SMI0 is a mangled version of MDIO. The main low level difference is
the MDIO C22 OP code is always 0, not 0x2 or 0x1 for Read/Write. The
read/write information is instead encoded in the PHY address.
Extend the bit-bang code to allow the op code to be overridden, but
default to normal C22 values. Add an extra compatible to the mdio-gpio
driver, and when this compatible is present, set the op codes to 0.
A higher level driver, sitting on top of the basic MDIO bus driver can
then implement the rest of the microchip SMI0 odderties.
This code was ported from the kernel v6.0-rc2.
Signed-off-by: Oleksij Rempel <o.rempel@xxxxxxxxxxxxxx>
---
drivers/net/phy/mdio-bitbang.c | 8 ++++++--
drivers/net/phy/mdio-gpio.c | 8 ++++++++
include/linux/mdio-bitbang.h | 3 +++
3 files changed, 17 insertions(+), 2 deletions(-)
diff --git a/drivers/net/phy/mdio-bitbang.c b/drivers/net/phy/mdio-bitbang.c
index 839a7d1eb8..656557589d 100644
--- a/drivers/net/phy/mdio-bitbang.c
+++ b/drivers/net/phy/mdio-bitbang.c
@@ -158,7 +158,7 @@ static int mdiobb_read(struct mii_bus *bus, int phy, int reg)
reg = mdiobb_cmd_addr(ctrl, phy, reg);
mdiobb_cmd(ctrl, MDIO_C45_READ, phy, reg);
} else
- mdiobb_cmd(ctrl, MDIO_READ, phy, reg);
+ mdiobb_cmd(ctrl, ctrl->op_c22_read, phy, reg);
ctrl->ops->set_mdio_dir(ctrl, 0);
@@ -188,7 +188,7 @@ static int mdiobb_write(struct mii_bus *bus, int phy, int reg, u16 val)
reg = mdiobb_cmd_addr(ctrl, phy, reg);
mdiobb_cmd(ctrl, MDIO_C45_WRITE, phy, reg);
} else
- mdiobb_cmd(ctrl, MDIO_WRITE, phy, reg);
+ mdiobb_cmd(ctrl, ctrl->op_c22_write, phy, reg);
/* send the turnaround (10) */
mdiobb_send_bit(ctrl, 1);
@@ -219,6 +219,10 @@ struct mii_bus *alloc_mdio_bitbang(struct mdiobb_ctrl *ctrl)
bus->write = mdiobb_write;
bus->reset = mdiobb_reset;
bus->priv = ctrl;
+ if (!ctrl->override_op_c22) {
+ ctrl->op_c22_read = MDIO_READ;
+ ctrl->op_c22_write = MDIO_WRITE;
+ }
return bus;
}
diff --git a/drivers/net/phy/mdio-gpio.c b/drivers/net/phy/mdio-gpio.c
index 80d2394f4b..c64f2b3925 100644
--- a/drivers/net/phy/mdio-gpio.c
+++ b/drivers/net/phy/mdio-gpio.c
@@ -193,6 +193,13 @@ static int mdio_gpio_probe(struct device_d *dev)
goto free_mdo;
}
+ if (np &&
+ of_device_is_compatible(np, "microchip,mdio-smi0")) {
+ info->ctrl.op_c22_read = 0;
+ info->ctrl.op_c22_write = 0;
+ info->ctrl.override_op_c22 = 1;
+ }
+
bus = alloc_mdio_bitbang(&info->ctrl);
bus->parent = dev;
bus->dev.device_node = np;
@@ -217,6 +224,7 @@ free_info:
static const struct of_device_id gpio_mdio_dt_ids[] = {
{ .compatible = "virtual,mdio-gpio", },
+ { .compatible = "microchip,mdio-smi0" },
{ /* sentinel */ }
};
diff --git a/include/linux/mdio-bitbang.h b/include/linux/mdio-bitbang.h
index a6e6057886..49fe435429 100644
--- a/include/linux/mdio-bitbang.h
+++ b/include/linux/mdio-bitbang.h
@@ -36,6 +36,9 @@ struct mdiobb_ctrl {
const struct mdiobb_ops *ops;
/* reset callback */
int (*reset)(struct mii_bus *bus);
+ unsigned int override_op_c22;
+ u8 op_c22_read;
+ u8 op_c22_write;
};
/* The returned bus is not yet registered with the phy layer. */
--
2.30.2
