1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Copyright Altera Corporation (C) 2013-2014. All rights reserved
  4 */
  5
  6#include <linux/device.h>
  7#include <linux/interrupt.h>
  8#include <linux/io.h>
  9#include <linux/kernel.h>
 10#include <linux/mailbox_controller.h>
 11#include <linux/module.h>
 12#include <linux/of.h>
 13#include <linux/platform_device.h>
 14
 15#define DRIVER_NAME	"altera-mailbox"
 16
 17#define MAILBOX_CMD_REG			0x00
 18#define MAILBOX_PTR_REG			0x04
 19#define MAILBOX_STS_REG			0x08
 20#define MAILBOX_INTMASK_REG		0x0C
 21
 22#define INT_PENDING_MSK			0x1
 23#define INT_SPACE_MSK			0x2
 24
 25#define STS_PENDING_MSK			0x1
 26#define STS_FULL_MSK			0x2
 27#define STS_FULL_OFT			0x1
 28
 29#define MBOX_PENDING(status)	(((status) & STS_PENDING_MSK))
 30#define MBOX_FULL(status)	(((status) & STS_FULL_MSK) >> STS_FULL_OFT)
 31
 32enum altera_mbox_msg {
 33	MBOX_CMD = 0,
 34	MBOX_PTR,
 35};
 36
 37#define MBOX_POLLING_MS		5	/* polling interval 5ms */
 38
 39struct altera_mbox {
 40	bool is_sender;		/* 1-sender, 0-receiver */
 41	bool intr_mode;
 42	int irq;
 43	void __iomem *mbox_base;
 44	struct device *dev;
 45	struct mbox_controller controller;
 46
 47	/* If the controller supports only RX polling mode */
 48	struct timer_list rxpoll_timer;
 49	struct mbox_chan *chan;
 50};
 51
 52static struct altera_mbox *mbox_chan_to_altera_mbox(struct mbox_chan *chan)
 53{
 54	if (!chan || !chan->con_priv)
 55		return NULL;
 56
 57	return (struct altera_mbox *)chan->con_priv;
 58}
 59
 60static inline int altera_mbox_full(struct altera_mbox *mbox)
 61{
 62	u32 status;
 63
 64	status = readl_relaxed(mbox->mbox_base + MAILBOX_STS_REG);
 65	return MBOX_FULL(status);
 66}
 67
 68static inline int altera_mbox_pending(struct altera_mbox *mbox)
 69{
 70	u32 status;
 71
 72	status = readl_relaxed(mbox->mbox_base + MAILBOX_STS_REG);
 73	return MBOX_PENDING(status);
 74}
 75
 76static void altera_mbox_rx_intmask(struct altera_mbox *mbox, bool enable)
 77{
 78	u32 mask;
 79
 80	mask = readl_relaxed(mbox->mbox_base + MAILBOX_INTMASK_REG);
 81	if (enable)
 82		mask |= INT_PENDING_MSK;
 83	else
 84		mask &= ~INT_PENDING_MSK;
 85	writel_relaxed(mask, mbox->mbox_base + MAILBOX_INTMASK_REG);
 86}
 87
 88static void altera_mbox_tx_intmask(struct altera_mbox *mbox, bool enable)
 89{
 90	u32 mask;
 91
 92	mask = readl_relaxed(mbox->mbox_base + MAILBOX_INTMASK_REG);
 93	if (enable)
 94		mask |= INT_SPACE_MSK;
 95	else
 96		mask &= ~INT_SPACE_MSK;
 97	writel_relaxed(mask, mbox->mbox_base + MAILBOX_INTMASK_REG);
 98}
 99
100static bool altera_mbox_is_sender(struct altera_mbox *mbox)
101{
102	u32 reg;
103	/* Write a magic number to PTR register and read back this register.
104	 * This register is read-write if it is a sender.
105	 */
106	#define MBOX_MAGIC	0xA5A5AA55
107	writel_relaxed(MBOX_MAGIC, mbox->mbox_base + MAILBOX_PTR_REG);
108	reg = readl_relaxed(mbox->mbox_base + MAILBOX_PTR_REG);
109	if (reg == MBOX_MAGIC) {
110		/* Clear to 0 */
111		writel_relaxed(0, mbox->mbox_base + MAILBOX_PTR_REG);
112		return true;
113	}
114	return false;
115}
116
117static void altera_mbox_rx_data(struct mbox_chan *chan)
118{
119	struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);
120	u32 data[2];
121
122	if (altera_mbox_pending(mbox)) {
123		data[MBOX_PTR] =
124			readl_relaxed(mbox->mbox_base + MAILBOX_PTR_REG);
125		data[MBOX_CMD] =
126			readl_relaxed(mbox->mbox_base + MAILBOX_CMD_REG);
127		mbox_chan_received_data(chan, (void *)data);
128	}
129}
130
131static void altera_mbox_poll_rx(struct timer_list *t)
132{
133	struct altera_mbox *mbox = from_timer(mbox, t, rxpoll_timer);
134
135	altera_mbox_rx_data(mbox->chan);
136
137	mod_timer(&mbox->rxpoll_timer,
138		  jiffies + msecs_to_jiffies(MBOX_POLLING_MS));
139}
140
141static irqreturn_t altera_mbox_tx_interrupt(int irq, void *p)
142{
143	struct mbox_chan *chan = (struct mbox_chan *)p;
144	struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);
145
146	altera_mbox_tx_intmask(mbox, false);
147	mbox_chan_txdone(chan, 0);
148
149	return IRQ_HANDLED;
150}
151
152static irqreturn_t altera_mbox_rx_interrupt(int irq, void *p)
153{
154	struct mbox_chan *chan = (struct mbox_chan *)p;
155
156	altera_mbox_rx_data(chan);
157	return IRQ_HANDLED;
158}
159
160static int altera_mbox_startup_sender(struct mbox_chan *chan)
161{
162	int ret;
163	struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);
164
165	if (mbox->intr_mode) {
166		ret = request_irq(mbox->irq, altera_mbox_tx_interrupt, 0,
167				  DRIVER_NAME, chan);
168		if (unlikely(ret)) {
169			dev_err(mbox->dev,
170				"failed to register mailbox interrupt:%d\n",
171				ret);
172			return ret;
173		}
174	}
175
176	return 0;
177}
178
179static int altera_mbox_startup_receiver(struct mbox_chan *chan)
180{
181	int ret;
182	struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);
183
184	if (mbox->intr_mode) {
185		ret = request_irq(mbox->irq, altera_mbox_rx_interrupt, 0,
186				  DRIVER_NAME, chan);
187		if (unlikely(ret)) {
188			mbox->intr_mode = false;
189			goto polling; /* use polling if failed */
190		}
191
192		altera_mbox_rx_intmask(mbox, true);
193		return 0;
194	}
195
196polling:
197	/* Setup polling timer */
198	mbox->chan = chan;
199	timer_setup(&mbox->rxpoll_timer, altera_mbox_poll_rx, 0);
200	mod_timer(&mbox->rxpoll_timer,
201		  jiffies + msecs_to_jiffies(MBOX_POLLING_MS));
202
203	return 0;
204}
205
206static int altera_mbox_send_data(struct mbox_chan *chan, void *data)
207{
208	struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);
209	u32 *udata = (u32 *)data;
210
211	if (!mbox || !data)
212		return -EINVAL;
213	if (!mbox->is_sender) {
214		dev_warn(mbox->dev,
215			 "failed to send. This is receiver mailbox.\n");
216		return -EINVAL;
217	}
218
219	if (altera_mbox_full(mbox))
220		return -EBUSY;
221
222	/* Enable interrupt before send */
223	if (mbox->intr_mode)
224		altera_mbox_tx_intmask(mbox, true);
225
226	/* Pointer register must write before command register */
227	writel_relaxed(udata[MBOX_PTR], mbox->mbox_base + MAILBOX_PTR_REG);
228	writel_relaxed(udata[MBOX_CMD], mbox->mbox_base + MAILBOX_CMD_REG);
229
230	return 0;
231}
232
233static bool altera_mbox_last_tx_done(struct mbox_chan *chan)
234{
235	struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);
236
237	/* Return false if mailbox is full */
238	return altera_mbox_full(mbox) ? false : true;
239}
240
241static bool altera_mbox_peek_data(struct mbox_chan *chan)
242{
243	struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);
244
245	return altera_mbox_pending(mbox) ? true : false;
246}
247
248static int altera_mbox_startup(struct mbox_chan *chan)
249{
250	struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);
251	int ret = 0;
252
253	if (!mbox)
254		return -EINVAL;
255
256	if (mbox->is_sender)
257		ret = altera_mbox_startup_sender(chan);
258	else
259		ret = altera_mbox_startup_receiver(chan);
260
261	return ret;
262}
263
264static void altera_mbox_shutdown(struct mbox_chan *chan)
265{
266	struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);
267
268	if (mbox->intr_mode) {
269		/* Unmask all interrupt masks */
270		writel_relaxed(~0, mbox->mbox_base + MAILBOX_INTMASK_REG);
271		free_irq(mbox->irq, chan);
272	} else if (!mbox->is_sender) {
273		del_timer_sync(&mbox->rxpoll_timer);
274	}
275}
276
277static const struct mbox_chan_ops altera_mbox_ops = {
278	.send_data = altera_mbox_send_data,
279	.startup = altera_mbox_startup,
280	.shutdown = altera_mbox_shutdown,
281	.last_tx_done = altera_mbox_last_tx_done,
282	.peek_data = altera_mbox_peek_data,
283};
284
285static int altera_mbox_probe(struct platform_device *pdev)
286{
287	struct altera_mbox *mbox;
288	struct mbox_chan *chans;
289	int ret;
290
291	mbox = devm_kzalloc(&pdev->dev, sizeof(*mbox),
292			    GFP_KERNEL);
293	if (!mbox)
294		return -ENOMEM;
295
296	/* Allocated one channel */
297	chans = devm_kzalloc(&pdev->dev, sizeof(*chans), GFP_KERNEL);
298	if (!chans)
299		return -ENOMEM;
300
301	mbox->mbox_base = devm_platform_ioremap_resource(pdev, 0);
302	if (IS_ERR(mbox->mbox_base))
303		return PTR_ERR(mbox->mbox_base);
304
305	/* Check is it a sender or receiver? */
306	mbox->is_sender = altera_mbox_is_sender(mbox);
307
308	mbox->irq = platform_get_irq(pdev, 0);
309	if (mbox->irq >= 0)
310		mbox->intr_mode = true;
311
312	mbox->dev = &pdev->dev;
313
314	/* Hardware supports only one channel. */
315	chans[0].con_priv = mbox;
316	mbox->controller.dev = mbox->dev;
317	mbox->controller.num_chans = 1;
318	mbox->controller.chans = chans;
319	mbox->controller.ops = &altera_mbox_ops;
320
321	if (mbox->is_sender) {
322		if (mbox->intr_mode) {
323			mbox->controller.txdone_irq = true;
324		} else {
325			mbox->controller.txdone_poll = true;
326			mbox->controller.txpoll_period = MBOX_POLLING_MS;
327		}
328	}
329
330	ret = devm_mbox_controller_register(&pdev->dev, &mbox->controller);
331	if (ret) {
332		dev_err(&pdev->dev, "Register mailbox failed\n");
333		goto err;
334	}
335
336	platform_set_drvdata(pdev, mbox);
337err:
338	return ret;
339}
340
341static const struct of_device_id altera_mbox_match[] = {
342	{ .compatible = "altr,mailbox-1.0" },
343	{ /* Sentinel */ }
344};
345
346MODULE_DEVICE_TABLE(of, altera_mbox_match);
347
348static struct platform_driver altera_mbox_driver = {
349	.probe	= altera_mbox_probe,
350	.driver	= {
351		.name	= DRIVER_NAME,
352		.of_match_table	= altera_mbox_match,
353	},
354};
355
356module_platform_driver(altera_mbox_driver);
357
358MODULE_LICENSE("GPL v2");
359MODULE_DESCRIPTION("Altera mailbox specific functions");
360MODULE_AUTHOR("Ley Foon Tan <lftan@altera.com>");
361MODULE_ALIAS("platform:altera-mailbox");