netdev - Re: [PATCH v3 1/5] net: phy: Add support for microchip SMI0 MDIO bus

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Message-ID: <20200511154046.GN20451@pengutronix.de>
Date:   Mon, 11 May 2020 17:40:46 +0200
From:   Michael Grzeschik <mgr@...gutronix.de>
To:     Florian Fainelli <f.fainelli@...il.com>
Cc:     andrew@...n.ch, netdev@...r.kernel.org, davem@...emloft.net,
        kernel@...gutronix.de
Subject: Re: [PATCH v3 1/5] net: phy: Add support for microchip SMI0 MDIO bus

On Sat, May 09, 2020 at 10:28:05AM -0700, Florian Fainelli wrote:
>
>
>On 5/8/2020 8:43 AM, Michael Grzeschik wrote:
>>From: Andrew Lunn <andrew@...n.ch>
>>
>>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.
>>
>>Signed-off-by: Andrew Lunn <andrew@...n.ch>
>>Signed-off-by: Michael Grzeschik <m.grzeschik@...gutronix.de>
>>---
>>  drivers/net/phy/mdio-bitbang.c |  7 ++-----
>>  drivers/net/phy/mdio-gpio.c    | 13 +++++++++++++
>>  include/linux/mdio-bitbang.h   |  2 ++
>>  3 files changed, 17 insertions(+), 5 deletions(-)
>>
>>diff --git a/drivers/net/phy/mdio-bitbang.c b/drivers/net/phy/mdio-bitbang.c
>>index 5136275c8e7399..11255460ecb933 100644
>>--- a/drivers/net/phy/mdio-bitbang.c
>>+++ b/drivers/net/phy/mdio-bitbang.c
>>@@ -19,9 +19,6 @@
>>  #include <linux/types.h>
>>  #include <linux/delay.h>
>>-#define MDIO_READ 2
>>-#define MDIO_WRITE 1
>>-
>>  #define MDIO_C45 (1<<15)
>>  #define MDIO_C45_ADDR (MDIO_C45 | 0)
>>  #define MDIO_C45_READ (MDIO_C45 | 3)
>>@@ -158,7 +155,7 @@ 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);
>>@@ -189,7 +186,7 @@ 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);
>
>There are other users of the mdio-bitbang.c file which I believe you 
>are going to break here because they will not initialize op_c22_write 
>or op_c22_read, and thus they will be using 0, instead of MDIO_READ 
>and MDIO_WRITE. I believe you need something like the patch attached.
>-- 
>Florian

I will add that change to v4.

Michael

>diff --git a/drivers/net/phy/mdio-bitbang.c b/drivers/net/phy/mdio-bitbang.c
>index 11255460ecb9..528e255d1ffe 100644
>--- a/drivers/net/phy/mdio-bitbang.c
>+++ b/drivers/net/phy/mdio-bitbang.c
>@@ -19,6 +19,9 @@
> #include <linux/types.h>
> #include <linux/delay.h>
>
>+#define MDIO_READ 2
>+#define MDIO_WRITE 1
>+
> #define MDIO_C45 (1<<15)
> #define MDIO_C45_ADDR (MDIO_C45 | 0)
> #define MDIO_C45_READ (MDIO_C45 | 3)
>@@ -212,6 +215,10 @@ struct mii_bus *alloc_mdio_bitbang(struct mdiobb_ctrl *ctrl)
> 	bus->read = mdiobb_read;
> 	bus->write = mdiobb_write;
> 	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 d85bc1a98647..13ec31e89e94 100644
>--- a/drivers/net/phy/mdio-gpio.c
>+++ b/drivers/net/phy/mdio-gpio.c
>@@ -27,9 +27,6 @@
> #include <linux/gpio/consumer.h>
> #include <linux/of_mdio.h>
>
>-#define MDIO_READ 2
>-#define MDIO_WRITE 1
>-
> struct mdio_gpio_info {
> 	struct mdiobb_ctrl ctrl;
> 	struct gpio_desc *mdc, *mdio, *mdo;
>@@ -139,9 +136,7 @@ static struct mii_bus *mdio_gpio_bus_init(struct device *dev,
> 	    of_device_is_compatible(dev->of_node, "microchip,mdio-smi0")) {
> 		bitbang->ctrl.op_c22_read = 0;
> 		bitbang->ctrl.op_c22_write = 0;
>-	} else {
>-		bitbang->ctrl.op_c22_read = MDIO_READ;
>-		bitbang->ctrl.op_c22_write = MDIO_WRITE;
>+		bitbang->ctrl.override_op_c22 = 1;
> 	}
>
> 	dev_set_drvdata(dev, new_bus);
>diff --git a/include/linux/mdio-bitbang.h b/include/linux/mdio-bitbang.h
>index 8ae0b3835233..5016e6f60de3 100644
>--- a/include/linux/mdio-bitbang.h
>+++ b/include/linux/mdio-bitbang.h
>@@ -33,6 +33,7 @@ struct mdiobb_ops {
>
> struct mdiobb_ctrl {
> 	const struct mdiobb_ops *ops;
>+	unsigned int override_op_c22;
> 	u8 op_c22_read;
> 	u8 op_c22_write;
> };


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