[PATCH v4 3/5] net: can: flexcan: split the Message Buffer RAM area

[Pankaj Bansal <pankaj.bansal@xxxxxxx>]

The message buffer RAM area is not a contiguous 1KB area but 2 partitions
of 512 bytes each. Till now, we used Message buffers with payload size 8
bytes, which translates to 32 MBs per partition and no spare space is left
in any partition.
However, in upcoming SOC LX2160A the message buffers can have payload size
64 bytes. This results in less than 32 MBs per partition and some empty
area is left at the end of each partition.This empty area should not be
accessed.
Therefore, split the Message Buffer RAM area into two partitions.

Signed-off-by: Pankaj Bansal <pankaj.bansal@xxxxxxx>
---

Notes:
    V4:
     - Make regs->mb to 2D array
     - use bank terminology instead of block in flexcan_get_mb
    V3:
     - No change
    V2:
     - removed mb_count_block1 and mb_count_block2 from priv structure due to
       flexcan_get_mb function introduced in earlier patch

 drivers/net/can/flexcan.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c
index 8c7f96f29118..3106134f3ba4 100644
--- a/drivers/net/can/flexcan.c
+++ b/drivers/net/can/flexcan.c
@@ -224,7 +224,7 @@ struct flexcan_regs {
 	u32 rxfgmask;		/* 0x48 */
 	u32 rxfir;		/* 0x4c */
 	u32 _reserved3[12];	/* 0x50 */
-	u8  mb[1024];		/* 0x80 */
+	u8 mb[2][512];		/* 0x80 */
 	/* FIFO-mode:
 	 *			MB
 	 * 0x080...0x08f	0	RX message buffer
@@ -358,6 +358,8 @@ static struct flexcan_mb *flexcan_get_mb(const struct flexcan_priv *priv,
 					 u8 mb_index)
 {
 	u8 mb_size;
+	u8 mb_count_bank;
+	bool bank;
 
 	if (WARN_ON(mb_index >= priv->mb_count))
 		return NULL;
@@ -367,8 +369,13 @@ static struct flexcan_mb *flexcan_get_mb(const struct flexcan_priv *priv,
 	else
 		mb_size = sizeof(struct flexcan_mb) + CAN_MAX_DLEN;
 
+	mb_count_bank = sizeof(priv->regs->mb[0]) / mb_size;
+
+	bank = mb_index >= mb_count_bank;
+	mb_index -= (bank ? mb_count_bank : 0);
+
 	return (struct flexcan_mb __iomem *)
-		(&priv->regs->mb[mb_size * mb_index]);
+		(&priv->regs->mb[bank][mb_size * mb_index]);
 }
 
 static inline void flexcan_error_irq_enable(const struct flexcan_priv *priv)
@@ -1147,7 +1154,8 @@ static int flexcan_open(struct net_device *dev)
 		mb_size = sizeof(struct flexcan_mb) + CANFD_MAX_DLEN;
 	else
 		mb_size = sizeof(struct flexcan_mb) + CAN_MAX_DLEN;
-	priv->mb_count = sizeof(priv->regs->mb) / mb_size;
+	priv->mb_count = sizeof(priv->regs->mb[0]) / mb_size;
+	priv->mb_count += sizeof(priv->regs->mb[1]) / mb_size;
 
 	if (priv->devtype_data->quirks & FLEXCAN_QUIRK_USE_OFF_TIMESTAMP) {
 		priv->tx_mb_idx = FLEXCAN_TX_MB_OFF_TIMESTAMP;
-- 
2.17.1