From 9f68ff79ec2cb303f360a35eef5dd8f1f0f817e1 Mon Sep 17 00:00:00 2001 From: Cristian Marussi Date: Tue, 4 Apr 2023 12:50:26 +0100 Subject: [PATCH] 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: Cristian Marussi Link: https://lore.kernel.org/r/20230404115026.2828149-3-cristian.marussi@arm.com Signed-off-by: Sudeep Holla --- 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 112c285..1efa5e9 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; } -- 2.7.4