1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * System Control and Management Interface (SCMI) Message Mailbox Transport
4 * driver.
5 *
6 * Copyright (C) 2019 ARM Ltd.
7 */
8
9 #include <linux/err.h>
10 #include <linux/device.h>
11 #include <linux/mailbox_client.h>
12 #include <linux/of.h>
13 #include <linux/of_address.h>
14 #include <linux/slab.h>
15
16 #include "common.h"
17
18 /**
19 * struct scmi_mailbox - Structure representing a SCMI mailbox transport
20 *
21 * @cl: Mailbox Client
22 * @chan: Transmit/Receive mailbox uni/bi-directional channel
23 * @chan_receiver: Optional Receiver mailbox unidirectional channel
24 * @cinfo: SCMI channel info
25 * @shmem: Transmit/Receive shared memory area
26 */
27 struct scmi_mailbox {
28 struct mbox_client cl;
29 struct mbox_chan *chan;
30 struct mbox_chan *chan_receiver;
31 struct scmi_chan_info *cinfo;
32 struct scmi_shared_mem __iomem *shmem;
33 };
34
35 #define client_to_scmi_mailbox(c) container_of(c, struct scmi_mailbox, cl)
36
tx_prepare(struct mbox_client * cl,void * m)37 static void tx_prepare(struct mbox_client *cl, void *m)
38 {
39 struct scmi_mailbox *smbox = client_to_scmi_mailbox(cl);
40
41 shmem_tx_prepare(smbox->shmem, m, smbox->cinfo);
42 }
43
rx_callback(struct mbox_client * cl,void * m)44 static void rx_callback(struct mbox_client *cl, void *m)
45 {
46 struct scmi_mailbox *smbox = client_to_scmi_mailbox(cl);
47
48 scmi_rx_callback(smbox->cinfo, shmem_read_header(smbox->shmem), NULL);
49 }
50
mailbox_chan_available(struct device_node * of_node,int idx)51 static bool mailbox_chan_available(struct device_node *of_node, int idx)
52 {
53 int num_mb;
54
55 /*
56 * Just check if bidirrectional channels are involved, and check the
57 * index accordingly; proper full validation will be made later
58 * in mailbox_chan_setup().
59 */
60 num_mb = of_count_phandle_with_args(of_node, "mboxes", "#mbox-cells");
61 if (num_mb == 3 && idx == 1)
62 idx = 2;
63
64 return !of_parse_phandle_with_args(of_node, "mboxes",
65 "#mbox-cells", idx, NULL);
66 }
67
68 /**
69 * mailbox_chan_validate - Validate transport configuration and map channels
70 *
71 * @cdev: Reference to the underlying transport device carrying the
72 * of_node descriptor to analyze.
73 * @a2p_rx_chan: A reference to an optional unidirectional channel to use
74 * for replies on the a2p channel. Set as zero if not present.
75 * @p2a_chan: A reference to the optional p2a channel.
76 * Set as zero if not present.
77 *
78 * At first, validate the transport configuration as described in terms of
79 * 'mboxes' and 'shmem', then determin which mailbox channel indexes are
80 * appropriate to be use in the current configuration.
81 *
82 * Return: 0 on Success or error
83 */
mailbox_chan_validate(struct device * cdev,int * a2p_rx_chan,int * p2a_chan)84 static int mailbox_chan_validate(struct device *cdev,
85 int *a2p_rx_chan, int *p2a_chan)
86 {
87 int num_mb, num_sh, ret = 0;
88 struct device_node *np = cdev->of_node;
89
90 num_mb = of_count_phandle_with_args(np, "mboxes", "#mbox-cells");
91 num_sh = of_count_phandle_with_args(np, "shmem", NULL);
92 dev_dbg(cdev, "Found %d mboxes and %d shmems !\n", num_mb, num_sh);
93
94 /* Bail out if mboxes and shmem descriptors are inconsistent */
95 if (num_mb <= 0 || num_sh <= 0 || num_sh > 2 || num_mb > 3 ||
96 (num_mb == 1 && num_sh != 1) || (num_mb == 3 && num_sh != 2)) {
97 dev_warn(cdev,
98 "Invalid channel descriptor for '%s' - mbs:%d shm:%d\n",
99 of_node_full_name(np), num_mb, num_sh);
100 return -EINVAL;
101 }
102
103 /* Bail out if provided shmem descriptors do not refer distinct areas */
104 if (num_sh > 1) {
105 struct device_node *np_tx, *np_rx;
106
107 np_tx = of_parse_phandle(np, "shmem", 0);
108 np_rx = of_parse_phandle(np, "shmem", 1);
109 if (!np_tx || !np_rx || np_tx == np_rx) {
110 dev_warn(cdev, "Invalid shmem descriptor for '%s'\n",
111 of_node_full_name(np));
112 ret = -EINVAL;
113 }
114
115 of_node_put(np_tx);
116 of_node_put(np_rx);
117 }
118
119 /* Calculate channels IDs to use depending on mboxes/shmem layout */
120 if (!ret) {
121 switch (num_mb) {
122 case 1:
123 *a2p_rx_chan = 0;
124 *p2a_chan = 0;
125 break;
126 case 2:
127 if (num_sh == 2) {
128 *a2p_rx_chan = 0;
129 *p2a_chan = 1;
130 } else {
131 *a2p_rx_chan = 1;
132 *p2a_chan = 0;
133 }
134 break;
135 case 3:
136 *a2p_rx_chan = 1;
137 *p2a_chan = 2;
138 break;
139 }
140 }
141
142 return ret;
143 }
144
mailbox_chan_setup(struct scmi_chan_info * cinfo,struct device * dev,bool tx)145 static int mailbox_chan_setup(struct scmi_chan_info *cinfo, struct device *dev,
146 bool tx)
147 {
148 const char *desc = tx ? "Tx" : "Rx";
149 struct device *cdev = cinfo->dev;
150 struct scmi_mailbox *smbox;
151 struct device_node *shmem;
152 int ret, a2p_rx_chan, p2a_chan, idx = tx ? 0 : 1;
153 struct mbox_client *cl;
154 resource_size_t size;
155 struct resource res;
156
157 ret = mailbox_chan_validate(cdev, &a2p_rx_chan, &p2a_chan);
158 if (ret)
159 return ret;
160
161 if (!tx && !p2a_chan)
162 return -ENODEV;
163
164 smbox = devm_kzalloc(dev, sizeof(*smbox), GFP_KERNEL);
165 if (!smbox)
166 return -ENOMEM;
167
168 shmem = of_parse_phandle(cdev->of_node, "shmem", idx);
169 if (!of_device_is_compatible(shmem, "arm,scmi-shmem")) {
170 of_node_put(shmem);
171 return -ENXIO;
172 }
173
174 ret = of_address_to_resource(shmem, 0, &res);
175 of_node_put(shmem);
176 if (ret) {
177 dev_err(cdev, "failed to get SCMI %s shared memory\n", desc);
178 return ret;
179 }
180
181 size = resource_size(&res);
182 smbox->shmem = devm_ioremap(dev, res.start, size);
183 if (!smbox->shmem) {
184 dev_err(dev, "failed to ioremap SCMI %s shared memory\n", desc);
185 return -EADDRNOTAVAIL;
186 }
187
188 cl = &smbox->cl;
189 cl->dev = cdev;
190 cl->tx_prepare = tx ? tx_prepare : NULL;
191 cl->rx_callback = rx_callback;
192 cl->tx_block = false;
193 cl->knows_txdone = tx;
194
195 smbox->chan = mbox_request_channel(cl, tx ? 0 : p2a_chan);
196 if (IS_ERR(smbox->chan)) {
197 ret = PTR_ERR(smbox->chan);
198 if (ret != -EPROBE_DEFER)
199 dev_err(cdev,
200 "failed to request SCMI %s mailbox\n", desc);
201 return ret;
202 }
203
204 /* Additional unidirectional channel for TX if needed */
205 if (tx && a2p_rx_chan) {
206 smbox->chan_receiver = mbox_request_channel(cl, a2p_rx_chan);
207 if (IS_ERR(smbox->chan_receiver)) {
208 ret = PTR_ERR(smbox->chan_receiver);
209 if (ret != -EPROBE_DEFER)
210 dev_err(cdev, "failed to request SCMI Tx Receiver mailbox\n");
211 return ret;
212 }
213 }
214
215 cinfo->transport_info = smbox;
216 smbox->cinfo = cinfo;
217
218 return 0;
219 }
220
mailbox_chan_free(int id,void * p,void * data)221 static int mailbox_chan_free(int id, void *p, void *data)
222 {
223 struct scmi_chan_info *cinfo = p;
224 struct scmi_mailbox *smbox = cinfo->transport_info;
225
226 if (smbox && !IS_ERR(smbox->chan)) {
227 mbox_free_channel(smbox->chan);
228 mbox_free_channel(smbox->chan_receiver);
229 cinfo->transport_info = NULL;
230 smbox->chan = NULL;
231 smbox->chan_receiver = NULL;
232 smbox->cinfo = NULL;
233 }
234
235 return 0;
236 }
237
mailbox_send_message(struct scmi_chan_info * cinfo,struct scmi_xfer * xfer)238 static int mailbox_send_message(struct scmi_chan_info *cinfo,
239 struct scmi_xfer *xfer)
240 {
241 struct scmi_mailbox *smbox = cinfo->transport_info;
242 int ret;
243
244 ret = mbox_send_message(smbox->chan, xfer);
245
246 /* mbox_send_message returns non-negative value on success, so reset */
247 if (ret > 0)
248 ret = 0;
249
250 return ret;
251 }
252
mailbox_mark_txdone(struct scmi_chan_info * cinfo,int ret,struct scmi_xfer * __unused)253 static void mailbox_mark_txdone(struct scmi_chan_info *cinfo, int ret,
254 struct scmi_xfer *__unused)
255 {
256 struct scmi_mailbox *smbox = cinfo->transport_info;
257
258 /*
259 * NOTE: we might prefer not to need the mailbox ticker to manage the
260 * transfer queueing since the protocol layer queues things by itself.
261 * Unfortunately, we have to kick the mailbox framework after we have
262 * received our message.
263 */
264 mbox_client_txdone(smbox->chan, ret);
265 }
266
mailbox_fetch_response(struct scmi_chan_info * cinfo,struct scmi_xfer * xfer)267 static void mailbox_fetch_response(struct scmi_chan_info *cinfo,
268 struct scmi_xfer *xfer)
269 {
270 struct scmi_mailbox *smbox = cinfo->transport_info;
271
272 shmem_fetch_response(smbox->shmem, xfer);
273 }
274
mailbox_fetch_notification(struct scmi_chan_info * cinfo,size_t max_len,struct scmi_xfer * xfer)275 static void mailbox_fetch_notification(struct scmi_chan_info *cinfo,
276 size_t max_len, struct scmi_xfer *xfer)
277 {
278 struct scmi_mailbox *smbox = cinfo->transport_info;
279
280 shmem_fetch_notification(smbox->shmem, max_len, xfer);
281 }
282
mailbox_clear_channel(struct scmi_chan_info * cinfo)283 static void mailbox_clear_channel(struct scmi_chan_info *cinfo)
284 {
285 struct scmi_mailbox *smbox = cinfo->transport_info;
286
287 shmem_clear_channel(smbox->shmem);
288 }
289
290 static bool
mailbox_poll_done(struct scmi_chan_info * cinfo,struct scmi_xfer * xfer)291 mailbox_poll_done(struct scmi_chan_info *cinfo, struct scmi_xfer *xfer)
292 {
293 struct scmi_mailbox *smbox = cinfo->transport_info;
294
295 return shmem_poll_done(smbox->shmem, xfer);
296 }
297
298 static const struct scmi_transport_ops scmi_mailbox_ops = {
299 .chan_available = mailbox_chan_available,
300 .chan_setup = mailbox_chan_setup,
301 .chan_free = mailbox_chan_free,
302 .send_message = mailbox_send_message,
303 .mark_txdone = mailbox_mark_txdone,
304 .fetch_response = mailbox_fetch_response,
305 .fetch_notification = mailbox_fetch_notification,
306 .clear_channel = mailbox_clear_channel,
307 .poll_done = mailbox_poll_done,
308 };
309
310 const struct scmi_desc scmi_mailbox_desc = {
311 .ops = &scmi_mailbox_ops,
312 .max_rx_timeout_ms = 30, /* We may increase this if required */
313 .max_msg = 20, /* Limited by MBOX_TX_QUEUE_LEN */
314 .max_msg_size = 128,
315 };
316
