[PATCH v3 11/14] net: axienet: Wrap DMA pointer writes to prepare for 64 bit

From: Andre Przywara
Date: Tue Mar 24 2020 - 09:28:56 EST


Newer versions of the Xilink DMA IP support busses with more than 32
address bits, by introducing an MSB word for the registers holding DMA
pointers (tail/current, RX/TX descriptor addresses).
On IP configured for more than 32 bits, it is also *required* to write
both words, to let the IP recognise this as a start condition for an
MM2S request, for instance.

Wrap the DMA pointer writes with a separate function, to add this
functionality later. For now we stick to the lower 32 bits.

Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
---
.../net/ethernet/xilinx/xilinx_axienet_main.c | 26 ++++++++++++-------
1 file changed, 16 insertions(+), 10 deletions(-)

diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
index dc533d7a090c..e7469eb241ad 100644
--- a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
+++ b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
@@ -147,6 +147,12 @@ static inline void axienet_dma_out32(struct axienet_local *lp,
iowrite32(value, lp->dma_regs + reg);
}

+static void axienet_dma_out_addr(struct axienet_local *lp, off_t reg,
+ dma_addr_t addr)
+{
+ axienet_dma_out32(lp, reg, lower_32_bits(addr));
+}
+
/**
* axienet_dma_bd_release - Release buffer descriptor rings
* @ndev: Pointer to the net_device structure
@@ -285,18 +291,18 @@ static int axienet_dma_bd_init(struct net_device *ndev)
/* Populate the tail pointer and bring the Rx Axi DMA engine out of
* halted state. This will make the Rx side ready for reception.
*/
- axienet_dma_out32(lp, XAXIDMA_RX_CDESC_OFFSET, lp->rx_bd_p);
+ axienet_dma_out_addr(lp, XAXIDMA_RX_CDESC_OFFSET, lp->rx_bd_p);
cr = axienet_dma_in32(lp, XAXIDMA_RX_CR_OFFSET);
axienet_dma_out32(lp, XAXIDMA_RX_CR_OFFSET,
cr | XAXIDMA_CR_RUNSTOP_MASK);
- axienet_dma_out32(lp, XAXIDMA_RX_TDESC_OFFSET, lp->rx_bd_p +
- (sizeof(*lp->rx_bd_v) * (lp->rx_bd_num - 1)));
+ axienet_dma_out_addr(lp, XAXIDMA_RX_TDESC_OFFSET, lp->rx_bd_p +
+ (sizeof(*lp->rx_bd_v) * (lp->rx_bd_num - 1)));

/* Write to the RS (Run-stop) bit in the Tx channel control register.
* Tx channel is now ready to run. But only after we write to the
* tail pointer register that the Tx channel will start transmitting.
*/
- axienet_dma_out32(lp, XAXIDMA_TX_CDESC_OFFSET, lp->tx_bd_p);
+ axienet_dma_out_addr(lp, XAXIDMA_TX_CDESC_OFFSET, lp->tx_bd_p);
cr = axienet_dma_in32(lp, XAXIDMA_TX_CR_OFFSET);
axienet_dma_out32(lp, XAXIDMA_TX_CR_OFFSET,
cr | XAXIDMA_CR_RUNSTOP_MASK);
@@ -757,7 +763,7 @@ axienet_start_xmit(struct sk_buff *skb, struct net_device *ndev)

tail_p = lp->tx_bd_p + sizeof(*lp->tx_bd_v) * lp->tx_bd_tail;
/* Start the transfer */
- axienet_dma_out32(lp, XAXIDMA_TX_TDESC_OFFSET, tail_p);
+ axienet_dma_out_addr(lp, XAXIDMA_TX_TDESC_OFFSET, tail_p);
if (++lp->tx_bd_tail >= lp->tx_bd_num)
lp->tx_bd_tail = 0;

@@ -849,7 +855,7 @@ static void axienet_recv(struct net_device *ndev)
ndev->stats.rx_bytes += size;

if (tail_p)
- axienet_dma_out32(lp, XAXIDMA_RX_TDESC_OFFSET, tail_p);
+ axienet_dma_out_addr(lp, XAXIDMA_RX_TDESC_OFFSET, tail_p);
}

/**
@@ -1671,18 +1677,18 @@ static void axienet_dma_err_handler(struct work_struct *work)
/* Populate the tail pointer and bring the Rx Axi DMA engine out of
* halted state. This will make the Rx side ready for reception.
*/
- axienet_dma_out32(lp, XAXIDMA_RX_CDESC_OFFSET, lp->rx_bd_p);
+ axienet_dma_out_addr(lp, XAXIDMA_RX_CDESC_OFFSET, lp->rx_bd_p);
cr = axienet_dma_in32(lp, XAXIDMA_RX_CR_OFFSET);
axienet_dma_out32(lp, XAXIDMA_RX_CR_OFFSET,
cr | XAXIDMA_CR_RUNSTOP_MASK);
- axienet_dma_out32(lp, XAXIDMA_RX_TDESC_OFFSET, lp->rx_bd_p +
- (sizeof(*lp->rx_bd_v) * (lp->rx_bd_num - 1)));
+ axienet_dma_out_addr(lp, XAXIDMA_RX_TDESC_OFFSET, lp->rx_bd_p +
+ (sizeof(*lp->rx_bd_v) * (lp->rx_bd_num - 1)));

/* Write to the RS (Run-stop) bit in the Tx channel control register.
* Tx channel is now ready to run. But only after we write to the
* tail pointer register that the Tx channel will start transmitting
*/
- axienet_dma_out32(lp, XAXIDMA_TX_CDESC_OFFSET, lp->tx_bd_p);
+ axienet_dma_out_addr(lp, XAXIDMA_TX_CDESC_OFFSET, lp->tx_bd_p);
cr = axienet_dma_in32(lp, XAXIDMA_TX_CR_OFFSET);
axienet_dma_out32(lp, XAXIDMA_TX_CR_OFFSET,
cr | XAXIDMA_CR_RUNSTOP_MASK);
--
2.17.1