driver: net: ethernet: cpsw: implement interrupt pacing via ethtool

This patch implements support for interrupt pacing block of CPSW via ethtool
Inetrrupt pacing block is common of both the ethernet interface in
dual emac mode

Signed-off-by: Mugunthan V N <mugunthanvnm@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 104 insertions, 0 deletions

diff --git a/drivers/net/ethernet/ti/cpsw.c b/drivers/net/ethernet/ti/cpsw.c
index 83ce890d6e97..d6cf6982904e 100644
--- a/drivers/net/ethernet/ti/cpsw.c
+++ b/drivers/net/ethernet/ti/cpsw.c
@@ -126,6 +126,13 @@ do {								\
 #define CPSW_FIFO_DUAL_MAC_MODE         (1 << 15)
 #define CPSW_FIFO_RATE_LIMIT_MODE       (2 << 15)
 
+#define CPSW_INTPACEEN          (0x3f << 16)
+#define CPSW_INTPRESCALE_MASK   (0x7FF << 0)
+#define CPSW_CMINTMAX_CNT       63
+#define CPSW_CMINTMIN_CNT       2
+#define CPSW_CMINTMAX_INTVL     (1000 / CPSW_CMINTMIN_CNT)
+#define CPSW_CMINTMIN_INTVL     ((1000 / CPSW_CMINTMAX_CNT) + 1)
+
 #define cpsw_enable_irq(priv)   \
         do {                    \
                 u32 i;          \
@@ -164,6 +171,15 @@ struct cpsw_wr_regs {
         u32     rx_en;
         u32     tx_en;
         u32     misc_en;
+        u32     mem_allign1[8];
+        u32     rx_thresh_stat;
+        u32     rx_stat;
+        u32     tx_stat;
+        u32     misc_stat;
+        u32     mem_allign2[8];
+        u32     rx_imax;
+        u32     tx_imax;
+
 };
 
 struct cpsw_ss_regs {
@@ -318,6 +334,8 @@ struct cpsw_priv {
         struct cpsw_host_regs __iomem   *host_port_regs;
         u32                             msg_enable;
         u32                             version;
+        u32                             coal_intvl;
+        u32                             bus_freq_mhz;
         struct net_device_stats         stats;
         int                             rx_packet_max;
         int                             host_port;
@@ -616,6 +634,77 @@ static void cpsw_adjust_link(struct net_device *ndev)
         }
 }
 
+static int cpsw_get_coalesce(struct net_device *ndev,
+                                struct ethtool_coalesce *coal)
+{
+        struct cpsw_priv *priv = netdev_priv(ndev);
+
+        coal->rx_coalesce_usecs = priv->coal_intvl;
+        return 0;
+}
+
+static int cpsw_set_coalesce(struct net_device *ndev,
+                                struct ethtool_coalesce *coal)
+{
+        struct cpsw_priv *priv = netdev_priv(ndev);
+        u32 int_ctrl;
+        u32 num_interrupts = 0;
+        u32 prescale = 0;
+        u32 addnl_dvdr = 1;
+        u32 coal_intvl = 0;
+
+        if (!coal->rx_coalesce_usecs)
+                return -EINVAL;
+
+        coal_intvl = coal->rx_coalesce_usecs;
+
+        int_ctrl =  readl(&priv->wr_regs->int_control);
+        prescale = priv->bus_freq_mhz * 4;
+
+        if (coal_intvl < CPSW_CMINTMIN_INTVL)
+                coal_intvl = CPSW_CMINTMIN_INTVL;
+
+        if (coal_intvl > CPSW_CMINTMAX_INTVL) {
+                /* Interrupt pacer works with 4us Pulse, we can
+                 * throttle further by dilating the 4us pulse.
+                 */
+                addnl_dvdr = CPSW_INTPRESCALE_MASK / prescale;
+
+                if (addnl_dvdr > 1) {
+                        prescale *= addnl_dvdr;
+                        if (coal_intvl > (CPSW_CMINTMAX_INTVL * addnl_dvdr))
+                                coal_intvl = (CPSW_CMINTMAX_INTVL
+                                                * addnl_dvdr);
+                } else {
+                        addnl_dvdr = 1;
+                        coal_intvl = CPSW_CMINTMAX_INTVL;
+                }
+        }
+
+        num_interrupts = (1000 * addnl_dvdr) / coal_intvl;
+        writel(num_interrupts, &priv->wr_regs->rx_imax);
+        writel(num_interrupts, &priv->wr_regs->tx_imax);
+
+        int_ctrl |= CPSW_INTPACEEN;
+        int_ctrl &= (~CPSW_INTPRESCALE_MASK);
+        int_ctrl |= (prescale & CPSW_INTPRESCALE_MASK);
+        writel(int_ctrl, &priv->wr_regs->int_control);
+
+        cpsw_notice(priv, timer, "Set coalesce to %d usecs.\n", coal_intvl);
+        if (priv->data.dual_emac) {
+                int i;
+
+                for (i = 0; i < priv->data.slaves; i++) {
+                        priv = netdev_priv(priv->slaves[i].ndev);
+                        priv->coal_intvl = coal_intvl;
+                }
+        } else {
+                priv->coal_intvl = coal_intvl;
+        }
+
+        return 0;
+}
+
 static inline int __show_stat(char *buf, int maxlen, const char *name, u32 val)
 {
         static char *leader = "........................................";
@@ -838,6 +927,14 @@ static int cpsw_ndo_open(struct net_device *ndev)
                 cpsw_info(priv, ifup, "submitted %d rx descriptors\n", i);
         }
 
+        /* Enable Interrupt pacing if configured */
+        if (priv->coal_intvl != 0) {
+                struct ethtool_coalesce coal;
+
+                coal.rx_coalesce_usecs = (priv->coal_intvl << 4);
+                cpsw_set_coalesce(ndev, &coal);
+        }
+
         cpdma_ctlr_start(priv->dma);
         cpsw_intr_enable(priv);
         napi_enable(&priv->napi);
@@ -1279,6 +1376,8 @@ static const struct ethtool_ops cpsw_ethtool_ops = {
         .get_ts_info    = cpsw_get_ts_info,
         .get_settings   = cpsw_get_settings,
         .set_settings   = cpsw_set_settings,
+        .get_coalesce   = cpsw_get_coalesce,
+        .set_coalesce   = cpsw_set_coalesce,
 };
 
 static void cpsw_slave_init(struct cpsw_slave *slave, struct cpsw_priv *priv,
@@ -1466,6 +1565,9 @@ static int cpsw_probe_dual_emac(struct platform_device *pdev,
         priv_sl2->slaves = priv->slaves;
         priv_sl2->clk = priv->clk;
 
+        priv_sl2->coal_intvl = 0;
+        priv_sl2->bus_freq_mhz = priv->bus_freq_mhz;
+
         priv_sl2->cpsw_res = priv->cpsw_res;
         priv_sl2->regs = priv->regs;
         priv_sl2->host_port = priv->host_port;
@@ -1575,6 +1677,8 @@ static int cpsw_probe(struct platform_device *pdev)
                 ret = -ENODEV;
                 goto clean_slave_ret;
         }
+        priv->coal_intvl = 0;
+        priv->bus_freq_mhz = clk_get_rate(priv->clk) / 1000000;
 
         priv->cpsw_res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
         if (!priv->cpsw_res) {