[PATCH 2/2] firmware: arm_scmi: Add support for unidirectional mailbox channels
Cristian Marussi
cristian.marussi at arm.com
Mon Mar 27 07:03:42 PDT 2023
Extend the SCMI transport layer to support mailbox controllers that expose
communication channels that are unidirectional by nature.
Signed-off-by: Cristian Marussi <cristian.marussi at arm.com>
---
drivers/firmware/arm_scmi/mailbox.c | 95 +++++++++++++++++++++++++----
1 file changed, 84 insertions(+), 11 deletions(-)
diff --git a/drivers/firmware/arm_scmi/mailbox.c b/drivers/firmware/arm_scmi/mailbox.c
index 112c285deb97..1efa5e9392c4 100644
--- a/drivers/firmware/arm_scmi/mailbox.c
+++ b/drivers/firmware/arm_scmi/mailbox.c
@@ -19,13 +19,15 @@
* struct scmi_mailbox - Structure representing a SCMI mailbox transport
*
* @cl: Mailbox Client
- * @chan: Transmit/Receive mailbox channel
+ * @chan: Transmit/Receive mailbox uni/bi-directional channel
+ * @chan_receiver: Optional Receiver mailbox unidirectional channel
* @cinfo: SCMI channel info
* @shmem: Transmit/Receive shared memory area
*/
struct scmi_mailbox {
struct mbox_client cl;
struct mbox_chan *chan;
+ struct mbox_chan *chan_receiver;
struct scmi_chan_info *cinfo;
struct scmi_shared_mem __iomem *shmem;
};
@@ -48,30 +50,62 @@ static void rx_callback(struct mbox_client *cl, void *m)
static bool mailbox_chan_available(struct device_node *of_node, int idx)
{
+ int num_mb;
+
+ /*
+ * Just check if bidirrectional channels are involved, and check the
+ * index accordingly; proper full validation will be made later
+ * in mailbox_chan_setup().
+ */
+ num_mb = of_count_phandle_with_args(of_node, "mboxes", "#mbox-cells");
+ if (num_mb == 3 && idx == 1)
+ idx = 2;
+
return !of_parse_phandle_with_args(of_node, "mboxes",
"#mbox-cells", idx, NULL);
}
-static int mailbox_chan_validate(struct device *cdev)
+/**
+ * mailbox_chan_validate - Validate transport configuration and map channels
+ *
+ * @cdev: Reference to the underlying transport device carrying the
+ * of_node descriptor to analyze.
+ * @a2p_rx_chan: A reference to an optional unidirectional channel to use
+ * for replies on the a2p channel. Set as zero if not present.
+ * @p2a_chan: A reference to the optional p2a channel.
+ * Set as zero if not present.
+ *
+ * At first, validate the transport configuration as described in terms of
+ * 'mboxes' and 'shmem', then determin which mailbox channel indexes are
+ * appropriate to be use in the current configuration.
+ *
+ * Return: 0 on Success or error
+ */
+static int mailbox_chan_validate(struct device *cdev,
+ int *a2p_rx_chan, int *p2a_chan)
{
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);
+ dev_dbg(cdev, "Found %d mboxes and %d shmems !\n", num_mb, num_sh);
+
/* 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));
+ if (num_mb <= 0 || num_sh <= 0 || num_sh > 2 || num_mb > 3 ||
+ (num_mb == 1 && num_sh != 1) || (num_mb == 3 && num_sh != 2)) {
+ dev_warn(cdev,
+ "Invalid channel descriptor for '%s' - mbs:%d shm:%d\n",
+ of_node_full_name(np), num_mb, num_sh);
return -EINVAL;
}
+ /* Bail out if provided shmem descriptors do not refer distinct areas */
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));
@@ -82,6 +116,29 @@ static int mailbox_chan_validate(struct device *cdev)
of_node_put(np_rx);
}
+ /* Calculate channels IDs to use depending on mboxes/shmem layout */
+ if (!ret) {
+ switch (num_mb) {
+ case 1:
+ *a2p_rx_chan = 0;
+ *p2a_chan = 0;
+ break;
+ case 2:
+ if (num_sh == 2) {
+ *a2p_rx_chan = 0;
+ *p2a_chan = 1;
+ } else {
+ *a2p_rx_chan = 1;
+ *p2a_chan = 0;
+ }
+ break;
+ case 3:
+ *a2p_rx_chan = 1;
+ *p2a_chan = 2;
+ break;
+ }
+ }
+
return ret;
}
@@ -92,15 +149,18 @@ static int mailbox_chan_setup(struct scmi_chan_info *cinfo, struct device *dev,
struct device *cdev = cinfo->dev;
struct scmi_mailbox *smbox;
struct device_node *shmem;
- int ret, idx = tx ? 0 : 1;
+ int ret, a2p_rx_chan, p2a_chan, idx = tx ? 0 : 1;
struct mbox_client *cl;
resource_size_t size;
struct resource res;
- ret = mailbox_chan_validate(cdev);
+ ret = mailbox_chan_validate(cdev, &a2p_rx_chan, &p2a_chan);
if (ret)
return ret;
+ if (!tx && !p2a_chan)
+ return -ENODEV;
+
smbox = devm_kzalloc(dev, sizeof(*smbox), GFP_KERNEL);
if (!smbox)
return -ENOMEM;
@@ -130,15 +190,26 @@ static int mailbox_chan_setup(struct scmi_chan_info *cinfo, struct device *dev,
cl->tx_block = false;
cl->knows_txdone = tx;
- smbox->chan = mbox_request_channel(cl, tx ? 0 : 1);
+ smbox->chan = mbox_request_channel(cl, tx ? 0 : p2a_chan);
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");
+ dev_err(cdev,
+ "failed to request SCMI %s mailbox\n", desc);
return ret;
}
+ /* Additional unidirectional channel for TX if needed */
+ if (tx && a2p_rx_chan) {
+ smbox->chan_receiver = mbox_request_channel(cl, a2p_rx_chan);
+ if (IS_ERR(smbox->chan_receiver)) {
+ ret = PTR_ERR(smbox->chan_receiver);
+ if (ret != -EPROBE_DEFER)
+ dev_err(cdev, "failed to request SCMI Tx Receiver mailbox\n");
+ return ret;
+ }
+ }
+
cinfo->transport_info = smbox;
smbox->cinfo = cinfo;
@@ -152,8 +223,10 @@ static int mailbox_chan_free(int id, void *p, void *data)
if (smbox && !IS_ERR(smbox->chan)) {
mbox_free_channel(smbox->chan);
+ mbox_free_channel(smbox->chan_receiver);
cinfo->transport_info = NULL;
smbox->chan = NULL;
+ smbox->chan_receiver = NULL;
smbox->cinfo = NULL;
}
--
2.34.1
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