| // 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 uni/bi-directional channel |
| * @chan_receiver: Optional Receiver mailbox unidirectional channel |
| * @chan_platform_receiver: Optional Platform 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 mbox_chan *chan_platform_receiver; |
| 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, smbox->cinfo); |
| } |
| |
| static void rx_callback(struct mbox_client *cl, void *m) |
| { |
| struct scmi_mailbox *smbox = client_to_scmi_mailbox(cl); |
| |
| /* |
| * An A2P IRQ is NOT valid when received while the platform still has |
| * the ownership of the channel, because the platform at first releases |
| * the SMT channel and then sends the completion interrupt. |
| * |
| * This addresses a possible race condition in which a spurious IRQ from |
| * a previous timed-out reply which arrived late could be wrongly |
| * associated with the next pending transaction. |
| */ |
| if (cl->knows_txdone && !shmem_channel_free(smbox->shmem)) { |
| dev_warn(smbox->cinfo->dev, "Ignoring spurious A2P IRQ !\n"); |
| scmi_bad_message_trace(smbox->cinfo, |
| shmem_read_header(smbox->shmem), |
| MSG_MBOX_SPURIOUS); |
| return; |
| } |
| |
| scmi_rx_callback(smbox->cinfo, shmem_read_header(smbox->shmem), NULL); |
| } |
| |
| 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); |
| } |
| |
| /** |
| * 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. |
| * @p2a_rx_chan: A reference to the optional p2a completion 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 *p2a_rx_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 <= 0 || num_sh > 2 || num_mb > 4 || |
| (num_mb == 1 && num_sh != 1) || (num_mb == 3 && num_sh != 2) || |
| (num_mb == 4 && 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); |
| 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); |
| } |
| |
| /* Calculate channels IDs to use depending on mboxes/shmem layout */ |
| if (!ret) { |
| switch (num_mb) { |
| case 1: |
| *a2p_rx_chan = 0; |
| *p2a_chan = 0; |
| *p2a_rx_chan = 0; |
| break; |
| case 2: |
| if (num_sh == 2) { |
| *a2p_rx_chan = 0; |
| *p2a_chan = 1; |
| } else { |
| *a2p_rx_chan = 1; |
| *p2a_chan = 0; |
| } |
| *p2a_rx_chan = 0; |
| break; |
| case 3: |
| *a2p_rx_chan = 1; |
| *p2a_chan = 2; |
| *p2a_rx_chan = 0; |
| break; |
| case 4: |
| *a2p_rx_chan = 1; |
| *p2a_chan = 2; |
| *p2a_rx_chan = 3; |
| break; |
| } |
| } |
| |
| 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, a2p_rx_chan, p2a_chan, p2a_rx_chan, idx = tx ? 0 : 1; |
| struct mbox_client *cl; |
| resource_size_t size; |
| struct resource res; |
| |
| ret = mailbox_chan_validate(cdev, &a2p_rx_chan, &p2a_chan, &p2a_rx_chan); |
| if (ret) |
| return ret; |
| |
| if (!tx && !p2a_chan) |
| return -ENODEV; |
| |
| smbox = devm_kzalloc(dev, sizeof(*smbox), GFP_KERNEL); |
| if (!smbox) |
| return -ENOMEM; |
| |
| shmem = of_parse_phandle(cdev->of_node, "shmem", idx); |
| if (!of_device_is_compatible(shmem, "arm,scmi-shmem")) { |
| of_node_put(shmem); |
| return -ENXIO; |
| } |
| |
| 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 : 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", 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; |
| } |
| } |
| |
| if (!tx && p2a_rx_chan) { |
| smbox->chan_platform_receiver = mbox_request_channel(cl, p2a_rx_chan); |
| if (IS_ERR(smbox->chan_platform_receiver)) { |
| ret = PTR_ERR(smbox->chan_platform_receiver); |
| if (ret != -EPROBE_DEFER) |
| dev_err(cdev, "failed to request SCMI P2A Receiver mailbox\n"); |
| 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); |
| mbox_free_channel(smbox->chan_receiver); |
| mbox_free_channel(smbox->chan_platform_receiver); |
| cinfo->transport_info = NULL; |
| smbox->chan = NULL; |
| smbox->chan_receiver = NULL; |
| smbox->chan_platform_receiver = NULL; |
| smbox->cinfo = NULL; |
| } |
| |
| 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_xfer *__unused) |
| { |
| 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; |
| struct mbox_chan *intr_chan; |
| int ret; |
| |
| shmem_clear_channel(smbox->shmem); |
| |
| if (!shmem_channel_intr_enabled(smbox->shmem)) |
| return; |
| |
| if (smbox->chan_platform_receiver) |
| intr_chan = smbox->chan_platform_receiver; |
| else if (smbox->chan) |
| intr_chan = smbox->chan; |
| else |
| return; |
| |
| ret = mbox_send_message(intr_chan, NULL); |
| /* mbox_send_message returns non-negative value on success, so reset */ |
| if (ret > 0) |
| ret = 0; |
| |
| mbox_client_txdone(intr_chan, ret); |
| } |
| |
| 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, |
| }; |