can: peak_usb: PCAN-USB: add support of loopback and one-shot mode

The CAN - USB PCAN-USB interface is able to generate one-shot frames
as well as loopback frames that it transmits starting from version 4.1
of its firmware.

This patch adds support for the one-shot and loopback functionality to
the driver, that can be activated if the embedded firmware allows it.
If the driver detects that the PCAN-USB device runs an old firmware
(< 4.1) it prints a message suggesting to contact
<support@peak-system.com> for a possible firmware update.

Link: https://lore.kernel.org/r/20210625130931.27438-3-s.grosjean@peak-system.com
Signed-off-by: Stephane Grosjean <s.grosjean@peak-system.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

diff --git a/drivers/net/can/usb/peak_usb/pcan_usb.c b/drivers/net/can/usb/peak_usb/pcan_usb.c
index 9f3e166..2362ac8 100644 (file)
--- a/drivers/net/can/usb/peak_usb/pcan_usb.c
+++ b/drivers/net/can/usb/peak_usb/pcan_usb.c
@@ -73,6 +73,10 @@
 #define PCAN_USB_STATUSLEN_RTR         (1 << 4)
 #define PCAN_USB_STATUSLEN_DLC         (0xf)
 
+/* PCAN-USB 4.1 CAN Id tx extended flags */
+#define PCAN_USB_TX_SRR                        0x01    /* SJA1000 SRR command */
+#define PCAN_USB_TX_AT                 0x02    /* SJA1000 AT command */
+
 /* PCAN-USB error flags */
 #define PCAN_USB_ERROR_TXFULL          0x01
 #define PCAN_USB_ERROR_RXQOVR          0x02
@@ -705,6 +709,7 @@ static int pcan_usb_decode_data(struct pcan_usb_msg_context *mc, u8 status_len)
        struct sk_buff *skb;
        struct can_frame *cf;
        struct skb_shared_hwtstamps *hwts;
+       u32 can_id_flags;
 
        skb = alloc_can_skb(mc->netdev, &cf);
        if (!skb)
@@ -714,13 +719,15 @@ static int pcan_usb_decode_data(struct pcan_usb_msg_context *mc, u8 status_len)
                if ((mc->ptr + 4) > mc->end)
                        goto decode_failed;
 
-               cf->can_id = get_unaligned_le32(mc->ptr) >> 3 | CAN_EFF_FLAG;
+               can_id_flags = get_unaligned_le32(mc->ptr);
+               cf->can_id = can_id_flags >> 3 | CAN_EFF_FLAG;
                mc->ptr += 4;
        } else {
                if ((mc->ptr + 2) > mc->end)
                        goto decode_failed;
 
-               cf->can_id = get_unaligned_le16(mc->ptr) >> 5;
+               can_id_flags = get_unaligned_le16(mc->ptr);
+               cf->can_id = can_id_flags >> 5;
                mc->ptr += 2;
        }
 
@@ -743,6 +750,10 @@ static int pcan_usb_decode_data(struct pcan_usb_msg_context *mc, u8 status_len)
 
                memcpy(cf->data, mc->ptr, cf->len);
                mc->ptr += rec_len;
+
+               /* Ignore next byte (client private id) if SRR bit is set */
+               if (can_id_flags & PCAN_USB_TX_SRR)
+                       mc->ptr++;
        }
 
        /* convert timestamp into kernel time */
@@ -820,6 +831,7 @@ static int pcan_usb_encode_msg(struct peak_usb_device *dev, struct sk_buff *skb,
        struct net_device *netdev = dev->netdev;
        struct net_device_stats *stats = &netdev->stats;
        struct can_frame *cf = (struct can_frame *)skb->data;
+       u32 can_id_flags = cf->can_id & CAN_ERR_MASK;
        u8 *pc;
 
        obuf[0] = 2;
@@ -838,12 +850,28 @@ static int pcan_usb_encode_msg(struct peak_usb_device *dev, struct sk_buff *skb,
                *pc |= PCAN_USB_STATUSLEN_EXT_ID;
                pc++;
 
-               put_unaligned_le32((cf->can_id & CAN_ERR_MASK) << 3, pc);
+               can_id_flags <<= 3;
+
+               if (dev->can.ctrlmode & CAN_CTRLMODE_LOOPBACK)
+                       can_id_flags |= PCAN_USB_TX_SRR;
+
+               if (dev->can.ctrlmode & CAN_CTRLMODE_ONE_SHOT)
+                       can_id_flags |= PCAN_USB_TX_AT;
+
+               put_unaligned_le32(can_id_flags, pc);
                pc += 4;
        } else {
                pc++;
 
-               put_unaligned_le16((cf->can_id & CAN_ERR_MASK) << 5, pc);
+               can_id_flags <<= 5;
+
+               if (dev->can.ctrlmode & CAN_CTRLMODE_LOOPBACK)
+                       can_id_flags |= PCAN_USB_TX_SRR;
+
+               if (dev->can.ctrlmode & CAN_CTRLMODE_ONE_SHOT)
+                       can_id_flags |= PCAN_USB_TX_AT;
+
+               put_unaligned_le16(can_id_flags, pc);
                pc += 2;
        }
 
@@ -853,6 +881,10 @@ static int pcan_usb_encode_msg(struct peak_usb_device *dev, struct sk_buff *skb,
                pc += cf->len;
        }
 
+       /* SRR bit needs a writer id (useless here) */
+       if (can_id_flags & PCAN_USB_TX_SRR)
+               *pc++ = 0x80;
+
        obuf[(*size)-1] = (u8)(stats->tx_packets & 0xff);
 
        return 0;
@@ -927,6 +959,19 @@ static int pcan_usb_init(struct peak_usb_device *dev)
                return err;
        }
 
+       /* Since rev 4.1, PCAN-USB is able to make single-shot as well as
+        * looped back frames.
+        */
+       if (dev->device_rev >= 41) {
+               struct can_priv *priv = netdev_priv(dev->netdev);
+
+               priv->ctrlmode_supported |= CAN_CTRLMODE_ONE_SHOT |
+                                           CAN_CTRLMODE_LOOPBACK;
+       } else {
+               dev_info(dev->netdev->dev.parent,
+                        "Firmware update available. Please contact support@peak-system.com\n");
+       }
+
        dev_info(dev->netdev->dev.parent,
                 "PEAK-System %s adapter hwrev %u serial %08X (%u channel)\n",
                 pcan_usb.name, dev->device_rev, serial_number,