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- // SPDX-License-Identifier: GPL-2.0
- /*
- * System Control and Management Interface (SCMI) Message Mailbox Transport
- * driver.
- *
- * Copyright (C) 2019 ARM Ltd.
- */
- #include <linux/err.h>
- #include <linux/device.h>
- #include <linux/mailbox_client.h>
- #include <linux/of.h>
- #include <linux/of_address.h>
- #include <linux/slab.h>
- #include "common.h"
- /**
- * struct scmi_mailbox - Structure representing a SCMI mailbox transport
- *
- * @cl: Mailbox Client
- * @chan: Transmit/Receive mailbox channel
- * @cinfo: SCMI channel info
- * @shmem: Transmit/Receive shared memory area
- */
- struct scmi_mailbox {
- struct mbox_client cl;
- struct mbox_chan *chan;
- struct scmi_chan_info *cinfo;
- struct scmi_shared_mem __iomem *shmem;
- };
- #define client_to_scmi_mailbox(c) container_of(c, struct scmi_mailbox, cl)
- static void tx_prepare(struct mbox_client *cl, void *m)
- {
- struct scmi_mailbox *smbox = client_to_scmi_mailbox(cl);
- shmem_tx_prepare(smbox->shmem, m);
- }
- static void rx_callback(struct mbox_client *cl, void *m)
- {
- struct scmi_mailbox *smbox = client_to_scmi_mailbox(cl);
- scmi_rx_callback(smbox->cinfo, shmem_read_header(smbox->shmem));
- }
- static bool mailbox_chan_available(struct device *dev, int idx)
- {
- return !of_parse_phandle_with_args(dev->of_node, "mboxes",
- "#mbox-cells", idx, NULL);
- }
- static int mailbox_chan_setup(struct scmi_chan_info *cinfo, struct device *dev,
- bool tx)
- {
- const char *desc = tx ? "Tx" : "Rx";
- struct device *cdev = cinfo->dev;
- struct scmi_mailbox *smbox;
- struct device_node *shmem;
- int ret, idx = tx ? 0 : 1;
- struct mbox_client *cl;
- resource_size_t size;
- struct resource res;
- smbox = devm_kzalloc(dev, sizeof(*smbox), GFP_KERNEL);
- if (!smbox)
- return -ENOMEM;
- shmem = of_parse_phandle(cdev->of_node, "shmem", idx);
- ret = of_address_to_resource(shmem, 0, &res);
- of_node_put(shmem);
- if (ret) {
- dev_err(cdev, "failed to get SCMI %s shared memory\n", desc);
- return ret;
- }
- size = resource_size(&res);
- smbox->shmem = devm_ioremap(dev, res.start, size);
- if (!smbox->shmem) {
- dev_err(dev, "failed to ioremap SCMI %s shared memory\n", desc);
- return -EADDRNOTAVAIL;
- }
- cl = &smbox->cl;
- cl->dev = cdev;
- cl->tx_prepare = tx ? tx_prepare : NULL;
- cl->rx_callback = rx_callback;
- cl->tx_block = false;
- cl->knows_txdone = tx;
- smbox->chan = mbox_request_channel(cl, tx ? 0 : 1);
- if (IS_ERR(smbox->chan)) {
- ret = PTR_ERR(smbox->chan);
- if (ret != -EPROBE_DEFER)
- dev_err(cdev, "failed to request SCMI %s mailbox\n",
- tx ? "Tx" : "Rx");
- return ret;
- }
- cinfo->transport_info = smbox;
- smbox->cinfo = cinfo;
- return 0;
- }
- static int mailbox_chan_free(int id, void *p, void *data)
- {
- struct scmi_chan_info *cinfo = p;
- struct scmi_mailbox *smbox = cinfo->transport_info;
- if (smbox && !IS_ERR(smbox->chan)) {
- mbox_free_channel(smbox->chan);
- cinfo->transport_info = NULL;
- smbox->chan = NULL;
- smbox->cinfo = NULL;
- }
- scmi_free_channel(cinfo, data, id);
- return 0;
- }
- static int mailbox_send_message(struct scmi_chan_info *cinfo,
- struct scmi_xfer *xfer)
- {
- struct scmi_mailbox *smbox = cinfo->transport_info;
- int ret;
- ret = mbox_send_message(smbox->chan, xfer);
- /* mbox_send_message returns non-negative value on success, so reset */
- if (ret > 0)
- ret = 0;
- return ret;
- }
- static void mailbox_mark_txdone(struct scmi_chan_info *cinfo, int ret)
- {
- struct scmi_mailbox *smbox = cinfo->transport_info;
- /*
- * NOTE: we might prefer not to need the mailbox ticker to manage the
- * transfer queueing since the protocol layer queues things by itself.
- * Unfortunately, we have to kick the mailbox framework after we have
- * received our message.
- */
- mbox_client_txdone(smbox->chan, ret);
- }
- static void mailbox_fetch_response(struct scmi_chan_info *cinfo,
- struct scmi_xfer *xfer)
- {
- struct scmi_mailbox *smbox = cinfo->transport_info;
- shmem_fetch_response(smbox->shmem, xfer);
- }
- static void mailbox_fetch_notification(struct scmi_chan_info *cinfo,
- size_t max_len, struct scmi_xfer *xfer)
- {
- struct scmi_mailbox *smbox = cinfo->transport_info;
- shmem_fetch_notification(smbox->shmem, max_len, xfer);
- }
- static void mailbox_clear_channel(struct scmi_chan_info *cinfo)
- {
- struct scmi_mailbox *smbox = cinfo->transport_info;
- shmem_clear_channel(smbox->shmem);
- }
- static bool
- mailbox_poll_done(struct scmi_chan_info *cinfo, struct scmi_xfer *xfer)
- {
- struct scmi_mailbox *smbox = cinfo->transport_info;
- return shmem_poll_done(smbox->shmem, xfer);
- }
- static const struct scmi_transport_ops scmi_mailbox_ops = {
- .chan_available = mailbox_chan_available,
- .chan_setup = mailbox_chan_setup,
- .chan_free = mailbox_chan_free,
- .send_message = mailbox_send_message,
- .mark_txdone = mailbox_mark_txdone,
- .fetch_response = mailbox_fetch_response,
- .fetch_notification = mailbox_fetch_notification,
- .clear_channel = mailbox_clear_channel,
- .poll_done = mailbox_poll_done,
- };
- const struct scmi_desc scmi_mailbox_desc = {
- .ops = &scmi_mailbox_ops,
- .max_rx_timeout_ms = 30, /* We may increase this if required */
- .max_msg = 20, /* Limited by MBOX_TX_QUEUE_LEN */
- .max_msg_size = 128,
- };
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