[PATCH 4.9 57/88] net: ks8851-ml: Remove 8-bit bus accessors

Greg Kroah-Hartman
2020-03-10T12:46:22Z

From: Marek Vasut <marex@denx.de>

[ Upstream commit 69233bba6543a37755158ca3382765387b8078df ]

This driver is mixing 8-bit and 16-bit bus accessors for reasons unknown,
however the speculation is that this was some sort of attempt to support
the 8-bit bus mode.

As per the KS8851-16MLL documentation, all two registers accessed via the
8-bit accessors are internally 16-bit registers, so reading them using
16-bit accessors is fine. The KS_CCR read can be converted to 16-bit read
outright, as it is already a concatenation of two 8-bit reads of that
register. The KS_RXQCR accesses are 8-bit only, however writing the top
8 bits of the register is OK as well, since the driver caches the entire
16-bit register value anyway.

Finally, the driver is not used by any hardware in the kernel right now.
The only hardware available to me is one with 16-bit bus, so I have no
way to test the 8-bit bus mode, however it is unlikely this ever really
worked anyway. If the 8-bit bus mode is ever required, it can be easily
added by adjusting the 16-bit accessors to do 2 consecutive accesses,
which is how this should have been done from the beginning.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: David S. Miller <davem@davemloft.net>
Cc: Lukas Wunner <lukas@wunner.de>
Cc: Petr Stetiar <ynezz@true.cz>
Cc: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/ethernet/micrel/ks8851_mll.c | 45 +++---------------------
1 file changed, 5 insertions(+), 40 deletions(-)

diff --git a/drivers/net/ethernet/micrel/ks8851_mll.c b/drivers/net/ethernet/micrel/ks8851_mll.c
index 8dc1f0277117d..721f851674531 100644
--- a/drivers/net/ethernet/micrel/ks8851_mll.c
+++ b/drivers/net/ethernet/micrel/ks8851_mll.c
@@ -474,24 +474,6 @@ static int msg_enable;
* chip is busy transferring packet data (RX/TX FIFO accesses).
*/

-/**
- * ks_rdreg8 - read 8 bit register from device
- * @ks : The chip information
- * @offset: The register address
- *
- * Read a 8bit register from the chip, returning the result
- */
-static u8 ks_rdreg8(struct ks_net *ks, int offset)
-{
- u16 data;
- u8 shift_bit = offset & 0x03;
- u8 shift_data = (offset & 1) << 3;
- ks->cmd_reg_cache = (u16) offset | (u16)(BE0 << shift_bit);
- iowrite16(ks->cmd_reg_cache, ks->hw_addr_cmd);
- data = ioread16(ks->hw_addr);
- return (u8)(data >> shift_data);
-}
-
/**
* ks_rdreg16 - read 16 bit register from device
* @ks : The chip information
@@ -507,22 +489,6 @@ static u16 ks_rdreg16(struct ks_net *ks, int offset)
return ioread16(ks->hw_addr);
}

-/**
- * ks_wrreg8 - write 8bit register value to chip
- * @ks: The chip information
- * @offset: The register address
- * @value: The value to write
- *
- */
-static void ks_wrreg8(struct ks_net *ks, int offset, u8 value)
-{
- u8 shift_bit = (offset & 0x03);
- u16 value_write = (u16)(value << ((offset & 1) << 3));
- ks->cmd_reg_cache = (u16)offset | (BE0 << shift_bit);
- iowrite16(ks->cmd_reg_cache, ks->hw_addr_cmd);
- iowrite16(value_write, ks->hw_addr);
-}
-
/**
* ks_wrreg16 - write 16bit register value to chip
* @ks: The chip information
@@ -642,8 +608,7 @@ static void ks_read_config(struct ks_net *ks)
u16 reg_data = 0;

/* Regardless of bus width, 8 bit read should always work.*/
- reg_data = ks_rdreg8(ks, KS_CCR) & 0x00FF;
- reg_data |= ks_rdreg8(ks, KS_CCR+1) << 8;
+ reg_data = ks_rdreg16(ks, KS_CCR);

/* addr/data bus are multiplexed */
ks->sharedbus = (reg_data & CCR_SHARED) == CCR_SHARED;
@@ -747,7 +712,7 @@ static inline void ks_read_qmu(struct ks_net *ks, u16 *buf, u32 len)

/* 1. set sudo DMA mode */
ks_wrreg16(ks, KS_RXFDPR, RXFDPR_RXFPAI);
- ks_wrreg8(ks, KS_RXQCR, (ks->rc_rxqcr | RXQCR_SDA) & 0xff);
+ ks_wrreg16(ks, KS_RXQCR, ks->rc_rxqcr | RXQCR_SDA);

/* 2. read prepend data */
/**
@@ -764,7 +729,7 @@ static inline void ks_read_qmu(struct ks_net *ks, u16 *buf, u32 len)
ks_inblk(ks, buf, ALIGN(len, 4));

/* 4. reset sudo DMA Mode */
- ks_wrreg8(ks, KS_RXQCR, ks->rc_rxqcr);
+ ks_wrreg16(ks, KS_RXQCR, ks->rc_rxqcr);
}

/**
@@ -997,13 +962,13 @@ static void ks_write_qmu(struct ks_net *ks, u8 *pdata, u16 len)
ks->txh.txw[1] = cpu_to_le16(len);

/* 1. set sudo-DMA mode */
- ks_wrreg8(ks, KS_RXQCR, (ks->rc_rxqcr | RXQCR_SDA) & 0xff);
+ ks_wrreg16(ks, KS_RXQCR, ks->rc_rxqcr | RXQCR_SDA);
/* 2. write status/lenth info */
ks_outblk(ks, ks->txh.txw, 4);
/* 3. write pkt data */
ks_outblk(ks, (u16 *)pdata, ALIGN(len, 4));
/* 4. reset sudo-DMA mode */
- ks_wrreg8(ks, KS_RXQCR, ks->rc_rxqcr);
+ ks_wrreg16(ks, KS_RXQCR, ks->rc_rxqcr);
/* 5. Enqueue Tx(move the pkt from TX buffer into TXQ) */
ks_wrreg16(ks, KS_TXQCR, TXQCR_METFE);
/* 6. wait until TXQCR_METFE is auto-cleared */
--
2.20.1