Subject: Re: [PATCH] net/phy: micrel: Add clock support for KSZ8021/KSZ8031

From: Florian Fainelli <[email-masked]>
Date: Thu, 09 Oct 2014 10:01:15 -0700

On 10/09/2014 05:32 AM, Sascha Hauer wrote:
> The KSZ8021 and KSZ8031 support RMII reference input clocks of 25MHz
> and 50MHz. Both PHYs differ in the default frequency they expect
> after reset. If this differs from the actual input clock, then
> register 0x1f bit 7 must be changed.

Looks reasonable to me, some minor comments below:

> 
> Signed-off-by: Sascha Hauer <[email-masked]>
> ---
>  Documentation/devicetree/bindings/net/micrel.txt |  6 ++++++
>  drivers/net/phy/micrel.c                         | 19 +++++++++++++++++--
>  include/linux/micrel_phy.h                       |  1 +
>  3 files changed, 24 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/net/micrel.txt b/Documentation/devicetree/bindings/net/micrel.txt
> index 98a3e61..e1d99b9 100644
> --- a/Documentation/devicetree/bindings/net/micrel.txt
> +++ b/Documentation/devicetree/bindings/net/micrel.txt
> @@ -16,3 +16,9 @@ Optional properties:
>  	      KSZ8051: register 0x1f, bits 5..4
>  
>                See the respective PHY datasheet for the mode values.
> +
> + - clocks, clock-names: contains clocks according to the common clock bindings.
> +
> +              supported clocks:
> +	      - KSZ8021, KSZ8031: "rmii-ref": The RMII refence input clock. Used
> +		to determine the XI input clock.
> diff --git a/drivers/net/phy/micrel.c b/drivers/net/phy/micrel.c
> index 011dbda..ca130e9 100644
> --- a/drivers/net/phy/micrel.c
> +++ b/drivers/net/phy/micrel.c
> @@ -26,6 +26,7 @@
>  #include <linux/phy.h>
>  #include <linux/micrel_phy.h>
>  #include <linux/of.h>
> +#include <linux/clk.h>
>  
>  /* Operation Mode Strap Override */
>  #define MII_KSZPHY_OMSO				0x16
> @@ -72,9 +73,12 @@ static int ksz_config_flags(struct phy_device *phydev)
>  {
>  	int regval;
>  
> -	if (phydev->dev_flags & MICREL_PHY_50MHZ_CLK) {
> +	if (phydev->dev_flags & (MICREL_PHY_50MHZ_CLK | MICREL_PHY_25MHZ_CLK)) {
>  		regval = phy_read(phydev, MII_KSZPHY_CTRL);
> -		regval |= KSZ8051_RMII_50MHZ_CLK;
> +		if (phydev->dev_flags & MICREL_PHY_50MHZ_CLK)
> +			regval |= KSZ8051_RMII_50MHZ_CLK;
> +		else
> +			regval &= ~KSZ8051_RMII_50MHZ_CLK;
>  		return phy_write(phydev, MII_KSZPHY_CTRL, regval);
>  	}
>  	return 0;
> @@ -187,9 +191,20 @@ static int kszphy_config_init_led8041(struct phy_device *phydev)
>  
>  static int ksz8021_config_init(struct phy_device *phydev)
>  {
> +	struct clk *clk;
>  	const u16 val = KSZPHY_OMSO_B_CAST_OFF | KSZPHY_OMSO_RMII_OVERRIDE;
>  	int rc;
>  
> +	clk = devm_clk_get(&phydev->dev, "rmii-ref");
> +	if (!IS_ERR(clk)) {
> +		unsigned long rate = clk_get_rate(clk);
> +
> +		if (rate > 24500000 && rate < 25500000)
> +			phydev->dev_flags |= MICREL_PHY_25MHZ_CLK;
> +		else if (rate > 49500000 && rate < 50500000)
> +			phydev->dev_flags |= MICREL_PHY_50MHZ_CLK;
> +	}

I suppose that you could move this to the PHY driver probe() callback,
and perform the rate checking from here, rejecting a clock whose rate is
out of the acceptable range, and return an error to prevent the PHY
driver registration? It is really up to you though.

> +
>  	rc = kszphy_setup_led(phydev, 0x1f, 4);
>  	if (rc)
>  		dev_err(&phydev->dev, "failed to set led mode\n");
> diff --git a/include/linux/micrel_phy.h b/include/linux/micrel_phy.h
> index 2e5b194..53d33de 100644
> --- a/include/linux/micrel_phy.h
> +++ b/include/linux/micrel_phy.h
> @@ -37,6 +37,7 @@
>  
>  /* struct phy_device dev_flags definitions */
>  #define MICREL_PHY_50MHZ_CLK	0x00000001
> +#define MICREL_PHY_25MHZ_CLK	0x00000002
>  
>  #define MICREL_KSZ9021_EXTREG_CTRL	0xB
>  #define MICREL_KSZ9021_EXTREG_DATA_WRITE	0xC
>