net: macb: add capability to not set the clock rate

SAMA7G5's ethernet IPs TX clock could be provided by its generic clock or
by the external clock provided by the PHY. The internal IP logic divides
properly this clock depending on the link speed. The patch adds a new
capability so that macb_set_tx_clock() to not be called for IPs having
this capability (the clock rate, in case of generic clock, is set at the
boot time via device tree and the driver only enables it).
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/cadence/macb.h

@@ -699,6 +699,7 @@
 #define MACB_CAPS_GEM_HAS_PTP			0x00000040
 #define MACB_CAPS_BD_RD_PREFETCH		0x00000080
 #define MACB_CAPS_NEEDS_RSTONUBR		0x00000100
+#define MACB_CAPS_CLK_HW_CHG			0x04000000
 #define MACB_CAPS_MACB_IS_EMAC			0x08000000
 #define MACB_CAPS_FIFO_MODE			0x10000000
 #define MACB_CAPS_GIGABIT_MODE_AVAILABLE	0x20000000

drivers/net/ethernet/cadence/macb_main.c

@@ -460,15 +460,14 @@ static void macb_init_buffers(struct macb *bp)
 
 /**
  * macb_set_tx_clk() - Set a clock to a new frequency
- * @clk:	Pointer to the clock to change
+ * @bp:		pointer to struct macb
  * @speed:	New frequency in Hz
- * @dev:	Pointer to the struct net_device
  */
-static void macb_set_tx_clk(struct clk *clk, int speed, struct net_device *dev)
+static void macb_set_tx_clk(struct macb *bp, int speed)
 {
 	long ferr, rate, rate_rounded;
 
-	if (!clk)
+	if (!bp->tx_clk || !(bp->caps & MACB_CAPS_CLK_HW_CHG))
 		return;
 
 	switch (speed) {
@@ -485,7 +484,7 @@ static void macb_set_tx_clk(struct clk *clk, int speed, struct net_device *dev)
 		return;
 	}
 
-	rate_rounded = clk_round_rate(clk, rate);
+	rate_rounded = clk_round_rate(bp->tx_clk, rate);
 	if (rate_rounded < 0)
 		return;
 
@@ -495,11 +494,12 @@ static void macb_set_tx_clk(struct clk *clk, int speed, struct net_device *dev)
 	ferr = abs(rate_rounded - rate);
 	ferr = DIV_ROUND_UP(ferr, rate / 100000);
 	if (ferr > 5)
-		netdev_warn(dev, "unable to generate target frequency: %ld Hz\n",
+		netdev_warn(bp->dev,
+			    "unable to generate target frequency: %ld Hz\n",
 			    rate);
 
-	if (clk_set_rate(clk, rate_rounded))
-		netdev_err(dev, "adjusting tx_clk failed.\n");
+	if (clk_set_rate(bp->tx_clk, rate_rounded))
+		netdev_err(bp->dev, "adjusting tx_clk failed.\n");
 }
 
 static void macb_validate(struct phylink_config *config,
@@ -751,7 +751,7 @@ static void macb_mac_link_up(struct phylink_config *config,
 		if (rx_pause)
 			ctrl |= MACB_BIT(PAE);
 
-		macb_set_tx_clk(bp->tx_clk, speed, ndev);
+		macb_set_tx_clk(bp, speed);
 
 		/* Initialize rings & buffers as clearing MACB_BIT(TE) in link down
 		 * cleared the pipeline and control registers.