[M] Change in coreboot[master]: drivers/net/phy/m88e1512: Add a way to set output impedance manually

[Felix Held (Code Review)]

Felix Held has submitted this change. ( https://review.coreboot.org/c/coreboot/+/73018 )

Change subject: drivers/net/phy/m88e1512: Add a way to set output impedance manually
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drivers/net/phy/m88e1512: Add a way to set output impedance manually

This patch provides the functionality to set the RGMII output impedance
manually. To ensure that no race condition occurs, the driver strength
values for PMOS and NMOS should be written to the RGMII output impedance
calibration override register first and then the force bit should be
enabled with a second write to this register.

Link to the Marvell PHY 88E1512 datasheet:
https://web.archive.org/web/20230125074158/https://www.marvell.com/content/d...

Change-Id: I87fa03aa49514cdc33d2911d7f23386c8f69d95b
Signed-off-by: Mario Scheithauer 
Reviewed-on: https://review.coreboot.org/c/coreboot/+/73018
Tested-by: build bot (Jenkins) 
Reviewed-by: Werner Zeh 
---
M src/drivers/net/phy/m88e1512/chip.h
M src/drivers/net/phy/m88e1512/m88e1512.c
M src/drivers/net/phy/m88e1512/m88e1512.h
3 files changed, 50 insertions(+), 0 deletions(-)

Approvals:
  build bot (Jenkins): Verified
  Werner Zeh: Looks good to me, approved

diff --git a/src/drivers/net/phy/m88e1512/chip.h b/src/drivers/net/phy/m88e1512/chip.h
index 915001a..f1e313b 100644
--- a/src/drivers/net/phy/m88e1512/chip.h
+++ b/src/drivers/net/phy/m88e1512/chip.h
@@ -11,4 +11,7 @@
    /* 1x, 2x,...8x is the number of times the PHY attempts to establish Gigabit link
       before the PHY downshifts to the next highest speed. */
    unsigned char downshift_cnt;
+	bool force_mos;			/* Force PMOS/NMOS manually */
+	unsigned char pmos_val;		/* Set PMOS calibration value */
+	unsigned char nmos_val;		/* Set NMOS calibration value */
 };
diff --git a/src/drivers/net/phy/m88e1512/m88e1512.c b/src/drivers/net/phy/m88e1512/m88e1512.c
index 5ce9b40..2e8994c 100644
--- a/src/drivers/net/phy/m88e1512/m88e1512.c
+++ b/src/drivers/net/phy/m88e1512/m88e1512.c
@@ -67,6 +67,25 @@
    	mdio_write(dev, LED_TIMER_CTRL_REG, reg);
    }

+	/* Set RGMII output impedance manually. */
+	if (config->force_mos) {
+		printk(BIOS_DEBUG, "%s: Set RGMII driver strength manually for %s.\n",
+				dev_path(dev->bus->dev), dev->chip_ops->name);
+
+		/* Select page 2 to access RGMII output impedance calibration override
+		   register. */
+		switch_page(dev, 2);
+
+		reg = mdio_read(dev, OUT_IMP_CAL_OVERRIDE_REG);
+		/* Set first only NMOS/PMOS values. */
+		clrsetbits16(&reg, MOS_VALUE_MASK, PMOS_VALUE(config->pmos_val) |
+				NMOS_VALUE(config->nmos_val));
+		mdio_write(dev, OUT_IMP_CAL_OVERRIDE_REG, reg);
+		/* Activate the new setting. */
+		setbits16(&reg, FORCE_MOS);
+		mdio_write(dev, OUT_IMP_CAL_OVERRIDE_REG, reg);
+	}
+
    /* Switch back to page 0. */
    switch_page(dev, 0);
 }
diff --git a/src/drivers/net/phy/m88e1512/m88e1512.h b/src/drivers/net/phy/m88e1512/m88e1512.h
index 449cc57..3310c8b 100644
--- a/src/drivers/net/phy/m88e1512/m88e1512.h
+++ b/src/drivers/net/phy/m88e1512/m88e1512.h
@@ -13,6 +13,12 @@
 #define DOWNSHIFT_CNT_MAX	8
 #define  DOWNSHIFT_CNT(cnt)	((cnt - 1) << 12)
 #define  DOWNSHIFT_EN		(1 << 11)
+/* Page 2 registers */
+#define OUT_IMP_CAL_OVERRIDE_REG	0x18
+#define MOS_VALUE_MASK			0x0F4F
+#define  PMOS_VALUE(pmos)		(pmos << 8)
+#define  FORCE_MOS			(1 << 6)
+#define  NMOS_VALUE(nmos)		(nmos << 0)
 /* Page 3 registers */
 #define LED_FUNC_CTRL_REG	0x10
 #define LED_FUNC_CTRL_MASK	0x0FFF