Re: [PATCH 3/4] net: ethernet: cpsw: add support for hardware interface mode config

From: Mugunthan V N <mugunthanvnm@ti.com>
To: Daniel Mack <zonque@gmail.com>
Cc: <netdev@vger.kernel.org>, <davem@davemloft.net>,
	<ujhelyi.m@gmail.com>, <vaibhav.bedia@ti.com>, <d-gerlach@ti.com>,
	<linux-arm-kernel@lists.infradead.org>,
	<linux-omap@vger.kernel.org>, <devicetree@vger.kernel.org>
Subject: Re: [PATCH 3/4] net: ethernet: cpsw: add support for hardware interface mode config
Date: Fri, 23 Aug 2013 11:41:14 +0530	[thread overview]
Message-ID: <5216FD02.7030009@ti.com> (raw)
In-Reply-To: <1377171448-27924-4-git-send-email-zonque@gmail.com>

On Thursday 22 August 2013 05:07 PM, Daniel Mack wrote:
> The cpsw currently lacks code to properly set up the hardware interface
> mode on AM33xx. Other platforms might be equally affected.
>
> Usually, the bootloader will configure the control module register, so
> probably that's why such support wasn't needed in the past. In suspend
> mode though, this register is modified, and so it needs reprogramming
> after resume.
>
> This patch adds code that makes use of the previously added and optional
> support for passing the control mode register, and configures the
> correct register bits from _cpsw_adjust_link().
>
> The AM33xx also has a bit for each slave to configure the RMII reference
> clock direction. Setting it is now supported by a per-slave DT property.
>
> This code path introducted by this patch is currently exclusive for
> am33xx.
>
> Signed-off-by: Daniel Mack <zonque@gmail.com>
> ---
>  Documentation/devicetree/bindings/net/cpsw.txt |  2 ++
>  drivers/net/ethernet/ti/cpsw.c                 | 49 ++++++++++++++++++++++++++
>  include/linux/platform_data/cpsw.h             |  1 +
>  3 files changed, 52 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/net/cpsw.txt b/Documentation/devicetree/bindings/net/cpsw.txt
> index 4e5ca54..0ccf01f 100644
> --- a/Documentation/devicetree/bindings/net/cpsw.txt
> +++ b/Documentation/devicetree/bindings/net/cpsw.txt
> @@ -33,6 +33,8 @@ Required properties:
>  - phy_id		: Specifies slave phy id
>  - phy-mode		: The interface between the SoC and the PHY (a string
>  			  that of_get_phy_mode() can understand)
> +- ti,rmii-clock-ext	: If present, the driver will configure the RMII
> +			  interface to external clock usage
>  - mac-address		: Specifies slave MAC address
>  
>  Optional properties:
> diff --git a/drivers/net/ethernet/ti/cpsw.c b/drivers/net/ethernet/ti/cpsw.c
> index 4855d8e..d18ae43 100644
> --- a/drivers/net/ethernet/ti/cpsw.c
> +++ b/drivers/net/ethernet/ti/cpsw.c
> @@ -138,6 +138,14 @@ do {								\
>  #define CPSW_CMINTMAX_INTVL	(1000 / CPSW_CMINTMIN_CNT)
>  #define CPSW_CMINTMIN_INTVL	((1000 / CPSW_CMINTMAX_CNT) + 1)
>  
> +#define AM33XX_GMII_SEL_MODE_MII	(0)
> +#define AM33XX_GMII_SEL_MODE_RMII	(1)
> +#define AM33XX_GMII_SEL_MODE_RGMII	(2)
> +#define AM33XX_GMII_SEL_MODE_UNUSED	(3)
> +
> +#define AM33XX_GMII_SEL_RMII2_IO_CLK_EN	BIT(7)
> +#define AM33XX_GMII_SEL_RMII1_IO_CLK_EN	BIT(6)
> +
>  #define cpsw_enable_irq(priv)	\
>  	do {			\
>  		u32 i;		\
> @@ -728,6 +736,44 @@ static void _cpsw_adjust_link(struct cpsw_slave *slave,
>  	u32			mac_control = 0;
>  	u32			slave_port;
>  
> +	if (priv->gmii_sel_reg && of_machine_is_compatible("ti,am33xx")) {
> +		u32 reg = __raw_readl(priv->gmii_sel_reg);
> +		u32 mode = AM33XX_GMII_SEL_MODE_UNUSED;

If phy interface is other than the below handled case then you will be
writing UNUSED bit to gmii sel bits which is wrong as it should not be
used as per hardware design guys. Please refer the following thread in
U-Boot which had a discussion about the UNUSED bit combination usage.
http://comments.gmane.org/gmane.comp.boot-loaders.u-boot/166689

> +		u32 mask;
> +
> +		if (phy) {
> +			switch (phy->interface) {
> +			case PHY_INTERFACE_MODE_MII:
> +				mode = AM33XX_GMII_SEL_MODE_MII;
> +				break;
> +			case PHY_INTERFACE_MODE_RMII:
> +				mode = AM33XX_GMII_SEL_MODE_RMII;
> +				break;
> +			case PHY_INTERFACE_MODE_RGMII:
> +				mode = AM33XX_GMII_SEL_MODE_RGMII;
> +				break;
> +			default:
> +				break;
> +			};
> +		}
> +
> +		mask = 0x3 << (slave->slave_num * 2) |
> +		       BIT(slave->slave_num + 6);
> +		mode <<= slave->slave_num * 2;
> +
> +		if (slave->data->rmii_clock_external) {
> +			if (slave->slave_num == 0)
> +				mode |= AM33XX_GMII_SEL_RMII1_IO_CLK_EN;
> +			else
> +				mode |= AM33XX_GMII_SEL_RMII2_IO_CLK_EN;
> +		}
> +
> +		reg &= ~mask;
> +		reg |= mode;
> +
> +		__raw_writel(reg, priv->gmii_sel_reg);
> +	}
> +

This is not the proper location to add phy interface enable and rmii
external clock enable. This should be moved to open as this api is
called from phy poll work queue at constant interval to detect phy link
changes. The above init has required only once and not to be done regularly.

>  	if (!phy)
>  		return;
>  
> @@ -1798,6 +1844,9 @@ static int cpsw_probe_dt(struct cpsw_platform_data *data,
>  			memcpy(slave_data->mac_addr, mac_addr, ETH_ALEN);
>  
>  		slave_data->phy_if = of_get_phy_mode(slave_node);
> +		if (of_find_property(slave_node, "ti,rmii-clock-external",
> +				     NULL))
> +			slave_data->rmii_clock_external = true;
>  
>  		if (data->dual_emac) {
>  			if (of_property_read_u32(slave_node, "dual_emac_res_vlan",
> diff --git a/include/linux/platform_data/cpsw.h b/include/linux/platform_data/cpsw.h
> index bb3cd58..a29c48b 100644
> --- a/include/linux/platform_data/cpsw.h
> +++ b/include/linux/platform_data/cpsw.h

In net-next this file is moved to drivers/net/ethernet/ti folder itself
as this driver only supports DT boot.

Regards
Mugunthan V N