netdev - Re: [PATCH 2/2] drivers: net: phy: at803x: LED control via led subsystem

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Message-ID: <CAGXE3d8WRU2fmRZ9DAQ4_Y=WZQwNmt9DVbLys=LkJaRPz=7FAw@mail.gmail.com>
Date:	Thu, 11 Jul 2013 14:57:47 +0200
From:	Helmut Schaa <helmut.schaa@...glemail.com>
To:	Florian Fainelli <florian@...nwrt.org>
Cc:	netdev <netdev@...r.kernel.org>, David Miller <davem@...emloft.net>
Subject: Re: [PATCH 2/2] drivers: net: phy: at803x: LED control via led subsystem

On Thu, Jul 11, 2013 at 2:15 PM, Florian Fainelli <florian@...nwrt.org> wrote:
> Hello Helmut,
>
> 2013/7/11 Helmut Schaa <helmut.schaa@...glemail.com>:
>> The AT8035 PHY allows to control the LED PIN behavior from software.
>> Expose this functionality by registering an LED device.
>>
>> Signed-off-by: Helmut Schaa <helmut.schaa@...glemail.com>
>> ---
>>  drivers/net/phy/Kconfig  |    7 ++++
>>  drivers/net/phy/at803x.c |   87 ++++++++++++++++++++++++++++++++++++++++++++++
>>  2 files changed, 94 insertions(+)
>>
>> diff --git a/drivers/net/phy/Kconfig b/drivers/net/phy/Kconfig
>> index 3a316b3..5e855b7 100644
>> --- a/drivers/net/phy/Kconfig
>> +++ b/drivers/net/phy/Kconfig
>> @@ -19,6 +19,13 @@ config AT803X_PHY
>>         ---help---
>>           Currently supports the AT8030 and AT8035 model
>>
>> +config AT803X_LEDS
>> +       bool "Enable access to PHY connected LEDs"
>> +       depends on AT803X_PHY && LEDS_CLASS
>> +       ---help---
>> +         Select this to be able to control LEDs connected to the
>> +         PHY from userspace
>> +
>>  config AMD_PHY
>>         tristate "Drivers for the AMD PHYs"
>>         ---help---
>> diff --git a/drivers/net/phy/at803x.c b/drivers/net/phy/at803x.c
>> index ac22283..49ef6306 100644
>> --- a/drivers/net/phy/at803x.c
>> +++ b/drivers/net/phy/at803x.c
>> @@ -16,6 +16,7 @@
>>  #include <linux/string.h>
>>  #include <linux/netdevice.h>
>>  #include <linux/etherdevice.h>
>> +#include <linux/leds.h>
>>
>>  #define AT803X_INTR_ENABLE                     0x12
>>  #define AT803X_INTR_STATUS                     0x13
>> @@ -31,6 +32,8 @@
>>  #define AT803X_DEBUG_DATA                      0x1E
>>  #define AT803X_DEBUG_SYSTEM_MODE_CTRL          0x05
>>  #define AT803X_DEBUG_RGMII_TX_CLK_DLY          BIT(8)
>> +#define AT8035_LED_CTRL                                0x18
>> +#define AT8035_LED_CTRL_OFF                    BIT(15)
>>
>>  MODULE_DESCRIPTION("Atheros 803x PHY driver");
>>  MODULE_AUTHOR("Matus Ujhelyi");
>> @@ -152,6 +155,86 @@ static int at803x_config_init(struct phy_device *phydev)
>>         return 0;
>>  }
>>
>> +#ifdef CONFIG_AT803X_LEDS
>> +
>> +struct at8035_priv {
>> +       struct led_classdev led;
>> +       struct phy_device *phydev;
>> +       struct work_struct led_work;
>> +       bool stop;
>> +};
>> +
>> +static void at8035_led_work(struct work_struct *work)
>> +{
>> +       struct at8035_priv *priv =
>> +               container_of(work, struct at8035_priv, led_work);
>> +       struct phy_device *phydev = priv->phydev;
>> +       int val;
>> +
>> +       if (priv->stop)
>> +               return;
>> +
>> +       val = phy_read(phydev, AT8035_LED_CTRL);
>> +
>> +       if (priv->led.brightness > 0)
>> +               phy_write(phydev, AT8035_LED_CTRL, val & ~AT8035_LED_CTRL_OFF);
>> +       else
>> +               phy_write(phydev, AT8035_LED_CTRL, val | AT8035_LED_CTRL_OFF);
>> +}
>
> I do like this and I believe that there is nothing specific that would
> prevent you from making software controllable LEDs from being used
> with other PHYs. How about you create a small LED class helper that
> PHY drivers supporting controllable LEDs can hook into and provide
> their own callback and LED name for setting the LED state?

Hmm, nice idea. However, there is not much complexity in the code. The only
thing worth to make generic would be the delayed register access via workqueue.
The rest is just registering the led device :)

I thought about moving the code into the generic phy code and using a new
phy_driver callback for setting the LED state but there might be more then one
LED pin on some PHYs (activity, speed, duplexmode etc.).

>> +
>> +static void at8035_led_brightness_set(struct led_classdev *led,
>> +                                     enum led_brightness brightness)
>> +{
>> +       struct at8035_priv *priv = container_of(led, struct at8035_priv, led);
>> +
>> +       /* MDIO bus can only be used from process context */
>> +       if (!priv->stop)
>> +               schedule_work(&priv->led_work);
>
> It seems to me that you could remove the stop boolean if you move
> led_classdev_unregister upper, provided that it guarantees it will not
> schedule the workqueue.

led_classdev_unregister will try to set brightness to 0 and thus schedule
the work.

Thanks,
Helmut
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