Re: [PATCH v1 1/6] net/can: Initial host SocketCan support for CAN FD.

[Vikram Garhwal]

Hi Jan,
A couple of comments on this patch.
On Tue, Jul 14, 2020 at 02:20:14PM +0200, pisa@cmp.felk.cvut.cz wrote:
> From: Jan Charvat <charvj10@fel.cvut.cz>
>
> Signed-off-by: Jan Charvat <charvj10@fel.cvut.cz>
> Signed-off-by: Pavel Pisa <pisa@cmp.felk.cvut.cz>
> ---
>  hw/net/can/can_sja1000.c |  2 ++
>  include/net/can_emu.h    |  8 ++++++-
>  net/can/can_socketcan.c  | 47 +++++++++++++++++++++++++++++++++++++---
>  3 files changed, 53 insertions(+), 4 deletions(-)
>
> diff --git a/hw/net/can/can_sja1000.c b/hw/net/can/can_sja1000.c
> index ea915a023a..d83c550edc 100644
> --- a/hw/net/can/can_sja1000.c
> +++ b/hw/net/can/can_sja1000.c
> @@ -268,6 +268,7 @@ static void buff2frame_pel(const uint8_t *buff, 
> qemu_can_frame *frame)
>  {
>      uint8_t i;
>
> +    frame->flags = 0;
>      frame->can_id = 0;
>      if (buff[0] & 0x40) { /* RTR */
>          frame->can_id = QEMU_CAN_RTR_FLAG;
> @@ -303,6 +304,7 @@ static void buff2frame_bas(const uint8_t *buff, 
> qemu_can_frame *frame)
>  {
>      uint8_t i;
>
> +    frame->flags = 0;
>      frame->can_id = ((buff[0] << 3) & (0xff << 3)) + ((buff[1] >> 5) & 0x07);
>      if (buff[1] & 0x10) { /* RTR */
>          frame->can_id = QEMU_CAN_RTR_FLAG;
> diff --git a/include/net/can_emu.h b/include/net/can_emu.h
> index fce9770928..c6164dcfb4 100644
> --- a/include/net/can_emu.h
> +++ b/include/net/can_emu.h
> @@ -46,7 +46,8 @@ typedef uint32_t qemu_canid_t;
>  typedef struct qemu_can_frame {
>      qemu_canid_t    can_id;  /* 32 bit CAN_ID + EFF/RTR/ERR flags */
>      uint8_t         can_dlc; /* data length code: 0 .. 8 */
> -    uint8_t         data[8] QEMU_ALIGNED(8);
> +    uint8_t         flags;
> +    uint8_t         data[64] QEMU_ALIGNED(8);
>  } qemu_can_frame;
>
>  /* Keep defines for QEMU separate from Linux ones for now */
> @@ -58,6 +59,10 @@ typedef struct qemu_can_frame {
>  #define QEMU_CAN_SFF_MASK 0x000007FFU /* standard frame format (SFF) */
>  #define QEMU_CAN_EFF_MASK 0x1FFFFFFFU /* extended frame format (EFF) */
>
> +#define QEMU_CAN_FRMF_BRS     0x01 /* bit rate switch (2nd bitrate for data) 
> */
> +#define QEMU_CAN_FRMF_ESI     0x02 /* error state ind. of transmitting node 
> */
> +#define QEMU_CAN_FRMF_TYPE_FD 0x10 /* internal bit ind. of CAN FD frame */
> +
>  /**
>   * struct qemu_can_filter - CAN ID based filter in can_register().
>   * @can_id:   relevant bits of CAN ID which are not masked out.
> @@ -97,6 +102,7 @@ struct CanBusClientState {
>      char *model;
>      char *name;
>      void (*destructor)(CanBusClientState *);
> +    bool fd_mode;
>  };
>
>  #define TYPE_CAN_BUS "can-bus"
> diff --git a/net/can/can_socketcan.c b/net/can/can_socketcan.c
> index b7ef63ec0e..fbc0b62ea4 100644
> --- a/net/can/can_socketcan.c
> +++ b/net/can/can_socketcan.c
> @@ -103,6 +103,14 @@ static void can_host_socketcan_read(void *opaque)
>          return;
>      }
>
> +    if (!ch->bus_client.fd_mode) {
> +        c->buf[0].flags = 0;
> +    } else {
> +        if (c->bufcnt > CAN_MTU) {
> +            c->buf[0].flags |= QEMU_CAN_FRMF_TYPE_FD;
> +        }
> +    }
> +
>      can_bus_client_send(&ch->bus_client, c->buf, 1);
>
>      if (DEBUG_CAN) {
> @@ -121,12 +129,21 @@ static ssize_t 
> can_host_socketcan_receive(CanBusClientState *client,
>      CanHostState *ch = container_of(client, CanHostState, bus_client);
>      CanHostSocketCAN *c = CAN_HOST_SOCKETCAN(ch);
>
> -    size_t len = sizeof(qemu_can_frame);
> +    size_t len;
>      int res;
>
>      if (c->fd < 0) {
>          return -1;
>      }
> +    if (frames->flags & QEMU_CAN_FRMF_TYPE_FD) {
> +        if (!ch->bus_client.fd_mode) {
> +            return 0;
> +        }
> +        len = CANFD_MTU;
> +    } else {
> +        len = CAN_MTU;
> +
> +    }
>
>      res = write(c->fd, frames, len);
>
> @@ -172,6 +189,8 @@ static void can_host_socketcan_connect(CanHostState *ch, 
> Error **errp)
>  {
>      CanHostSocketCAN *c = CAN_HOST_SOCKETCAN(ch);
>      int s; /* can raw socket */
> +    int mtu;
> +    int enable_canfd = 1;
>      struct sockaddr_can addr;
>      struct ifreq ifr;
>
> @@ -185,13 +204,34 @@ static void can_host_socketcan_connect(CanHostState 
> *ch, Error **errp)
>      addr.can_family = AF_CAN;
>      memset(&ifr.ifr_name, 0, sizeof(ifr.ifr_name));
>      strcpy(ifr.ifr_name, c->ifname);
> +    /* check if the frame fits into the CAN netdevice */
>      if (ioctl(s, SIOCGIFINDEX, &ifr) < 0) {
>          error_setg_errno(errp, errno,
> -                         "SocketCAN host interface %s not available", 
> c->ifname);
> +                         "SocketCAN host interface %s not available",
> +                         c->ifname);
May be this formatting change in a different patch? As this is not related to
CANFD.
>          goto fail;
>      }
>      addr.can_ifindex = ifr.ifr_ifindex;
>
> +    if (ioctl(s, SIOCGIFMTU, &ifr) < 0) {
> +        error_setg_errno(errp, errno,
> +                         "SocketCAN host interface %s SIOCGIFMTU failed",
> +                         c->ifname);
> +        goto fail;
> +    }
> +    mtu = ifr.ifr_mtu;
> +
> +    if (mtu >= CANFD_MTU) {
> +        /* interface is ok - try to switch the socket into CAN FD mode */
> +        if (setsockopt(s, SOL_CAN_RAW, CAN_RAW_FD_FRAMES,
> +                        &enable_canfd, sizeof(enable_canfd))) {
> +            warn_report("SocketCAN host interface %s enabling CAN FD failed",
> +                        c->ifname);
> +        } else {
> +            c->parent.bus_client.fd_mode = true;
> +        }
> +    }
> +
>      c->err_mask = 0xffffffff; /* Receive error frame. */
>      setsockopt(s, SOL_CAN_RAW, CAN_RAW_ERR_FILTER,
>                     &c->err_mask, sizeof(c->err_mask));
> @@ -232,7 +272,8 @@ static char *can_host_socketcan_get_if(Object *obj, Error 
> **errp)
>      return g_strdup(c->ifname);
>  }
>
> -static void can_host_socketcan_set_if(Object *obj, const char *value, Error 
> **errp)
> +static void can_host_socketcan_set_if(Object *obj, const char *value,
> +                                      Error **errp)
This one also not relevant change for CANFD. Rest of the patch looks good.
>  {
>      CanHostSocketCAN *c = CAN_HOST_SOCKETCAN(obj);
>      struct ifreq ifr;
> --
> 2.20.1
>
>