1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Spreadtrum mailbox driver
4  *
5  * Copyright (c) 2020 Spreadtrum Communications Inc.
6  */
7 
8 #include <linux/delay.h>
9 #include <linux/err.h>
10 #include <linux/interrupt.h>
11 #include <linux/io.h>
12 #include <linux/mailbox_controller.h>
13 #include <linux/module.h>
14 #include <linux/of.h>
15 #include <linux/platform_device.h>
16 #include <linux/clk.h>
17 
18 #define SPRD_MBOX_ID		0x0
19 #define SPRD_MBOX_MSG_LOW	0x4
20 #define SPRD_MBOX_MSG_HIGH	0x8
21 #define SPRD_MBOX_TRIGGER	0xc
22 #define SPRD_MBOX_FIFO_RST	0x10
23 #define SPRD_MBOX_FIFO_STS	0x14
24 #define SPRD_MBOX_IRQ_STS	0x18
25 #define SPRD_MBOX_IRQ_MSK	0x1c
26 #define SPRD_MBOX_LOCK		0x20
27 #define SPRD_MBOX_FIFO_DEPTH	0x24
28 
29 /* Bit and mask definition for inbox's SPRD_MBOX_FIFO_STS register */
30 #define SPRD_INBOX_FIFO_DELIVER_MASK		GENMASK(23, 16)
31 #define SPRD_INBOX_FIFO_OVERLOW_MASK		GENMASK(15, 8)
32 #define SPRD_INBOX_FIFO_DELIVER_SHIFT		16
33 #define SPRD_INBOX_FIFO_BUSY_MASK		GENMASK(7, 0)
34 
35 /* Bit and mask definition for SPRD_MBOX_IRQ_STS register */
36 #define SPRD_MBOX_IRQ_CLR			BIT(0)
37 
38 /* Bit and mask definition for outbox's SPRD_MBOX_FIFO_STS register */
39 #define SPRD_OUTBOX_FIFO_FULL			BIT(2)
40 #define SPRD_OUTBOX_FIFO_WR_SHIFT		16
41 #define SPRD_OUTBOX_FIFO_RD_SHIFT		24
42 #define SPRD_OUTBOX_FIFO_POS_MASK		GENMASK(7, 0)
43 
44 /* Bit and mask definition for inbox's SPRD_MBOX_IRQ_MSK register */
45 #define SPRD_INBOX_FIFO_BLOCK_IRQ		BIT(0)
46 #define SPRD_INBOX_FIFO_OVERFLOW_IRQ		BIT(1)
47 #define SPRD_INBOX_FIFO_DELIVER_IRQ		BIT(2)
48 #define SPRD_INBOX_FIFO_IRQ_MASK		GENMASK(2, 0)
49 
50 /* Bit and mask definition for outbox's SPRD_MBOX_IRQ_MSK register */
51 #define SPRD_OUTBOX_FIFO_NOT_EMPTY_IRQ		BIT(0)
52 #define SPRD_OUTBOX_FIFO_IRQ_MASK		GENMASK(4, 0)
53 
54 #define SPRD_OUTBOX_BASE_SPAN			0x1000
55 #define SPRD_MBOX_CHAN_MAX			8
56 #define SPRD_SUPP_INBOX_ID_SC9863A		7
57 
58 struct sprd_mbox_priv {
59 	struct mbox_controller	mbox;
60 	struct device		*dev;
61 	void __iomem		*inbox_base;
62 	void __iomem		*outbox_base;
63 	/*  Base register address for supplementary outbox */
64 	void __iomem		*supp_base;
65 	struct clk		*clk;
66 	u32			outbox_fifo_depth;
67 
68 	struct mutex		lock;
69 	u32			refcnt;
70 	struct mbox_chan	chan[SPRD_MBOX_CHAN_MAX];
71 };
72 
73 static struct sprd_mbox_priv *to_sprd_mbox_priv(struct mbox_controller *mbox)
74 {
75 	return container_of(mbox, struct sprd_mbox_priv, mbox);
76 }
77 
78 static u32 sprd_mbox_get_fifo_len(struct sprd_mbox_priv *priv, u32 fifo_sts)
79 {
80 	u32 wr_pos = (fifo_sts >> SPRD_OUTBOX_FIFO_WR_SHIFT) &
81 		SPRD_OUTBOX_FIFO_POS_MASK;
82 	u32 rd_pos = (fifo_sts >> SPRD_OUTBOX_FIFO_RD_SHIFT) &
83 		SPRD_OUTBOX_FIFO_POS_MASK;
84 	u32 fifo_len;
85 
86 	/*
87 	 * If the read pointer is equal with write pointer, which means the fifo
88 	 * is full or empty.
89 	 */
90 	if (wr_pos == rd_pos) {
91 		if (fifo_sts & SPRD_OUTBOX_FIFO_FULL)
92 			fifo_len = priv->outbox_fifo_depth;
93 		else
94 			fifo_len = 0;
95 	} else if (wr_pos > rd_pos) {
96 		fifo_len = wr_pos - rd_pos;
97 	} else {
98 		fifo_len = priv->outbox_fifo_depth - rd_pos + wr_pos;
99 	}
100 
101 	return fifo_len;
102 }
103 
104 static irqreturn_t do_outbox_isr(void __iomem *base, struct sprd_mbox_priv *priv)
105 {
106 	struct mbox_chan *chan;
107 	u32 fifo_sts, fifo_len, msg[2];
108 	int i, id;
109 
110 	fifo_sts = readl(base + SPRD_MBOX_FIFO_STS);
111 
112 	fifo_len = sprd_mbox_get_fifo_len(priv, fifo_sts);
113 	if (!fifo_len) {
114 		dev_warn_ratelimited(priv->dev, "spurious outbox interrupt\n");
115 		return IRQ_NONE;
116 	}
117 
118 	for (i = 0; i < fifo_len; i++) {
119 		msg[0] = readl(base + SPRD_MBOX_MSG_LOW);
120 		msg[1] = readl(base + SPRD_MBOX_MSG_HIGH);
121 		id = readl(base + SPRD_MBOX_ID);
122 
123 		chan = &priv->chan[id];
124 		if (chan->cl)
125 			mbox_chan_received_data(chan, (void *)msg);
126 		else
127 			dev_warn_ratelimited(priv->dev,
128 				    "message's been dropped at ch[%d]\n", id);
129 
130 		/* Trigger to update outbox FIFO pointer */
131 		writel(0x1, base + SPRD_MBOX_TRIGGER);
132 	}
133 
134 	/* Clear irq status after reading all message. */
135 	writel(SPRD_MBOX_IRQ_CLR, base + SPRD_MBOX_IRQ_STS);
136 
137 	return IRQ_HANDLED;
138 }
139 
140 static irqreturn_t sprd_mbox_outbox_isr(int irq, void *data)
141 {
142 	struct sprd_mbox_priv *priv = data;
143 
144 	return do_outbox_isr(priv->outbox_base, priv);
145 }
146 
147 static irqreturn_t sprd_mbox_supp_isr(int irq, void *data)
148 {
149 	struct sprd_mbox_priv *priv = data;
150 
151 	return do_outbox_isr(priv->supp_base, priv);
152 }
153 
154 static irqreturn_t sprd_mbox_inbox_isr(int irq, void *data)
155 {
156 	struct sprd_mbox_priv *priv = data;
157 	struct mbox_chan *chan;
158 	u32 fifo_sts, send_sts, busy, id;
159 
160 	fifo_sts = readl(priv->inbox_base + SPRD_MBOX_FIFO_STS);
161 
162 	/* Get the inbox data delivery status */
163 	send_sts = (fifo_sts & SPRD_INBOX_FIFO_DELIVER_MASK) >>
164 		SPRD_INBOX_FIFO_DELIVER_SHIFT;
165 	if (!send_sts) {
166 		dev_warn_ratelimited(priv->dev, "spurious inbox interrupt\n");
167 		return IRQ_NONE;
168 	}
169 
170 	while (send_sts) {
171 		id = __ffs(send_sts);
172 		send_sts &= (send_sts - 1);
173 
174 		chan = &priv->chan[id];
175 
176 		/*
177 		 * Check if the message was fetched by remote target, if yes,
178 		 * that means the transmission has been completed.
179 		 */
180 		busy = fifo_sts & SPRD_INBOX_FIFO_BUSY_MASK;
181 		if (!(busy & BIT(id)))
182 			mbox_chan_txdone(chan, 0);
183 	}
184 
185 	/* Clear FIFO delivery and overflow status */
186 	writel(fifo_sts &
187 	       (SPRD_INBOX_FIFO_DELIVER_MASK | SPRD_INBOX_FIFO_OVERLOW_MASK),
188 	       priv->inbox_base + SPRD_MBOX_FIFO_RST);
189 
190 	/* Clear irq status */
191 	writel(SPRD_MBOX_IRQ_CLR, priv->inbox_base + SPRD_MBOX_IRQ_STS);
192 
193 	return IRQ_HANDLED;
194 }
195 
196 static int sprd_mbox_send_data(struct mbox_chan *chan, void *msg)
197 {
198 	struct sprd_mbox_priv *priv = to_sprd_mbox_priv(chan->mbox);
199 	unsigned long id = (unsigned long)chan->con_priv;
200 	u32 *data = msg;
201 
202 	/* Write data into inbox FIFO, and only support 8 bytes every time */
203 	writel(data[0], priv->inbox_base + SPRD_MBOX_MSG_LOW);
204 	writel(data[1], priv->inbox_base + SPRD_MBOX_MSG_HIGH);
205 
206 	/* Set target core id */
207 	writel(id, priv->inbox_base + SPRD_MBOX_ID);
208 
209 	/* Trigger remote request */
210 	writel(0x1, priv->inbox_base + SPRD_MBOX_TRIGGER);
211 
212 	return 0;
213 }
214 
215 static int sprd_mbox_flush(struct mbox_chan *chan, unsigned long timeout)
216 {
217 	struct sprd_mbox_priv *priv = to_sprd_mbox_priv(chan->mbox);
218 	unsigned long id = (unsigned long)chan->con_priv;
219 	u32 busy;
220 
221 	timeout = jiffies + msecs_to_jiffies(timeout);
222 
223 	while (time_before(jiffies, timeout)) {
224 		busy = readl(priv->inbox_base + SPRD_MBOX_FIFO_STS) &
225 			SPRD_INBOX_FIFO_BUSY_MASK;
226 		if (!(busy & BIT(id))) {
227 			mbox_chan_txdone(chan, 0);
228 			return 0;
229 		}
230 
231 		udelay(1);
232 	}
233 
234 	return -ETIME;
235 }
236 
237 static int sprd_mbox_startup(struct mbox_chan *chan)
238 {
239 	struct sprd_mbox_priv *priv = to_sprd_mbox_priv(chan->mbox);
240 	u32 val;
241 
242 	mutex_lock(&priv->lock);
243 	if (priv->refcnt++ == 0) {
244 		/* Select outbox FIFO mode and reset the outbox FIFO status */
245 		writel(0x0, priv->outbox_base + SPRD_MBOX_FIFO_RST);
246 
247 		/* Enable inbox FIFO overflow and delivery interrupt */
248 		val = readl(priv->inbox_base + SPRD_MBOX_IRQ_MSK);
249 		val &= ~(SPRD_INBOX_FIFO_OVERFLOW_IRQ | SPRD_INBOX_FIFO_DELIVER_IRQ);
250 		writel(val, priv->inbox_base + SPRD_MBOX_IRQ_MSK);
251 
252 		/* Enable outbox FIFO not empty interrupt */
253 		val = readl(priv->outbox_base + SPRD_MBOX_IRQ_MSK);
254 		val &= ~SPRD_OUTBOX_FIFO_NOT_EMPTY_IRQ;
255 		writel(val, priv->outbox_base + SPRD_MBOX_IRQ_MSK);
256 
257 		/* Enable supplementary outbox as the fundamental one */
258 		if (priv->supp_base) {
259 			writel(0x0, priv->supp_base + SPRD_MBOX_FIFO_RST);
260 			val = readl(priv->supp_base + SPRD_MBOX_IRQ_MSK);
261 			val &= ~SPRD_OUTBOX_FIFO_NOT_EMPTY_IRQ;
262 			writel(val, priv->supp_base + SPRD_MBOX_IRQ_MSK);
263 		}
264 	}
265 	mutex_unlock(&priv->lock);
266 
267 	return 0;
268 }
269 
270 static void sprd_mbox_shutdown(struct mbox_chan *chan)
271 {
272 	struct sprd_mbox_priv *priv = to_sprd_mbox_priv(chan->mbox);
273 
274 	mutex_lock(&priv->lock);
275 	if (--priv->refcnt == 0) {
276 		/* Disable inbox & outbox interrupt */
277 		writel(SPRD_INBOX_FIFO_IRQ_MASK, priv->inbox_base + SPRD_MBOX_IRQ_MSK);
278 		writel(SPRD_OUTBOX_FIFO_IRQ_MASK, priv->outbox_base + SPRD_MBOX_IRQ_MSK);
279 
280 		if (priv->supp_base)
281 			writel(SPRD_OUTBOX_FIFO_IRQ_MASK,
282 			       priv->supp_base + SPRD_MBOX_IRQ_MSK);
283 	}
284 	mutex_unlock(&priv->lock);
285 }
286 
287 static const struct mbox_chan_ops sprd_mbox_ops = {
288 	.send_data	= sprd_mbox_send_data,
289 	.flush		= sprd_mbox_flush,
290 	.startup	= sprd_mbox_startup,
291 	.shutdown	= sprd_mbox_shutdown,
292 };
293 
294 static void sprd_mbox_disable(void *data)
295 {
296 	struct sprd_mbox_priv *priv = data;
297 
298 	clk_disable_unprepare(priv->clk);
299 }
300 
301 static int sprd_mbox_probe(struct platform_device *pdev)
302 {
303 	struct device *dev = &pdev->dev;
304 	struct sprd_mbox_priv *priv;
305 	int ret, inbox_irq, outbox_irq, supp_irq;
306 	unsigned long id, supp;
307 
308 	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
309 	if (!priv)
310 		return -ENOMEM;
311 
312 	priv->dev = dev;
313 	mutex_init(&priv->lock);
314 
315 	/*
316 	 * Unisoc mailbox uses an inbox to send messages to the target
317 	 * core, and uses (an) outbox(es) to receive messages from other
318 	 * cores.
319 	 *
320 	 * Thus in general the mailbox controller supplies 2 different
321 	 * register addresses and IRQ numbers for inbox and outbox.
322 	 *
323 	 * If necessary, a supplementary inbox could be enabled optionally
324 	 * with an independent FIFO and an extra interrupt.
325 	 */
326 	priv->inbox_base = devm_platform_ioremap_resource(pdev, 0);
327 	if (IS_ERR(priv->inbox_base))
328 		return PTR_ERR(priv->inbox_base);
329 
330 	priv->outbox_base = devm_platform_ioremap_resource(pdev, 1);
331 	if (IS_ERR(priv->outbox_base))
332 		return PTR_ERR(priv->outbox_base);
333 
334 	priv->clk = devm_clk_get(dev, "enable");
335 	if (IS_ERR(priv->clk)) {
336 		dev_err(dev, "failed to get mailbox clock\n");
337 		return PTR_ERR(priv->clk);
338 	}
339 
340 	ret = clk_prepare_enable(priv->clk);
341 	if (ret)
342 		return ret;
343 
344 	ret = devm_add_action_or_reset(dev, sprd_mbox_disable, priv);
345 	if (ret) {
346 		dev_err(dev, "failed to add mailbox disable action\n");
347 		return ret;
348 	}
349 
350 	inbox_irq = platform_get_irq_byname(pdev, "inbox");
351 	if (inbox_irq < 0)
352 		return inbox_irq;
353 
354 	ret = devm_request_irq(dev, inbox_irq, sprd_mbox_inbox_isr,
355 			       IRQF_NO_SUSPEND, dev_name(dev), priv);
356 	if (ret) {
357 		dev_err(dev, "failed to request inbox IRQ: %d\n", ret);
358 		return ret;
359 	}
360 
361 	outbox_irq = platform_get_irq_byname(pdev, "outbox");
362 	if (outbox_irq < 0)
363 		return outbox_irq;
364 
365 	ret = devm_request_irq(dev, outbox_irq, sprd_mbox_outbox_isr,
366 			       IRQF_NO_SUSPEND, dev_name(dev), priv);
367 	if (ret) {
368 		dev_err(dev, "failed to request outbox IRQ: %d\n", ret);
369 		return ret;
370 	}
371 
372 	/* Supplementary outbox IRQ is optional */
373 	supp_irq = platform_get_irq_byname(pdev, "supp-outbox");
374 	if (supp_irq > 0) {
375 		ret = devm_request_irq(dev, supp_irq, sprd_mbox_supp_isr,
376 				       IRQF_NO_SUSPEND, dev_name(dev), priv);
377 		if (ret) {
378 			dev_err(dev, "failed to request outbox IRQ: %d\n", ret);
379 			return ret;
380 		}
381 
382 		supp = (unsigned long) of_device_get_match_data(dev);
383 		if (!supp) {
384 			dev_err(dev, "no supplementary outbox specified\n");
385 			return -ENODEV;
386 		}
387 		priv->supp_base = priv->outbox_base + (SPRD_OUTBOX_BASE_SPAN * supp);
388 	}
389 
390 	/* Get the default outbox FIFO depth */
391 	priv->outbox_fifo_depth =
392 		readl(priv->outbox_base + SPRD_MBOX_FIFO_DEPTH) + 1;
393 	priv->mbox.dev = dev;
394 	priv->mbox.chans = &priv->chan[0];
395 	priv->mbox.num_chans = SPRD_MBOX_CHAN_MAX;
396 	priv->mbox.ops = &sprd_mbox_ops;
397 	priv->mbox.txdone_irq = true;
398 
399 	for (id = 0; id < SPRD_MBOX_CHAN_MAX; id++)
400 		priv->chan[id].con_priv = (void *)id;
401 
402 	ret = devm_mbox_controller_register(dev, &priv->mbox);
403 	if (ret) {
404 		dev_err(dev, "failed to register mailbox: %d\n", ret);
405 		return ret;
406 	}
407 
408 	return 0;
409 }
410 
411 static const struct of_device_id sprd_mbox_of_match[] = {
412 	{ .compatible = "sprd,sc9860-mailbox" },
413 	{ .compatible = "sprd,sc9863a-mailbox",
414 	  .data = (void *)SPRD_SUPP_INBOX_ID_SC9863A },
415 	{ },
416 };
417 MODULE_DEVICE_TABLE(of, sprd_mbox_of_match);
418 
419 static struct platform_driver sprd_mbox_driver = {
420 	.driver = {
421 		.name = "sprd-mailbox",
422 		.of_match_table = sprd_mbox_of_match,
423 	},
424 	.probe	= sprd_mbox_probe,
425 };
426 module_platform_driver(sprd_mbox_driver);
427 
428 MODULE_AUTHOR("Baolin Wang <baolin.wang@unisoc.com>");
429 MODULE_DESCRIPTION("Spreadtrum mailbox driver");
430 MODULE_LICENSE("GPL v2");
431