xref: /openbmc/linux/drivers/mailbox/arm_mhu_db.c (revision e9803aac)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (C) 2013-2015 Fujitsu Semiconductor Ltd.
4  * Copyright (C) 2015 Linaro Ltd.
5  * Based on ARM MHU driver by Jassi Brar <jaswinder.singh@linaro.org>
6  * Copyright (C) 2020 ARM Ltd.
7  */
8 
9 #include <linux/amba/bus.h>
10 #include <linux/device.h>
11 #include <linux/err.h>
12 #include <linux/interrupt.h>
13 #include <linux/io.h>
14 #include <linux/kernel.h>
15 #include <linux/mailbox_controller.h>
16 #include <linux/module.h>
17 #include <linux/of.h>
18 
19 #define INTR_STAT_OFS	0x0
20 #define INTR_SET_OFS	0x8
21 #define INTR_CLR_OFS	0x10
22 
23 #define MHU_LP_OFFSET	0x0
24 #define MHU_HP_OFFSET	0x20
25 #define MHU_SEC_OFFSET	0x200
26 #define TX_REG_OFFSET	0x100
27 
28 #define MHU_CHANS	3	/* Secure, Non-Secure High and Low Priority */
29 #define MHU_CHAN_MAX	20	/* Max channels to save on unused RAM */
30 #define MHU_NUM_DOORBELLS	32
31 
32 struct mhu_db_link {
33 	unsigned int irq;
34 	void __iomem *tx_reg;
35 	void __iomem *rx_reg;
36 };
37 
38 struct arm_mhu {
39 	void __iomem *base;
40 	struct mhu_db_link mlink[MHU_CHANS];
41 	struct mbox_controller mbox;
42 	struct device *dev;
43 };
44 
45 /**
46  * struct mhu_db_channel - ARM MHU Mailbox allocated channel information
47  *
48  * @mhu: Pointer to parent mailbox device
49  * @pchan: Physical channel within which this doorbell resides in
50  * @doorbell: doorbell number pertaining to this channel
51  */
52 struct mhu_db_channel {
53 	struct arm_mhu *mhu;
54 	unsigned int pchan;
55 	unsigned int doorbell;
56 };
57 
58 static inline struct mbox_chan *
mhu_db_mbox_to_channel(struct mbox_controller * mbox,unsigned int pchan,unsigned int doorbell)59 mhu_db_mbox_to_channel(struct mbox_controller *mbox, unsigned int pchan,
60 		       unsigned int doorbell)
61 {
62 	int i;
63 	struct mhu_db_channel *chan_info;
64 
65 	for (i = 0; i < mbox->num_chans; i++) {
66 		chan_info = mbox->chans[i].con_priv;
67 		if (chan_info && chan_info->pchan == pchan &&
68 		    chan_info->doorbell == doorbell)
69 			return &mbox->chans[i];
70 	}
71 
72 	return NULL;
73 }
74 
mhu_db_mbox_clear_irq(struct mbox_chan * chan)75 static void mhu_db_mbox_clear_irq(struct mbox_chan *chan)
76 {
77 	struct mhu_db_channel *chan_info = chan->con_priv;
78 	void __iomem *base = chan_info->mhu->mlink[chan_info->pchan].rx_reg;
79 
80 	writel_relaxed(BIT(chan_info->doorbell), base + INTR_CLR_OFS);
81 }
82 
mhu_db_mbox_irq_to_pchan_num(struct arm_mhu * mhu,int irq)83 static unsigned int mhu_db_mbox_irq_to_pchan_num(struct arm_mhu *mhu, int irq)
84 {
85 	unsigned int pchan;
86 
87 	for (pchan = 0; pchan < MHU_CHANS; pchan++)
88 		if (mhu->mlink[pchan].irq == irq)
89 			break;
90 	return pchan;
91 }
92 
93 static struct mbox_chan *
mhu_db_mbox_irq_to_channel(struct arm_mhu * mhu,unsigned int pchan)94 mhu_db_mbox_irq_to_channel(struct arm_mhu *mhu, unsigned int pchan)
95 {
96 	unsigned long bits;
97 	unsigned int doorbell;
98 	struct mbox_chan *chan = NULL;
99 	struct mbox_controller *mbox = &mhu->mbox;
100 	void __iomem *base = mhu->mlink[pchan].rx_reg;
101 
102 	bits = readl_relaxed(base + INTR_STAT_OFS);
103 	if (!bits)
104 		/* No IRQs fired in specified physical channel */
105 		return NULL;
106 
107 	/* An IRQ has fired, find the associated channel */
108 	for (doorbell = 0; bits; doorbell++) {
109 		if (!test_and_clear_bit(doorbell, &bits))
110 			continue;
111 
112 		chan = mhu_db_mbox_to_channel(mbox, pchan, doorbell);
113 		if (chan)
114 			break;
115 		dev_err(mbox->dev,
116 			"Channel not registered: pchan: %d doorbell: %d\n",
117 			pchan, doorbell);
118 	}
119 
120 	return chan;
121 }
122 
mhu_db_mbox_rx_handler(int irq,void * data)123 static irqreturn_t mhu_db_mbox_rx_handler(int irq, void *data)
124 {
125 	struct mbox_chan *chan;
126 	struct arm_mhu *mhu = data;
127 	unsigned int pchan = mhu_db_mbox_irq_to_pchan_num(mhu, irq);
128 
129 	while (NULL != (chan = mhu_db_mbox_irq_to_channel(mhu, pchan))) {
130 		mbox_chan_received_data(chan, NULL);
131 		mhu_db_mbox_clear_irq(chan);
132 	}
133 
134 	return IRQ_HANDLED;
135 }
136 
mhu_db_last_tx_done(struct mbox_chan * chan)137 static bool mhu_db_last_tx_done(struct mbox_chan *chan)
138 {
139 	struct mhu_db_channel *chan_info = chan->con_priv;
140 	void __iomem *base = chan_info->mhu->mlink[chan_info->pchan].tx_reg;
141 
142 	if (readl_relaxed(base + INTR_STAT_OFS) & BIT(chan_info->doorbell))
143 		return false;
144 
145 	return true;
146 }
147 
mhu_db_send_data(struct mbox_chan * chan,void * data)148 static int mhu_db_send_data(struct mbox_chan *chan, void *data)
149 {
150 	struct mhu_db_channel *chan_info = chan->con_priv;
151 	void __iomem *base = chan_info->mhu->mlink[chan_info->pchan].tx_reg;
152 
153 	/* Send event to co-processor */
154 	writel_relaxed(BIT(chan_info->doorbell), base + INTR_SET_OFS);
155 
156 	return 0;
157 }
158 
mhu_db_startup(struct mbox_chan * chan)159 static int mhu_db_startup(struct mbox_chan *chan)
160 {
161 	mhu_db_mbox_clear_irq(chan);
162 	return 0;
163 }
164 
mhu_db_shutdown(struct mbox_chan * chan)165 static void mhu_db_shutdown(struct mbox_chan *chan)
166 {
167 	struct mhu_db_channel *chan_info = chan->con_priv;
168 	struct mbox_controller *mbox = &chan_info->mhu->mbox;
169 	int i;
170 
171 	for (i = 0; i < mbox->num_chans; i++)
172 		if (chan == &mbox->chans[i])
173 			break;
174 
175 	if (mbox->num_chans == i) {
176 		dev_warn(mbox->dev, "Request to free non-existent channel\n");
177 		return;
178 	}
179 
180 	/* Reset channel */
181 	mhu_db_mbox_clear_irq(chan);
182 	devm_kfree(mbox->dev, chan->con_priv);
183 	chan->con_priv = NULL;
184 }
185 
mhu_db_mbox_xlate(struct mbox_controller * mbox,const struct of_phandle_args * spec)186 static struct mbox_chan *mhu_db_mbox_xlate(struct mbox_controller *mbox,
187 					   const struct of_phandle_args *spec)
188 {
189 	struct arm_mhu *mhu = dev_get_drvdata(mbox->dev);
190 	struct mhu_db_channel *chan_info;
191 	struct mbox_chan *chan;
192 	unsigned int pchan = spec->args[0];
193 	unsigned int doorbell = spec->args[1];
194 	int i;
195 
196 	/* Bounds checking */
197 	if (pchan >= MHU_CHANS || doorbell >= MHU_NUM_DOORBELLS) {
198 		dev_err(mbox->dev,
199 			"Invalid channel requested pchan: %d doorbell: %d\n",
200 			pchan, doorbell);
201 		return ERR_PTR(-EINVAL);
202 	}
203 
204 	/* Is requested channel free? */
205 	chan = mhu_db_mbox_to_channel(mbox, pchan, doorbell);
206 	if (chan) {
207 		dev_err(mbox->dev, "Channel in use: pchan: %d doorbell: %d\n",
208 			pchan, doorbell);
209 		return ERR_PTR(-EBUSY);
210 	}
211 
212 	/* Find the first free slot */
213 	for (i = 0; i < mbox->num_chans; i++)
214 		if (!mbox->chans[i].con_priv)
215 			break;
216 
217 	if (mbox->num_chans == i) {
218 		dev_err(mbox->dev, "No free channels left\n");
219 		return ERR_PTR(-EBUSY);
220 	}
221 
222 	chan = &mbox->chans[i];
223 
224 	chan_info = devm_kzalloc(mbox->dev, sizeof(*chan_info), GFP_KERNEL);
225 	if (!chan_info)
226 		return ERR_PTR(-ENOMEM);
227 
228 	chan_info->mhu = mhu;
229 	chan_info->pchan = pchan;
230 	chan_info->doorbell = doorbell;
231 
232 	chan->con_priv = chan_info;
233 
234 	dev_dbg(mbox->dev, "mbox: created channel phys: %d doorbell: %d\n",
235 		pchan, doorbell);
236 
237 	return chan;
238 }
239 
240 static const struct mbox_chan_ops mhu_db_ops = {
241 	.send_data = mhu_db_send_data,
242 	.startup = mhu_db_startup,
243 	.shutdown = mhu_db_shutdown,
244 	.last_tx_done = mhu_db_last_tx_done,
245 };
246 
mhu_db_probe(struct amba_device * adev,const struct amba_id * id)247 static int mhu_db_probe(struct amba_device *adev, const struct amba_id *id)
248 {
249 	u32 cell_count;
250 	int i, err, max_chans;
251 	struct arm_mhu *mhu;
252 	struct mbox_chan *chans;
253 	struct device *dev = &adev->dev;
254 	struct device_node *np = dev->of_node;
255 	int mhu_reg[MHU_CHANS] = {
256 		MHU_LP_OFFSET, MHU_HP_OFFSET, MHU_SEC_OFFSET,
257 	};
258 
259 	if (!of_device_is_compatible(np, "arm,mhu-doorbell"))
260 		return -ENODEV;
261 
262 	err = of_property_read_u32(np, "#mbox-cells", &cell_count);
263 	if (err) {
264 		dev_err(dev, "failed to read #mbox-cells in '%pOF'\n", np);
265 		return err;
266 	}
267 
268 	if (cell_count == 2) {
269 		max_chans = MHU_CHAN_MAX;
270 	} else {
271 		dev_err(dev, "incorrect value of #mbox-cells in '%pOF'\n", np);
272 		return -EINVAL;
273 	}
274 
275 	mhu = devm_kzalloc(dev, sizeof(*mhu), GFP_KERNEL);
276 	if (!mhu)
277 		return -ENOMEM;
278 
279 	mhu->base = devm_ioremap_resource(dev, &adev->res);
280 	if (IS_ERR(mhu->base))
281 		return PTR_ERR(mhu->base);
282 
283 	chans = devm_kcalloc(dev, max_chans, sizeof(*chans), GFP_KERNEL);
284 	if (!chans)
285 		return -ENOMEM;
286 
287 	mhu->dev = dev;
288 	mhu->mbox.dev = dev;
289 	mhu->mbox.chans = chans;
290 	mhu->mbox.num_chans = max_chans;
291 	mhu->mbox.txdone_irq = false;
292 	mhu->mbox.txdone_poll = true;
293 	mhu->mbox.txpoll_period = 1;
294 
295 	mhu->mbox.of_xlate = mhu_db_mbox_xlate;
296 	amba_set_drvdata(adev, mhu);
297 
298 	mhu->mbox.ops = &mhu_db_ops;
299 
300 	err = devm_mbox_controller_register(dev, &mhu->mbox);
301 	if (err) {
302 		dev_err(dev, "Failed to register mailboxes %d\n", err);
303 		return err;
304 	}
305 
306 	for (i = 0; i < MHU_CHANS; i++) {
307 		int irq = mhu->mlink[i].irq = adev->irq[i];
308 
309 		if (irq <= 0) {
310 			dev_dbg(dev, "No IRQ found for Channel %d\n", i);
311 			continue;
312 		}
313 
314 		mhu->mlink[i].rx_reg = mhu->base + mhu_reg[i];
315 		mhu->mlink[i].tx_reg = mhu->mlink[i].rx_reg + TX_REG_OFFSET;
316 
317 		err = devm_request_threaded_irq(dev, irq, NULL,
318 						mhu_db_mbox_rx_handler,
319 						IRQF_ONESHOT, "mhu_db_link", mhu);
320 		if (err) {
321 			dev_err(dev, "Can't claim IRQ %d\n", irq);
322 			mbox_controller_unregister(&mhu->mbox);
323 			return err;
324 		}
325 	}
326 
327 	dev_info(dev, "ARM MHU Doorbell mailbox registered\n");
328 	return 0;
329 }
330 
331 static struct amba_id mhu_ids[] = {
332 	{
333 		.id	= 0x1bb098,
334 		.mask	= 0xffffff,
335 	},
336 	{ 0, 0 },
337 };
338 MODULE_DEVICE_TABLE(amba, mhu_ids);
339 
340 static struct amba_driver arm_mhu_db_driver = {
341 	.drv = {
342 		.name	= "mhu-doorbell",
343 	},
344 	.id_table	= mhu_ids,
345 	.probe		= mhu_db_probe,
346 };
347 module_amba_driver(arm_mhu_db_driver);
348 
349 MODULE_LICENSE("GPL v2");
350 MODULE_DESCRIPTION("ARM MHU Doorbell Driver");
351 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
352