linux-kernel - Re: [net-next PATCH v7 4/4] net: phy: add support for PHY package MMD read/write

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Message-ID: <ZXs2L0zfMaXTf+Ls@shell.armlinux.org.uk>
Date:   Thu, 14 Dec 2023 17:06:55 +0000
From:   "Russell King (Oracle)" <linux@...linux.org.uk>
To:     Christian Marangi <ansuelsmth@...il.com>
Cc:     Florian Fainelli <florian.fainelli@...adcom.com>,
        Broadcom internal kernel review list 
        <bcm-kernel-feedback-list@...adcom.com>,
        Andrew Lunn <andrew@...n.ch>,
        Heiner Kallweit <hkallweit1@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Vladimir Oltean <olteanv@...il.com>,
        David Epping <david.epping@...singlinkelectronics.com>,
        Harini Katakam <harini.katakam@....com>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [net-next PATCH v7 4/4] net: phy: add support for PHY package
 MMD read/write

On Thu, Dec 14, 2023 at 01:10:26PM +0100, Christian Marangi wrote:
> Some PHY in PHY package may require to read/write MMD regs to correctly
> configure the PHY package.
> 
> Add support for these additional required function in both lock and no
> lock variant.
> 
> It's assumed that the entire PHY package is either C22 or C45. We use
> C22 or C45 way of writing/reading to mmd regs based on the passed phydev
> whether it's C22 or C45.
> 
> Signed-off-by: Christian Marangi <ansuelsmth@...il.com>
> ---
> Changes v7:
> - Change addr to u8
> Changes v6:
> - Fix copy paste error for kdoc
> Changes v5:
> - Improve function description
> Changes v4:
> - Drop function comments in header file
> Changes v3:
> - Move in phy-core.c from phy.h
> - Base c45 from phydev
> Changes v2:
> - Rework to use newly introduced helper
> - Add common check for regnum and devad
> 
>  drivers/net/phy/phy-core.c | 144 +++++++++++++++++++++++++++++++++++++
>  include/linux/phy.h        |  16 +++++
>  2 files changed, 160 insertions(+)
> 
> diff --git a/drivers/net/phy/phy-core.c b/drivers/net/phy/phy-core.c
> index b729ac8b2640..7af935c6abe5 100644
> --- a/drivers/net/phy/phy-core.c
> +++ b/drivers/net/phy/phy-core.c
> @@ -650,6 +650,150 @@ int phy_write_mmd(struct phy_device *phydev, int devad, u32 regnum, u16 val)
>  }
>  EXPORT_SYMBOL(phy_write_mmd);
>  
> +/**
> + * __phy_package_read_mmd - read MMD reg relative to PHY package base addr
> + * @phydev: The phy_device struct
> + * @addr_offset: The offset to be added to PHY package base_addr
> + * @devad: The MMD to read from
> + * @regnum: The register on the MMD to read
> + *
> + * Convenience helper for reading a register of an MMD on a given PHY
> + * using the PHY package base address. The base address is added to
> + * the addr_offset value.
> + *
> + * Same calling rules as for __phy_read();
> + *
> + * NOTE: It's assumed that the entire PHY package is either C22 or C45.
> + */
> +int __phy_package_read_mmd(struct phy_device *phydev,
> +			   unsigned int addr_offset, int devad,
> +			   u32 regnum)
> +{
> +	struct phy_package_shared *shared = phydev->shared;
> +	u8 addr = shared->base_addr + addr_offset;
> +
> +	if (addr >= PHY_MAX_ADDR)
> +		return -EIO;

The helper I mentioned in the previous patch (whether or not we do the
rest of the range checks) would probably be a good idea to get away from
the repetitive nature of this logic. This patch adds four more!

-- 
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