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