133
134static void sti_mbox_disable_channel(struct mbox_chan *chan)
135{
136	struct sti_channel *chan_info = chan->con_priv;
137	struct sti_mbox_device *mdev = chan_info->mdev;
138	unsigned int instance = chan_info->instance;
139	unsigned int channel = chan_info->channel;
140	unsigned long flags;
141	void __iomem *base = MBOX_BASE(mdev, instance);
142
143	spin_lock_irqsave(&mdev->lock, flags);
144	mdev->enabled[instance] &= ~BIT(channel);
145	writel_relaxed(BIT(channel), base + STI_ENA_CLR_OFFSET);
146	spin_unlock_irqrestore(&mdev->lock, flags);
147}
148
149static void sti_mbox_clear_irq(struct mbox_chan *chan)
150{
151	struct sti_channel *chan_info = chan->con_priv;
152	struct sti_mbox_device *mdev = chan_info->mdev;
153	unsigned int instance = chan_info->instance;
154	unsigned int channel = chan_info->channel;
155	void __iomem *base = MBOX_BASE(mdev, instance);
156
157	writel_relaxed(BIT(channel), base + STI_IRQ_CLR_OFFSET);
158}
159
160static struct mbox_chan *sti_mbox_irq_to_channel(struct sti_mbox_device *mdev,
161						 unsigned int instance)
162{
163	struct mbox_controller *mbox = mdev->mbox;
164	struct mbox_chan *chan = NULL;
165	unsigned int channel;
166	unsigned long bits;
167	void __iomem *base = MBOX_BASE(mdev, instance);
168
169	bits = readl_relaxed(base + STI_IRQ_VAL_OFFSET);
170	if (!bits)
171		/* No IRQs fired in specified instance */
172		return NULL;
173
174	/* An IRQ has fired, find the associated channel */
175	for (channel = 0; bits; channel++) {
176		if (!test_and_clear_bit(channel, &bits))
177			continue;
178
179		chan = sti_mbox_to_channel(mbox, instance, channel);
180		if (chan) {
181			dev_dbg(mbox->dev,
182				"IRQ fired on instance: %d channel: %d\n",
183				instance, channel);
184			break;
185		}
186	}
187
188	return chan;
189}
190
191static irqreturn_t sti_mbox_thread_handler(int irq, void *data)
192{
193	struct sti_mbox_device *mdev = data;
194	struct sti_mbox_pdata *pdata = dev_get_platdata(mdev->dev);
195	struct mbox_chan *chan;
196	unsigned int instance;
197
198	for (instance = 0; instance < pdata->num_inst; instance++) {
199keep_looking:
200		chan = sti_mbox_irq_to_channel(mdev, instance);
201		if (!chan)
202			continue;
203
204		mbox_chan_received_data(chan, NULL);
205		sti_mbox_clear_irq(chan);
206		sti_mbox_enable_channel(chan);
207		goto keep_looking;
208	}
209
210	return IRQ_HANDLED;
211}
212
213static irqreturn_t sti_mbox_irq_handler(int irq, void *data)
214{
215	struct sti_mbox_device *mdev = data;
216	struct sti_mbox_pdata *pdata = dev_get_platdata(mdev->dev);
217	struct sti_channel *chan_info;
218	struct mbox_chan *chan;
219	unsigned int instance;
220	int ret = IRQ_NONE;
221
222	for (instance = 0; instance < pdata->num_inst; instance++) {
223		chan = sti_mbox_irq_to_channel(mdev, instance);
224		if (!chan)
225			continue;
226		chan_info = chan->con_priv;
227
228		if (!sti_mbox_channel_is_enabled(chan)) {
229			dev_warn(mdev->dev,
230				 "Unexpected IRQ: %s\n"
231				 "  instance: %d: channel: %d [enabled: %x]\n",
232				 mdev->name, chan_info->instance,
233				 chan_info->channel, mdev->enabled[instance]);
234
235			/* Only handle IRQ if no other valid IRQs were found */
236			if (ret == IRQ_NONE)
237				ret = IRQ_HANDLED;
238			continue;
239		}
240
241		sti_mbox_disable_channel(chan);
242		ret = IRQ_WAKE_THREAD;
243	}
244
245	if (ret == IRQ_NONE)
246		dev_err(mdev->dev, "Spurious IRQ - was a channel requested?\n");
247
248	return ret;
249}
250
251static bool sti_mbox_tx_is_ready(struct mbox_chan *chan)
252{
253	struct sti_channel *chan_info = chan->con_priv;
254	struct sti_mbox_device *mdev = chan_info->mdev;
255	unsigned int instance = chan_info->instance;
256	unsigned int channel = chan_info->channel;
257	void __iomem *base = MBOX_BASE(mdev, instance);
258
259	if (!(readl_relaxed(base + STI_ENA_VAL_OFFSET) & BIT(channel))) {
260		dev_dbg(mdev->dev, "Mbox: %s: inst: %d, chan: %d disabled\n",
261			mdev->name, instance, channel);
262		return false;
263	}
264
265	if (readl_relaxed(base + STI_IRQ_VAL_OFFSET) & BIT(channel)) {
266		dev_dbg(mdev->dev, "Mbox: %s: inst: %d, chan: %d not ready\n",
267			mdev->name, instance, channel);
268		return false;
269	}
270
271	return true;
272}
273
274static int sti_mbox_send_data(struct mbox_chan *chan, void *data)
275{
276	struct sti_channel *chan_info = chan->con_priv;
277	struct sti_mbox_device *mdev = chan_info->mdev;
278	unsigned int instance = chan_info->instance;
279	unsigned int channel = chan_info->channel;
280	void __iomem *base = MBOX_BASE(mdev, instance);
281
282	/* Send event to co-processor */
283	writel_relaxed(BIT(channel), base + STI_IRQ_SET_OFFSET);
284
285	dev_dbg(mdev->dev,
286		"Sent via Mailbox %s: instance: %d channel: %d\n",
287		mdev->name, instance, channel);
288
289	return 0;
290}
291
292static int sti_mbox_startup_chan(struct mbox_chan *chan)
293{
294	sti_mbox_clear_irq(chan);
295	sti_mbox_enable_channel(chan);
296
297	return 0;
298}
299
300static void sti_mbox_shutdown_chan(struct mbox_chan *chan)
301{
302	struct sti_channel *chan_info = chan->con_priv;
303	struct mbox_controller *mbox = chan_info->mdev->mbox;
304	int i;
305
306	for (i = 0; i < mbox->num_chans; i++)
307		if (chan == &mbox->chans[i])
308			break;
309
310	if (mbox->num_chans == i) {
311		dev_warn(mbox->dev, "Request to free non-existent channel\n");
312		return;
313	}
314
315	/* Reset channel */
316	sti_mbox_disable_channel(chan);
317	sti_mbox_clear_irq(chan);
318	chan->con_priv = NULL;
319}
320
321static struct mbox_chan *sti_mbox_xlate(struct mbox_controller *mbox,
322					const struct of_phandle_args *spec)
323{
324	struct sti_mbox_device *mdev = dev_get_drvdata(mbox->dev);
325	struct sti_mbox_pdata *pdata = dev_get_platdata(mdev->dev);
326	struct sti_channel *chan_info;
327	struct mbox_chan *chan = NULL;
328	unsigned int instance  = spec->args[0];
329	unsigned int channel   = spec->args[1];
330	int i;
331
332	/* Bounds checking */
333	if (instance >= pdata->num_inst || channel  >= pdata->num_chan) {
334		dev_err(mbox->dev,
335			"Invalid channel requested instance: %d channel: %d\n",
336			instance, channel);
337		return ERR_PTR(-EINVAL);
338	}
339
340	for (i = 0; i < mbox->num_chans; i++) {
341		chan_info = mbox->chans[i].con_priv;
342
343		/* Is requested channel free? */
344		if (chan_info &&
345		    mbox->dev == chan_info->mdev->dev &&
346		    instance == chan_info->instance &&
347		    channel == chan_info->channel) {
348
349			dev_err(mbox->dev, "Channel in use\n");
350			return ERR_PTR(-EBUSY);
351		}
352
353		/*
354		 * Find the first free slot, then continue checking
355		 * to see if requested channel is in use
356		 */
357		if (!chan && !chan_info)
358			chan = &mbox->chans[i];
359	}
360
361	if (!chan) {
362		dev_err(mbox->dev, "No free channels left\n");
363		return ERR_PTR(-EBUSY);
364	}
365
366	chan_info = devm_kzalloc(mbox->dev, sizeof(*chan_info), GFP_KERNEL);
367	if (!chan_info)
368		return ERR_PTR(-ENOMEM);
369
370	chan_info->mdev		= mdev;
371	chan_info->instance	= instance;
372	chan_info->channel	= channel;
373
374	chan->con_priv = chan_info;
375
376	dev_info(mbox->dev,
377		 "Mbox: %s: Created channel: instance: %d channel: %d\n",
378		 mdev->name, instance, channel);
379
380	return chan;
381}
382
383static const struct mbox_chan_ops sti_mbox_ops = {
384	.startup	= sti_mbox_startup_chan,
385	.shutdown	= sti_mbox_shutdown_chan,
386	.send_data	= sti_mbox_send_data,
387	.last_tx_done	= sti_mbox_tx_is_ready,
388};
389
390static const struct sti_mbox_pdata mbox_stih407_pdata = {
391	.num_inst	= 4,
392	.num_chan	= 32,
393};
394
395static const struct of_device_id sti_mailbox_match[] = {
396	{
397		.compatible = "st,stih407-mailbox",
398		.data = (void *)&mbox_stih407_pdata
399	},
400	{ }
401};
402MODULE_DEVICE_TABLE(of, sti_mailbox_match);
403
404static int sti_mbox_probe(struct platform_device *pdev)
405{
406	struct mbox_controller *mbox;
407	struct sti_mbox_device *mdev;
408	struct device_node *np = pdev->dev.of_node;
409	struct mbox_chan *chans;
410	int irq;
411	int ret;
412
413	pdev->dev.platform_data = (struct sti_mbox_pdata *)device_get_match_data(&pdev->dev);
414	if (!pdev->dev.platform_data) {
415		dev_err(&pdev->dev, "No configuration found\n");
416		return -ENODEV;
417	}
418
419	mdev = devm_kzalloc(&pdev->dev, sizeof(*mdev), GFP_KERNEL);
420	if (!mdev)
421		return -ENOMEM;
422
423	platform_set_drvdata(pdev, mdev);
424
425	mdev->base = devm_platform_ioremap_resource(pdev, 0);
426	if (IS_ERR(mdev->base))
427		return PTR_ERR(mdev->base);
428
429	ret = of_property_read_string(np, "mbox-name", &mdev->name);
430	if (ret)
431		mdev->name = np->full_name;
432
433	mbox = devm_kzalloc(&pdev->dev, sizeof(*mbox), GFP_KERNEL);
434	if (!mbox)
435		return -ENOMEM;
436
437	chans = devm_kcalloc(&pdev->dev,
438			     STI_MBOX_CHAN_MAX, sizeof(*chans), GFP_KERNEL);
439	if (!chans)
440		return -ENOMEM;
441
442	mdev->dev		= &pdev->dev;
443	mdev->mbox		= mbox;
444
445	spin_lock_init(&mdev->lock);
446
447	/* STi Mailbox does not have a Tx-Done or Tx-Ready IRQ */
448	mbox->txdone_irq	= false;
449	mbox->txdone_poll	= true;
450	mbox->txpoll_period	= 100;
451	mbox->ops		= &sti_mbox_ops;
452	mbox->dev		= mdev->dev;
453	mbox->of_xlate		= sti_mbox_xlate;
454	mbox->chans		= chans;
455	mbox->num_chans		= STI_MBOX_CHAN_MAX;
456
457	ret = devm_mbox_controller_register(&pdev->dev, mbox);
458	if (ret)
459		return ret;
460
461	/* It's okay for Tx Mailboxes to not supply IRQs */
462	irq = platform_get_irq(pdev, 0);
463	if (irq < 0) {
464		dev_info(&pdev->dev,
465			 "%s: Registered Tx only Mailbox\n", mdev->name);
466		return 0;
467	}
468
469	ret = devm_request_threaded_irq(&pdev->dev, irq,
470					sti_mbox_irq_handler,
471					sti_mbox_thread_handler,
472					IRQF_ONESHOT, mdev->name, mdev);
473	if (ret) {
474		dev_err(&pdev->dev, "Can't claim IRQ %d\n", irq);
475		return -EINVAL;
476	}
477
478	dev_info(&pdev->dev, "%s: Registered Tx/Rx Mailbox\n", mdev->name);
479
480	return 0;
481}
482
483static struct platform_driver sti_mbox_driver = {
484	.probe = sti_mbox_probe,
485	.driver = {
486		.name = "sti-mailbox",
487		.of_match_table = sti_mailbox_match,
488	},
489};
490module_platform_driver(sti_mbox_driver);
491
492MODULE_LICENSE("GPL");
493MODULE_DESCRIPTION("STMicroelectronics Mailbox Controller");
494MODULE_AUTHOR("Lee Jones <lee.jones@linaro.org");
495MODULE_ALIAS("platform:mailbox-sti");
496