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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_validate(struct device *cdev)
{
int num_mb, num_sh, ret = 0;
struct device_node *np = cdev->of_node;
num_mb = of_count_phandle_with_args(np, "mboxes", "#mbox-cells");
num_sh = of_count_phandle_with_args(np, "shmem", NULL);
/* Bail out if mboxes and shmem descriptors are inconsistent */
if (num_mb <= 0 || num_sh > 2 || num_mb != num_sh) {
dev_warn(cdev, "Invalid channel descriptor for '%s'\n",
of_node_full_name(np));
return -EINVAL;
}
if (num_sh > 1) {
struct device_node *np_tx, *np_rx;
np_tx = of_parse_phandle(np, "shmem", 0);
np_rx = of_parse_phandle(np, "shmem", 1);
/* SCMI Tx and Rx shared mem areas have to be distinct */
if (!np_tx || !np_rx || np_tx == np_rx) {
dev_warn(cdev, "Invalid shmem descriptor for '%s'\n",
of_node_full_name(np));
ret = -EINVAL;
}
of_node_put(np_tx);
of_node_put(np_rx);
}
return ret;
}
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;
ret = mailbox_chan_validate(cdev);
if (ret)
return ret;
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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