@@ -3,6 +3,7 @@ if MCTP
menu "MCTP Device Drivers"
+
config MCTP_SERIAL
tristate "MCTP serial transport"
depends on TTY
@@ -21,6 +22,18 @@ config MCTP_SERIAL
Say y here if you need to connect to MCTP endpoints over serial. To
compile as a module, use m; the module will be called mctp-serial.
+config MCTP_TRANSPORT_I2C
+ tristate "MCTP SMBus/I2C transport"
+ # i2c-mux is optional, but we must build as a module if i2c-mux is a module
+ depends on I2C_MUX || !I2C_MUX
+ depends on I2C
+ depends on I2C_SLAVE
+ select MCTP_FLOWS
+ help
+ Provides a driver to access MCTP devices over SMBus/I2C transport,
+ from DMTF specification DSP0237. A MCTP protocol network device is
+ created for each I2C bus that has been assigned a mctp-i2c device.
+
endmenu
endif
@@ -1 +1,2 @@
obj-$(CONFIG_MCTP_SERIAL) += mctp-serial.o
+obj-$(CONFIG_MCTP_TRANSPORT_I2C) += mctp-i2c.o
new file mode 100644
@@ -0,0 +1,1002 @@
+// 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,
+};
+
+static struct {
+ /* lock protects clients and also prevents adding/removing adapters
+ * during mctp_i2c_client probe/remove.
+ */
+ struct mutex lock;
+ // list of struct mctp_i2c_client
+ struct list_head clients;
+} mi_driver_state;
+
+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 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_t flow_lock; // protects i2c_lock_count and release_count
+ int i2c_lock_count;
+ int release_count;
+};
+
+/* 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 curr_lock; // protects sel
+
+ struct list_head list; // for mi_driver_state.clients
+};
+
+// Header on the wire
+struct mctp_i2c_hdr {
+ u8 dest_slave;
+ u8 command;
+ 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 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
+}
+
+static ssize_t mctp_current_mux_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct mctp_i2c_client *mcli = i2c_get_clientdata(to_i2c_client(dev));
+ struct net_device *ndev = NULL;
+ unsigned long flags;
+ ssize_t l;
+
+ spin_lock_irqsave(&mcli->curr_lock, flags);
+ if (mcli->sel) {
+ ndev = mcli->sel->ndev;
+ dev_hold(ndev);
+ }
+ spin_unlock_irqrestore(&mcli->curr_lock, flags);
+ l = scnprintf(buf, PAGE_SIZE, "%s\n", ndev ? ndev->name : "(none)");
+ if (ndev)
+ dev_put(ndev);
+ return l;
+}
+static DEVICE_ATTR_RO(mctp_current_mux);
+
+/* 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, "%s failed, MCTP requires a 7-bit I2C address, addr=0x%x",
+ __func__, client->addr);
+ rc = -EINVAL;
+ goto err;
+ }
+
+ root = mux_root_adapter(client->adapter);
+ if (!root) {
+ dev_err(&client->dev, "%s failed to find root adapter\n", __func__);
+ 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->curr_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, "%s i2c register failed %d\n", __func__, rc);
+ mcli->client = NULL;
+ i2c_set_clientdata(client, NULL);
+ goto err;
+ }
+
+ rc = device_create_file(&client->dev, &dev_attr_mctp_current_mux);
+ if (rc < 0) {
+ dev_err(&client->dev, "%s adding sysfs \"%s\" failed %d\n", __func__,
+ dev_attr_mctp_current_mux.attr.name, rc);
+ // continue anyway
+ }
+
+ return mcli;
+err:
+ if (mcli) {
+ if (mcli->client) {
+ device_remove_file(&mcli->client->dev, &dev_attr_mctp_current_mux);
+ 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(&mi_driver_state.lock));
+ WARN_ON(!list_empty(&mcli->devs));
+ WARN_ON(mcli->sel); // sanity check, no locking
+
+ device_remove_file(&mcli->client->dev, &dev_attr_mctp_current_mux);
+ rc = i2c_slave_unregister(mcli->client);
+ // leak if it fails, we can't propagate errors upwards
+ if (rc < 0)
+ dev_err(&mcli->client->dev, "%s i2c unregister failed %d\n", __func__, rc);
+ else
+ kfree(mcli);
+}
+
+/* Switch the mctp i2c device to receive responses.
+ * Call with curr_lock held
+ */
+static void __mctp_i2c_device_select(struct mctp_i2c_client *mcli,
+ struct mctp_i2c_dev *midev)
+{
+ assert_spin_locked(&mcli->curr_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->curr_lock, flags);
+ __mctp_i2c_device_select(mcli, midev);
+ spin_unlock_irqrestore(&mcli->curr_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->curr_lock, flags);
+ midev = mcli->sel;
+ if (midev)
+ dev_hold(midev->ndev);
+ spin_unlock_irqrestore(&mcli->curr_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;
+ u8 pec, calc_pec;
+ size_t recvlen;
+
+ /* + 1 for the PEC */
+ if (midev->rx_pos < MCTP_I2C_MINLEN + 1) {
+ ndev->stats.rx_length_errors++;
+ return -EINVAL;
+ }
+ recvlen = midev->rx_pos - 1;
+
+ hdr = (void *)midev->rx_buffer;
+ if (hdr->command != MCTP_I2C_COMMANDCODE) {
+ ndev->stats.rx_dropped++;
+ 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;
+
+ if (netif_rx(skb) == NET_RX_SUCCESS) {
+ ndev->stats.rx_packets++;
+ ndev->stats.rx_bytes += skb->len;
+ } 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->flow_lock, flags);
+ lock = midev->i2c_lock_count == 0;
+ midev->i2c_lock_count++;
+ spin_unlock_irqrestore(&midev->flow_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->flow_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->flow_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 %zu 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,
+ "%s __i2c_transfer failed %d", __func__, 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->flow_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->flow_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;
+
+ 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;
+ if (hdr->byte_count > MCTP_I2C_MAXBLOCK)
+ return -EMSGSIZE;
+ hdr->source_slave = ((llsrc << 1) & 0xff) | 0x01;
+ mhdr->ver = 0x01;
+
+ return 0;
+}
+
+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->flow_lock, flags);
+ midev->release_count++;
+ spin_unlock_irqrestore(&midev->flow_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,
+};
+
+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;
+ dev->needs_free_netdev = true;
+}
+
+static int mctp_i2c_add_netdev(struct mctp_i2c_client *mcli,
+ struct i2c_adapter *adap)
+{
+ unsigned long flags;
+ struct mctp_i2c_dev *midev = NULL;
+ struct net_device *ndev = NULL;
+ struct i2c_adapter *root;
+ 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",
+ mcli->client->adapter->name, root->name);
+ return -EINVAL;
+ }
+
+ WARN_ON(!mutex_is_locked(&mi_driver_state.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, "%s alloc netdev failed\n", __func__);
+ 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 = netdev_priv(ndev);
+ skb_queue_head_init(&midev->tx_queue);
+ INIT_LIST_HEAD(&midev->list);
+ midev->adapter = adap;
+ midev->client = mcli;
+ spin_lock_init(&midev->flow_lock);
+ midev->i2c_lock_count = 0;
+ midev->release_count = 0;
+ /* Hold references */
+ get_device(&midev->adapter->dev);
+ get_device(&midev->client->client->dev);
+ midev->ndev = ndev;
+ init_waitqueue_head(&midev->tx_wq);
+ midev->tx_thread = kthread_create(mctp_i2c_tx_thread, midev,
+ "%s/tx", namebuf);
+ if (IS_ERR_OR_NULL(midev->tx_thread)) {
+ rc = -ENOMEM;
+ goto err_free;
+ }
+
+ rc = mctp_register_netdev(ndev, &mctp_i2c_mctp_ops);
+ if (rc < 0) {
+ dev_err(&mcli->client->dev,
+ "%s register netdev \"%s\" failed %d\n", __func__,
+ ndev->name, rc);
+ goto err_stop_kthread;
+ }
+ spin_lock_irqsave(&mcli->curr_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->curr_lock, flags);
+
+ wake_up_process(midev->tx_thread);
+
+ return 0;
+
+err_stop_kthread:
+ kthread_stop(midev->tx_thread);
+
+err_free:
+ free_netdev(ndev);
+
+err:
+ return rc;
+}
+
+// Removes and unregisters a mctp-i2c netdev
+static void mctp_i2c_free_netdev(struct mctp_i2c_dev *midev)
+{
+ struct mctp_i2c_client *mcli = midev->client;
+ unsigned long flags;
+
+ netif_stop_queue(midev->ndev);
+ kthread_stop(midev->tx_thread);
+ skb_queue_purge(&midev->tx_queue);
+
+ /* Release references, used only for TX which has stopped */
+ put_device(&midev->adapter->dev);
+ put_device(&mcli->client->dev);
+
+ /* Remove it from the parent mcli */
+ spin_lock_irqsave(&mcli->curr_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->curr_lock, flags);
+
+ /* Remove netdev. mctp_i2c_slave_cb() takes a dev_hold() so removing
+ * it now is safe. unregister_netdev() frees ndev and midev.
+ */
+ mctp_unregister_netdev(midev->ndev);
+}
+
+// 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)
+{
+ unsigned long flags;
+ struct mctp_i2c_dev *midev = NULL, *m = NULL;
+
+ WARN_ON(!mutex_is_locked(&mi_driver_state.lock));
+ spin_lock_irqsave(&mcli->curr_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->curr_lock, flags);
+
+ if (midev)
+ mctp_i2c_free_netdev(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, "%s failed to find root adapter for %s\n",
+ __func__, 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(&mi_driver_state.lock);
+ list_for_each_entry(m, &mi_driver_state.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, "%s Failed adding mctp-i2c device",
+ __func__);
+ }
+ mutex_unlock(&mi_driver_state.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(&mi_driver_state.lock);
+ list_for_each_entry(mcli, &mi_driver_state.clients, list) {
+ if (mcli->client->adapter == root) {
+ mctp_i2c_remove_netdev(mcli, adap);
+ break;
+ }
+ }
+ mutex_unlock(&mi_driver_state.lock);
+}
+
+static int mctp_i2c_probe(struct i2c_client *client)
+{
+ struct mctp_i2c_client *mcli = NULL;
+ int rc;
+
+ mutex_lock(&mi_driver_state.lock);
+ mcli = mctp_i2c_new_client(client);
+ if (IS_ERR(mcli)) {
+ rc = PTR_ERR(mcli);
+ mcli = NULL;
+ goto out;
+ } else {
+ list_add(&mcli->list, &mi_driver_state.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(&mi_driver_state.lock);
+ return rc;
+}
+
+static int 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(&mi_driver_state.lock);
+ list_del(&mcli->list);
+ // Remove all child adapter netdevs
+ list_for_each_entry_safe(midev, tmp, &mcli->devs, list)
+ mctp_i2c_free_netdev(midev);
+
+ mctp_i2c_free_client(mcli);
+ mutex_unlock(&mi_driver_state.lock);
+ // Callers ignore return code
+ return 0;
+}
+
+/* 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", 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",
+ .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_init(void)
+{
+ int rc;
+
+ INIT_LIST_HEAD(&mi_driver_state.clients);
+ mutex_init(&mi_driver_state.lock);
+ pr_info("MCTP SMBus/I2C transport 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_exit(void)
+{
+ int rc;
+
+ rc = bus_unregister_notifier(&i2c_bus_type, &mctp_i2c_notifier);
+ if (rc < 0)
+ pr_warn("%s Could not unregister notifier, %d", __func__, rc);
+ i2c_del_driver(&mctp_i2c_driver);
+}
+
+module_init(mctp_i2c_init);
+module_exit(mctp_i2c_exit);
+
+MODULE_DESCRIPTION("MCTP SMBus/I2C device");
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Matt Johnston <matt@codeconstruct.com.au>");