via-velocity: Add ethtool interrupt coalescing support

(Partially from the upstream VIA driver). Tweaking the number of
frames-per-interrupt and timer-until-interrupt can reduce the amount of
CPU work quite a lot.
Signed-off-by: Simon Kagstrom <simon.kagstrom@netinsight.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/via-velocity.c

@@ -1246,6 +1246,66 @@ static void mii_init(struct velocity_info *vptr, u32 mii_status)
 	}
 }
 
+/**
+ * setup_queue_timers	-	Setup interrupt timers
+ *
+ * Setup interrupt frequency during suppression (timeout if the frame
+ * count isn't filled).
+ */
+static void setup_queue_timers(struct velocity_info *vptr)
+{
+	/* Only for newer revisions */
+	if (vptr->rev_id >= REV_ID_VT3216_A0) {
+		u8 txqueue_timer = 0;
+		u8 rxqueue_timer = 0;
+
+		if (vptr->mii_status & (VELOCITY_SPEED_1000 |
+				VELOCITY_SPEED_100)) {
+			txqueue_timer = vptr->options.txqueue_timer;
+			rxqueue_timer = vptr->options.rxqueue_timer;
+		}
+
+		writeb(txqueue_timer, &vptr->mac_regs->TQETMR);
+		writeb(rxqueue_timer, &vptr->mac_regs->RQETMR);
+	}
+}
+/**
+ * setup_adaptive_interrupts  -  Setup interrupt suppression
+ *
+ * @vptr velocity adapter
+ *
+ * The velocity is able to suppress interrupt during high interrupt load.
+ * This function turns on that feature.
+ */
+static void setup_adaptive_interrupts(struct velocity_info *vptr)
+{
+	struct mac_regs __iomem *regs = vptr->mac_regs;
+	u16 tx_intsup = vptr->options.tx_intsup;
+	u16 rx_intsup = vptr->options.rx_intsup;
+
+	/* Setup default interrupt mask (will be changed below) */
+	vptr->int_mask = INT_MASK_DEF;
+
+	/* Set Tx Interrupt Suppression Threshold */
+	writeb(CAMCR_PS0, &regs->CAMCR);
+	if (tx_intsup != 0) {
+		vptr->int_mask &= ~(ISR_PTXI | ISR_PTX0I | ISR_PTX1I |
+				ISR_PTX2I | ISR_PTX3I);
+		writew(tx_intsup, &regs->ISRCTL);
+	} else
+		writew(ISRCTL_TSUPDIS, &regs->ISRCTL);
+
+	/* Set Rx Interrupt Suppression Threshold */
+	writeb(CAMCR_PS1, &regs->CAMCR);
+	if (rx_intsup != 0) {
+		vptr->int_mask &= ~ISR_PRXI;
+		writew(rx_intsup, &regs->ISRCTL);
+	} else
+		writew(ISRCTL_RSUPDIS, &regs->ISRCTL);
+
+	/* Select page to interrupt hold timer */
+	writeb(0, &regs->CAMCR);
+}
 
 /**
  *	velocity_init_registers	-	initialise MAC registers
@@ -1332,7 +1392,7 @@ static void velocity_init_registers(struct velocity_info *vptr,
 		 */
 		enable_mii_autopoll(regs);
 
-		vptr->int_mask = INT_MASK_DEF;
+		setup_adaptive_interrupts(vptr);
 
 		writel(vptr->rx.pool_dma, &regs->RDBaseLo);
 		writew(vptr->options.numrx - 1, &regs->RDCSize);
@@ -1789,6 +1849,8 @@ static void velocity_error(struct velocity_info *vptr, int status)
 				BYTE_REG_BITS_OFF(TESTCFG_HBDIS, &regs->TESTCFG);
 			else
 				BYTE_REG_BITS_ON(TESTCFG_HBDIS, &regs->TESTCFG);
+
+			setup_queue_timers(vptr);
 		}
 		/*
 		 *	Get link status from PHYSR0
@@ -3199,6 +3261,100 @@ static void velocity_set_msglevel(struct net_device *dev, u32 value)
 	 msglevel = value;
 }
 
+static int get_pending_timer_val(int val)
+{
+	int mult_bits = val >> 6;
+	int mult = 1;
+
+	switch (mult_bits)
+	{
+	case 1:
+		mult = 4; break;
+	case 2:
+		mult = 16; break;
+	case 3:
+		mult = 64; break;
+	case 0:
+	default:
+		break;
+	}
+
+	return (val & 0x3f) * mult;
+}
+
+static void set_pending_timer_val(int *val, u32 us)
+{
+	u8 mult = 0;
+	u8 shift = 0;
+
+	if (us >= 0x3f) {
+		mult = 1; /* mult with 4 */
+		shift = 2;
+	}
+	if (us >= 0x3f * 4) {
+		mult = 2; /* mult with 16 */
+		shift = 4;
+	}
+	if (us >= 0x3f * 16) {
+		mult = 3; /* mult with 64 */
+		shift = 6;
+	}
+
+	*val = (mult << 6) | ((us >> shift) & 0x3f);
+}
+
+
+static int velocity_get_coalesce(struct net_device *dev,
+		struct ethtool_coalesce *ecmd)
+{
+	struct velocity_info *vptr = netdev_priv(dev);
+
+	ecmd->tx_max_coalesced_frames = vptr->options.tx_intsup;
+	ecmd->rx_max_coalesced_frames = vptr->options.rx_intsup;
+
+	ecmd->rx_coalesce_usecs = get_pending_timer_val(vptr->options.rxqueue_timer);
+	ecmd->tx_coalesce_usecs = get_pending_timer_val(vptr->options.txqueue_timer);
+
+	return 0;
+}
+
+static int velocity_set_coalesce(struct net_device *dev,
+		struct ethtool_coalesce *ecmd)
+{
+	struct velocity_info *vptr = netdev_priv(dev);
+	int max_us = 0x3f * 64;
+
+	/* 6 bits of  */
+	if (ecmd->tx_coalesce_usecs > max_us)
+		return -EINVAL;
+	if (ecmd->rx_coalesce_usecs > max_us)
+		return -EINVAL;
+
+	if (ecmd->tx_max_coalesced_frames > 0xff)
+		return -EINVAL;
+	if (ecmd->rx_max_coalesced_frames > 0xff)
+		return -EINVAL;
+
+	vptr->options.rx_intsup = ecmd->rx_max_coalesced_frames;
+	vptr->options.tx_intsup = ecmd->tx_max_coalesced_frames;
+
+	set_pending_timer_val(&vptr->options.rxqueue_timer,
+			ecmd->rx_coalesce_usecs);
+	set_pending_timer_val(&vptr->options.txqueue_timer,
+			ecmd->tx_coalesce_usecs);
+
+	/* Setup the interrupt suppression and queue timers */
+	mac_disable_int(vptr->mac_regs);
+	setup_adaptive_interrupts(vptr);
+	setup_queue_timers(vptr);
+
+	mac_write_int_mask(vptr->int_mask, vptr->mac_regs);
+	mac_clear_isr(vptr->mac_regs);
+	mac_enable_int(vptr->mac_regs);
+
+	return 0;
+}
+
 static const struct ethtool_ops velocity_ethtool_ops = {
 	.get_settings	=	velocity_get_settings,
 	.set_settings	=	velocity_set_settings,
@@ -3208,6 +3364,8 @@ static const struct ethtool_ops velocity_ethtool_ops = {
 	.get_msglevel	=	velocity_get_msglevel,
 	.set_msglevel	=	velocity_set_msglevel,
 	.get_link	=	velocity_get_link,
+	.get_coalesce	=	velocity_get_coalesce,
+	.set_coalesce	=	velocity_set_coalesce,
 	.begin		=	velocity_ethtool_up,
 	.complete	=	velocity_ethtool_down
 };

drivers/net/via-velocity.h

@@ -1005,7 +1005,8 @@ struct mac_regs {
 
 	volatile __le32 RDBaseLo;	/* 0x38 */
 	volatile __le16 RDIdx;		/* 0x3C */
-	volatile __le16 reserved_3E;
+	volatile u8 TQETMR;		/* 0x3E, VT3216 and above only */
+	volatile u8 RQETMR;		/* 0x3F, VT3216 and above only */
 
 	volatile __le32 TDBaseLo[4];	/* 0x40 */
 
@@ -1491,6 +1492,10 @@ struct velocity_opt {
 	int rx_bandwidth_hi;
 	int rx_bandwidth_lo;
 	int rx_bandwidth_en;
+	int rxqueue_timer;
+	int txqueue_timer;
+	int tx_intsup;
+	int rx_intsup;
 	u32 flags;
 };