diff options
Diffstat (limited to 'drivers/net/mctp/mctp-i3c.c')
| -rw-r--r-- | drivers/net/mctp/mctp-i3c.c | 755 |
1 files changed, 755 insertions, 0 deletions
diff --git a/drivers/net/mctp/mctp-i3c.c b/drivers/net/mctp/mctp-i3c.c new file mode 100644 index 0000000000..8e989c157c --- /dev/null +++ b/drivers/net/mctp/mctp-i3c.c @@ -0,0 +1,755 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Implements DMTF specification + * "DSP0233 Management Component Transport Protocol (MCTP) I3C Transport + * Binding" + * https://www.dmtf.org/sites/default/files/standards/documents/DSP0233_1.0.0.pdf + * + * Copyright (c) 2023 Code Construct + */ + +#include <linux/module.h> +#include <linux/netdevice.h> +#include <linux/i3c/device.h> +#include <linux/i3c/master.h> +#include <linux/if_arp.h> +#include <asm/unaligned.h> +#include <net/mctp.h> +#include <net/mctpdevice.h> + +#define MCTP_I3C_MAXBUF 65536 +/* 48 bit Provisioned Id */ +#define PID_SIZE 6 + +/* 64 byte payload, 4 byte MCTP header */ +static const int MCTP_I3C_MINMTU = 64 + 4; +/* One byte less to allow for the PEC */ +static const int MCTP_I3C_MAXMTU = MCTP_I3C_MAXBUF - 1; +/* 4 byte MCTP header, no data, 1 byte PEC */ +static const int MCTP_I3C_MINLEN = 4 + 1; + +/* Sufficient for 64kB at min mtu */ +static const int MCTP_I3C_TX_QUEUE_LEN = 1100; + +/* Somewhat arbitrary */ +static const int MCTP_I3C_IBI_SLOTS = 8; + +/* Mandatory Data Byte in an IBI, from DSP0233 */ +#define I3C_MDB_MCTP 0xAE +/* From MIPI Device Characteristics Register (DCR) Assignments */ +#define I3C_DCR_MCTP 0xCC + +static const char *MCTP_I3C_OF_PROP = "mctp-controller"; + +/* List of mctp_i3c_busdev */ +static LIST_HEAD(busdevs); +/* Protects busdevs, as well as mctp_i3c_bus.devs lists */ +static DEFINE_MUTEX(busdevs_lock); + +struct mctp_i3c_bus { + struct net_device *ndev; + + struct task_struct *tx_thread; + wait_queue_head_t tx_wq; + /* tx_lock protects tx_skb and devs */ + spinlock_t tx_lock; + /* Next skb to transmit */ + struct sk_buff *tx_skb; + /* Scratch buffer for xmit */ + u8 tx_scratch[MCTP_I3C_MAXBUF]; + + /* Element of busdevs */ + struct list_head list; + + /* Provisioned ID of our controller */ + u64 pid; + + struct i3c_bus *bus; + /* Head of mctp_i3c_device.list. Protected by busdevs_lock */ + struct list_head devs; +}; + +struct mctp_i3c_device { + struct i3c_device *i3c; + struct mctp_i3c_bus *mbus; + struct list_head list; /* Element of mctp_i3c_bus.devs */ + + /* Held while tx_thread is using this device */ + struct mutex lock; + + /* Whether BCR indicates MDB is present in IBI */ + bool have_mdb; + /* I3C dynamic address */ + u8 addr; + /* Maximum read length */ + u16 mrl; + /* Maximum write length */ + u16 mwl; + /* Provisioned ID */ + u64 pid; +}; + +/* We synthesise a mac header using the Provisioned ID. + * Used to pass dest to mctp_i3c_start_xmit. + */ +struct mctp_i3c_internal_hdr { + u8 dest[PID_SIZE]; + u8 source[PID_SIZE]; +} __packed; + +static int mctp_i3c_read(struct mctp_i3c_device *mi) +{ + struct i3c_priv_xfer xfer = { .rnw = 1, .len = mi->mrl }; + struct net_device_stats *stats = &mi->mbus->ndev->stats; + struct mctp_i3c_internal_hdr *ihdr = NULL; + struct sk_buff *skb = NULL; + struct mctp_skb_cb *cb; + int net_status, rc; + u8 pec, addr; + + skb = netdev_alloc_skb(mi->mbus->ndev, + mi->mrl + sizeof(struct mctp_i3c_internal_hdr)); + if (!skb) { + stats->rx_dropped++; + rc = -ENOMEM; + goto err; + } + + skb->protocol = htons(ETH_P_MCTP); + /* Create a header for internal use */ + skb_reset_mac_header(skb); + ihdr = skb_put(skb, sizeof(struct mctp_i3c_internal_hdr)); + put_unaligned_be48(mi->pid, ihdr->source); + put_unaligned_be48(mi->mbus->pid, ihdr->dest); + skb_pull(skb, sizeof(struct mctp_i3c_internal_hdr)); + + xfer.data.in = skb_put(skb, mi->mrl); + + rc = i3c_device_do_priv_xfers(mi->i3c, &xfer, 1); + if (rc < 0) + goto err; + + if (WARN_ON_ONCE(xfer.len > mi->mrl)) { + /* Bad i3c bus driver */ + rc = -EIO; + goto err; + } + if (xfer.len < MCTP_I3C_MINLEN) { + stats->rx_length_errors++; + rc = -EIO; + goto err; + } + + /* check PEC, including address byte */ + addr = mi->addr << 1 | 1; + pec = i2c_smbus_pec(0, &addr, 1); + pec = i2c_smbus_pec(pec, xfer.data.in, xfer.len - 1); + if (pec != ((u8 *)xfer.data.in)[xfer.len - 1]) { + stats->rx_crc_errors++; + rc = -EINVAL; + goto err; + } + + /* Remove PEC */ + skb_trim(skb, xfer.len - 1); + + cb = __mctp_cb(skb); + cb->halen = PID_SIZE; + put_unaligned_be48(mi->pid, cb->haddr); + + net_status = netif_rx(skb); + + if (net_status == NET_RX_SUCCESS) { + stats->rx_packets++; + stats->rx_bytes += xfer.len - 1; + } else { + stats->rx_dropped++; + } + + return 0; +err: + kfree_skb(skb); + return rc; +} + +static void mctp_i3c_ibi_handler(struct i3c_device *i3c, + const struct i3c_ibi_payload *payload) +{ + struct mctp_i3c_device *mi = i3cdev_get_drvdata(i3c); + + if (WARN_ON_ONCE(!mi)) + return; + + if (mi->have_mdb) { + if (payload->len > 0) { + if (((u8 *)payload->data)[0] != I3C_MDB_MCTP) { + /* Not a mctp-i3c interrupt, ignore it */ + return; + } + } else { + /* The BCR advertised a Mandatory Data Byte but the + * device didn't send one. + */ + dev_warn_once(i3cdev_to_dev(i3c), "IBI with missing MDB"); + } + } + + mctp_i3c_read(mi); +} + +static int mctp_i3c_setup(struct mctp_i3c_device *mi) +{ + const struct i3c_ibi_setup ibi = { + .max_payload_len = 1, + .num_slots = MCTP_I3C_IBI_SLOTS, + .handler = mctp_i3c_ibi_handler, + }; + struct i3c_device_info info; + int rc; + + i3c_device_get_info(mi->i3c, &info); + mi->have_mdb = info.bcr & BIT(2); + mi->addr = info.dyn_addr; + mi->mwl = info.max_write_len; + mi->mrl = info.max_read_len; + mi->pid = info.pid; + + rc = i3c_device_request_ibi(mi->i3c, &ibi); + if (rc == -ENOTSUPP) { + /* This driver only supports In-Band Interrupt mode. + * Support for Polling Mode could be added if required. + * (ENOTSUPP is from the i3c layer, not EOPNOTSUPP). + */ + dev_warn(i3cdev_to_dev(mi->i3c), + "Failed, bus driver doesn't support In-Band Interrupts"); + goto err; + } else if (rc < 0) { + dev_err(i3cdev_to_dev(mi->i3c), + "Failed requesting IBI (%d)\n", rc); + goto err; + } + + rc = i3c_device_enable_ibi(mi->i3c); + if (rc < 0) { + /* Assume a driver supporting request_ibi also + * supports enable_ibi. + */ + dev_err(i3cdev_to_dev(mi->i3c), "Failed enabling IBI (%d)\n", rc); + goto err_free_ibi; + } + + return 0; + +err_free_ibi: + i3c_device_free_ibi(mi->i3c); + +err: + return rc; +} + +/* Adds a new MCTP i3c_device to a bus */ +static int mctp_i3c_add_device(struct mctp_i3c_bus *mbus, + struct i3c_device *i3c) +__must_hold(&busdevs_lock) +{ + struct mctp_i3c_device *mi = NULL; + int rc; + + mi = kzalloc(sizeof(*mi), GFP_KERNEL); + if (!mi) { + rc = -ENOMEM; + goto err; + } + mi->mbus = mbus; + mi->i3c = i3c; + mutex_init(&mi->lock); + list_add(&mi->list, &mbus->devs); + + i3cdev_set_drvdata(i3c, mi); + rc = mctp_i3c_setup(mi); + if (rc < 0) + goto err_free; + + return 0; + +err_free: + list_del(&mi->list); + kfree(mi); + +err: + dev_warn(i3cdev_to_dev(i3c), "Error adding mctp-i3c device, %d\n", rc); + return rc; +} + +static int mctp_i3c_probe(struct i3c_device *i3c) +{ + struct mctp_i3c_bus *b = NULL, *mbus = NULL; + + /* Look for a known bus */ + mutex_lock(&busdevs_lock); + list_for_each_entry(b, &busdevs, list) + if (b->bus == i3c->bus) { + mbus = b; + break; + } + mutex_unlock(&busdevs_lock); + + if (!mbus) { + /* probably no "mctp-controller" property on the i3c bus */ + return -ENODEV; + } + + return mctp_i3c_add_device(mbus, i3c); +} + +static void mctp_i3c_remove_device(struct mctp_i3c_device *mi) +__must_hold(&busdevs_lock) +{ + /* Ensure the tx thread isn't using the device */ + mutex_lock(&mi->lock); + + /* Counterpart of mctp_i3c_setup */ + i3c_device_disable_ibi(mi->i3c); + i3c_device_free_ibi(mi->i3c); + + /* Counterpart of mctp_i3c_add_device */ + i3cdev_set_drvdata(mi->i3c, NULL); + list_del(&mi->list); + + /* Safe to unlock after removing from the list */ + mutex_unlock(&mi->lock); + kfree(mi); +} + +static void mctp_i3c_remove(struct i3c_device *i3c) +{ + struct mctp_i3c_device *mi = i3cdev_get_drvdata(i3c); + + /* We my have received a Bus Remove notify prior to device remove, + * so mi will already be removed. + */ + if (!mi) + return; + + mutex_lock(&busdevs_lock); + mctp_i3c_remove_device(mi); + mutex_unlock(&busdevs_lock); +} + +/* Returns the device for an address, with mi->lock held */ +static struct mctp_i3c_device * +mctp_i3c_lookup(struct mctp_i3c_bus *mbus, u64 pid) +{ + struct mctp_i3c_device *mi = NULL, *ret = NULL; + + mutex_lock(&busdevs_lock); + list_for_each_entry(mi, &mbus->devs, list) + if (mi->pid == pid) { + ret = mi; + mutex_lock(&mi->lock); + break; + } + mutex_unlock(&busdevs_lock); + return ret; +} + +static void mctp_i3c_xmit(struct mctp_i3c_bus *mbus, struct sk_buff *skb) +{ + struct net_device_stats *stats = &mbus->ndev->stats; + struct i3c_priv_xfer xfer = { .rnw = false }; + struct mctp_i3c_internal_hdr *ihdr = NULL; + struct mctp_i3c_device *mi = NULL; + unsigned int data_len; + u8 *data = NULL; + u8 addr, pec; + int rc = 0; + u64 pid; + + skb_pull(skb, sizeof(struct mctp_i3c_internal_hdr)); + data_len = skb->len; + + ihdr = (void *)skb_mac_header(skb); + + pid = get_unaligned_be48(ihdr->dest); + mi = mctp_i3c_lookup(mbus, pid); + if (!mi) { + /* I3C endpoint went away after the packet was enqueued? */ + stats->tx_dropped++; + goto out; + } + + if (WARN_ON_ONCE(data_len + 1 > MCTP_I3C_MAXBUF)) + goto out; + + if (data_len + 1 > (unsigned int)mi->mwl) { + /* Route MTU was larger than supported by the endpoint */ + stats->tx_dropped++; + goto out; + } + + /* Need a linear buffer with space for the PEC */ + xfer.len = data_len + 1; + if (skb_tailroom(skb) >= 1) { + skb_put(skb, 1); + data = skb->data; + } else { + /* Otherwise need to copy the buffer */ + skb_copy_bits(skb, 0, mbus->tx_scratch, skb->len); + data = mbus->tx_scratch; + } + + /* PEC calculation */ + addr = mi->addr << 1; + pec = i2c_smbus_pec(0, &addr, 1); + pec = i2c_smbus_pec(pec, data, data_len); + data[data_len] = pec; + + xfer.data.out = data; + rc = i3c_device_do_priv_xfers(mi->i3c, &xfer, 1); + if (rc == 0) { + stats->tx_bytes += data_len; + stats->tx_packets++; + } else { + stats->tx_errors++; + } + +out: + if (mi) + mutex_unlock(&mi->lock); +} + +static int mctp_i3c_tx_thread(void *data) +{ + struct mctp_i3c_bus *mbus = data; + struct sk_buff *skb; + + for (;;) { + if (kthread_should_stop()) + break; + + spin_lock_bh(&mbus->tx_lock); + skb = mbus->tx_skb; + mbus->tx_skb = NULL; + spin_unlock_bh(&mbus->tx_lock); + + if (netif_queue_stopped(mbus->ndev)) + netif_wake_queue(mbus->ndev); + + if (skb) { + mctp_i3c_xmit(mbus, skb); + kfree_skb(skb); + } else { + wait_event_idle(mbus->tx_wq, + mbus->tx_skb || kthread_should_stop()); + } + } + + return 0; +} + +static netdev_tx_t mctp_i3c_start_xmit(struct sk_buff *skb, + struct net_device *ndev) +{ + struct mctp_i3c_bus *mbus = netdev_priv(ndev); + netdev_tx_t ret; + + spin_lock(&mbus->tx_lock); + netif_stop_queue(ndev); + if (mbus->tx_skb) { + dev_warn_ratelimited(&ndev->dev, "TX with queue stopped"); + ret = NETDEV_TX_BUSY; + } else { + mbus->tx_skb = skb; + ret = NETDEV_TX_OK; + } + spin_unlock(&mbus->tx_lock); + + if (ret == NETDEV_TX_OK) + wake_up(&mbus->tx_wq); + + return ret; +} + +static void mctp_i3c_bus_free(struct mctp_i3c_bus *mbus) +__must_hold(&busdevs_lock) +{ + struct mctp_i3c_device *mi = NULL, *tmp = NULL; + + if (mbus->tx_thread) { + kthread_stop(mbus->tx_thread); + mbus->tx_thread = NULL; + } + + /* Remove any child devices */ + list_for_each_entry_safe(mi, tmp, &mbus->devs, list) { + mctp_i3c_remove_device(mi); + } + + kfree_skb(mbus->tx_skb); + list_del(&mbus->list); +} + +static void mctp_i3c_ndo_uninit(struct net_device *ndev) +{ + struct mctp_i3c_bus *mbus = netdev_priv(ndev); + + /* Perform cleanup here to ensure there are no remaining references */ + mctp_i3c_bus_free(mbus); +} + +static int mctp_i3c_header_create(struct sk_buff *skb, struct net_device *dev, + unsigned short type, const void *daddr, + const void *saddr, unsigned int len) +{ + struct mctp_i3c_internal_hdr *ihdr; + + skb_push(skb, sizeof(struct mctp_i3c_internal_hdr)); + skb_reset_mac_header(skb); + ihdr = (void *)skb_mac_header(skb); + memcpy(ihdr->dest, daddr, PID_SIZE); + memcpy(ihdr->source, saddr, PID_SIZE); + return 0; +} + +static const struct net_device_ops mctp_i3c_ops = { + .ndo_start_xmit = mctp_i3c_start_xmit, + .ndo_uninit = mctp_i3c_ndo_uninit, +}; + +static const struct header_ops mctp_i3c_headops = { + .create = mctp_i3c_header_create, +}; + +static void mctp_i3c_net_setup(struct net_device *dev) +{ + dev->type = ARPHRD_MCTP; + + dev->mtu = MCTP_I3C_MAXMTU; + dev->min_mtu = MCTP_I3C_MINMTU; + dev->max_mtu = MCTP_I3C_MAXMTU; + dev->tx_queue_len = MCTP_I3C_TX_QUEUE_LEN; + + dev->hard_header_len = sizeof(struct mctp_i3c_internal_hdr); + dev->addr_len = PID_SIZE; + + dev->netdev_ops = &mctp_i3c_ops; + dev->header_ops = &mctp_i3c_headops; +} + +static bool mctp_i3c_is_mctp_controller(struct i3c_bus *bus) +{ + struct i3c_dev_desc *master = bus->cur_master; + + if (!master) + return false; + + return of_property_read_bool(master->common.master->dev.of_node, + MCTP_I3C_OF_PROP); +} + +/* Returns the Provisioned Id of a local bus master */ +static int mctp_i3c_bus_local_pid(struct i3c_bus *bus, u64 *ret_pid) +{ + struct i3c_dev_desc *master; + + master = bus->cur_master; + if (WARN_ON_ONCE(!master)) + return -ENOENT; + *ret_pid = master->info.pid; + + return 0; +} + +/* Returns an ERR_PTR on failure */ +static struct mctp_i3c_bus *mctp_i3c_bus_add(struct i3c_bus *bus) +__must_hold(&busdevs_lock) +{ + struct mctp_i3c_bus *mbus = NULL; + struct net_device *ndev = NULL; + char namebuf[IFNAMSIZ]; + u8 addr[PID_SIZE]; + int rc; + + if (!mctp_i3c_is_mctp_controller(bus)) + return ERR_PTR(-ENOENT); + + snprintf(namebuf, sizeof(namebuf), "mctpi3c%d", bus->id); + ndev = alloc_netdev(sizeof(*mbus), namebuf, NET_NAME_ENUM, + mctp_i3c_net_setup); + if (!ndev) { + rc = -ENOMEM; + goto err; + } + + mbus = netdev_priv(ndev); + mbus->ndev = ndev; + mbus->bus = bus; + INIT_LIST_HEAD(&mbus->devs); + list_add(&mbus->list, &busdevs); + + rc = mctp_i3c_bus_local_pid(bus, &mbus->pid); + if (rc < 0) { + dev_err(&ndev->dev, "No I3C PID available\n"); + goto err_free_uninit; + } + put_unaligned_be48(mbus->pid, addr); + dev_addr_set(ndev, addr); + + init_waitqueue_head(&mbus->tx_wq); + spin_lock_init(&mbus->tx_lock); + mbus->tx_thread = kthread_run(mctp_i3c_tx_thread, mbus, + "%s/tx", ndev->name); + if (IS_ERR(mbus->tx_thread)) { + dev_warn(&ndev->dev, "Error creating thread: %pe\n", + mbus->tx_thread); + rc = PTR_ERR(mbus->tx_thread); + mbus->tx_thread = NULL; + goto err_free_uninit; + } + + rc = mctp_register_netdev(ndev, NULL); + if (rc < 0) { + dev_warn(&ndev->dev, "netdev register failed: %d\n", rc); + goto err_free_netdev; + } + return mbus; + +err_free_uninit: + /* uninit will not get called if a netdev has not been registered, + * so we perform the same mbus cleanup manually. + */ + mctp_i3c_bus_free(mbus); + +err_free_netdev: + free_netdev(ndev); + +err: + return ERR_PTR(rc); +} + +static void mctp_i3c_bus_remove(struct mctp_i3c_bus *mbus) +__must_hold(&busdevs_lock) +{ + /* Unregister calls through to ndo_uninit -> mctp_i3c_bus_free() */ + mctp_unregister_netdev(mbus->ndev); + + free_netdev(mbus->ndev); + /* mbus is deallocated */ +} + +/* Removes all mctp-i3c busses */ +static void mctp_i3c_bus_remove_all(void) +{ + struct mctp_i3c_bus *mbus = NULL, *tmp = NULL; + + mutex_lock(&busdevs_lock); + list_for_each_entry_safe(mbus, tmp, &busdevs, list) { + mctp_i3c_bus_remove(mbus); + } + mutex_unlock(&busdevs_lock); +} + +/* Adds a i3c_bus if it isn't already in the busdevs list. + * Suitable as an i3c_for_each_bus_locked callback. + */ +static int mctp_i3c_bus_add_new(struct i3c_bus *bus, void *data) +{ + struct mctp_i3c_bus *mbus = NULL, *tmp = NULL; + bool exists = false; + + mutex_lock(&busdevs_lock); + list_for_each_entry_safe(mbus, tmp, &busdevs, list) + if (mbus->bus == bus) + exists = true; + + /* It is OK for a bus to already exist. That can occur due to + * the race in mod_init between notifier and for_each_bus + */ + if (!exists) + mctp_i3c_bus_add(bus); + mutex_unlock(&busdevs_lock); + return 0; +} + +static void mctp_i3c_notify_bus_remove(struct i3c_bus *bus) +{ + struct mctp_i3c_bus *mbus = NULL, *tmp; + + mutex_lock(&busdevs_lock); + list_for_each_entry_safe(mbus, tmp, &busdevs, list) + if (mbus->bus == bus) + mctp_i3c_bus_remove(mbus); + mutex_unlock(&busdevs_lock); +} + +static int mctp_i3c_notifier_call(struct notifier_block *nb, + unsigned long action, void *data) +{ + switch (action) { + case I3C_NOTIFY_BUS_ADD: + mctp_i3c_bus_add_new((struct i3c_bus *)data, NULL); + break; + case I3C_NOTIFY_BUS_REMOVE: + mctp_i3c_notify_bus_remove((struct i3c_bus *)data); + break; + } + return NOTIFY_DONE; +} + +static struct notifier_block mctp_i3c_notifier = { + .notifier_call = mctp_i3c_notifier_call, +}; + +static const struct i3c_device_id mctp_i3c_ids[] = { + I3C_CLASS(I3C_DCR_MCTP, NULL), + { 0 }, +}; + +static struct i3c_driver mctp_i3c_driver = { + .driver = { + .name = "mctp-i3c", + }, + .probe = mctp_i3c_probe, + .remove = mctp_i3c_remove, + .id_table = mctp_i3c_ids, +}; + +static __init int mctp_i3c_mod_init(void) +{ + int rc; + + rc = i3c_register_notifier(&mctp_i3c_notifier); + if (rc < 0) { + i3c_driver_unregister(&mctp_i3c_driver); + return rc; + } + + i3c_for_each_bus_locked(mctp_i3c_bus_add_new, NULL); + + rc = i3c_driver_register(&mctp_i3c_driver); + if (rc < 0) + return rc; + + return 0; +} + +static __exit void mctp_i3c_mod_exit(void) +{ + int rc; + + i3c_driver_unregister(&mctp_i3c_driver); + + rc = i3c_unregister_notifier(&mctp_i3c_notifier); + if (rc < 0) + pr_warn("MCTP I3C could not unregister notifier, %d\n", rc); + + mctp_i3c_bus_remove_all(); +} + +module_init(mctp_i3c_mod_init); +module_exit(mctp_i3c_mod_exit); + +MODULE_DEVICE_TABLE(i3c, mctp_i3c_ids); +MODULE_DESCRIPTION("MCTP I3C device"); +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Matt Johnston <matt@codeconstruct.com.au>"); |