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Date: Thu, 29 Sep 2011 17:01:11 -0500
From: Grant Likely <grant.likely@...retlab.ca>
To: David Daney <david.daney@...ium.com>
Cc: devicetree-discuss@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
netdev@...r.kernel.org, davem@...emloft.net
Subject: Re: [PATCH v2 3/3] netdev/of/phy: Add MDIO bus multiplexer driven by
GPIO lines.
On Tue, Sep 27, 2011 at 04:26:55PM -0700, David Daney wrote:
> The GPIO pins select which sub bus is connected to the master.
>
> Initially tested with an sn74cbtlv3253 switch device wired into the
> MDIO bus.
>
> Signed-off-by: David Daney <david.daney@...ium.com>
> Cc: Grant Likely <grant.likely@...retlab.ca>
> Cc: "David S. Miller" <davem@...emloft.net>
> ---
> .../devicetree/bindings/net/mdio-mux-gpio.txt | 129 ++++++++++++++++++
> drivers/net/phy/Kconfig | 9 ++
> drivers/net/phy/Makefile | 1 +
> drivers/net/phy/mdio-mux-gpio.c | 143 ++++++++++++++++++++
> 4 files changed, 282 insertions(+), 0 deletions(-)
> create mode 100644 Documentation/devicetree/bindings/net/mdio-mux-gpio.txt
> create mode 100644 drivers/net/phy/mdio-mux-gpio.c
>
> diff --git a/Documentation/devicetree/bindings/net/mdio-mux-gpio.txt b/Documentation/devicetree/bindings/net/mdio-mux-gpio.txt
> new file mode 100644
> index 0000000..8d0f945
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/net/mdio-mux-gpio.txt
> @@ -0,0 +1,129 @@
> +Properties for an MDIO bus multiplexer/switch controlled by GPIO pins.
> +
> +This is a special case of a MDIO bus multiplexer. One or more GPIO
> +lines are used to control which child bus is connected.
> +
> +Required properties in addition to the generic multiplexer properties:
> +
> +- compatible : Should define the compatible device type for the
> + multiplexer. Currently "cavium,mdio-mux-sn74cbtlv3253"
> + is defined, others are possible.
> +- gpios : GPIO specifiers for each GPIO line. One or more must be specified.
> +
> +
> +Example :
> +
> + /* The parent MDIO bus. */
> + smi1: mdio@...0000001900 {
> + compatible = "cavium,octeon-3860-mdio";
> + #address-cells = <1>;
> + #size-cells = <0>;
> + reg = <0x11800 0x00001900 0x0 0x40>;
> + };
> +
> + /*
> + An NXP sn74cbtlv3253 dual 1-of-4 switch controlled by a
> + pair of GPIO lines. Child busses 2 and 3 populated with 4
> + PHYs each.
> + */
> + mdio-mux {
> + compatible = "cavium,mdio-mux-sn74cbtlv3253", "cavium,mdio-mux";
> + gpios = <&gpio1 3 0>, <&gpio1 4 0>;
> + mdio-parent-bus = <&smi1>;
> + #address-cells = <1>;
> + #size-cells = <0>;
> +
> + mdio@2 {
> + reg = <2>;
> + #address-cells = <1>;
> + #size-cells = <0>;
> +
> + phy11: ethernet-phy@1 {
> + reg = <1>;
> + compatible = "marvell,88e1149r";
> + marvell,reg-init = <3 0x10 0 0x5777>,
> + <3 0x11 0 0x00aa>,
> + <3 0x12 0 0x4105>,
> + <3 0x13 0 0x0a60>;
> + interrupt-parent = <&gpio>;
> + interrupts = <10 8>; /* Pin 10, active low */
> + };
> + phy12: ethernet-phy@2 {
> + reg = <2>;
> + compatible = "marvell,88e1149r";
> + marvell,reg-init = <3 0x10 0 0x5777>,
> + <3 0x11 0 0x00aa>,
> + <3 0x12 0 0x4105>,
> + <3 0x13 0 0x0a60>;
> + interrupt-parent = <&gpio>;
> + interrupts = <10 8>; /* Pin 10, active low */
> + };
> + phy13: ethernet-phy@3 {
> + reg = <3>;
> + compatible = "marvell,88e1149r";
> + marvell,reg-init = <3 0x10 0 0x5777>,
> + <3 0x11 0 0x00aa>,
> + <3 0x12 0 0x4105>,
> + <3 0x13 0 0x0a60>;
> + interrupt-parent = <&gpio>;
> + interrupts = <10 8>; /* Pin 10, active low */
> + };
> + phy14: ethernet-phy@4 {
> + reg = <4>;
> + compatible = "marvell,88e1149r";
> + marvell,reg-init = <3 0x10 0 0x5777>,
> + <3 0x11 0 0x00aa>,
> + <3 0x12 0 0x4105>,
> + <3 0x13 0 0x0a60>;
> + interrupt-parent = <&gpio>;
> + interrupts = <10 8>; /* Pin 10, active low */
> + };
> + };
> +
> + mdio@3 {
> + reg = <3>;
> + #address-cells = <1>;
> + #size-cells = <0>;
> +
> + phy21: ethernet-phy@1 {
> + reg = <1>;
> + compatible = "marvell,88e1149r";
> + marvell,reg-init = <3 0x10 0 0x5777>,
> + <3 0x11 0 0x00aa>,
> + <3 0x12 0 0x4105>,
> + <3 0x13 0 0x0a60>;
> + interrupt-parent = <&gpio>;
> + interrupts = <12 8>; /* Pin 12, active low */
> + };
> + phy22: ethernet-phy@2 {
> + reg = <2>;
> + compatible = "marvell,88e1149r";
> + marvell,reg-init = <3 0x10 0 0x5777>,
> + <3 0x11 0 0x00aa>,
> + <3 0x12 0 0x4105>,
> + <3 0x13 0 0x0a60>;
> + interrupt-parent = <&gpio>;
> + interrupts = <12 8>; /* Pin 12, active low */
> + };
> + phy23: ethernet-phy@3 {
> + reg = <3>;
> + compatible = "marvell,88e1149r";
> + marvell,reg-init = <3 0x10 0 0x5777>,
> + <3 0x11 0 0x00aa>,
> + <3 0x12 0 0x4105>,
> + <3 0x13 0 0x0a60>;
> + interrupt-parent = <&gpio>;
> + interrupts = <12 8>; /* Pin 12, active low */
> + };
> + phy24: ethernet-phy@4 {
> + reg = <4>;
> + compatible = "marvell,88e1149r";
> + marvell,reg-init = <3 0x10 0 0x5777>,
> + <3 0x11 0 0x00aa>,
> + <3 0x12 0 0x4105>,
> + <3 0x13 0 0x0a60>;
> + interrupt-parent = <&gpio>;
> + interrupts = <12 8>; /* Pin 12, active low */
> + };
> + };
> + };
> diff --git a/drivers/net/phy/Kconfig b/drivers/net/phy/Kconfig
> index 59848bc..59b3b17 100644
> --- a/drivers/net/phy/Kconfig
> +++ b/drivers/net/phy/Kconfig
> @@ -127,6 +127,15 @@ config MDIO_BUS_MUX
> to a parent bus. Switching between child busses is done by
> device specific drivers.
>
> +config MDIO_BUS_MUX_GPIO
> + tristate "Support for GPIO controlled MDIO bus multiplexers"
> + depends on MDIO_BUS_MUX && GENERIC_GPIO
> + help
> + This module provides a driver for MDIO bus multiplexers that
> + are controlled via GPIO lines. The multiplexer connects one of
> + several child MDIO busses to a parent bus. Child bus
> + selection is under the control of GPIO lines.
> +
> config MDIO_OCTEON
> tristate "Support for MDIO buses on Octeon SOCs"
> depends on CPU_CAVIUM_OCTEON
> diff --git a/drivers/net/phy/Makefile b/drivers/net/phy/Makefile
> index 0c081d5..d1a1927 100644
> --- a/drivers/net/phy/Makefile
> +++ b/drivers/net/phy/Makefile
> @@ -24,3 +24,4 @@ obj-$(CONFIG_STE10XP) += ste10Xp.o
> obj-$(CONFIG_MICREL_PHY) += micrel.o
> obj-$(CONFIG_MDIO_OCTEON) += mdio-octeon.o
> obj-$(CONFIG_MDIO_BUS_MUX) += mdio-mux.o
> +obj-$(CONFIG_MDIO_BUS_MUX_GPIO) += mdio-mux-gpio.o
> diff --git a/drivers/net/phy/mdio-mux-gpio.c b/drivers/net/phy/mdio-mux-gpio.c
> new file mode 100644
> index 0000000..3cdad35
> --- /dev/null
> +++ b/drivers/net/phy/mdio-mux-gpio.c
> @@ -0,0 +1,143 @@
> +/*
> + * This file is subject to the terms and conditions of the GNU General Public
> + * License. See the file "COPYING" in the main directory of this archive
> + * for more details.
> + *
> + * Copyright (C) 2011 Cavium Networks
> + */
> +
> +#include <linux/platform_device.h>
> +#include <linux/of_mdio.h>
> +#include <linux/module.h>
> +#include <linux/init.h>
> +#include <linux/gfp.h>
> +#include <linux/phy.h>
> +#include <linux/mdio-mux.h>
> +#include <linux/of_gpio.h>
> +
> +#define DRV_VERSION "1.0"
> +#define DRV_DESCRIPTION "GPIO controlled MDIO bus multiplexer driver"
> +
> +#define MDIO_MUX_GPIO_MAX_BITS 8
> +
> +struct mdio_mux_gpio_state {
> + int gpio[MDIO_MUX_GPIO_MAX_BITS];
> + unsigned int num_gpios;
> +};
> +
> +static int mdio_mux_gpio_switch_fn(int current_child, int desired_child,
> + void *data)
> +{
> + int change;
> + unsigned int n;
> + struct mdio_mux_gpio_state *s = data;
> +
> + if (current_child == desired_child)
> + return 0;
> +
> + change = current_child == -1 ? -1 : current_child ^ desired_child;
> +
> + for (n = 0; n < s->num_gpios; n++) {
> + if (change & 1)
> + gpio_set_value_cansleep(s->gpio[n],
> + (desired_child & 1) != 0);
> + change >>= 1;
> + desired_child >>= 1;
> + }
> +
> + return 0;
> +}
> +
> +static int __devinit mdio_mux_gpio_probe(struct platform_device *pdev)
> +{
> + enum of_gpio_flags f;
> + struct mdio_mux_gpio_state *s;
> + unsigned int num_gpios;
> + unsigned int n;
> + int r;
> +
> + if (!pdev->dev.of_node)
> + return -ENODEV;
> +
> + num_gpios = of_gpio_count(pdev->dev.of_node);
> + if (num_gpios == 0 || num_gpios > MDIO_MUX_GPIO_MAX_BITS)
> + return -ENODEV;
> +
> + s = devm_kzalloc(&pdev->dev, sizeof(*s), GFP_KERNEL);
> + if (!s)
> + return -ENOMEM;
> +
> + s->num_gpios = num_gpios;
> +
> + for (n = 0; n < num_gpios; ) {
> + int gpio = of_get_named_gpio_flags(pdev->dev.of_node,
> + "gpios", n, &f);
> + s->gpio[n] = gpio;
> + if (gpio < 0) {
> + r = -ENODEV;
> + goto err;
> + }
> +
> + n++;
> +
> + r = gpio_request(gpio, "mdio_mux_gpio");
> + if (r)
> + goto err;
> +
> + r = gpio_direction_output(gpio, 0);
> + if (r)
> + goto err;
> + }
> +
> + r = mdio_mux_probe(pdev, mdio_mux_gpio_switch_fn, s);
> +
> + if (r == 0)
> + return 0;
> +err:
> + while (n) {
> + n--;
> + gpio_free(s->gpio[n]);
> + }
> + devm_kfree(&pdev->dev, s);
Don't need to do this. The probe failed, so the free will automatically happen because devm_kzalloc was used.
> + return r;
> +}
> +
> +static int __devexit mdio_mux_gpio_remove(struct platform_device *pdev)
> +{
> + return 0;
> +}
Don't do empty remove functions.
This driver looks okay, but it needs the unwind stuff for removal, or
it needs to be explicit that it cannot be removed (which also means
that the mdio parent driver becomes unremovable too).
g.
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