1 /*
2  * Copyright Altera Corporation (C) 2013-2014. All rights reserved
3  *
4  * This program is free software; you can redistribute it and/or modify it
5  * under the terms and conditions of the GNU General Public License,
6  * version 2, as published by the Free Software Foundation.
7  *
8  * This program is distributed in the hope it will be useful, but WITHOUT
9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
11  * more details.
12  *
13  * You should have received a copy of the GNU General Public License along with
14  * this program.  If not, see <http://www.gnu.org/licenses/>.
15  */
16 
17 #include <linux/device.h>
18 #include <linux/interrupt.h>
19 #include <linux/io.h>
20 #include <linux/kernel.h>
21 #include <linux/mailbox_controller.h>
22 #include <linux/module.h>
23 #include <linux/of.h>
24 #include <linux/platform_device.h>
25 
26 #define DRIVER_NAME	"altera-mailbox"
27 
28 #define MAILBOX_CMD_REG			0x00
29 #define MAILBOX_PTR_REG			0x04
30 #define MAILBOX_STS_REG			0x08
31 #define MAILBOX_INTMASK_REG		0x0C
32 
33 #define INT_PENDING_MSK			0x1
34 #define INT_SPACE_MSK			0x2
35 
36 #define STS_PENDING_MSK			0x1
37 #define STS_FULL_MSK			0x2
38 #define STS_FULL_OFT			0x1
39 
40 #define MBOX_PENDING(status)	(((status) & STS_PENDING_MSK))
41 #define MBOX_FULL(status)	(((status) & STS_FULL_MSK) >> STS_FULL_OFT)
42 
43 enum altera_mbox_msg {
44 	MBOX_CMD = 0,
45 	MBOX_PTR,
46 };
47 
48 #define MBOX_POLLING_MS		5	/* polling interval 5ms */
49 
50 struct altera_mbox {
51 	bool is_sender;		/* 1-sender, 0-receiver */
52 	bool intr_mode;
53 	int irq;
54 	void __iomem *mbox_base;
55 	struct device *dev;
56 	struct mbox_controller controller;
57 
58 	/* If the controller supports only RX polling mode */
59 	struct timer_list rxpoll_timer;
60 	struct mbox_chan *chan;
61 };
62 
63 static struct altera_mbox *mbox_chan_to_altera_mbox(struct mbox_chan *chan)
64 {
65 	if (!chan || !chan->con_priv)
66 		return NULL;
67 
68 	return (struct altera_mbox *)chan->con_priv;
69 }
70 
71 static inline int altera_mbox_full(struct altera_mbox *mbox)
72 {
73 	u32 status;
74 
75 	status = readl_relaxed(mbox->mbox_base + MAILBOX_STS_REG);
76 	return MBOX_FULL(status);
77 }
78 
79 static inline int altera_mbox_pending(struct altera_mbox *mbox)
80 {
81 	u32 status;
82 
83 	status = readl_relaxed(mbox->mbox_base + MAILBOX_STS_REG);
84 	return MBOX_PENDING(status);
85 }
86 
87 static void altera_mbox_rx_intmask(struct altera_mbox *mbox, bool enable)
88 {
89 	u32 mask;
90 
91 	mask = readl_relaxed(mbox->mbox_base + MAILBOX_INTMASK_REG);
92 	if (enable)
93 		mask |= INT_PENDING_MSK;
94 	else
95 		mask &= ~INT_PENDING_MSK;
96 	writel_relaxed(mask, mbox->mbox_base + MAILBOX_INTMASK_REG);
97 }
98 
99 static void altera_mbox_tx_intmask(struct altera_mbox *mbox, bool enable)
100 {
101 	u32 mask;
102 
103 	mask = readl_relaxed(mbox->mbox_base + MAILBOX_INTMASK_REG);
104 	if (enable)
105 		mask |= INT_SPACE_MSK;
106 	else
107 		mask &= ~INT_SPACE_MSK;
108 	writel_relaxed(mask, mbox->mbox_base + MAILBOX_INTMASK_REG);
109 }
110 
111 static bool altera_mbox_is_sender(struct altera_mbox *mbox)
112 {
113 	u32 reg;
114 	/* Write a magic number to PTR register and read back this register.
115 	 * This register is read-write if it is a sender.
116 	 */
117 	#define MBOX_MAGIC	0xA5A5AA55
118 	writel_relaxed(MBOX_MAGIC, mbox->mbox_base + MAILBOX_PTR_REG);
119 	reg = readl_relaxed(mbox->mbox_base + MAILBOX_PTR_REG);
120 	if (reg == MBOX_MAGIC) {
121 		/* Clear to 0 */
122 		writel_relaxed(0, mbox->mbox_base + MAILBOX_PTR_REG);
123 		return true;
124 	}
125 	return false;
126 }
127 
128 static void altera_mbox_rx_data(struct mbox_chan *chan)
129 {
130 	struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);
131 	u32 data[2];
132 
133 	if (altera_mbox_pending(mbox)) {
134 		data[MBOX_PTR] =
135 			readl_relaxed(mbox->mbox_base + MAILBOX_PTR_REG);
136 		data[MBOX_CMD] =
137 			readl_relaxed(mbox->mbox_base + MAILBOX_CMD_REG);
138 		mbox_chan_received_data(chan, (void *)data);
139 	}
140 }
141 
142 static void altera_mbox_poll_rx(struct timer_list *t)
143 {
144 	struct altera_mbox *mbox = from_timer(mbox, t, rxpoll_timer);
145 
146 	altera_mbox_rx_data(mbox->chan);
147 
148 	mod_timer(&mbox->rxpoll_timer,
149 		  jiffies + msecs_to_jiffies(MBOX_POLLING_MS));
150 }
151 
152 static irqreturn_t altera_mbox_tx_interrupt(int irq, void *p)
153 {
154 	struct mbox_chan *chan = (struct mbox_chan *)p;
155 	struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);
156 
157 	altera_mbox_tx_intmask(mbox, false);
158 	mbox_chan_txdone(chan, 0);
159 
160 	return IRQ_HANDLED;
161 }
162 
163 static irqreturn_t altera_mbox_rx_interrupt(int irq, void *p)
164 {
165 	struct mbox_chan *chan = (struct mbox_chan *)p;
166 
167 	altera_mbox_rx_data(chan);
168 	return IRQ_HANDLED;
169 }
170 
171 static int altera_mbox_startup_sender(struct mbox_chan *chan)
172 {
173 	int ret;
174 	struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);
175 
176 	if (mbox->intr_mode) {
177 		ret = request_irq(mbox->irq, altera_mbox_tx_interrupt, 0,
178 				  DRIVER_NAME, chan);
179 		if (unlikely(ret)) {
180 			dev_err(mbox->dev,
181 				"failed to register mailbox interrupt:%d\n",
182 				ret);
183 			return ret;
184 		}
185 	}
186 
187 	return 0;
188 }
189 
190 static int altera_mbox_startup_receiver(struct mbox_chan *chan)
191 {
192 	int ret;
193 	struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);
194 
195 	if (mbox->intr_mode) {
196 		ret = request_irq(mbox->irq, altera_mbox_rx_interrupt, 0,
197 				  DRIVER_NAME, chan);
198 		if (unlikely(ret)) {
199 			mbox->intr_mode = false;
200 			goto polling; /* use polling if failed */
201 		}
202 
203 		altera_mbox_rx_intmask(mbox, true);
204 		return 0;
205 	}
206 
207 polling:
208 	/* Setup polling timer */
209 	mbox->chan = chan;
210 	timer_setup(&mbox->rxpoll_timer, altera_mbox_poll_rx, 0);
211 	mod_timer(&mbox->rxpoll_timer,
212 		  jiffies + msecs_to_jiffies(MBOX_POLLING_MS));
213 
214 	return 0;
215 }
216 
217 static int altera_mbox_send_data(struct mbox_chan *chan, void *data)
218 {
219 	struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);
220 	u32 *udata = (u32 *)data;
221 
222 	if (!mbox || !data)
223 		return -EINVAL;
224 	if (!mbox->is_sender) {
225 		dev_warn(mbox->dev,
226 			 "failed to send. This is receiver mailbox.\n");
227 		return -EINVAL;
228 	}
229 
230 	if (altera_mbox_full(mbox))
231 		return -EBUSY;
232 
233 	/* Enable interrupt before send */
234 	if (mbox->intr_mode)
235 		altera_mbox_tx_intmask(mbox, true);
236 
237 	/* Pointer register must write before command register */
238 	writel_relaxed(udata[MBOX_PTR], mbox->mbox_base + MAILBOX_PTR_REG);
239 	writel_relaxed(udata[MBOX_CMD], mbox->mbox_base + MAILBOX_CMD_REG);
240 
241 	return 0;
242 }
243 
244 static bool altera_mbox_last_tx_done(struct mbox_chan *chan)
245 {
246 	struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);
247 
248 	/* Return false if mailbox is full */
249 	return altera_mbox_full(mbox) ? false : true;
250 }
251 
252 static bool altera_mbox_peek_data(struct mbox_chan *chan)
253 {
254 	struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);
255 
256 	return altera_mbox_pending(mbox) ? true : false;
257 }
258 
259 static int altera_mbox_startup(struct mbox_chan *chan)
260 {
261 	struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);
262 	int ret = 0;
263 
264 	if (!mbox)
265 		return -EINVAL;
266 
267 	if (mbox->is_sender)
268 		ret = altera_mbox_startup_sender(chan);
269 	else
270 		ret = altera_mbox_startup_receiver(chan);
271 
272 	return ret;
273 }
274 
275 static void altera_mbox_shutdown(struct mbox_chan *chan)
276 {
277 	struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);
278 
279 	if (mbox->intr_mode) {
280 		/* Unmask all interrupt masks */
281 		writel_relaxed(~0, mbox->mbox_base + MAILBOX_INTMASK_REG);
282 		free_irq(mbox->irq, chan);
283 	} else if (!mbox->is_sender) {
284 		del_timer_sync(&mbox->rxpoll_timer);
285 	}
286 }
287 
288 static const struct mbox_chan_ops altera_mbox_ops = {
289 	.send_data = altera_mbox_send_data,
290 	.startup = altera_mbox_startup,
291 	.shutdown = altera_mbox_shutdown,
292 	.last_tx_done = altera_mbox_last_tx_done,
293 	.peek_data = altera_mbox_peek_data,
294 };
295 
296 static int altera_mbox_probe(struct platform_device *pdev)
297 {
298 	struct altera_mbox *mbox;
299 	struct resource	*regs;
300 	struct mbox_chan *chans;
301 	int ret;
302 
303 	mbox = devm_kzalloc(&pdev->dev, sizeof(*mbox),
304 			    GFP_KERNEL);
305 	if (!mbox)
306 		return -ENOMEM;
307 
308 	/* Allocated one channel */
309 	chans = devm_kzalloc(&pdev->dev, sizeof(*chans), GFP_KERNEL);
310 	if (!chans)
311 		return -ENOMEM;
312 
313 	regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
314 
315 	mbox->mbox_base = devm_ioremap_resource(&pdev->dev, regs);
316 	if (IS_ERR(mbox->mbox_base))
317 		return PTR_ERR(mbox->mbox_base);
318 
319 	/* Check is it a sender or receiver? */
320 	mbox->is_sender = altera_mbox_is_sender(mbox);
321 
322 	mbox->irq = platform_get_irq(pdev, 0);
323 	if (mbox->irq >= 0)
324 		mbox->intr_mode = true;
325 
326 	mbox->dev = &pdev->dev;
327 
328 	/* Hardware supports only one channel. */
329 	chans[0].con_priv = mbox;
330 	mbox->controller.dev = mbox->dev;
331 	mbox->controller.num_chans = 1;
332 	mbox->controller.chans = chans;
333 	mbox->controller.ops = &altera_mbox_ops;
334 
335 	if (mbox->is_sender) {
336 		if (mbox->intr_mode) {
337 			mbox->controller.txdone_irq = true;
338 		} else {
339 			mbox->controller.txdone_poll = true;
340 			mbox->controller.txpoll_period = MBOX_POLLING_MS;
341 		}
342 	}
343 
344 	ret = mbox_controller_register(&mbox->controller);
345 	if (ret) {
346 		dev_err(&pdev->dev, "Register mailbox failed\n");
347 		goto err;
348 	}
349 
350 	platform_set_drvdata(pdev, mbox);
351 err:
352 	return ret;
353 }
354 
355 static int altera_mbox_remove(struct platform_device *pdev)
356 {
357 	struct altera_mbox *mbox = platform_get_drvdata(pdev);
358 
359 	if (!mbox)
360 		return -EINVAL;
361 
362 	mbox_controller_unregister(&mbox->controller);
363 
364 	return 0;
365 }
366 
367 static const struct of_device_id altera_mbox_match[] = {
368 	{ .compatible = "altr,mailbox-1.0" },
369 	{ /* Sentinel */ }
370 };
371 
372 MODULE_DEVICE_TABLE(of, altera_mbox_match);
373 
374 static struct platform_driver altera_mbox_driver = {
375 	.probe	= altera_mbox_probe,
376 	.remove	= altera_mbox_remove,
377 	.driver	= {
378 		.name	= DRIVER_NAME,
379 		.of_match_table	= altera_mbox_match,
380 	},
381 };
382 
383 module_platform_driver(altera_mbox_driver);
384 
385 MODULE_LICENSE("GPL v2");
386 MODULE_DESCRIPTION("Altera mailbox specific functions");
387 MODULE_AUTHOR("Ley Foon Tan <lftan@altera.com>");
388 MODULE_ALIAS("platform:altera-mailbox");
389