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