Commit 9f68ff79 authored by Cristian Marussi's avatar Cristian Marussi Committed by Sudeep Holla
Browse files

firmware: arm_scmi: Add support for unidirectional mailbox channels 



Extend the SCMI transport layer to support mailbox controllers that expose
communication channels that are unidirectional by nature.

Signed-off-by: default avatarCristian Marussi <cristian.marussi@arm.com>
Link: https://lore.kernel.org/r/20230404115026.2828149-3-cristian.marussi@arm.com


Signed-off-by: default avatarSudeep Holla <sudeep.holla@arm.com>
parent 92ac94f7

drivers/firmware/arm_scmi/mailbox.c

+84 −11
Original line number Diff line number Diff line
@@ -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;

	}