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 channel
23 * @cinfo: SCMI channel info
24 * @shmem: Transmit/Receive shared memory area
27 struct mbox_client cl;
28 struct mbox_chan *chan;
29 struct scmi_chan_info *cinfo;
30 struct scmi_shared_mem __iomem *shmem;
33 #define client_to_scmi_mailbox(c) container_of(c, struct scmi_mailbox, cl)
35 static void tx_prepare(struct mbox_client *cl, void *m)
37 struct scmi_mailbox *smbox = client_to_scmi_mailbox(cl);
39 shmem_tx_prepare(smbox->shmem, m);
42 static void rx_callback(struct mbox_client *cl, void *m)
44 struct scmi_mailbox *smbox = client_to_scmi_mailbox(cl);
46 scmi_rx_callback(smbox->cinfo, shmem_read_header(smbox->shmem), NULL);
49 static bool mailbox_chan_available(struct device *dev, int idx)
51 return !of_parse_phandle_with_args(dev->of_node, "mboxes",
52 "#mbox-cells", idx, NULL);
55 static int mailbox_chan_setup(struct scmi_chan_info *cinfo, struct device *dev,
58 const char *desc = tx ? "Tx" : "Rx";
59 struct device *cdev = cinfo->dev;
60 struct scmi_mailbox *smbox;
61 struct device_node *shmem;
62 int ret, idx = tx ? 0 : 1;
63 struct mbox_client *cl;
67 smbox = devm_kzalloc(dev, sizeof(*smbox), GFP_KERNEL);
71 shmem = of_parse_phandle(cdev->of_node, "shmem", idx);
72 if (!of_device_is_compatible(shmem, "arm,scmi-shmem"))
75 ret = of_address_to_resource(shmem, 0, &res);
78 dev_err(cdev, "failed to get SCMI %s shared memory\n", desc);
82 size = resource_size(&res);
83 smbox->shmem = devm_ioremap(dev, res.start, size);
85 dev_err(dev, "failed to ioremap SCMI %s shared memory\n", desc);
86 return -EADDRNOTAVAIL;
91 cl->tx_prepare = tx ? tx_prepare : NULL;
92 cl->rx_callback = rx_callback;
94 cl->knows_txdone = tx;
96 smbox->chan = mbox_request_channel(cl, tx ? 0 : 1);
97 if (IS_ERR(smbox->chan)) {
98 ret = PTR_ERR(smbox->chan);
99 if (ret != -EPROBE_DEFER)
100 dev_err(cdev, "failed to request SCMI %s mailbox\n",
105 cinfo->transport_info = smbox;
106 smbox->cinfo = cinfo;
111 static int mailbox_chan_free(int id, void *p, void *data)
113 struct scmi_chan_info *cinfo = p;
114 struct scmi_mailbox *smbox = cinfo->transport_info;
116 if (smbox && !IS_ERR(smbox->chan)) {
117 mbox_free_channel(smbox->chan);
118 cinfo->transport_info = NULL;
123 scmi_free_channel(cinfo, data, id);
128 static int mailbox_send_message(struct scmi_chan_info *cinfo,
129 struct scmi_xfer *xfer)
131 struct scmi_mailbox *smbox = cinfo->transport_info;
134 ret = mbox_send_message(smbox->chan, xfer);
136 /* mbox_send_message returns non-negative value on success, so reset */
143 static void mailbox_mark_txdone(struct scmi_chan_info *cinfo, int ret)
145 struct scmi_mailbox *smbox = cinfo->transport_info;
148 * NOTE: we might prefer not to need the mailbox ticker to manage the
149 * transfer queueing since the protocol layer queues things by itself.
150 * Unfortunately, we have to kick the mailbox framework after we have
151 * received our message.
153 mbox_client_txdone(smbox->chan, ret);
156 static void mailbox_fetch_response(struct scmi_chan_info *cinfo,
157 struct scmi_xfer *xfer)
159 struct scmi_mailbox *smbox = cinfo->transport_info;
161 shmem_fetch_response(smbox->shmem, xfer);
164 static void mailbox_fetch_notification(struct scmi_chan_info *cinfo,
165 size_t max_len, struct scmi_xfer *xfer)
167 struct scmi_mailbox *smbox = cinfo->transport_info;
169 shmem_fetch_notification(smbox->shmem, max_len, xfer);
172 static void mailbox_clear_channel(struct scmi_chan_info *cinfo)
174 struct scmi_mailbox *smbox = cinfo->transport_info;
176 shmem_clear_channel(smbox->shmem);
180 mailbox_poll_done(struct scmi_chan_info *cinfo, struct scmi_xfer *xfer)
182 struct scmi_mailbox *smbox = cinfo->transport_info;
184 return shmem_poll_done(smbox->shmem, xfer);
187 static const struct scmi_transport_ops scmi_mailbox_ops = {
188 .chan_available = mailbox_chan_available,
189 .chan_setup = mailbox_chan_setup,
190 .chan_free = mailbox_chan_free,
191 .send_message = mailbox_send_message,
192 .mark_txdone = mailbox_mark_txdone,
193 .fetch_response = mailbox_fetch_response,
194 .fetch_notification = mailbox_fetch_notification,
195 .clear_channel = mailbox_clear_channel,
196 .poll_done = mailbox_poll_done,
199 const struct scmi_desc scmi_mailbox_desc = {
200 .ops = &scmi_mailbox_ops,
201 .max_rx_timeout_ms = 30, /* We may increase this if required */
202 .max_msg = 20, /* Limited by MBOX_TX_QUEUE_LEN */