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Subject[RFC PATCH 1/3] net: macb: Add support for extended BD with a config option
Date
Cadence GEM supports extended buffer descriptors.
This patch adds a config option to enable use of extended BD.
This adds two extra words to the TX BD and RX BD by configuring the
necessary registers. Corresponding variables are added to the
macb_dma_desc structure.

Signed-off-by: Harini Katakam <harinik@xilinx.com>
---
drivers/net/ethernet/cadence/Kconfig | 8 ++++++++
drivers/net/ethernet/cadence/macb.c | 4 ++++
drivers/net/ethernet/cadence/macb.h | 8 ++++++++
3 files changed, 20 insertions(+)

diff --git a/drivers/net/ethernet/cadence/Kconfig b/drivers/net/ethernet/cadence/Kconfig
index f0bcb15..33e4198 100644
--- a/drivers/net/ethernet/cadence/Kconfig
+++ b/drivers/net/ethernet/cadence/Kconfig
@@ -31,4 +31,12 @@ config MACB
To compile this driver as a module, choose M here: the module
will be called macb.

+config MACB_EXT_BD
+ tristate "Cadence MACB/GEM extended buffer descriptor"
+ depends on HAS_DMA && MACB
+ ---help---
+ The Cadence MACB host supports use of extended buffer descriptor.
+ This option enables additon of two extra words to TX BD and RX BD.
+ These two extra words are currently used to obtain PTP timestamp.
+
endif # NET_CADENCE
diff --git a/drivers/net/ethernet/cadence/macb.c b/drivers/net/ethernet/cadence/macb.c
index 88c1e1a..bb2932c 100644
--- a/drivers/net/ethernet/cadence/macb.c
+++ b/drivers/net/ethernet/cadence/macb.c
@@ -1665,6 +1665,10 @@ static void macb_configure_dma(struct macb *bp)
dmacfg |= GEM_BIT(TXCOEN);
else
dmacfg &= ~GEM_BIT(TXCOEN);
+#ifdef CONFIG_MACB_EXT_BD
+ dmacfg |= GEM_BIT(RXBDEXT);
+ dmacfg |= GEM_BIT(TXBDEXT);
+#endif
netdev_dbg(bp->dev, "Cadence configure DMA with 0x%08x\n",
dmacfg);
gem_writel(bp, DMACFG, dmacfg);
diff --git a/drivers/net/ethernet/cadence/macb.h b/drivers/net/ethernet/cadence/macb.h
index 6e1faea..58c9870 100644
--- a/drivers/net/ethernet/cadence/macb.h
+++ b/drivers/net/ethernet/cadence/macb.h
@@ -244,6 +244,10 @@
#define GEM_RXBS_SIZE 8
#define GEM_DDRP_OFFSET 24 /* disc_when_no_ahb */
#define GEM_DDRP_SIZE 1
+#define GEM_RXBDEXT_OFFSET 28 /* Extended RX BD */
+#define GEM_RXBDEXT_SIZE 1
+#define GEM_TXBDEXT_OFFSET 29 /* Extended TX BD */
+#define GEM_TXBDEXT_SIZE 1


/* Bitfields in NSR */
@@ -466,6 +470,10 @@
struct macb_dma_desc {
u32 addr;
u32 ctrl;
+#ifdef CONFIG_MACB_EXT_BD
+ u32 tsl;
+ u32 tsh;
+#endif
};

/* DMA descriptor bitfields */
--
1.7.9.5


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