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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#include <linux/of_device.h>
19
20#define INTR_STAT_OFS 0x0
21#define INTR_SET_OFS 0x8
22#define INTR_CLR_OFS 0x10
23
24#define MHU_LP_OFFSET 0x0
25#define MHU_HP_OFFSET 0x20
26#define MHU_SEC_OFFSET 0x200
27#define TX_REG_OFFSET 0x100
28
29#define MHU_CHANS 3
30#define MHU_CHAN_MAX 20
31#define MHU_NUM_DOORBELLS 32
32
33struct mhu_db_link {
34 unsigned int irq;
35 void __iomem *tx_reg;
36 void __iomem *rx_reg;
37};
38
39struct arm_mhu {
40 void __iomem *base;
41 struct mhu_db_link mlink[MHU_CHANS];
42 struct mbox_controller mbox;
43 struct device *dev;
44};
45
46
47
48
49
50
51
52
53struct mhu_db_channel {
54 struct arm_mhu *mhu;
55 unsigned int pchan;
56 unsigned int doorbell;
57};
58
59static inline struct mbox_chan *
60mhu_db_mbox_to_channel(struct mbox_controller *mbox, unsigned int pchan,
61 unsigned int doorbell)
62{
63 int i;
64 struct mhu_db_channel *chan_info;
65
66 for (i = 0; i < mbox->num_chans; i++) {
67 chan_info = mbox->chans[i].con_priv;
68 if (chan_info && chan_info->pchan == pchan &&
69 chan_info->doorbell == doorbell)
70 return &mbox->chans[i];
71 }
72
73 return NULL;
74}
75
76static void mhu_db_mbox_clear_irq(struct mbox_chan *chan)
77{
78 struct mhu_db_channel *chan_info = chan->con_priv;
79 void __iomem *base = chan_info->mhu->mlink[chan_info->pchan].rx_reg;
80
81 writel_relaxed(BIT(chan_info->doorbell), base + INTR_CLR_OFS);
82}
83
84static unsigned int mhu_db_mbox_irq_to_pchan_num(struct arm_mhu *mhu, int irq)
85{
86 unsigned int pchan;
87
88 for (pchan = 0; pchan < MHU_CHANS; pchan++)
89 if (mhu->mlink[pchan].irq == irq)
90 break;
91 return pchan;
92}
93
94static struct mbox_chan *
95mhu_db_mbox_irq_to_channel(struct arm_mhu *mhu, unsigned int pchan)
96{
97 unsigned long bits;
98 unsigned int doorbell;
99 struct mbox_chan *chan = NULL;
100 struct mbox_controller *mbox = &mhu->mbox;
101 void __iomem *base = mhu->mlink[pchan].rx_reg;
102
103 bits = readl_relaxed(base + INTR_STAT_OFS);
104 if (!bits)
105
106 return NULL;
107
108
109 for (doorbell = 0; bits; doorbell++) {
110 if (!test_and_clear_bit(doorbell, &bits))
111 continue;
112
113 chan = mhu_db_mbox_to_channel(mbox, pchan, doorbell);
114 if (chan)
115 break;
116 dev_err(mbox->dev,
117 "Channel not registered: pchan: %d doorbell: %d\n",
118 pchan, doorbell);
119 }
120
121 return chan;
122}
123
124static irqreturn_t mhu_db_mbox_rx_handler(int irq, void *data)
125{
126 struct mbox_chan *chan;
127 struct arm_mhu *mhu = data;
128 unsigned int pchan = mhu_db_mbox_irq_to_pchan_num(mhu, irq);
129
130 while (NULL != (chan = mhu_db_mbox_irq_to_channel(mhu, pchan))) {
131 mbox_chan_received_data(chan, NULL);
132 mhu_db_mbox_clear_irq(chan);
133 }
134
135 return IRQ_HANDLED;
136}
137
138static bool mhu_db_last_tx_done(struct mbox_chan *chan)
139{
140 struct mhu_db_channel *chan_info = chan->con_priv;
141 void __iomem *base = chan_info->mhu->mlink[chan_info->pchan].tx_reg;
142
143 if (readl_relaxed(base + INTR_STAT_OFS) & BIT(chan_info->doorbell))
144 return false;
145
146 return true;
147}
148
149static int mhu_db_send_data(struct mbox_chan *chan, void *data)
150{
151 struct mhu_db_channel *chan_info = chan->con_priv;
152 void __iomem *base = chan_info->mhu->mlink[chan_info->pchan].tx_reg;
153
154
155 writel_relaxed(BIT(chan_info->doorbell), base + INTR_SET_OFS);
156
157 return 0;
158}
159
160static int mhu_db_startup(struct mbox_chan *chan)
161{
162 mhu_db_mbox_clear_irq(chan);
163 return 0;
164}
165
166static void mhu_db_shutdown(struct mbox_chan *chan)
167{
168 struct mhu_db_channel *chan_info = chan->con_priv;
169 struct mbox_controller *mbox = &chan_info->mhu->mbox;
170 int i;
171
172 for (i = 0; i < mbox->num_chans; i++)
173 if (chan == &mbox->chans[i])
174 break;
175
176 if (mbox->num_chans == i) {
177 dev_warn(mbox->dev, "Request to free non-existent channel\n");
178 return;
179 }
180
181
182 mhu_db_mbox_clear_irq(chan);
183 devm_kfree(mbox->dev, chan->con_priv);
184 chan->con_priv = NULL;
185}
186
187static struct mbox_chan *mhu_db_mbox_xlate(struct mbox_controller *mbox,
188 const struct of_phandle_args *spec)
189{
190 struct arm_mhu *mhu = dev_get_drvdata(mbox->dev);
191 struct mhu_db_channel *chan_info;
192 struct mbox_chan *chan;
193 unsigned int pchan = spec->args[0];
194 unsigned int doorbell = spec->args[1];
195 int i;
196
197
198 if (pchan >= MHU_CHANS || doorbell >= MHU_NUM_DOORBELLS) {
199 dev_err(mbox->dev,
200 "Invalid channel requested pchan: %d doorbell: %d\n",
201 pchan, doorbell);
202 return ERR_PTR(-EINVAL);
203 }
204
205
206 chan = mhu_db_mbox_to_channel(mbox, pchan, doorbell);
207 if (chan) {
208 dev_err(mbox->dev, "Channel in use: pchan: %d doorbell: %d\n",
209 pchan, doorbell);
210 return ERR_PTR(-EBUSY);
211 }
212
213
214 for (i = 0; i < mbox->num_chans; i++)
215 if (!mbox->chans[i].con_priv)
216 break;
217
218 if (mbox->num_chans == i) {
219 dev_err(mbox->dev, "No free channels left\n");
220 return ERR_PTR(-EBUSY);
221 }
222
223 chan = &mbox->chans[i];
224
225 chan_info = devm_kzalloc(mbox->dev, sizeof(*chan_info), GFP_KERNEL);
226 if (!chan_info)
227 return ERR_PTR(-ENOMEM);
228
229 chan_info->mhu = mhu;
230 chan_info->pchan = pchan;
231 chan_info->doorbell = doorbell;
232
233 chan->con_priv = chan_info;
234
235 dev_dbg(mbox->dev, "mbox: created channel phys: %d doorbell: %d\n",
236 pchan, doorbell);
237
238 return chan;
239}
240
241static const struct mbox_chan_ops mhu_db_ops = {
242 .send_data = mhu_db_send_data,
243 .startup = mhu_db_startup,
244 .shutdown = mhu_db_shutdown,
245 .last_tx_done = mhu_db_last_tx_done,
246};
247
248static int mhu_db_probe(struct amba_device *adev, const struct amba_id *id)
249{
250 u32 cell_count;
251 int i, err, max_chans;
252 struct arm_mhu *mhu;
253 struct mbox_chan *chans;
254 struct device *dev = &adev->dev;
255 struct device_node *np = dev->of_node;
256 int mhu_reg[MHU_CHANS] = {
257 MHU_LP_OFFSET, MHU_HP_OFFSET, MHU_SEC_OFFSET,
258 };
259
260 if (!of_device_is_compatible(np, "arm,mhu-doorbell"))
261 return -ENODEV;
262
263 err = of_property_read_u32(np, "#mbox-cells", &cell_count);
264 if (err) {
265 dev_err(dev, "failed to read #mbox-cells in '%pOF'\n", np);
266 return err;
267 }
268
269 if (cell_count == 2) {
270 max_chans = MHU_CHAN_MAX;
271 } else {
272 dev_err(dev, "incorrect value of #mbox-cells in '%pOF'\n", np);
273 return -EINVAL;
274 }
275
276 mhu = devm_kzalloc(dev, sizeof(*mhu), GFP_KERNEL);
277 if (!mhu)
278 return -ENOMEM;
279
280 mhu->base = devm_ioremap_resource(dev, &adev->res);
281 if (IS_ERR(mhu->base))
282 return PTR_ERR(mhu->base);
283
284 chans = devm_kcalloc(dev, max_chans, sizeof(*chans), GFP_KERNEL);
285 if (!chans)
286 return -ENOMEM;
287
288 mhu->dev = dev;
289 mhu->mbox.dev = dev;
290 mhu->mbox.chans = chans;
291 mhu->mbox.num_chans = max_chans;
292 mhu->mbox.txdone_irq = false;
293 mhu->mbox.txdone_poll = true;
294 mhu->mbox.txpoll_period = 1;
295
296 mhu->mbox.of_xlate = mhu_db_mbox_xlate;
297 amba_set_drvdata(adev, mhu);
298
299 mhu->mbox.ops = &mhu_db_ops;
300
301 err = devm_mbox_controller_register(dev, &mhu->mbox);
302 if (err) {
303 dev_err(dev, "Failed to register mailboxes %d\n", err);
304 return err;
305 }
306
307 for (i = 0; i < MHU_CHANS; i++) {
308 int irq = mhu->mlink[i].irq = adev->irq[i];
309
310 if (irq <= 0) {
311 dev_dbg(dev, "No IRQ found for Channel %d\n", i);
312 continue;
313 }
314
315 mhu->mlink[i].rx_reg = mhu->base + mhu_reg[i];
316 mhu->mlink[i].tx_reg = mhu->mlink[i].rx_reg + TX_REG_OFFSET;
317
318 err = devm_request_threaded_irq(dev, irq, NULL,
319 mhu_db_mbox_rx_handler,
320 IRQF_ONESHOT, "mhu_db_link", mhu);
321 if (err) {
322 dev_err(dev, "Can't claim IRQ %d\n", irq);
323 mbox_controller_unregister(&mhu->mbox);
324 return err;
325 }
326 }
327
328 dev_info(dev, "ARM MHU Doorbell mailbox registered\n");
329 return 0;
330}
331
332static struct amba_id mhu_ids[] = {
333 {
334 .id = 0x1bb098,
335 .mask = 0xffffff,
336 },
337 { 0, 0 },
338};
339MODULE_DEVICE_TABLE(amba, mhu_ids);
340
341static struct amba_driver arm_mhu_db_driver = {
342 .drv = {
343 .name = "mhu-doorbell",
344 },
345 .id_table = mhu_ids,
346 .probe = mhu_db_probe,
347};
348module_amba_driver(arm_mhu_db_driver);
349
350MODULE_LICENSE("GPL v2");
351MODULE_DESCRIPTION("ARM MHU Doorbell Driver");
352MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
353
