soc: ti: knav_dma: rename pad in struct knav_dma_desc to sw_data

Rename the pad to sw_data as per description of this field in the hardware
spec(refer sprugr9 from www.ti.com). Latest version of the document is
at http://www.ti.com/lit/ug/sprugr9h/sprugr9h.pdf and section 3.1
Host Packet Descriptor describes this field.

Define and use a constant for the size of sw_data field similar to
other fields in the struct for desc and document the sw_data field
in the header. As the sw_data is not touched by hw, it's type can be
changed to u32.

Rename the helpers to match with the updated dma desc field sw_data.

Cc: Wingman Kwok <[e-mail]>
Cc: Mugunthan V N <[e-mail]>
CC: Arnd Bergmann <[e-mail]>
CC: Grygorii Strashko <[e-mail]>
CC: David Laight <[e-mail]>
Signed-off-by: Murali Karicheri <[e-mail]>
Acked-by: Arnd Bergmann <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/ethernet/ti/netcp_core.c

···
 	*ndesc = le32_to_cpu(desc->next_desc);
 }
 
-static void get_pad_info(u32 *pad0, u32 *pad1, struct knav_dma_desc *desc)
+static void get_sw_data(u32 *data0, u32 *data1, struct knav_dma_desc *desc)
 {
-	*pad0 = le32_to_cpu(desc->pad[0]);
-	*pad1 = le32_to_cpu(desc->pad[1]);
+	/* No Endian conversion needed as this data is untouched by hw */
+	*data0 = desc->sw_data[0];
+	*data1 = desc->sw_data[1];
 }
 
 static void get_org_pkt_info(dma_addr_t *buff, u32 *buff_len,
···
 	desc->packet_info = cpu_to_le32(pkt_info);
 }
 
-static void set_pad_info(u32 pad0, u32 pad1, struct knav_dma_desc *desc)
+static void set_sw_data(u32 data0, u32 data1, struct knav_dma_desc *desc)
 {
-	desc->pad[0] = cpu_to_le32(pad0);
-	desc->pad[1] = cpu_to_le32(pad1);
+	/* No Endian conversion needed as this data is untouched by hw */
+	desc->sw_data[0] = data0;
+	desc->sw_data[1] = data1;
 }
 
 static void set_org_pkt_info(dma_addr_t buff, u32 buff_len,
···
 			break;
 		}
 		get_pkt_info(&dma_buf, &tmp, &dma_desc, ndesc);
-		get_pad_info((u32 *)&buf_ptr, &buf_len, ndesc);
+		get_sw_data((u32 *)&buf_ptr, &buf_len, ndesc);
 		dma_unmap_page(netcp->dev, dma_buf, PAGE_SIZE, DMA_FROM_DEVICE);
 		__free_page(buf_ptr);
 		knav_pool_desc_put(netcp->rx_pool, desc);
 	}
-	get_pad_info((u32 *)&buf_ptr, &buf_len, desc);
+	get_sw_data((u32 *)&buf_ptr, &buf_len, desc);
 
 	if (buf_ptr)
 		netcp_frag_free(buf_len <= PAGE_SIZE, buf_ptr);
···
 	}
 
 	get_pkt_info(&dma_buff, &buf_len, &dma_desc, desc);
-	get_pad_info((u32 *)&org_buf_ptr, &org_buf_len, desc);
+	get_sw_data((u32 *)&org_buf_ptr, &org_buf_len, desc);
 
 	if (unlikely(!org_buf_ptr)) {
 		dev_err(netcp->ndev_dev, "NULL bufptr in desc\n");
···
 		}
 
 		get_pkt_info(&dma_buff, &buf_len, &dma_desc, ndesc);
-		get_pad_info((u32 *)&page, &tmp, ndesc);
+		get_sw_data((u32 *)&page, &tmp, ndesc);
 
 		if (likely(dma_buff && buf_len && page)) {
 			dma_unmap_page(netcp->dev, dma_buff, PAGE_SIZE,
···
 		}
 
 		get_org_pkt_info(&dma, &buf_len, desc);
-		get_pad_info((u32 *)&buf_ptr, &tmp, desc);
+		get_sw_data((u32 *)&buf_ptr, &tmp, desc);
 
 		if (unlikely(!dma)) {
 			dev_err(netcp->ndev_dev, "NULL orig_buff in desc\n");
···
 	struct page *page;
 	dma_addr_t dma;
 	void *bufptr;
-	u32 pad[2];
+	u32 sw_data[2];
 
 	/* Allocate descriptor */
 	hwdesc = knav_pool_desc_get(netcp->rx_pool);
···
 				SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
 
 		bufptr = netdev_alloc_frag(primary_buf_len);
-		pad[1] = primary_buf_len;
+		sw_data[1] = primary_buf_len;
 
 		if (unlikely(!bufptr)) {
 			dev_warn_ratelimited(netcp->ndev_dev,
···
 		if (unlikely(dma_mapping_error(netcp->dev, dma)))
 			goto fail;
 
-		pad[0] = (u32)bufptr;
+		sw_data[0] = (u32)bufptr;
 	} else {
 		/* Allocate a secondary receive queue entry */
 		page = alloc_page(GFP_ATOMIC | GFP_DMA | __GFP_COLD);
···
 		}
 		buf_len = PAGE_SIZE;
 		dma = dma_map_page(netcp->dev, page, 0, buf_len, DMA_TO_DEVICE);
-		pad[0] = (u32)page;
-		pad[1] = 0;
+		sw_data[0] = (u32)page;
+		sw_data[1] = 0;
 	}
 
 	desc_info =  KNAV_DMA_DESC_PS_INFO_IN_DESC;
···
 	pkt_info |= (netcp->rx_queue_id & KNAV_DMA_DESC_RETQ_MASK) <<
 		    KNAV_DMA_DESC_RETQ_SHIFT;
 	set_org_pkt_info(dma, buf_len, hwdesc);
-	set_pad_info(pad[0], pad[1], hwdesc);
+	set_sw_data(sw_data[0], sw_data[1], hwdesc);
 	set_desc_info(desc_info, pkt_info, hwdesc);
 
 	/* Push to FDQs */
···
 			continue;
 		}
 
-		get_pad_info((u32 *)&skb, &tmp, desc);
+		get_sw_data((u32 *)&skb, &tmp, desc);
 		netcp_free_tx_desc_chain(netcp, desc, dma_sz);
 		if (!skb) {
 			dev_err(netcp->ndev_dev, "No skb in Tx desc\n");
···
 	}
 
 	set_words(&tmp, 1, &desc->packet_info);
-	set_words((u32 *)&skb, 1, &desc->pad[0]);
+	set_sw_data((u32)skb, 0, desc);
 
 	if (tx_pipe->flags & SWITCH_TO_PORT_IN_TAGINFO) {
 		tmp = tx_pipe->switch_to_port;

include/linux/soc/ti/knav_dma.h

···
 
 #define KNAV_DMA_NUM_EPIB_WORDS			4
 #define KNAV_DMA_NUM_PS_WORDS			16
+#define KNAV_DMA_NUM_SW_DATA_WORDS		4
 #define KNAV_DMA_FDQ_PER_CHAN			4
 
 /* Tx channel scheduling priority */
···
  * @orig_buff:			buff pointer since 'buff' can be overwritten
  * @epib:			Extended packet info block
  * @psdata:			Protocol specific
+ * @sw_data:			Software private data not touched by h/w
  */
 struct knav_dma_desc {
 	__le32	desc_info;
···
 	__le32	orig_buff;
 	__le32	epib[KNAV_DMA_NUM_EPIB_WORDS];
 	__le32	psdata[KNAV_DMA_NUM_PS_WORDS];
-	__le32	pad[4];
+	u32	sw_data[KNAV_DMA_NUM_SW_DATA_WORDS];
 } ____cacheline_aligned;
 
 #if IS_ENABLED(CONFIG_KEYSTONE_NAVIGATOR_DMA)