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 
32 enum altera_mbox_msg {
33 	MBOX_CMD = 0,
34 	MBOX_PTR,
35 };
36 
37 #define MBOX_POLLING_MS		5	/* polling interval 5ms */
38 
39 struct 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 
52 static 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 
60 static 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 
68 static 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 
76 static 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 
88 static 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 
100 static 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 
117 static 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 
131 static 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 
141 static 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 
152 static 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 
160 static 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 
179 static 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 
196 polling:
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 
206 static 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 
233 static 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 
241 static 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 
248 static 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 
264 static 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 
277 static 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 
285 static 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);
337 err:
338 	return ret;
339 }
340 
341 static const struct of_device_id altera_mbox_match[] = {
342 	{ .compatible = "altr,mailbox-1.0" },
343 	{ /* Sentinel */ }
344 };
345 
346 MODULE_DEVICE_TABLE(of, altera_mbox_match);
347 
348 static 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 
356 module_platform_driver(altera_mbox_driver);
357 
358 MODULE_LICENSE("GPL v2");
359 MODULE_DESCRIPTION("Altera mailbox specific functions");
360 MODULE_AUTHOR("Ley Foon Tan <lftan@altera.com>");
361 MODULE_ALIAS("platform:altera-mailbox");
362