On Tue, Dec 07, 2021 at 10:08:53AM +0100, Clément Léger wrote:
> Ethernet frames can be extracted or injected autonomously to or from
> the device’s DDR3/DDR3L memory and/or PCIe memory space. Linked list
> data structures in memory are used for injecting or extracting Ethernet
> frames. The FDMA generates interrupts when frame extraction or
> injection is done and when the linked lists need updating.
>
> The FDMA is shared between all the ethernet ports of the switch and
> uses a linked list of descriptors (DCB) to inject and extract packets.
> Before adding descriptors, the FDMA channels must be stopped. It would
> be inefficient to do that each time a descriptor would be added so the
> channels are restarted only once they stopped.
>
> Both channels uses ring-like structure to feed the DCBs to the FDMA.
> head and tail are never touched by hardware and are completely handled
> by the driver. On top of that, page recycling has been added and is
> mostly taken from gianfar driver.
>
> Co-developed-by: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxx>
> Signed-off-by: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxx>
> Signed-off-by: Clément Léger <clement.leger@xxxxxxxxxxx>
> ---
> +static void ocelot_fdma_send_skb(struct ocelot *ocelot,
> + struct ocelot_fdma *fdma, struct sk_buff *skb)
> +{
> + struct ocelot_fdma_tx_ring *tx_ring = &fdma->tx_ring;
> + struct ocelot_fdma_tx_buf *tx_buf;
> + struct ocelot_fdma_dcb *dcb;
> + dma_addr_t dma;
> + u16 next_idx;
> +
> + dcb = &tx_ring->dcbs[tx_ring->next_to_use];
> + tx_buf = &tx_ring->bufs[tx_ring->next_to_use];
> + if (!ocelot_fdma_tx_dcb_set_skb(ocelot, tx_buf, dcb, skb)) {
> + dev_kfree_skb_any(skb);
> + return;
> + }
> +
> + next_idx = ocelot_fdma_idx_next(tx_ring->next_to_use,
> + OCELOT_FDMA_TX_RING_SIZE);
> + /* If the FDMA TX chan is empty, then enqueue the DCB directly */
> + if (ocelot_fdma_tx_ring_empty(fdma)) {
> + dma = ocelot_fdma_idx_dma(tx_ring->dcbs_dma, tx_ring->next_to_use);
> + ocelot_fdma_activate_chan(ocelot, dma, MSCC_FDMA_INJ_CHAN);
> + } else {
> + /* Chain the DCBs */
> + dcb->llp = ocelot_fdma_idx_dma(tx_ring->dcbs_dma, next_idx);
> + }
> + skb_tx_timestamp(skb);
> +
> + tx_ring->next_to_use = next_idx;
You've decided against moving these before ocelot_fdma_activate_chan?
The skb may be freed by ocelot_fdma_tx_cleanup() before
skb_tx_timestamp() has a chance to run, is this not true?
> +}
> diff --git a/drivers/net/ethernet/mscc/ocelot_vsc7514.c b/drivers/net/ethernet/mscc/ocelot_vsc7514.c
> index cd3eb101f159..bee883a0b5b8 100644
> --- a/drivers/net/ethernet/mscc/ocelot_vsc7514.c
> +++ b/drivers/net/ethernet/mscc/ocelot_vsc7514.c
> @@ -18,6 +18,7 @@
>
> #include <soc/mscc/ocelot_vcap.h>
> #include <soc/mscc/ocelot_hsio.h>
> +#include "ocelot_fdma.h"
> #include "ocelot.h"
>
> #define VSC7514_VCAP_POLICER_BASE 128
> @@ -275,6 +276,18 @@ static const u32 ocelot_ptp_regmap[] = {
> REG(PTP_CLK_CFG_ADJ_FREQ, 0x0000a8),
> };
>
> +static const u32 ocelot_fdma_regmap[] = {
> + REG(PTP_PIN_CFG, 0x000000),
> + REG(PTP_PIN_TOD_SEC_MSB, 0x000004),
> + REG(PTP_PIN_TOD_SEC_LSB, 0x000008),
> + REG(PTP_PIN_TOD_NSEC, 0x00000c),
> + REG(PTP_PIN_WF_HIGH_PERIOD, 0x000014),
> + REG(PTP_PIN_WF_LOW_PERIOD, 0x000018),
> + REG(PTP_CFG_MISC, 0x0000a0),
> + REG(PTP_CLK_CFG_ADJ_CFG, 0x0000a4),
> + REG(PTP_CLK_CFG_ADJ_FREQ, 0x0000a8),
> +};
drivers/net/ethernet/mscc/ocelot_vsc7514.c:279:18: warning: ‘ocelot_fdma_regmap’ defined but not used [-Wunused-const-variable=]
279 | static const u32 ocelot_fdma_regmap[] = {
| ^~~~~~~~~~~~~~~~~~
Not to mention this isn't even the FDMA regmap.
> +
> static const u32 ocelot_dev_gmii_regmap[] = {
> REG(DEV_CLOCK_CFG, 0x0),
> REG(DEV_PORT_MISC, 0x4),
> @@ -1048,6 +1061,7 @@ static int mscc_ocelot_probe(struct platform_device *pdev)
> { S1, "s1" },
> { S2, "s2" },
> { PTP, "ptp", 1 },
> + { FDMA, "fdma", 1 },
> };
