can: kvaser_pciefd: Empty SRB buffer in probe

commit c589557dd1426f5adf90c7a919d4fde5a3e4ef64 upstream.

Empty the "Shared receive buffer" (SRB) in probe, to assure we start in a
known state, and don't process any irrelevant packets.

Fixes: 26ad340e582d ("can: kvaser_pciefd: Add driver for Kvaser PCIEcan devices")
Cc: stable@vger.kernel.org
Signed-off-by: Jimmy Assarsson <extja@kvaser.com>
Link: https://lore.kernel.org/r/20230516134318.104279-5-extja@kvaser.com
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/net/can/kvaser_pciefd.c b/drivers/net/can/kvaser_pciefd.c
index 85e8459a1a23bd793329abe7836875afed48abb4..52d649d5f05f0f53d4b4918309659a4d3f77af18 100644 (file)
--- a/drivers/net/can/kvaser_pciefd.c
+++ b/drivers/net/can/kvaser_pciefd.c
@@ -70,10 +70,12 @@ MODULE_DESCRIPTION("CAN driver for Kvaser CAN/PCIe devices");
 #define KVASER_PCIEFD_SYSID_BUILD_REG (KVASER_PCIEFD_SYSID_BASE + 0x14)
 /* Shared receive buffer registers */
 #define KVASER_PCIEFD_SRB_BASE 0x1f200
+#define KVASER_PCIEFD_SRB_FIFO_LAST_REG (KVASER_PCIEFD_SRB_BASE + 0x1f4)
 #define KVASER_PCIEFD_SRB_CMD_REG (KVASER_PCIEFD_SRB_BASE + 0x200)
 #define KVASER_PCIEFD_SRB_IEN_REG (KVASER_PCIEFD_SRB_BASE + 0x204)
 #define KVASER_PCIEFD_SRB_IRQ_REG (KVASER_PCIEFD_SRB_BASE + 0x20c)
 #define KVASER_PCIEFD_SRB_STAT_REG (KVASER_PCIEFD_SRB_BASE + 0x210)
+#define KVASER_PCIEFD_SRB_RX_NR_PACKETS_REG (KVASER_PCIEFD_SRB_BASE + 0x214)
 #define KVASER_PCIEFD_SRB_CTRL_REG (KVASER_PCIEFD_SRB_BASE + 0x218)
 /* EPCS flash controller registers */
 #define KVASER_PCIEFD_SPI_BASE 0x1fc00
@@ -110,6 +112,9 @@ MODULE_DESCRIPTION("CAN driver for Kvaser CAN/PCIe devices");
 /* DMA support */
 #define KVASER_PCIEFD_SRB_STAT_DMA BIT(24)
 
+/* SRB current packet level */
+#define KVASER_PCIEFD_SRB_RX_NR_PACKETS_MASK 0xff
+
 /* DMA Enable */
 #define KVASER_PCIEFD_SRB_CTRL_DMA_ENABLE BIT(0)
 
@@ -1053,6 +1058,7 @@ static int kvaser_pciefd_setup_dma(struct kvaser_pciefd *pcie)
 {
        int i;
        u32 srb_status;
+       u32 srb_packet_count;
        dma_addr_t dma_addr[KVASER_PCIEFD_DMA_COUNT];
 
        /* Disable the DMA */
@@ -1080,6 +1086,15 @@ static int kvaser_pciefd_setup_dma(struct kvaser_pciefd *pcie)
                  KVASER_PCIEFD_SRB_CMD_RDB1,
                  pcie->reg_base + KVASER_PCIEFD_SRB_CMD_REG);
 
+       /* Empty Rx FIFO */
+       srb_packet_count = ioread32(pcie->reg_base + KVASER_PCIEFD_SRB_RX_NR_PACKETS_REG) &
+                          KVASER_PCIEFD_SRB_RX_NR_PACKETS_MASK;
+       while (srb_packet_count) {
+               /* Drop current packet in FIFO */
+               ioread32(pcie->reg_base + KVASER_PCIEFD_SRB_FIFO_LAST_REG);
+               srb_packet_count--;
+       }
+
        srb_status = ioread32(pcie->reg_base + KVASER_PCIEFD_SRB_STAT_REG);
        if (!(srb_status & KVASER_PCIEFD_SRB_STAT_DI)) {
                dev_err(&pcie->pci->dev, "DMA not idle before enabling\n");