[PATCH net-next 3/3] net: phy: dp83867: implement support for io_impedance_ctrl nvmem cell

Rasmus Villemoes
2022-06-06T20:22:56Z

We have a board where measurements indicate that the current three
options - leaving IO_IMPEDANCE_CTRL at the (factory calibrated) reset
value or using one of the two boolean properties to set it to the
min/max value - are too coarse.

Implement support for the newly added binding allowing device tree to
specify an nvmem cell containing an appropriate value for this
specific board.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
drivers/net/phy/dp83867.c | 55 ++++++++++++++++++++++++++++++++++-----
1 file changed, 49 insertions(+), 6 deletions(-)

diff --git a/drivers/net/phy/dp83867.c b/drivers/net/phy/dp83867.c
index 8561f2d4443b..45d8a9298251 100644
--- a/drivers/net/phy/dp83867.c
+++ b/drivers/net/phy/dp83867.c
@@ -14,6 +14,7 @@
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/bitfield.h>
+#include <linux/nvmem-consumer.h>

#include <dt-bindings/net/ti-dp83867.h>

@@ -521,6 +522,51 @@ static int dp83867_verify_rgmii_cfg(struct phy_device *phydev)
}

#if IS_ENABLED(CONFIG_OF_MDIO)
+static int dp83867_of_init_io_impedance(struct phy_device *phydev)
+{
+ struct dp83867_private *dp83867 = phydev->priv;
+ struct device *dev = &phydev->mdio.dev;
+ struct device_node *of_node = dev->of_node;
+ struct nvmem_cell *cell;
+ u8 *buf, val;
+ int ret;
+
+ cell = of_nvmem_cell_get(of_node, "io_impedance_ctrl");
+ if (IS_ERR(cell)) {
+ ret = PTR_ERR(cell);
+ if (ret != -ENOENT)
+ return phydev_err_probe(phydev, ret,
+ "failed to get nvmem cell io_impedance_ctrl\n");
+
+ /* If no nvmem cell, check for the boolean properties. */
+ if (of_property_read_bool(of_node, "ti,max-output-impedance"))
+ dp83867->io_impedance = DP83867_IO_MUX_CFG_IO_IMPEDANCE_MAX;
+ else if (of_property_read_bool(of_node, "ti,min-output-impedance"))
+ dp83867->io_impedance = DP83867_IO_MUX_CFG_IO_IMPEDANCE_MIN;
+ else
+ dp83867->io_impedance = -1; /* leave at default */
+
+ return 0;
+ }
+
+ buf = nvmem_cell_read(cell, NULL);
+ nvmem_cell_put(cell);
+
+ if (IS_ERR(buf))
+ return PTR_ERR(buf);
+
+ val = *buf;
+ kfree(buf);
+
+ if ((val & DP83867_IO_MUX_CFG_IO_IMPEDANCE_MASK) != val) {
+ phydev_err(phydev, "nvmem cell 'io_impedance_ctrl' contents out of range\n");
+ return -ERANGE;
+ }
+ dp83867->io_impedance = val;
+
+ return 0;
+}
+
static int dp83867_of_init(struct phy_device *phydev)
{
struct dp83867_private *dp83867 = phydev->priv;
@@ -548,12 +594,9 @@ static int dp83867_of_init(struct phy_device *phydev)
}
}

- if (of_property_read_bool(of_node, "ti,max-output-impedance"))
- dp83867->io_impedance = DP83867_IO_MUX_CFG_IO_IMPEDANCE_MAX;
- else if (of_property_read_bool(of_node, "ti,min-output-impedance"))
- dp83867->io_impedance = DP83867_IO_MUX_CFG_IO_IMPEDANCE_MIN;
- else
- dp83867->io_impedance = -1; /* leave at default */
+ ret = dp83867_of_init_io_impedance(phydev);
+ if (ret)
+ return ret;

dp83867->rxctrl_strap_quirk = of_property_read_bool(of_node,
"ti,dp83867-rxctrl-strap-quirk");
--
2.31.1