1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2013-2015 Fujitsu Semiconductor Ltd.
4 * Copyright (C) 2015 Linaro Ltd.
5 * Based on ARM MHU driver by Jassi Brar <jaswinder.singh@linaro.org>
6 * Copyright (C) 2020 ARM Ltd.
7 */
8
9#include <linux/amba/bus.h>
10#include <linux/device.h>
11#include <linux/err.h>
12#include <linux/interrupt.h>
13#include <linux/io.h>
14#include <linux/kernel.h>
15#include <linux/mailbox_controller.h>
16#include <linux/module.h>
17#include <linux/of.h>
18
19#define INTR_STAT_OFS	0x0
20#define INTR_SET_OFS	0x8
21#define INTR_CLR_OFS	0x10
22
23#define MHU_LP_OFFSET	0x0
24#define MHU_HP_OFFSET	0x20
25#define MHU_SEC_OFFSET	0x200
26#define TX_REG_OFFSET	0x100
27
28#define MHU_CHANS	3	/* Secure, Non-Secure High and Low Priority */
29#define MHU_CHAN_MAX	20	/* Max channels to save on unused RAM */
30#define MHU_NUM_DOORBELLS	32
31
32struct mhu_db_link {
33	unsigned int irq;
34	void __iomem *tx_reg;
35	void __iomem *rx_reg;
36};
37
38struct arm_mhu {
39	void __iomem *base;
40	struct mhu_db_link mlink[MHU_CHANS];
41	struct mbox_controller mbox;
42	struct device *dev;
43};
44
45/**
46 * struct mhu_db_channel - ARM MHU Mailbox allocated channel information
47 *
48 * @mhu: Pointer to parent mailbox device
49 * @pchan: Physical channel within which this doorbell resides in
50 * @doorbell: doorbell number pertaining to this channel
51 */
52struct mhu_db_channel {
53	struct arm_mhu *mhu;
54	unsigned int pchan;
55	unsigned int doorbell;
56};
57
58static inline struct mbox_chan *
59mhu_db_mbox_to_channel(struct mbox_controller *mbox, unsigned int pchan,
60		       unsigned int doorbell)
61{
62	int i;
63	struct mhu_db_channel *chan_info;
64
65	for (i = 0; i < mbox->num_chans; i++) {
66		chan_info = mbox->chans[i].con_priv;
67		if (chan_info && chan_info->pchan == pchan &&
68		    chan_info->doorbell == doorbell)
69			return &mbox->chans[i];
70	}
71
72	return NULL;
73}
74
75static void mhu_db_mbox_clear_irq(struct mbox_chan *chan)
76{
77	struct mhu_db_channel *chan_info = chan->con_priv;
78	void __iomem *base = chan_info->mhu->mlink[chan_info->pchan].rx_reg;
79
80	writel_relaxed(BIT(chan_info->doorbell), base + INTR_CLR_OFS);
81}
82
83static unsigned int mhu_db_mbox_irq_to_pchan_num(struct arm_mhu *mhu, int irq)
84{
85	unsigned int pchan;
86
87	for (pchan = 0; pchan < MHU_CHANS; pchan++)
88		if (mhu->mlink[pchan].irq == irq)
89			break;
90	return pchan;
91}
92
93static struct mbox_chan *
94mhu_db_mbox_irq_to_channel(struct arm_mhu *mhu, unsigned int pchan)
95{
96	unsigned long bits;
97	unsigned int doorbell;
98	struct mbox_chan *chan = NULL;
99	struct mbox_controller *mbox = &mhu->mbox;
100	void __iomem *base = mhu->mlink[pchan].rx_reg;
101
102	bits = readl_relaxed(base + INTR_STAT_OFS);
103	if (!bits)
104		/* No IRQs fired in specified physical channel */
105		return NULL;
106
107	/* An IRQ has fired, find the associated channel */
108	for (doorbell = 0; bits; doorbell++) {
109		if (!test_and_clear_bit(doorbell, &bits))
110			continue;
111
112		chan = mhu_db_mbox_to_channel(mbox, pchan, doorbell);
113		if (chan)
114			break;
115		dev_err(mbox->dev,
116			"Channel not registered: pchan: %d doorbell: %d\n",
117			pchan, doorbell);
118	}
119
120	return chan;
121}
122
123static irqreturn_t mhu_db_mbox_rx_handler(int irq, void *data)
124{
125	struct mbox_chan *chan;
126	struct arm_mhu *mhu = data;
127	unsigned int pchan = mhu_db_mbox_irq_to_pchan_num(mhu, irq);
128
129	while (NULL != (chan = mhu_db_mbox_irq_to_channel(mhu, pchan))) {
130		mbox_chan_received_data(chan, NULL);
131		mhu_db_mbox_clear_irq(chan);
132	}
133
134	return IRQ_HANDLED;
135}
136
137static bool mhu_db_last_tx_done(struct mbox_chan *chan)
138{
139	struct mhu_db_channel *chan_info = chan->con_priv;
140	void __iomem *base = chan_info->mhu->mlink[chan_info->pchan].tx_reg;
141
142	if (readl_relaxed(base + INTR_STAT_OFS) & BIT(chan_info->doorbell))
143		return false;
144
145	return true;
146}
147
148static int mhu_db_send_data(struct mbox_chan *chan, void *data)
149{
150	struct mhu_db_channel *chan_info = chan->con_priv;
151	void __iomem *base = chan_info->mhu->mlink[chan_info->pchan].tx_reg;
152
153	/* Send event to co-processor */
154	writel_relaxed(BIT(chan_info->doorbell), base + INTR_SET_OFS);
155
156	return 0;
157}
158
159static int mhu_db_startup(struct mbox_chan *chan)
160{
161	mhu_db_mbox_clear_irq(chan);
162	return 0;
163}
164
165static void mhu_db_shutdown(struct mbox_chan *chan)
166{
167	struct mhu_db_channel *chan_info = chan->con_priv;
168	struct mbox_controller *mbox = &chan_info->mhu->mbox;
169	int i;
170
171	for (i = 0; i < mbox->num_chans; i++)
172		if (chan == &mbox->chans[i])
173			break;
174
175	if (mbox->num_chans == i) {
176		dev_warn(mbox->dev, "Request to free non-existent channel\n");
177		return;
178	}
179
180	/* Reset channel */
181	mhu_db_mbox_clear_irq(chan);
182	devm_kfree(mbox->dev, chan->con_priv);
183	chan->con_priv = NULL;
184}
185
186static struct mbox_chan *mhu_db_mbox_xlate(struct mbox_controller *mbox,
187					   const struct of_phandle_args *spec)
188{
189	struct arm_mhu *mhu = dev_get_drvdata(mbox->dev);
190	struct mhu_db_channel *chan_info;
191	struct mbox_chan *chan;
192	unsigned int pchan = spec->args[0];
193	unsigned int doorbell = spec->args[1];
194	int i;
195
196	/* Bounds checking */
197	if (pchan >= MHU_CHANS || doorbell >= MHU_NUM_DOORBELLS) {
198		dev_err(mbox->dev,
199			"Invalid channel requested pchan: %d doorbell: %d\n",
200			pchan, doorbell);
201		return ERR_PTR(-EINVAL);
202	}
203
204	/* Is requested channel free? */
205	chan = mhu_db_mbox_to_channel(mbox, pchan, doorbell);
206	if (chan) {
207		dev_err(mbox->dev, "Channel in use: pchan: %d doorbell: %d\n",
208			pchan, doorbell);
209		return ERR_PTR(-EBUSY);
210	}
211
212	/* Find the first free slot */
213	for (i = 0; i < mbox->num_chans; i++)
214		if (!mbox->chans[i].con_priv)
215			break;
216
217	if (mbox->num_chans == i) {
218		dev_err(mbox->dev, "No free channels left\n");
219		return ERR_PTR(-EBUSY);
220	}
221
222	chan = &mbox->chans[i];
223
224	chan_info = devm_kzalloc(mbox->dev, sizeof(*chan_info), GFP_KERNEL);
225	if (!chan_info)
226		return ERR_PTR(-ENOMEM);
227
228	chan_info->mhu = mhu;
229	chan_info->pchan = pchan;
230	chan_info->doorbell = doorbell;
231
232	chan->con_priv = chan_info;
233
234	dev_dbg(mbox->dev, "mbox: created channel phys: %d doorbell: %d\n",
235		pchan, doorbell);
236
237	return chan;
238}
239
240static const struct mbox_chan_ops mhu_db_ops = {
241	.send_data = mhu_db_send_data,
242	.startup = mhu_db_startup,
243	.shutdown = mhu_db_shutdown,
244	.last_tx_done = mhu_db_last_tx_done,
245};
246
247static int mhu_db_probe(struct amba_device *adev, const struct amba_id *id)
248{
249	u32 cell_count;
250	int i, err, max_chans;
251	struct arm_mhu *mhu;
252	struct mbox_chan *chans;
253	struct device *dev = &adev->dev;
254	struct device_node *np = dev->of_node;
255	int mhu_reg[MHU_CHANS] = {
256		MHU_LP_OFFSET, MHU_HP_OFFSET, MHU_SEC_OFFSET,
257	};
258
259	if (!of_device_is_compatible(np, "arm,mhu-doorbell"))
260		return -ENODEV;
261
262	err = of_property_read_u32(np, "#mbox-cells", &cell_count);
263	if (err) {
264		dev_err(dev, "failed to read #mbox-cells in '%pOF'\n", np);
265		return err;
266	}
267
268	if (cell_count == 2) {
269		max_chans = MHU_CHAN_MAX;
270	} else {
271		dev_err(dev, "incorrect value of #mbox-cells in '%pOF'\n", np);
272		return -EINVAL;
273	}
274
275	mhu = devm_kzalloc(dev, sizeof(*mhu), GFP_KERNEL);
276	if (!mhu)
277		return -ENOMEM;
278
279	mhu->base = devm_ioremap_resource(dev, &adev->res);
280	if (IS_ERR(mhu->base))
281		return PTR_ERR(mhu->base);
282
283	chans = devm_kcalloc(dev, max_chans, sizeof(*chans), GFP_KERNEL);
284	if (!chans)
285		return -ENOMEM;
286
287	mhu->dev = dev;
288	mhu->mbox.dev = dev;
289	mhu->mbox.chans = chans;
290	mhu->mbox.num_chans = max_chans;
291	mhu->mbox.txdone_irq = false;
292	mhu->mbox.txdone_poll = true;
293	mhu->mbox.txpoll_period = 1;
294
295	mhu->mbox.of_xlate = mhu_db_mbox_xlate;
296	amba_set_drvdata(adev, mhu);
297
298	mhu->mbox.ops = &mhu_db_ops;
299
300	err = devm_mbox_controller_register(dev, &mhu->mbox);
301	if (err) {
302		dev_err(dev, "Failed to register mailboxes %d\n", err);
303		return err;
304	}
305
306	for (i = 0; i < MHU_CHANS; i++) {
307		int irq = mhu->mlink[i].irq = adev->irq[i];
308
309		if (irq <= 0) {
310			dev_dbg(dev, "No IRQ found for Channel %d\n", i);
311			continue;
312		}
313
314		mhu->mlink[i].rx_reg = mhu->base + mhu_reg[i];
315		mhu->mlink[i].tx_reg = mhu->mlink[i].rx_reg + TX_REG_OFFSET;
316
317		err = devm_request_threaded_irq(dev, irq, NULL,
318						mhu_db_mbox_rx_handler,
319						IRQF_ONESHOT, "mhu_db_link", mhu);
320		if (err) {
321			dev_err(dev, "Can't claim IRQ %d\n", irq);
322			mbox_controller_unregister(&mhu->mbox);
323			return err;
324		}
325	}
326
327	dev_info(dev, "ARM MHU Doorbell mailbox registered\n");
328	return 0;
329}
330
331static struct amba_id mhu_ids[] = {
332	{
333		.id	= 0x1bb098,
334		.mask	= 0xffffff,
335	},
336	{ 0, 0 },
337};
338MODULE_DEVICE_TABLE(amba, mhu_ids);
339
340static struct amba_driver arm_mhu_db_driver = {
341	.drv = {
342		.name	= "mhu-doorbell",
343	},
344	.id_table	= mhu_ids,
345	.probe		= mhu_db_probe,
346};
347module_amba_driver(arm_mhu_db_driver);
348
349MODULE_LICENSE("GPL v2");
350MODULE_DESCRIPTION("ARM MHU Doorbell Driver");
351MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
352