1 // SPDX-License-Identifier: GPL-2.0
3 * System Control and Management Interface (SCMI) Message Mailbox Transport
6 * Copyright (C) 2019 ARM Ltd.
10 #include <linux/device.h>
11 #include <linux/mailbox_client.h>
13 #include <linux/of_address.h>
14 #include <linux/slab.h>
19 * struct scmi_mailbox - Structure representing a SCMI mailbox transport
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
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;
35 #define client_to_scmi_mailbox(c) container_of(c, struct scmi_mailbox, cl)
37 static void tx_prepare(struct mbox_client *cl, void *m)
39 struct scmi_mailbox *smbox = client_to_scmi_mailbox(cl);
41 shmem_tx_prepare(smbox->shmem, m, smbox->cinfo);
44 static void rx_callback(struct mbox_client *cl, void *m)
46 struct scmi_mailbox *smbox = client_to_scmi_mailbox(cl);
49 * An A2P IRQ is NOT valid when received while the platform still has
50 * the ownership of the channel, because the platform at first releases
51 * the SMT channel and then sends the completion interrupt.
53 * This addresses a possible race condition in which a spurious IRQ from
54 * a previous timed-out reply which arrived late could be wrongly
55 * associated with the next pending transaction.
57 if (cl->knows_txdone && !shmem_channel_free(smbox->shmem)) {
58 dev_warn(smbox->cinfo->dev, "Ignoring spurious A2P IRQ !\n");
62 scmi_rx_callback(smbox->cinfo, shmem_read_header(smbox->shmem), NULL);
65 static bool mailbox_chan_available(struct device_node *of_node, int idx)
70 * Just check if bidirrectional channels are involved, and check the
71 * index accordingly; proper full validation will be made later
72 * in mailbox_chan_setup().
74 num_mb = of_count_phandle_with_args(of_node, "mboxes", "#mbox-cells");
75 if (num_mb == 3 && idx == 1)
78 return !of_parse_phandle_with_args(of_node, "mboxes",
79 "#mbox-cells", idx, NULL);
83 * mailbox_chan_validate - Validate transport configuration and map channels
85 * @cdev: Reference to the underlying transport device carrying the
86 * of_node descriptor to analyze.
87 * @a2p_rx_chan: A reference to an optional unidirectional channel to use
88 * for replies on the a2p channel. Set as zero if not present.
89 * @p2a_chan: A reference to the optional p2a channel.
90 * Set as zero if not present.
92 * At first, validate the transport configuration as described in terms of
93 * 'mboxes' and 'shmem', then determin which mailbox channel indexes are
94 * appropriate to be use in the current configuration.
96 * Return: 0 on Success or error
98 static int mailbox_chan_validate(struct device *cdev,
99 int *a2p_rx_chan, int *p2a_chan)
101 int num_mb, num_sh, ret = 0;
102 struct device_node *np = cdev->of_node;
104 num_mb = of_count_phandle_with_args(np, "mboxes", "#mbox-cells");
105 num_sh = of_count_phandle_with_args(np, "shmem", NULL);
106 dev_dbg(cdev, "Found %d mboxes and %d shmems !\n", num_mb, num_sh);
108 /* Bail out if mboxes and shmem descriptors are inconsistent */
109 if (num_mb <= 0 || num_sh <= 0 || num_sh > 2 || num_mb > 3 ||
110 (num_mb == 1 && num_sh != 1) || (num_mb == 3 && num_sh != 2)) {
112 "Invalid channel descriptor for '%s' - mbs:%d shm:%d\n",
113 of_node_full_name(np), num_mb, num_sh);
117 /* Bail out if provided shmem descriptors do not refer distinct areas */
119 struct device_node *np_tx, *np_rx;
121 np_tx = of_parse_phandle(np, "shmem", 0);
122 np_rx = of_parse_phandle(np, "shmem", 1);
123 if (!np_tx || !np_rx || np_tx == np_rx) {
124 dev_warn(cdev, "Invalid shmem descriptor for '%s'\n",
125 of_node_full_name(np));
133 /* Calculate channels IDs to use depending on mboxes/shmem layout */
159 static int mailbox_chan_setup(struct scmi_chan_info *cinfo, struct device *dev,
162 const char *desc = tx ? "Tx" : "Rx";
163 struct device *cdev = cinfo->dev;
164 struct scmi_mailbox *smbox;
165 struct device_node *shmem;
166 int ret, a2p_rx_chan, p2a_chan, idx = tx ? 0 : 1;
167 struct mbox_client *cl;
168 resource_size_t size;
171 ret = mailbox_chan_validate(cdev, &a2p_rx_chan, &p2a_chan);
175 if (!tx && !p2a_chan)
178 smbox = devm_kzalloc(dev, sizeof(*smbox), GFP_KERNEL);
182 shmem = of_parse_phandle(cdev->of_node, "shmem", idx);
183 if (!of_device_is_compatible(shmem, "arm,scmi-shmem")) {
188 ret = of_address_to_resource(shmem, 0, &res);
191 dev_err(cdev, "failed to get SCMI %s shared memory\n", desc);
195 size = resource_size(&res);
196 smbox->shmem = devm_ioremap(dev, res.start, size);
198 dev_err(dev, "failed to ioremap SCMI %s shared memory\n", desc);
199 return -EADDRNOTAVAIL;
204 cl->tx_prepare = tx ? tx_prepare : NULL;
205 cl->rx_callback = rx_callback;
206 cl->tx_block = false;
207 cl->knows_txdone = tx;
209 smbox->chan = mbox_request_channel(cl, tx ? 0 : p2a_chan);
210 if (IS_ERR(smbox->chan)) {
211 ret = PTR_ERR(smbox->chan);
212 if (ret != -EPROBE_DEFER)
214 "failed to request SCMI %s mailbox\n", desc);
218 /* Additional unidirectional channel for TX if needed */
219 if (tx && a2p_rx_chan) {
220 smbox->chan_receiver = mbox_request_channel(cl, a2p_rx_chan);
221 if (IS_ERR(smbox->chan_receiver)) {
222 ret = PTR_ERR(smbox->chan_receiver);
223 if (ret != -EPROBE_DEFER)
224 dev_err(cdev, "failed to request SCMI Tx Receiver mailbox\n");
229 cinfo->transport_info = smbox;
230 smbox->cinfo = cinfo;
235 static int mailbox_chan_free(int id, void *p, void *data)
237 struct scmi_chan_info *cinfo = p;
238 struct scmi_mailbox *smbox = cinfo->transport_info;
240 if (smbox && !IS_ERR(smbox->chan)) {
241 mbox_free_channel(smbox->chan);
242 mbox_free_channel(smbox->chan_receiver);
243 cinfo->transport_info = NULL;
245 smbox->chan_receiver = NULL;
252 static int mailbox_send_message(struct scmi_chan_info *cinfo,
253 struct scmi_xfer *xfer)
255 struct scmi_mailbox *smbox = cinfo->transport_info;
258 ret = mbox_send_message(smbox->chan, xfer);
260 /* mbox_send_message returns non-negative value on success, so reset */
267 static void mailbox_mark_txdone(struct scmi_chan_info *cinfo, int ret,
268 struct scmi_xfer *__unused)
270 struct scmi_mailbox *smbox = cinfo->transport_info;
273 * NOTE: we might prefer not to need the mailbox ticker to manage the
274 * transfer queueing since the protocol layer queues things by itself.
275 * Unfortunately, we have to kick the mailbox framework after we have
276 * received our message.
278 mbox_client_txdone(smbox->chan, ret);
281 static void mailbox_fetch_response(struct scmi_chan_info *cinfo,
282 struct scmi_xfer *xfer)
284 struct scmi_mailbox *smbox = cinfo->transport_info;
286 shmem_fetch_response(smbox->shmem, xfer);
289 static void mailbox_fetch_notification(struct scmi_chan_info *cinfo,
290 size_t max_len, struct scmi_xfer *xfer)
292 struct scmi_mailbox *smbox = cinfo->transport_info;
294 shmem_fetch_notification(smbox->shmem, max_len, xfer);
297 static void mailbox_clear_channel(struct scmi_chan_info *cinfo)
299 struct scmi_mailbox *smbox = cinfo->transport_info;
301 shmem_clear_channel(smbox->shmem);
305 mailbox_poll_done(struct scmi_chan_info *cinfo, struct scmi_xfer *xfer)
307 struct scmi_mailbox *smbox = cinfo->transport_info;
309 return shmem_poll_done(smbox->shmem, xfer);
312 static const struct scmi_transport_ops scmi_mailbox_ops = {
313 .chan_available = mailbox_chan_available,
314 .chan_setup = mailbox_chan_setup,
315 .chan_free = mailbox_chan_free,
316 .send_message = mailbox_send_message,
317 .mark_txdone = mailbox_mark_txdone,
318 .fetch_response = mailbox_fetch_response,
319 .fetch_notification = mailbox_fetch_notification,
320 .clear_channel = mailbox_clear_channel,
321 .poll_done = mailbox_poll_done,
324 const struct scmi_desc scmi_mailbox_desc = {
325 .ops = &scmi_mailbox_ops,
326 .max_rx_timeout_ms = 30, /* We may increase this if required */
327 .max_msg = 20, /* Limited by MBOX_TX_QUEUE_LEN */