[PATCH v3 04/16] net: phy: Add helper for mapping RGMII link speed to clock rate

[Jan Petrous via B4 Relay <devnull+jan.petrous.oss.nxp.com@kernel.org>]

From: "Jan Petrous (OSS)" <jan.petrous@oss.nxp.com>

The helper rgmii_clock() implemented Russel's hint during stmmac
glue driver review:

  > We seem to have multiple cases of very similar logic in lots of stmmac
  > platform drivers, and I think it's about time we said no more to this.
  > So, what I think we should do is as follows:
  >
  > add the following helper - either in stmmac, or more generically
  > (phylib? - in which case its name will need changing.)
  >
  > static long stmmac_get_rgmii_clock(int speed)
  > {
  >        switch (speed) {
  >        case SPEED_10:
  >                return 2500000;
  >
  >        case SPEED_100:
  >                return 25000000;
  >
  >        case SPEED_1000:
  >                return 125000000;
  >
  >        default:
  >                return -ENVAL;
  >        }
  > }
  >
  > Then, this can become:
  >
  >        long tx_clk_rate;
  >
  >        ...
  >
  >        tx_clk_rate = stmmac_get_rgmii_clock(speed);
  >        if (tx_clk_rate < 0) {
  >                dev_err(gmac->dev, "Unsupported/Invalid speed: %d\n", speed);
  >                return;
  >        }
  >
  >        ret = clk_set_rate(gmac->tx_clk, tx_clk_rate);

Suggested-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Jan Petrous (OSS) <jan.petrous@oss.nxp.com>
---
 include/linux/phy.h | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/include/linux/phy.h b/include/linux/phy.h
index a98bc91a0cde..7f6d9e7533ce 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -298,6 +298,27 @@ static inline const char *phy_modes(phy_interface_t interface)
 	}
 }
 
+/**
+ * rgmii_clock - map link speed to the clock rate
+ * @speed: link speed value
+ *
+ * Description: maps RGMII supported link speeds
+ * into the clock rates.
+ */
+static inline long rgmii_clock(int speed)
+{
+	switch (speed) {
+	case SPEED_10:
+		return 2500000;
+	case SPEED_100:
+		return 25000000;
+	case SPEED_1000:
+		return 125000000;
+	default:
+		return -EINVAL;
+	}
+}
+
 #define PHY_INIT_TIMEOUT	100000
 #define PHY_FORCE_TIMEOUT	10
 

-- 
2.46.0