diff options
Diffstat (limited to 'drivers/net/mctp/mctp-i2c.c')
| -rw-r--r-- | drivers/net/mctp/mctp-i2c.c | 1080 |
1 files changed, 1080 insertions, 0 deletions
diff --git a/drivers/net/mctp/mctp-i2c.c b/drivers/net/mctp/mctp-i2c.c new file mode 100644 index 000000000000..0762c735dd8a --- /dev/null +++ b/drivers/net/mctp/mctp-i2c.c @@ -0,0 +1,1080 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Management Controller Transport Protocol (MCTP) + * Implements DMTF specification + * "DSP0237 Management Component Transport Protocol (MCTP) SMBus/I2C + * Transport Binding" + * https://www.dmtf.org/sites/default/files/standards/documents/DSP0237_1.2.0.pdf + * + * A netdev is created for each I2C bus that handles MCTP. In the case of an I2C + * mux topology a single I2C client is attached to the root of the mux topology, + * shared between all mux I2C busses underneath. For non-mux cases an I2C client + * is attached per netdev. + * + * mctp-i2c-controller.yml devicetree binding has further details. + * + * Copyright (c) 2022 Code Construct + * Copyright (c) 2022 Google + */ + +#include <linux/module.h> +#include <linux/netdevice.h> +#include <linux/i2c.h> +#include <linux/i2c-mux.h> +#include <linux/if_arp.h> +#include <net/mctp.h> +#include <net/mctpdevice.h> + +/* byte_count is limited to u8 */ +#define MCTP_I2C_MAXBLOCK 255 +/* One byte is taken by source_slave */ +#define MCTP_I2C_MAXMTU (MCTP_I2C_MAXBLOCK - 1) +#define MCTP_I2C_MINMTU (64 + 4) +/* Allow space for dest_address, command, byte_count, data, PEC */ +#define MCTP_I2C_BUFSZ (3 + MCTP_I2C_MAXBLOCK + 1) +#define MCTP_I2C_MINLEN 8 +#define MCTP_I2C_COMMANDCODE 0x0f +#define MCTP_I2C_TX_WORK_LEN 100 +/* Sufficient for 64kB at min mtu */ +#define MCTP_I2C_TX_QUEUE_LEN 1100 + +#define MCTP_I2C_OF_PROP "mctp-controller" + +enum { + MCTP_I2C_FLOW_STATE_NEW = 0, + MCTP_I2C_FLOW_STATE_ACTIVE, +}; + +/* List of all struct mctp_i2c_client + * Lock protects driver_clients and also prevents adding/removing adapters + * during mctp_i2c_client probe/remove. + */ +static DEFINE_MUTEX(driver_clients_lock); +static LIST_HEAD(driver_clients); + +struct mctp_i2c_client; + +/* The netdev structure. One of these per I2C adapter. */ +struct mctp_i2c_dev { + struct net_device *ndev; + struct i2c_adapter *adapter; + struct mctp_i2c_client *client; + struct list_head list; /* For mctp_i2c_client.devs */ + + size_t rx_pos; + u8 rx_buffer[MCTP_I2C_BUFSZ]; + struct completion rx_done; + + struct task_struct *tx_thread; + wait_queue_head_t tx_wq; + struct sk_buff_head tx_queue; + u8 tx_scratch[MCTP_I2C_BUFSZ]; + + /* A fake entry in our tx queue to perform an unlock operation */ + struct sk_buff unlock_marker; + + /* Spinlock protects i2c_lock_count, release_count, allow_rx */ + spinlock_t lock; + int i2c_lock_count; + int release_count; + /* Indicates that the netif is ready to receive incoming packets */ + bool allow_rx; + +}; + +/* The i2c client structure. One per hardware i2c bus at the top of the + * mux tree, shared by multiple netdevs + */ +struct mctp_i2c_client { + struct i2c_client *client; + u8 lladdr; + + struct mctp_i2c_dev *sel; + struct list_head devs; + spinlock_t sel_lock; /* Protects sel and devs */ + + struct list_head list; /* For driver_clients */ +}; + +/* Header on the wire. */ +struct mctp_i2c_hdr { + u8 dest_slave; + u8 command; + /* Count of bytes following byte_count, excluding PEC */ + u8 byte_count; + u8 source_slave; +}; + +static int mctp_i2c_recv(struct mctp_i2c_dev *midev); +static int mctp_i2c_slave_cb(struct i2c_client *client, + enum i2c_slave_event event, u8 *val); +static void mctp_i2c_ndo_uninit(struct net_device *dev); +static int mctp_i2c_ndo_open(struct net_device *dev); + +static struct i2c_adapter *mux_root_adapter(struct i2c_adapter *adap) +{ +#if IS_ENABLED(CONFIG_I2C_MUX) + return i2c_root_adapter(&adap->dev); +#else + /* In non-mux config all i2c adapters are root adapters */ + return adap; +#endif +} + +/* Creates a new i2c slave device attached to the root adapter. + * Sets up the slave callback. + * Must be called with a client on a root adapter. + */ +static struct mctp_i2c_client *mctp_i2c_new_client(struct i2c_client *client) +{ + struct mctp_i2c_client *mcli = NULL; + struct i2c_adapter *root = NULL; + int rc; + + if (client->flags & I2C_CLIENT_TEN) { + dev_err(&client->dev, "failed, MCTP requires a 7-bit I2C address, addr=0x%x\n", + client->addr); + rc = -EINVAL; + goto err; + } + + root = mux_root_adapter(client->adapter); + if (!root) { + dev_err(&client->dev, "failed to find root adapter\n"); + rc = -ENOENT; + goto err; + } + if (root != client->adapter) { + dev_err(&client->dev, + "A mctp-i2c-controller client cannot be placed on an I2C mux adapter.\n" + " It should be placed on the mux tree root adapter\n" + " then set mctp-controller property on adapters to attach\n"); + rc = -EINVAL; + goto err; + } + + mcli = kzalloc(sizeof(*mcli), GFP_KERNEL); + if (!mcli) { + rc = -ENOMEM; + goto err; + } + spin_lock_init(&mcli->sel_lock); + INIT_LIST_HEAD(&mcli->devs); + INIT_LIST_HEAD(&mcli->list); + mcli->lladdr = client->addr & 0xff; + mcli->client = client; + i2c_set_clientdata(client, mcli); + + rc = i2c_slave_register(mcli->client, mctp_i2c_slave_cb); + if (rc < 0) { + dev_err(&client->dev, "i2c register failed %d\n", rc); + mcli->client = NULL; + i2c_set_clientdata(client, NULL); + goto err; + } + + return mcli; +err: + if (mcli) { + if (mcli->client) + i2c_unregister_device(mcli->client); + kfree(mcli); + } + return ERR_PTR(rc); +} + +static void mctp_i2c_free_client(struct mctp_i2c_client *mcli) +{ + int rc; + + WARN_ON(!mutex_is_locked(&driver_clients_lock)); + WARN_ON(!list_empty(&mcli->devs)); + WARN_ON(mcli->sel); /* sanity check, no locking */ + + rc = i2c_slave_unregister(mcli->client); + /* Leak if it fails, we can't propagate errors upwards */ + if (rc < 0) + dev_err(&mcli->client->dev, "i2c unregister failed %d\n", rc); + else + kfree(mcli); +} + +/* Switch the mctp i2c device to receive responses. + * Call with sel_lock held + */ +static void __mctp_i2c_device_select(struct mctp_i2c_client *mcli, + struct mctp_i2c_dev *midev) +{ + assert_spin_locked(&mcli->sel_lock); + if (midev) + dev_hold(midev->ndev); + if (mcli->sel) + dev_put(mcli->sel->ndev); + mcli->sel = midev; +} + +/* Switch the mctp i2c device to receive responses */ +static void mctp_i2c_device_select(struct mctp_i2c_client *mcli, + struct mctp_i2c_dev *midev) +{ + unsigned long flags; + + spin_lock_irqsave(&mcli->sel_lock, flags); + __mctp_i2c_device_select(mcli, midev); + spin_unlock_irqrestore(&mcli->sel_lock, flags); +} + +static int mctp_i2c_slave_cb(struct i2c_client *client, + enum i2c_slave_event event, u8 *val) +{ + struct mctp_i2c_client *mcli = i2c_get_clientdata(client); + struct mctp_i2c_dev *midev = NULL; + unsigned long flags; + int rc = 0; + + spin_lock_irqsave(&mcli->sel_lock, flags); + midev = mcli->sel; + if (midev) + dev_hold(midev->ndev); + spin_unlock_irqrestore(&mcli->sel_lock, flags); + + if (!midev) + return 0; + + switch (event) { + case I2C_SLAVE_WRITE_RECEIVED: + if (midev->rx_pos < MCTP_I2C_BUFSZ) { + midev->rx_buffer[midev->rx_pos] = *val; + midev->rx_pos++; + } else { + midev->ndev->stats.rx_over_errors++; + } + + break; + case I2C_SLAVE_WRITE_REQUESTED: + /* dest_slave as first byte */ + midev->rx_buffer[0] = mcli->lladdr << 1; + midev->rx_pos = 1; + break; + case I2C_SLAVE_STOP: + rc = mctp_i2c_recv(midev); + break; + default: + break; + } + + dev_put(midev->ndev); + return rc; +} + +/* Processes incoming data that has been accumulated by the slave cb */ +static int mctp_i2c_recv(struct mctp_i2c_dev *midev) +{ + struct net_device *ndev = midev->ndev; + struct mctp_i2c_hdr *hdr; + struct mctp_skb_cb *cb; + struct sk_buff *skb; + unsigned long flags; + u8 pec, calc_pec; + size_t recvlen; + int status; + + /* + 1 for the PEC */ + if (midev->rx_pos < MCTP_I2C_MINLEN + 1) { + ndev->stats.rx_length_errors++; + return -EINVAL; + } + /* recvlen excludes PEC */ + recvlen = midev->rx_pos - 1; + + hdr = (void *)midev->rx_buffer; + if (hdr->command != MCTP_I2C_COMMANDCODE) { + ndev->stats.rx_dropped++; + return -EINVAL; + } + + if (hdr->byte_count + offsetof(struct mctp_i2c_hdr, source_slave) != recvlen) { + ndev->stats.rx_length_errors++; + return -EINVAL; + } + + pec = midev->rx_buffer[midev->rx_pos - 1]; + calc_pec = i2c_smbus_pec(0, midev->rx_buffer, recvlen); + if (pec != calc_pec) { + ndev->stats.rx_crc_errors++; + return -EINVAL; + } + + skb = netdev_alloc_skb(ndev, recvlen); + if (!skb) { + ndev->stats.rx_dropped++; + return -ENOMEM; + } + + skb->protocol = htons(ETH_P_MCTP); + skb_put_data(skb, midev->rx_buffer, recvlen); + skb_reset_mac_header(skb); + skb_pull(skb, sizeof(struct mctp_i2c_hdr)); + skb_reset_network_header(skb); + + cb = __mctp_cb(skb); + cb->halen = 1; + cb->haddr[0] = hdr->source_slave >> 1; + + /* We need to ensure that the netif is not used once netdev + * unregister occurs + */ + spin_lock_irqsave(&midev->lock, flags); + if (midev->allow_rx) { + reinit_completion(&midev->rx_done); + spin_unlock_irqrestore(&midev->lock, flags); + + status = netif_rx(skb); + complete(&midev->rx_done); + } else { + status = NET_RX_DROP; + spin_unlock_irqrestore(&midev->lock, flags); + } + + if (status == NET_RX_SUCCESS) { + ndev->stats.rx_packets++; + ndev->stats.rx_bytes += recvlen; + } else { + ndev->stats.rx_dropped++; + } + return 0; +} + +enum mctp_i2c_flow_state { + MCTP_I2C_TX_FLOW_INVALID, + MCTP_I2C_TX_FLOW_NONE, + MCTP_I2C_TX_FLOW_NEW, + MCTP_I2C_TX_FLOW_EXISTING, +}; + +static enum mctp_i2c_flow_state +mctp_i2c_get_tx_flow_state(struct mctp_i2c_dev *midev, struct sk_buff *skb) +{ + enum mctp_i2c_flow_state state; + struct mctp_sk_key *key; + struct mctp_flow *flow; + unsigned long flags; + + flow = skb_ext_find(skb, SKB_EXT_MCTP); + if (!flow) + return MCTP_I2C_TX_FLOW_NONE; + + key = flow->key; + if (!key) + return MCTP_I2C_TX_FLOW_NONE; + + spin_lock_irqsave(&key->lock, flags); + /* If the key is present but invalid, we're unlikely to be able + * to handle the flow at all; just drop now + */ + if (!key->valid) { + state = MCTP_I2C_TX_FLOW_INVALID; + + } else if (key->dev_flow_state == MCTP_I2C_FLOW_STATE_NEW) { + key->dev_flow_state = MCTP_I2C_FLOW_STATE_ACTIVE; + state = MCTP_I2C_TX_FLOW_NEW; + } else { + state = MCTP_I2C_TX_FLOW_EXISTING; + } + + spin_unlock_irqrestore(&key->lock, flags); + + return state; +} + +/* We're not contending with ourselves here; we only need to exclude other + * i2c clients from using the bus. refcounts are simply to prevent + * recursive locking. + */ +static void mctp_i2c_lock_nest(struct mctp_i2c_dev *midev) +{ + unsigned long flags; + bool lock; + + spin_lock_irqsave(&midev->lock, flags); + lock = midev->i2c_lock_count == 0; + midev->i2c_lock_count++; + spin_unlock_irqrestore(&midev->lock, flags); + + if (lock) + i2c_lock_bus(midev->adapter, I2C_LOCK_SEGMENT); +} + +static void mctp_i2c_unlock_nest(struct mctp_i2c_dev *midev) +{ + unsigned long flags; + bool unlock; + + spin_lock_irqsave(&midev->lock, flags); + if (!WARN_ONCE(midev->i2c_lock_count == 0, "lock count underflow!")) + midev->i2c_lock_count--; + unlock = midev->i2c_lock_count == 0; + spin_unlock_irqrestore(&midev->lock, flags); + + if (unlock) + i2c_unlock_bus(midev->adapter, I2C_LOCK_SEGMENT); +} + +/* Unlocks the bus if was previously locked, used for cleanup */ +static void mctp_i2c_unlock_reset(struct mctp_i2c_dev *midev) +{ + unsigned long flags; + bool unlock; + + spin_lock_irqsave(&midev->lock, flags); + unlock = midev->i2c_lock_count > 0; + midev->i2c_lock_count = 0; + spin_unlock_irqrestore(&midev->lock, flags); + + if (unlock) + i2c_unlock_bus(midev->adapter, I2C_LOCK_SEGMENT); +} + +static void mctp_i2c_xmit(struct mctp_i2c_dev *midev, struct sk_buff *skb) +{ + struct net_device_stats *stats = &midev->ndev->stats; + enum mctp_i2c_flow_state fs; + struct mctp_i2c_hdr *hdr; + struct i2c_msg msg = {0}; + u8 *pecp; + int rc; + + fs = mctp_i2c_get_tx_flow_state(midev, skb); + + hdr = (void *)skb_mac_header(skb); + /* Sanity check that packet contents matches skb length, + * and can't exceed MCTP_I2C_BUFSZ + */ + if (skb->len != hdr->byte_count + 3) { + dev_warn_ratelimited(&midev->adapter->dev, + "Bad tx length %d vs skb %u\n", + hdr->byte_count + 3, skb->len); + return; + } + + if (skb_tailroom(skb) >= 1) { + /* Linear case with space, we can just append the PEC */ + skb_put(skb, 1); + } else { + /* Otherwise need to copy the buffer */ + skb_copy_bits(skb, 0, midev->tx_scratch, skb->len); + hdr = (void *)midev->tx_scratch; + } + + pecp = (void *)&hdr->source_slave + hdr->byte_count; + *pecp = i2c_smbus_pec(0, (u8 *)hdr, hdr->byte_count + 3); + msg.buf = (void *)&hdr->command; + /* command, bytecount, data, pec */ + msg.len = 2 + hdr->byte_count + 1; + msg.addr = hdr->dest_slave >> 1; + + switch (fs) { + case MCTP_I2C_TX_FLOW_NONE: + /* no flow: full lock & unlock */ + mctp_i2c_lock_nest(midev); + mctp_i2c_device_select(midev->client, midev); + rc = __i2c_transfer(midev->adapter, &msg, 1); + mctp_i2c_unlock_nest(midev); + break; + + case MCTP_I2C_TX_FLOW_NEW: + /* new flow: lock, tx, but don't unlock; that will happen + * on flow release + */ + mctp_i2c_lock_nest(midev); + mctp_i2c_device_select(midev->client, midev); + fallthrough; + + case MCTP_I2C_TX_FLOW_EXISTING: + /* existing flow: we already have the lock; just tx */ + rc = __i2c_transfer(midev->adapter, &msg, 1); + break; + + case MCTP_I2C_TX_FLOW_INVALID: + return; + } + + if (rc < 0) { + dev_warn_ratelimited(&midev->adapter->dev, + "__i2c_transfer failed %d\n", rc); + stats->tx_errors++; + } else { + stats->tx_bytes += skb->len; + stats->tx_packets++; + } +} + +static void mctp_i2c_flow_release(struct mctp_i2c_dev *midev) +{ + unsigned long flags; + bool unlock; + + spin_lock_irqsave(&midev->lock, flags); + if (midev->release_count > midev->i2c_lock_count) { + WARN_ONCE(1, "release count overflow"); + midev->release_count = midev->i2c_lock_count; + } + + midev->i2c_lock_count -= midev->release_count; + unlock = midev->i2c_lock_count == 0 && midev->release_count > 0; + midev->release_count = 0; + spin_unlock_irqrestore(&midev->lock, flags); + + if (unlock) + i2c_unlock_bus(midev->adapter, I2C_LOCK_SEGMENT); +} + +static int mctp_i2c_header_create(struct sk_buff *skb, struct net_device *dev, + unsigned short type, const void *daddr, + const void *saddr, unsigned int len) +{ + struct mctp_i2c_hdr *hdr; + struct mctp_hdr *mhdr; + u8 lldst, llsrc; + + if (len > MCTP_I2C_MAXMTU) + return -EMSGSIZE; + + lldst = *((u8 *)daddr); + llsrc = *((u8 *)saddr); + + skb_push(skb, sizeof(struct mctp_i2c_hdr)); + skb_reset_mac_header(skb); + hdr = (void *)skb_mac_header(skb); + mhdr = mctp_hdr(skb); + hdr->dest_slave = (lldst << 1) & 0xff; + hdr->command = MCTP_I2C_COMMANDCODE; + hdr->byte_count = len + 1; + hdr->source_slave = ((llsrc << 1) & 0xff) | 0x01; + mhdr->ver = 0x01; + + return sizeof(struct mctp_i2c_hdr); +} + +static int mctp_i2c_tx_thread(void *data) +{ + struct mctp_i2c_dev *midev = data; + struct sk_buff *skb; + unsigned long flags; + + for (;;) { + if (kthread_should_stop()) + break; + + spin_lock_irqsave(&midev->tx_queue.lock, flags); + skb = __skb_dequeue(&midev->tx_queue); + if (netif_queue_stopped(midev->ndev)) + netif_wake_queue(midev->ndev); + spin_unlock_irqrestore(&midev->tx_queue.lock, flags); + + if (skb == &midev->unlock_marker) { + mctp_i2c_flow_release(midev); + + } else if (skb) { + mctp_i2c_xmit(midev, skb); + kfree_skb(skb); + + } else { + wait_event_idle(midev->tx_wq, + !skb_queue_empty(&midev->tx_queue) || + kthread_should_stop()); + } + } + + return 0; +} + +static netdev_tx_t mctp_i2c_start_xmit(struct sk_buff *skb, + struct net_device *dev) +{ + struct mctp_i2c_dev *midev = netdev_priv(dev); + unsigned long flags; + + spin_lock_irqsave(&midev->tx_queue.lock, flags); + if (skb_queue_len(&midev->tx_queue) >= MCTP_I2C_TX_WORK_LEN) { + netif_stop_queue(dev); + spin_unlock_irqrestore(&midev->tx_queue.lock, flags); + netdev_err(dev, "BUG! Tx Ring full when queue awake!\n"); + return NETDEV_TX_BUSY; + } + + __skb_queue_tail(&midev->tx_queue, skb); + if (skb_queue_len(&midev->tx_queue) == MCTP_I2C_TX_WORK_LEN) + netif_stop_queue(dev); + spin_unlock_irqrestore(&midev->tx_queue.lock, flags); + + wake_up(&midev->tx_wq); + return NETDEV_TX_OK; +} + +static void mctp_i2c_release_flow(struct mctp_dev *mdev, + struct mctp_sk_key *key) + +{ + struct mctp_i2c_dev *midev = netdev_priv(mdev->dev); + unsigned long flags; + + spin_lock_irqsave(&midev->lock, flags); + midev->release_count++; + spin_unlock_irqrestore(&midev->lock, flags); + + /* Ensure we have a release operation queued, through the fake + * marker skb + */ + spin_lock(&midev->tx_queue.lock); + if (!midev->unlock_marker.next) + __skb_queue_tail(&midev->tx_queue, &midev->unlock_marker); + spin_unlock(&midev->tx_queue.lock); + + wake_up(&midev->tx_wq); +} + +static const struct net_device_ops mctp_i2c_ops = { + .ndo_start_xmit = mctp_i2c_start_xmit, + .ndo_uninit = mctp_i2c_ndo_uninit, + .ndo_open = mctp_i2c_ndo_open, +}; + +static const struct header_ops mctp_i2c_headops = { + .create = mctp_i2c_header_create, +}; + +static const struct mctp_netdev_ops mctp_i2c_mctp_ops = { + .release_flow = mctp_i2c_release_flow, +}; + +static void mctp_i2c_net_setup(struct net_device *dev) +{ + dev->type = ARPHRD_MCTP; + + dev->mtu = MCTP_I2C_MAXMTU; + dev->min_mtu = MCTP_I2C_MINMTU; + dev->max_mtu = MCTP_I2C_MAXMTU; + dev->tx_queue_len = MCTP_I2C_TX_QUEUE_LEN; + + dev->hard_header_len = sizeof(struct mctp_i2c_hdr); + dev->addr_len = 1; + + dev->netdev_ops = &mctp_i2c_ops; + dev->header_ops = &mctp_i2c_headops; +} + +/* Populates the mctp_i2c_dev priv struct for a netdev. + * Returns an error pointer on failure. + */ +static struct mctp_i2c_dev *mctp_i2c_midev_init(struct net_device *dev, + struct mctp_i2c_client *mcli, + struct i2c_adapter *adap) +{ + struct mctp_i2c_dev *midev = netdev_priv(dev); + unsigned long flags; + + midev->tx_thread = kthread_create(mctp_i2c_tx_thread, midev, + "%s/tx", dev->name); + if (IS_ERR(midev->tx_thread)) + return ERR_CAST(midev->tx_thread); + + midev->ndev = dev; + get_device(&adap->dev); + midev->adapter = adap; + get_device(&mcli->client->dev); + midev->client = mcli; + INIT_LIST_HEAD(&midev->list); + spin_lock_init(&midev->lock); + midev->i2c_lock_count = 0; + midev->release_count = 0; + init_completion(&midev->rx_done); + complete(&midev->rx_done); + init_waitqueue_head(&midev->tx_wq); + skb_queue_head_init(&midev->tx_queue); + + /* Add to the parent mcli */ + spin_lock_irqsave(&mcli->sel_lock, flags); + list_add(&midev->list, &mcli->devs); + /* Select a device by default */ + if (!mcli->sel) + __mctp_i2c_device_select(mcli, midev); + spin_unlock_irqrestore(&mcli->sel_lock, flags); + + /* Start the worker thread */ + wake_up_process(midev->tx_thread); + + return midev; +} + +/* Counterpart of mctp_i2c_midev_init */ +static void mctp_i2c_midev_free(struct mctp_i2c_dev *midev) +{ + struct mctp_i2c_client *mcli = midev->client; + unsigned long flags; + + if (midev->tx_thread) { + kthread_stop(midev->tx_thread); + midev->tx_thread = NULL; + } + + /* Unconditionally unlock on close */ + mctp_i2c_unlock_reset(midev); + + /* Remove the netdev from the parent i2c client. */ + spin_lock_irqsave(&mcli->sel_lock, flags); + list_del(&midev->list); + if (mcli->sel == midev) { + struct mctp_i2c_dev *first; + + first = list_first_entry_or_null(&mcli->devs, struct mctp_i2c_dev, list); + __mctp_i2c_device_select(mcli, first); + } + spin_unlock_irqrestore(&mcli->sel_lock, flags); + + skb_queue_purge(&midev->tx_queue); + put_device(&midev->adapter->dev); + put_device(&mcli->client->dev); +} + +/* Stops, unregisters, and frees midev */ +static void mctp_i2c_unregister(struct mctp_i2c_dev *midev) +{ + unsigned long flags; + + /* Stop tx thread prior to unregister, it uses netif_() functions */ + kthread_stop(midev->tx_thread); + midev->tx_thread = NULL; + + /* Prevent any new rx in mctp_i2c_recv(), let any pending work finish */ + spin_lock_irqsave(&midev->lock, flags); + midev->allow_rx = false; + spin_unlock_irqrestore(&midev->lock, flags); + wait_for_completion(&midev->rx_done); + + mctp_unregister_netdev(midev->ndev); + /* midev has been freed now by mctp_i2c_ndo_uninit callback */ + + free_netdev(midev->ndev); +} + +static void mctp_i2c_ndo_uninit(struct net_device *dev) +{ + struct mctp_i2c_dev *midev = netdev_priv(dev); + + /* Perform cleanup here to ensure that mcli->sel isn't holding + * a reference that would prevent unregister_netdevice() + * from completing. + */ + mctp_i2c_midev_free(midev); +} + +static int mctp_i2c_ndo_open(struct net_device *dev) +{ + struct mctp_i2c_dev *midev = netdev_priv(dev); + unsigned long flags; + + /* i2c rx handler can only pass packets once the netdev is registered */ + spin_lock_irqsave(&midev->lock, flags); + midev->allow_rx = true; + spin_unlock_irqrestore(&midev->lock, flags); + + return 0; +} + +static int mctp_i2c_add_netdev(struct mctp_i2c_client *mcli, + struct i2c_adapter *adap) +{ + struct mctp_i2c_dev *midev = NULL; + struct net_device *ndev = NULL; + struct i2c_adapter *root; + unsigned long flags; + char namebuf[30]; + int rc; + + root = mux_root_adapter(adap); + if (root != mcli->client->adapter) { + dev_err(&mcli->client->dev, + "I2C adapter %s is not a child bus of %s\n", + mcli->client->adapter->name, root->name); + return -EINVAL; + } + + WARN_ON(!mutex_is_locked(&driver_clients_lock)); + snprintf(namebuf, sizeof(namebuf), "mctpi2c%d", adap->nr); + ndev = alloc_netdev(sizeof(*midev), namebuf, NET_NAME_ENUM, mctp_i2c_net_setup); + if (!ndev) { + dev_err(&mcli->client->dev, "alloc netdev failed\n"); + rc = -ENOMEM; + goto err; + } + dev_net_set(ndev, current->nsproxy->net_ns); + SET_NETDEV_DEV(ndev, &adap->dev); + dev_addr_set(ndev, &mcli->lladdr); + + midev = mctp_i2c_midev_init(ndev, mcli, adap); + if (IS_ERR(midev)) { + rc = PTR_ERR(midev); + midev = NULL; + goto err; + } + + rc = mctp_register_netdev(ndev, &mctp_i2c_mctp_ops); + if (rc < 0) { + dev_err(&mcli->client->dev, + "register netdev \"%s\" failed %d\n", + ndev->name, rc); + goto err; + } + + spin_lock_irqsave(&midev->lock, flags); + midev->allow_rx = false; + spin_unlock_irqrestore(&midev->lock, flags); + + return 0; +err: + if (midev) + mctp_i2c_midev_free(midev); + if (ndev) + free_netdev(ndev); + return rc; +} + +/* Removes any netdev for adap. mcli is the parent root i2c client */ +static void mctp_i2c_remove_netdev(struct mctp_i2c_client *mcli, + struct i2c_adapter *adap) +{ + struct mctp_i2c_dev *midev = NULL, *m = NULL; + unsigned long flags; + + WARN_ON(!mutex_is_locked(&driver_clients_lock)); + spin_lock_irqsave(&mcli->sel_lock, flags); + /* List size is limited by number of MCTP netdevs on a single hardware bus */ + list_for_each_entry(m, &mcli->devs, list) + if (m->adapter == adap) { + midev = m; + break; + } + spin_unlock_irqrestore(&mcli->sel_lock, flags); + + if (midev) + mctp_i2c_unregister(midev); +} + +/* Determines whether a device is an i2c adapter. + * Optionally returns the root i2c_adapter + */ +static struct i2c_adapter *mctp_i2c_get_adapter(struct device *dev, + struct i2c_adapter **ret_root) +{ + struct i2c_adapter *root, *adap; + + if (dev->type != &i2c_adapter_type) + return NULL; + adap = to_i2c_adapter(dev); + root = mux_root_adapter(adap); + WARN_ONCE(!root, "MCTP I2C failed to find root adapter for %s\n", + dev_name(dev)); + if (!root) + return NULL; + if (ret_root) + *ret_root = root; + return adap; +} + +/* Determines whether a device is an i2c adapter with the "mctp-controller" + * devicetree property set. If adap is not an OF node, returns match_no_of + */ +static bool mctp_i2c_adapter_match(struct i2c_adapter *adap, bool match_no_of) +{ + if (!adap->dev.of_node) + return match_no_of; + return of_property_read_bool(adap->dev.of_node, MCTP_I2C_OF_PROP); +} + +/* Called for each existing i2c device (adapter or client) when a + * new mctp-i2c client is probed. + */ +static int mctp_i2c_client_try_attach(struct device *dev, void *data) +{ + struct i2c_adapter *adap = NULL, *root = NULL; + struct mctp_i2c_client *mcli = data; + + adap = mctp_i2c_get_adapter(dev, &root); + if (!adap) + return 0; + if (mcli->client->adapter != root) + return 0; + /* Must either have mctp-controller property on the adapter, or + * be a root adapter if it's non-devicetree + */ + if (!mctp_i2c_adapter_match(adap, adap == root)) + return 0; + + return mctp_i2c_add_netdev(mcli, adap); +} + +static void mctp_i2c_notify_add(struct device *dev) +{ + struct mctp_i2c_client *mcli = NULL, *m = NULL; + struct i2c_adapter *root = NULL, *adap = NULL; + int rc; + + adap = mctp_i2c_get_adapter(dev, &root); + if (!adap) + return; + /* Check for mctp-controller property on the adapter */ + if (!mctp_i2c_adapter_match(adap, false)) + return; + + /* Find an existing mcli for adap's root */ + mutex_lock(&driver_clients_lock); + list_for_each_entry(m, &driver_clients, list) { + if (m->client->adapter == root) { + mcli = m; + break; + } + } + + if (mcli) { + rc = mctp_i2c_add_netdev(mcli, adap); + if (rc < 0) + dev_warn(dev, "Failed adding mctp-i2c net device\n"); + } + mutex_unlock(&driver_clients_lock); +} + +static void mctp_i2c_notify_del(struct device *dev) +{ + struct i2c_adapter *root = NULL, *adap = NULL; + struct mctp_i2c_client *mcli = NULL; + + adap = mctp_i2c_get_adapter(dev, &root); + if (!adap) + return; + + mutex_lock(&driver_clients_lock); + list_for_each_entry(mcli, &driver_clients, list) { + if (mcli->client->adapter == root) { + mctp_i2c_remove_netdev(mcli, adap); + break; + } + } + mutex_unlock(&driver_clients_lock); +} + +static int mctp_i2c_probe(struct i2c_client *client) +{ + struct mctp_i2c_client *mcli = NULL; + int rc; + + mutex_lock(&driver_clients_lock); + mcli = mctp_i2c_new_client(client); + if (IS_ERR(mcli)) { + rc = PTR_ERR(mcli); + mcli = NULL; + goto out; + } else { + list_add(&mcli->list, &driver_clients); + } + + /* Add a netdev for adapters that have a 'mctp-controller' property */ + i2c_for_each_dev(mcli, mctp_i2c_client_try_attach); + rc = 0; +out: + mutex_unlock(&driver_clients_lock); + return rc; +} + +static void mctp_i2c_remove(struct i2c_client *client) +{ + struct mctp_i2c_client *mcli = i2c_get_clientdata(client); + struct mctp_i2c_dev *midev = NULL, *tmp = NULL; + + mutex_lock(&driver_clients_lock); + list_del(&mcli->list); + /* Remove all child adapter netdevs */ + list_for_each_entry_safe(midev, tmp, &mcli->devs, list) + mctp_i2c_unregister(midev); + + mctp_i2c_free_client(mcli); + mutex_unlock(&driver_clients_lock); +} + +/* We look for a 'mctp-controller' property on I2C busses as they are + * added/deleted, creating/removing netdevs as required. + */ +static int mctp_i2c_notifier_call(struct notifier_block *nb, + unsigned long action, void *data) +{ + struct device *dev = data; + + switch (action) { + case BUS_NOTIFY_ADD_DEVICE: + mctp_i2c_notify_add(dev); + break; + case BUS_NOTIFY_DEL_DEVICE: + mctp_i2c_notify_del(dev); + break; + } + return NOTIFY_DONE; +} + +static struct notifier_block mctp_i2c_notifier = { + .notifier_call = mctp_i2c_notifier_call, +}; + +static const struct i2c_device_id mctp_i2c_id[] = { + { "mctp-i2c-interface", 0 }, + {}, +}; +MODULE_DEVICE_TABLE(i2c, mctp_i2c_id); + +static const struct of_device_id mctp_i2c_of_match[] = { + { .compatible = "mctp-i2c-controller" }, + {}, +}; +MODULE_DEVICE_TABLE(of, mctp_i2c_of_match); + +static struct i2c_driver mctp_i2c_driver = { + .driver = { + .name = "mctp-i2c-interface", + .of_match_table = mctp_i2c_of_match, + }, + .probe_new = mctp_i2c_probe, + .remove = mctp_i2c_remove, + .id_table = mctp_i2c_id, +}; + +static __init int mctp_i2c_mod_init(void) +{ + int rc; + + pr_info("MCTP I2C interface driver\n"); + rc = i2c_add_driver(&mctp_i2c_driver); + if (rc < 0) + return rc; + rc = bus_register_notifier(&i2c_bus_type, &mctp_i2c_notifier); + if (rc < 0) { + i2c_del_driver(&mctp_i2c_driver); + return rc; + } + return 0; +} + +static __exit void mctp_i2c_mod_exit(void) +{ + int rc; + + rc = bus_unregister_notifier(&i2c_bus_type, &mctp_i2c_notifier); + if (rc < 0) + pr_warn("MCTP I2C could not unregister notifier, %d\n", rc); + i2c_del_driver(&mctp_i2c_driver); +} + +module_init(mctp_i2c_mod_init); +module_exit(mctp_i2c_mod_exit); + +MODULE_DESCRIPTION("MCTP I2C device"); +MODULE_LICENSE("GPL v2"); +MODULE_AUTHOR("Matt Johnston <matt@codeconstruct.com.au>"); |