Subject: Re: [PATCH v2 3/3] net: macb: add support for high speed interface

From: Russell King - ARM Linux admin <[email-masked]>
Date: Sun, 15 Dec 2019 15:20:00 +0000

On Sun, Dec 15, 2019 at 03:12:49PM +0000, Russell King - ARM Linux admin wrote:
> On Fri, Dec 13, 2019 at 09:42:57AM +0000, Milind Parab wrote:
> > This patch add support for high speed USXGMII PCS and 10G
> > speed in Cadence ethernet controller driver.
> > 
> > Signed-off-by: Milind Parab <[email-masked]>
> > ---
> >  drivers/net/ethernet/cadence/macb.h      |  50 ++++++++
> >  drivers/net/ethernet/cadence/macb_main.c | 138 ++++++++++++++++++++---
> >  2 files changed, 170 insertions(+), 18 deletions(-)
> > 
> > diff --git a/drivers/net/ethernet/cadence/macb.h b/drivers/net/ethernet/cadence/macb.h
> > index dbf7070fcdba..b731807d1c49 100644
> > --- a/drivers/net/ethernet/cadence/macb.h
> > +++ b/drivers/net/ethernet/cadence/macb.h
> > @@ -76,10 +76,12 @@
> >  #define MACB_RBQPH		0x04D4
> >  
> >  /* GEM register offsets. */
> > +#define GEM_NCR			0x0000 /* Network Control */
> >  #define GEM_NCFGR		0x0004 /* Network Config */
> >  #define GEM_USRIO		0x000c /* User IO */
> >  #define GEM_DMACFG		0x0010 /* DMA Configuration */
> >  #define GEM_JML			0x0048 /* Jumbo Max Length */
> > +#define GEM_HS_MAC_CONFIG	0x0050 /* GEM high speed config */
> >  #define GEM_HRB			0x0080 /* Hash Bottom */
> >  #define GEM_HRT			0x0084 /* Hash Top */
> >  #define GEM_SA1B		0x0088 /* Specific1 Bottom */
> > @@ -164,6 +166,9 @@
> >  #define GEM_DCFG7		0x0298 /* Design Config 7 */
> >  #define GEM_DCFG8		0x029C /* Design Config 8 */
> >  #define GEM_DCFG10		0x02A4 /* Design Config 10 */
> > +#define GEM_DCFG12		0x02AC /* Design Config 12 */
> > +#define GEM_USX_CONTROL		0x0A80 /* USXGMII control register */
> > +#define GEM_USX_STATUS		0x0A88 /* USXGMII status register */
> >  
> >  #define GEM_TXBDCTRL	0x04cc /* TX Buffer Descriptor control register */
> >  #define GEM_RXBDCTRL	0x04d0 /* RX Buffer Descriptor control register */
> > @@ -270,11 +275,19 @@
> >  #define MACB_IRXFCS_OFFSET	19
> >  #define MACB_IRXFCS_SIZE	1
> >  
> > +/* GEM specific NCR bitfields. */
> > +#define GEM_ENABLE_HS_MAC_OFFSET	31
> > +#define GEM_ENABLE_HS_MAC_SIZE		1
> > +
> >  /* GEM specific NCFGR bitfields. */
> > +#define GEM_FD_OFFSET		1 /* Full duplex */
> > +#define GEM_FD_SIZE		1
> >  #define GEM_GBE_OFFSET		10 /* Gigabit mode enable */
> >  #define GEM_GBE_SIZE		1
> >  #define GEM_PCSSEL_OFFSET	11
> >  #define GEM_PCSSEL_SIZE		1
> > +#define GEM_PAE_OFFSET		13 /* Pause enable */
> > +#define GEM_PAE_SIZE		1
> >  #define GEM_CLK_OFFSET		18 /* MDC clock division */
> >  #define GEM_CLK_SIZE		3
> >  #define GEM_DBW_OFFSET		21 /* Data bus width */
> > @@ -455,11 +468,17 @@
> >  #define MACB_REV_OFFSET				0
> >  #define MACB_REV_SIZE				16
> >  
> > +/* Bitfield in HS_MAC_CONFIG */
> > +#define GEM_HS_MAC_SPEED_OFFSET			0
> > +#define GEM_HS_MAC_SPEED_SIZE			3
> > +
> >  /* Bitfields in DCFG1. */
> >  #define GEM_IRQCOR_OFFSET			23
> >  #define GEM_IRQCOR_SIZE				1
> >  #define GEM_DBWDEF_OFFSET			25
> >  #define GEM_DBWDEF_SIZE				3
> > +#define GEM_NO_PCS_OFFSET			0
> > +#define GEM_NO_PCS_SIZE				1
> >  
> >  /* Bitfields in DCFG2. */
> >  #define GEM_RX_PKT_BUFF_OFFSET			20
> > @@ -494,6 +513,34 @@
> >  #define GEM_RXBD_RDBUFF_OFFSET			8
> >  #define GEM_RXBD_RDBUFF_SIZE			4
> >  
> > +/* Bitfields in DCFG12. */
> > +#define GEM_HIGH_SPEED_OFFSET			26
> > +#define GEM_HIGH_SPEED_SIZE			1
> > +
> > +/* Bitfields in USX_CONTROL. */
> > +#define GEM_USX_CTRL_SPEED_OFFSET		14
> > +#define GEM_USX_CTRL_SPEED_SIZE			3
> > +#define GEM_SERDES_RATE_OFFSET			12
> > +#define GEM_SERDES_RATE_SIZE			2
> > +#define GEM_RX_SCR_BYPASS_OFFSET		9
> > +#define GEM_RX_SCR_BYPASS_SIZE			1
> > +#define GEM_TX_SCR_BYPASS_OFFSET		8
> > +#define GEM_TX_SCR_BYPASS_SIZE			1
> > +#define GEM_RX_SYNC_RESET_OFFSET		2
> > +#define GEM_RX_SYNC_RESET_SIZE			1
> > +#define GEM_TX_EN_OFFSET			1
> > +#define GEM_TX_EN_SIZE				1
> > +#define GEM_SIGNAL_OK_OFFSET			0
> > +#define GEM_SIGNAL_OK_SIZE			1
> > +
> > +/* Bitfields in USX_STATUS. */
> > +#define GEM_USX_TX_FAULT_OFFSET			28
> > +#define GEM_USX_TX_FAULT_SIZE			1
> > +#define GEM_USX_RX_FAULT_OFFSET			27
> > +#define GEM_USX_RX_FAULT_SIZE			1
> > +#define GEM_USX_BLOCK_LOCK_OFFSET		0
> > +#define GEM_USX_BLOCK_LOCK_SIZE			1
> > +
> >  /* Bitfields in TISUBN */
> >  #define GEM_SUBNSINCR_OFFSET			0
> >  #define GEM_SUBNSINCRL_OFFSET			24
> > @@ -656,6 +703,8 @@
> >  #define MACB_CAPS_GIGABIT_MODE_AVAILABLE	0x20000000
> >  #define MACB_CAPS_SG_DISABLED			0x40000000
> >  #define MACB_CAPS_MACB_IS_GEM			0x80000000
> > +#define MACB_CAPS_PCS				0x01000000
> > +#define MACB_CAPS_HIGH_SPEED			0x02000000
> >  
> >  /* LSO settings */
> >  #define MACB_LSO_UFO_ENABLE			0x01
> > @@ -724,6 +773,7 @@
> >  	})
> >  
> >  #define MACB_READ_NSR(bp)	macb_readl(bp, NSR)
> > +#define GEM_READ_USX_STATUS(bp)	gem_readl(bp, USX_STATUS)
> >  
> >  /* struct macb_dma_desc - Hardware DMA descriptor
> >   * @addr: DMA address of data buffer
> > diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
> > index ced32d2a85e1..5963a60d54b9 100644
> > --- a/drivers/net/ethernet/cadence/macb_main.c
> > +++ b/drivers/net/ethernet/cadence/macb_main.c
> > @@ -81,6 +81,14 @@ struct sifive_fu540_macb_mgmt {
> >  #define MACB_WOL_HAS_MAGIC_PACKET	(0x1 << 0)
> >  #define MACB_WOL_ENABLED		(0x1 << 1)
> >  
> > +#define HS_MAC_SPEED_100M	0
> > +#define HS_MAC_SPEED_1000M	1
> > +#define HS_MAC_SPEED_2500M	2
> > +#define HS_MAC_SPEED_5000M	3
> > +#define HS_MAC_SPEED_10000M	4
> > +
> > +#define MACB_SERDES_RATE_10G	1
> > +
> >  /* Graceful stop timeouts in us. We should allow up to
> >   * 1 frame time (10 Mbits/s, full-duplex, ignoring collisions)
> >   */
> > @@ -90,6 +98,8 @@ struct sifive_fu540_macb_mgmt {
> >  
> >  #define MACB_MDIO_TIMEOUT	1000000 /* in usecs */
> >  
> > +#define MACB_USX_BLOCK_LOCK_TIMEOUT	1000000 /* in usecs */
> > +
> >  /* DMA buffer descriptor might be different size
> >   * depends on hardware configuration:
> >   *
> > @@ -506,6 +516,7 @@ static void macb_validate(struct phylink_config *config,
> >  	    state->interface != PHY_INTERFACE_MODE_RMII &&
> >  	    state->interface != PHY_INTERFACE_MODE_GMII &&
> >  	    state->interface != PHY_INTERFACE_MODE_SGMII &&
> > +	    state->interface != PHY_INTERFACE_MODE_USXGMII &&
> >  	    !phy_interface_mode_is_rgmii(state->interface)) {
> >  		bitmap_zero(supported, __ETHTOOL_LINK_MODE_MASK_NBITS);
> >  		return;
> > @@ -518,6 +529,13 @@ static void macb_validate(struct phylink_config *config,
> >  		return;
> >  	}
> >  
> > +	if (state->interface == PHY_INTERFACE_MODE_USXGMII &&
> > +	    !(bp->caps & MACB_CAPS_HIGH_SPEED &&
> > +	      bp->caps & MACB_CAPS_PCS)) {
> > +		bitmap_zero(supported, __ETHTOOL_LINK_MODE_MASK_NBITS);
> > +		return;
> > +	}
> > +
> >  	phylink_set_port_modes(mask);
> >  	phylink_set(mask, Autoneg);
> >  	phylink_set(mask, Asym_Pause);
> > @@ -527,6 +545,22 @@ static void macb_validate(struct phylink_config *config,
> >  	phylink_set(mask, 100baseT_Half);
> >  	phylink_set(mask, 100baseT_Full);
> >  
> > +	if (bp->caps & MACB_CAPS_GIGABIT_MODE_AVAILABLE &&
> > +	    (state->interface == PHY_INTERFACE_MODE_NA ||
> > +	     state->interface == PHY_INTERFACE_MODE_USXGMII)) {
> > +		phylink_set(mask, 10000baseCR_Full);
> > +		phylink_set(mask, 10000baseER_Full);
> > +		phylink_set(mask, 10000baseKR_Full);
> > +		phylink_set(mask, 10000baseLR_Full);
> > +		phylink_set(mask, 10000baseLRM_Full);
> > +		phylink_set(mask, 10000baseSR_Full);
> > +		phylink_set(mask, 10000baseT_Full);
> > +		phylink_set(mask, 5000baseT_Full);
> > +		phylink_set(mask, 2500baseX_Full);
> > +		phylink_set(mask, 1000baseX_Full);
> > +		phylink_set(mask, 1000baseT_Full);
> > +	}
> > +
> >  	if (bp->caps & MACB_CAPS_GIGABIT_MODE_AVAILABLE &&
> >  	    (state->interface == PHY_INTERFACE_MODE_NA ||
> >  	     state->interface == PHY_INTERFACE_MODE_GMII ||
> > @@ -544,6 +578,60 @@ static void macb_validate(struct phylink_config *config,
> >  		   __ETHTOOL_LINK_MODE_MASK_NBITS);
> >  }
> >  
> > +static int gem_mac_usx_configure(struct macb *bp,
> > +				 const struct phylink_link_state *state)
> > +{
> > +	u32 speed, config, val;
> > +	int ret;
> > +
> > +	val = gem_readl(bp, NCFGR);
> > +	val = GEM_BIT(PCSSEL) | (~GEM_BIT(SGMIIEN) & val);
> > +	if (state->pause & MLO_PAUSE_TX)
> > +		val |= GEM_BIT(PAE);
> > +	gem_writel(bp, NCFGR, val);
> > +	gem_writel(bp, NCR, gem_readl(bp, NCR) | GEM_BIT(ENABLE_HS_MAC));
> > +	gem_writel(bp, NCFGR, gem_readl(bp, NCFGR) | GEM_BIT(FD));
> > +	config = gem_readl(bp, USX_CONTROL);
> > +	config = GEM_BFINS(SERDES_RATE, MACB_SERDES_RATE_10G, config);
> > +	config &= ~GEM_BIT(TX_SCR_BYPASS);
> > +	config &= ~GEM_BIT(RX_SCR_BYPASS);
> > +	gem_writel(bp, USX_CONTROL, config | GEM_BIT(TX_EN));
> > +	config = gem_readl(bp, USX_CONTROL);
> > +	gem_writel(bp, USX_CONTROL, config | GEM_BIT(SIGNAL_OK));
> > +	ret = readx_poll_timeout(GEM_READ_USX_STATUS, bp, val,
> > +				 val & GEM_BIT(USX_BLOCK_LOCK),
> > +				 1, MACB_USX_BLOCK_LOCK_TIMEOUT);
> > +	if (ret < 0) {
> > +		netdev_warn(bp->dev, "USXGMII block lock failed");
> > +		return -ETIMEDOUT;
> > +	}
> 
> I mentioned this last time around, so I'm a little surprised it's
> still here.  As I already stated, there is no requirement that the
> USXGMII locks before any of these functions return.
> 
> You're also waiting for up to a second in a work queue, which is not
> nice behaviour.
> 
> > +
> > +	switch (state->speed) {
> > +	case SPEED_10000:
> > +		speed = HS_MAC_SPEED_10000M;
> > +		break;
> > +	case SPEED_5000:
> > +		speed = HS_MAC_SPEED_5000M;
> > +		break;
> > +	case SPEED_2500:
> > +		speed = HS_MAC_SPEED_2500M;
> > +		break;
> > +	case SPEED_1000:
> > +		speed = HS_MAC_SPEED_1000M;
> > +		break;
> > +	default:
> > +	case SPEED_100:
> > +		speed = HS_MAC_SPEED_100M;
> > +		break;
> 
> macb_validate() goes down to 10Mbps, but you don't handle that here.
> If it isn't supported, then macb_validate() shouldn't allow it for this
> mode.
> 
> > +	}
> > +
> > +	gem_writel(bp, HS_MAC_CONFIG, GEM_BFINS(HS_MAC_SPEED, speed,
> > +						gem_readl(bp, HS_MAC_CONFIG)));
> > +	gem_writel(bp, USX_CONTROL, GEM_BFINS(USX_CTRL_SPEED, speed,
> > +					      gem_readl(bp, USX_CONTROL)));
> > +	return 0;
> > +}
> > +
> >  static void macb_mac_pcs_get_state(struct phylink_config *config,
> >  				   struct phylink_link_state *state)
> >  {
> > @@ -565,30 +653,39 @@ static void macb_mac_config(struct phylink_config *config, unsigned int mode,
> >  
> >  	spin_lock_irqsave(&bp->lock, flags);
> >  
> > -	old_ctrl = ctrl = macb_or_gem_readl(bp, NCFGR);
> > +	if (bp->phy_interface == PHY_INTERFACE_MODE_USXGMII) {
> 
> Why bp->phy_interface and not state->interface?
> 
> If you don't support selecting between USXGMII and other modes at
> runtime, should macb_validate() be allowing ethtool link modes for
> it when it's different from the configured setting?
> 
> > +		if (gem_mac_usx_configure(bp, state) < 0) {
> > +			spin_unlock_irqrestore(&bp->lock, flags);
> > +			phylink_mac_change(bp->phylink, false);
> 
> I guess this is the reason you're waiting for the USXGMII block
> to lock - do you not have any way to raise an interrupt when
> something changes with the USXGMII (or for that matter SGMII)
> blocks?  Without that, you're fixed to a single speed.

BTW, if you don't have an macb_mac_pcs_get_state() implementation,
and from what you described last time around, I don't see how SGMII
nor this new addition of USXGMII can work for you. Both these
protocols use in-band control words, which should be read and
interpreted in macb_mac_pcs_get_state().

What I think you're trying to do is to use your PCS PHY as a normal
PHY, or maybe you're ignoring the PCS PHY completely and relying on
an external PHY (and hence always using MLO_AN_PHY or MLO_AN_FIXED
mode.)

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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