diff options
Diffstat (limited to 'drivers/firmware/arm_scmi/transports/mailbox.c')
| -rw-r--r-- | drivers/firmware/arm_scmi/transports/mailbox.c | 373 |
1 files changed, 373 insertions, 0 deletions
diff --git a/drivers/firmware/arm_scmi/transports/mailbox.c b/drivers/firmware/arm_scmi/transports/mailbox.c new file mode 100644 index 000000000000..1a754dee24f7 --- /dev/null +++ b/drivers/firmware/arm_scmi/transports/mailbox.c @@ -0,0 +1,373 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * System Control and Management Interface (SCMI) Message Mailbox Transport + * driver. + * + * Copyright (C) 2019-2024 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/platform_device.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 struct scmi_transport_core_operations *core; + +static void tx_prepare(struct mbox_client *cl, void *m) +{ + struct scmi_mailbox *smbox = client_to_scmi_mailbox(cl); + + core->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 && + !core->shmem->channel_free(smbox->shmem)) { + dev_warn(smbox->cinfo->dev, "Ignoring spurious A2P IRQ !\n"); + core->bad_message_trace(smbox->cinfo, + core->shmem->read_header(smbox->shmem), + MSG_MBOX_SPURIOUS); + return; + } + + core->rx_callback(smbox->cinfo, + core->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 __free(device_node) = + of_parse_phandle(np, "shmem", 0); + struct device_node *np_rx __free(device_node) = + 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; + } + } + + /* 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; + int ret, a2p_rx_chan, p2a_chan, p2a_rx_chan; + struct mbox_client *cl; + + 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; + + smbox->shmem = core->shmem->setup_iomap(cinfo, dev, tx, NULL); + if (IS_ERR(smbox->shmem)) + return PTR_ERR(smbox->shmem); + + 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; + + core->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; + + core->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; + + core->shmem->clear_channel(smbox->shmem); + + if (!core->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 core->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, +}; + +static 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, +}; + +static const struct of_device_id scmi_of_match[] = { + { .compatible = "arm,scmi" }, + { /* Sentinel */ }, +}; + +DEFINE_SCMI_TRANSPORT_DRIVER(scmi_mailbox, scmi_mailbox_driver, + scmi_mailbox_desc, scmi_of_match, core); +module_platform_driver(scmi_mailbox_driver); + +MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>"); +MODULE_DESCRIPTION("SCMI Mailbox Transport driver"); +MODULE_LICENSE("GPL"); |