Re: [PATCH] net: macb: Add big endian CPU support

[Nicolas Ferre <nicolas.ferre@atmel.com>]

Le 24/02/2015 08:39, Arun Chandran a écrit :
> This patch converts all __raw_readl and __raw_writel function calls
> to their corresponding readl_relaxed and writel_relaxed variants.
> 
> It also tells the driver to set ahb_endian_swp_mgmt_en bit in dma_cfg
> when the cpu is configured in big endian mode.
> 
> Signed-off-by: Arun Chandran <achandran@mvista.com>
> ---
> 	This patch is tested on xilinx ZC702 evaluation board with
> 	CONFIG_CPU_BIG_ENDIAN=y and booting NFS rootfs
> 	Added on the fly IP endianness detection according to
> 	comments from Michal Simek.
> ---
> ---
>  drivers/net/ethernet/cadence/macb.c | 33 +++++++++++++++++++++++++++------
>  drivers/net/ethernet/cadence/macb.h | 15 ++++++++-------
>  2 files changed, 35 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/net/ethernet/cadence/macb.c b/drivers/net/ethernet/cadence/macb.c
> index ad76b8e..1642911 100644
> --- a/drivers/net/ethernet/cadence/macb.c
> +++ b/drivers/net/ethernet/cadence/macb.c
> @@ -449,7 +449,7 @@ static void macb_update_stats(struct macb *bp)
>  	WARN_ON((unsigned long)(end - p - 1) != (MACB_TPF - MACB_PFR) / 4);
>  
>  	for(; p < end; p++, reg++)
> -		*p += __raw_readl(reg);
> +		*p += readl_relaxed(reg);
>  }
>  
>  static int macb_halt_tx(struct macb *bp)
> @@ -1578,6 +1578,7 @@ static u32 macb_dbw(struct macb *bp)
>  static void macb_configure_dma(struct macb *bp)
>  {
>  	u32 dmacfg;
> +	u32 tmp, ncr;
>  
>  	if (macb_is_gem(bp)) {
>  		dmacfg = gem_readl(bp, DMACFG) & ~GEM_BF(RXBS, -1L);
> @@ -1585,7 +1586,25 @@ static void macb_configure_dma(struct macb *bp)
>  		if (bp->dma_burst_length)
>  			dmacfg = GEM_BFINS(FBLDO, bp->dma_burst_length, dmacfg);
>  		dmacfg |= GEM_BIT(TXPBMS) | GEM_BF(RXBMS, -1L);
> -		dmacfg &= ~GEM_BIT(ENDIA);
> +		dmacfg &= ~GEM_BIT(ENDIA_PKT);

I think this will fail... (see below)

> +
> +		/* Here we use the loopback bit of net_ctrl register to detect
> +		 * endianness on IP. save it first. Program swaped mode for
> +		 * management descriptor accesses if writing to loop back bit
> +		 * and reading it back brings no change in bit value.
> +		 */
> +		ncr = macb_readl(bp, NCR);
> +		__raw_writel(MACB_BIT(LLB), bp->regs + MACB_NCR);
> +		tmp =  __raw_readl(bp->regs + MACB_NCR);
> +
> +		if (tmp == MACB_BIT(LLB))
> +			dmacfg &= ~GEM_BIT(ENDIA_DESC);

Ditto

> +		else
> +			dmacfg |= GEM_BIT(ENDIA_DESC);

Ditto

> +
> +		/* Restore net_ctrl */
> +		macb_writel(bp, NCR, ncr);
> +
>  		if (bp->dev->features & NETIF_F_HW_CSUM)
>  			dmacfg |= GEM_BIT(TXCOEN);
>  		else
> @@ -1832,14 +1851,14 @@ static void gem_update_stats(struct macb *bp)
>  
>  	for (i = 0; i < GEM_STATS_LEN; ++i, ++p) {
>  		u32 offset = gem_statistics[i].offset;
> -		u64 val = __raw_readl(bp->regs + offset);
> +		u64 val = readl_relaxed(bp->regs + offset);
>  
>  		bp->ethtool_stats[i] += val;
>  		*p += val;
>  
>  		if (offset == GEM_OCTTXL || offset == GEM_OCTRXL) {
>  			/* Add GEM_OCTTXH, GEM_OCTRXH */
> -			val = __raw_readl(bp->regs + offset + 4);
> +			val = readl_relaxed(bp->regs + offset + 4);
>  			bp->ethtool_stats[i] += ((u64)val) << 32;
>  			*(++p) += val;
>  		}
> @@ -2191,12 +2210,14 @@ static void macb_probe_queues(void __iomem *mem,
>  	*num_queues = 1;
>  
>  	/* is it macb or gem ? */
> -	mid = __raw_readl(mem + MACB_MID);
> +	mid = readl_relaxed(mem + MACB_MID);
> +
>  	if (MACB_BFEXT(IDNUM, mid) != 0x2)
>  		return;
>  
>  	/* bit 0 is never set but queue 0 always exists */
> -	*queue_mask = __raw_readl(mem + GEM_DCFG6) & 0xff;
> +	*queue_mask = readl_relaxed(mem + GEM_DCFG6) & 0xff;
> +
>  	*queue_mask |= 0x1;
>  
>  	for (hw_q = 1; hw_q < MACB_MAX_QUEUES; ++hw_q)
> diff --git a/drivers/net/ethernet/cadence/macb.h b/drivers/net/ethernet/cadence/macb.h
> index 31dc080..57f0a1a 100644
> --- a/drivers/net/ethernet/cadence/macb.h
> +++ b/drivers/net/ethernet/cadence/macb.h
> @@ -229,7 +229,8 @@
>  /* Bitfields in DMACFG. */
>  #define GEM_FBLDO_OFFSET	0 /* fixed burst length for DMA */
>  #define GEM_FBLDO_SIZE		5
> -#define GEM_ENDIA_OFFSET	7 /* endian swap mode for packet data access */
> +#define GEM_ENDIA_DESC_OFFSET	6 /* endian swap mode for management descriptor access */
> +#define GEM_ENDIA_PKT_OFFSET	7 /* endian swap mode for packet data access */

here you would need to define as well:
#define GEM_ENDIA_DESC_SIZE 1
#define GEM_ENDIA_PKT_SIZE 1
Otherwise, I suspect that the GEM_BIT() macro won't work well.


>  #define GEM_ENDIA_SIZE		1

And you can remove this one ^^^^.

>  #define GEM_RXBMS_OFFSET	8 /* RX packet buffer memory size select */
>  #define GEM_RXBMS_SIZE		2
> @@ -423,17 +424,17 @@
>  
>  /* Register access macros */
>  #define macb_readl(port,reg)				\
> -	__raw_readl((port)->regs + MACB_##reg)
> +	readl_relaxed((port)->regs + MACB_##reg)
>  #define macb_writel(port,reg,value)			\
> -	__raw_writel((value), (port)->regs + MACB_##reg)
> +	writel_relaxed((value), (port)->regs + MACB_##reg)
>  #define gem_readl(port, reg)				\
> -	__raw_readl((port)->regs + GEM_##reg)
> +	readl_relaxed((port)->regs + GEM_##reg)
>  #define gem_writel(port, reg, value)			\
> -	__raw_writel((value), (port)->regs + GEM_##reg)
> +	writel_relaxed((value), (port)->regs + GEM_##reg)
>  #define queue_readl(queue, reg)				\
> -	__raw_readl((queue)->bp->regs + (queue)->reg)
> +	readl_relaxed((queue)->bp->regs + (queue)->reg)
>  #define queue_writel(queue, reg, value)			\
> -	__raw_writel((value), (queue)->bp->regs + (queue)->reg)
> +	writel_relaxed((value), (queue)->bp->regs + (queue)->reg)
>  
>  /* Conditional GEM/MACB macros.  These perform the operation to the correct
>   * register dependent on whether the device is a GEM or a MACB.  For registers
> 


-- 
Nicolas Ferre