> +#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;
Why static const and not #define? It would also be normal for
variables to be lower case, to make it clear they are in fact
variables, not #defines.
> +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;
> +};
Since you have commented about most of the members of these
structures, you could use kerneldoc.
> +/* 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;
> +
> +/* Returns the 48 bit Provisioned Id from an i3c_device_info.pid */
> +static void pid_to_addr(u64 pid, u8 addr[PID_SIZE])
> +{
> + pid = cpu_to_be64(pid);
> + memcpy(addr, ((u8 *)&pid) + 2, PID_SIZE);
> +}
> +
> +static u64 addr_to_pid(u8 addr[PID_SIZE])
> +{
> + u64 pid = 0;
> +
> + memcpy(((u8 *)&pid) + 2, addr, PID_SIZE);
> + return be64_to_cpu(pid);
> +}
I don't know anything about MCTP. But Ethernet MAC addresses are also
48 bits. Could you make use of u64_to_ether_addr() and ether_addr_to_u64()?
> +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,
> + };
> + bool ibi_set = false, ibi_enabled = false;
> + 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 == 0) {
> + ibi_set = true;
> + } else if (rc == -ENOTSUPP) {
In networking, we try to avoid ENOTSUPP and use EOPNOTSUPP:
https://lore.kernel.org/netdev/20200511165319.2251678-1-kuba@xxxxxxxxxx/
> +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);
ether_addr_copy() ?
> +/* 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;
> + u8 addr[PID_SIZE];
> + char namebuf[IFNAMSIZ];
> + 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) {
> + pr_warn("No memory for %s\n", namebuf);
pr_ functions are not liked too much. Is there a struct device you can
use with dev_warn()?
Andrew
