[PATCH v2 4/7] net: phy: add helper for mapping RGMII link speed to clock rate

From: Jan Petrous (OSS)
Date: Sun Aug 18 2024 - 17:52:07 EST


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);
---

Signed-off-by: Jan Petrous (OSS) <jan.petrous@xxxxxxxxxxx>
---
include/linux/phy.h | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)

diff --git a/include/linux/phy.h b/include/linux/phy.h
index 6b7d40d49129..bb797364d91c 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)
}
}

+/**
+ * rgmi_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