[PATCH net-next v4] net: phy: intel-xway: Add RGMII internal delay configuration

From: Martin Schiller
Date: Mon Jul 12 2021 - 03:40:54 EST


This adds the possibility to configure the RGMII RX/TX clock skew via
devicetree.

Simply set phy mode to "rgmii-id", "rgmii-rxid" or "rgmii-txid" and add
the "rx-internal-delay-ps" or "tx-internal-delay-ps" property to the
devicetree.

Furthermore, a warning is now issued if the phy mode is configured to
"rgmii" and an internal delay is set in the phy (e.g. by pin-strapping),
as in the dp83867 driver.

Signed-off-by: Martin Schiller <ms@xxxxxxxxxx>
---

Changes to v3:
o Fix typo in commit message
o use FIELD_PREP() and FIELD_GET() macros
o further code cleanups
o always mask rxskew AND txskew value in the register value

Changes to v2:
o Fix missing whitespace in warning.

Changes to v1:
o code cleanup and use phy_modify().
o use default of 2.0ns if delay property is absent instead of returning
an error.

---
drivers/net/phy/intel-xway.c | 85 ++++++++++++++++++++++++++++++++++++
1 file changed, 85 insertions(+)

diff --git a/drivers/net/phy/intel-xway.c b/drivers/net/phy/intel-xway.c
index d453ec016168..5a626cd27ed4 100644
--- a/drivers/net/phy/intel-xway.c
+++ b/drivers/net/phy/intel-xway.c
@@ -8,11 +8,16 @@
#include <linux/module.h>
#include <linux/phy.h>
#include <linux/of.h>
+#include <linux/bitfield.h>

+#define XWAY_MDIO_MIICTRL 0x17 /* mii control */
#define XWAY_MDIO_IMASK 0x19 /* interrupt mask */
#define XWAY_MDIO_ISTAT 0x1A /* interrupt status */
#define XWAY_MDIO_LED 0x1B /* led control */

+#define XWAY_MDIO_MIICTRL_RXSKEW_MASK GENMASK(14, 12)
+#define XWAY_MDIO_MIICTRL_TXSKEW_MASK GENMASK(10, 8)
+
/* bit 15:12 are reserved */
#define XWAY_MDIO_LED_LED3_EN BIT(11) /* Enable the integrated function of LED3 */
#define XWAY_MDIO_LED_LED2_EN BIT(10) /* Enable the integrated function of LED2 */
@@ -157,6 +162,82 @@
#define PHY_ID_PHY11G_VR9_1_2 0xD565A409
#define PHY_ID_PHY22F_VR9_1_2 0xD565A419

+#if IS_ENABLED(CONFIG_OF_MDIO)
+static const int xway_internal_delay[] = {0, 500, 1000, 1500, 2000, 2500,
+ 3000, 3500};
+
+static int xway_gphy_of_reg_init(struct phy_device *phydev)
+{
+ struct device *dev = &phydev->mdio.dev;
+ unsigned int delay_size = ARRAY_SIZE(xway_internal_delay);
+ s32 int_delay;
+ int val = 0;
+
+ if (!phy_interface_is_rgmii(phydev))
+ return 0;
+
+ /* Existing behavior was to use default pin strapping delay in rgmii
+ * mode, but rgmii should have meant no delay. Warn existing users,
+ * but do not change anything at the moment.
+ */
+ if (phydev->interface == PHY_INTERFACE_MODE_RGMII) {
+ u16 txskew, rxskew;
+
+ val = phy_read(phydev, XWAY_MDIO_MIICTRL);
+ if (val < 0)
+ return val;
+
+ txskew = FIELD_GET(XWAY_MDIO_MIICTRL_TXSKEW_MASK, val);
+ rxskew = FIELD_GET(XWAY_MDIO_MIICTRL_RXSKEW_MASK, val);
+
+ if (txskew > 0 || rxskew > 0)
+ phydev_warn(phydev,
+ "PHY has delays (e.g. via pin strapping), but phy-mode = 'rgmii'\n"
+ "Should be 'rgmii-id' to use internal delays txskew:%d ps rxskew:%d ps\n",
+ xway_internal_delay[txskew],
+ xway_internal_delay[rxskew]);
+ return 0;
+ }
+
+ if (phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
+ phydev->interface == PHY_INTERFACE_MODE_RGMII_RXID) {
+ int_delay = phy_get_internal_delay(phydev, dev,
+ xway_internal_delay,
+ delay_size, true);
+
+ if (int_delay < 0) {
+ phydev_warn(phydev, "rx-internal-delay-ps is missing, use default of 2.0 ns\n");
+ int_delay = 4; /* 2000 ps */
+ }
+
+ val |= FIELD_PREP(XWAY_MDIO_MIICTRL_RXSKEW_MASK, int_delay);
+ }
+
+ if (phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
+ phydev->interface == PHY_INTERFACE_MODE_RGMII_TXID) {
+ int_delay = phy_get_internal_delay(phydev, dev,
+ xway_internal_delay,
+ delay_size, false);
+
+ if (int_delay < 0) {
+ phydev_warn(phydev, "tx-internal-delay-ps is missing, use default of 2.0 ns\n");
+ int_delay = 4; /* 2000 ps */
+ }
+
+ val |= FIELD_PREP(XWAY_MDIO_MIICTRL_TXSKEW_MASK, int_delay);
+ }
+
+ return phy_modify(phydev, XWAY_MDIO_MIICTRL,
+ XWAY_MDIO_MIICTRL_RXSKEW_MASK |
+ XWAY_MDIO_MIICTRL_TXSKEW_MASK, val);
+}
+#else
+static int xway_gphy_of_reg_init(struct phy_device *phydev)
+{
+ return 0;
+}
+#endif /* CONFIG_OF_MDIO */
+
static int xway_gphy_config_init(struct phy_device *phydev)
{
int err;
@@ -204,6 +285,10 @@ static int xway_gphy_config_init(struct phy_device *phydev)
phy_write_mmd(phydev, MDIO_MMD_VEND2, XWAY_MMD_LED2H, ledxh);
phy_write_mmd(phydev, MDIO_MMD_VEND2, XWAY_MMD_LED2L, ledxl);

+ err = xway_gphy_of_reg_init(phydev);
+ if (err)
+ return err;
+
return 0;
}

--
2.20.1