Re: [PATCH RFC net-next 4/9] net: pcs: xpcs: add Qualcomm Nord platform support

[Lorenzo Bianconi]

> Qualcomm Nord exposes the DesignWare XPCS register blocks through
> separate direct-MMIO windows instead of the standard contiguous
> MMD/register layout. Add accessors that translate MMD accesses to the
> Nord windows:
> 
>   MMD 3 (PCS), standard registers: SR_XS at 0x0000
>   MMD 3 (PCS), vendor registers:   VR_XS at 0x2000
>   MMD 1 (PMA/PMD):                  SR_PMA at 0x3000
>   MMD 31 (VEND2), standard regs:    SR_MII at 0x4000
>   MMD 31 (VEND2), vendor registers: VR_MII at 0x5000
> 
> Each register uses a 32-bit MMIO stride. The vendor bit is removed from
> the register index before calculating a vendor-window offset.
> 
> Select these accessors using the Nord synthetic XPCS ID, allow its
> smaller direct-MMIO resource, and add the Nord USXGMII Clause 37
> compatibility.
> 
> Signed-off-by: Mohd Ayaan Anwar <mohd.anwar@xxxxxxxxxxxxxxxx>
> ---
>  drivers/net/pcs/Makefile        |  3 +-
>  drivers/net/pcs/pcs-xpcs-plat.c | 17 +++++++-
>  drivers/net/pcs/pcs-xpcs-qcom.c | 86 +++++++++++++++++++++++++++++++++++++++++
>  drivers/net/pcs/pcs-xpcs-qcom.h | 16 ++++++++
>  drivers/net/pcs/pcs-xpcs.c      | 13 +++++++
>  include/linux/pcs/pcs-xpcs.h    |  1 +
>  6 files changed, 134 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/pcs/Makefile b/drivers/net/pcs/Makefile
> index 4f7920618b90051e839a74a7101aaaf055a77f74..3d7cf1a5cd0783078edcefc6dfec626af469495d 100644
> --- a/drivers/net/pcs/Makefile
> +++ b/drivers/net/pcs/Makefile
> @@ -2,7 +2,8 @@
>  # Makefile for Linux PCS drivers
>  
>  pcs_xpcs-$(CONFIG_PCS_XPCS)	:= pcs-xpcs.o pcs-xpcs-plat.o \
> -				   pcs-xpcs-nxp.o pcs-xpcs-wx.o
> +				   pcs-xpcs-nxp.o pcs-xpcs-qcom.o \
> +				   pcs-xpcs-wx.o
>  
>  obj-$(CONFIG_PCS_XPCS)		+= pcs_xpcs.o
>  obj-$(CONFIG_PCS_LYNX)		+= pcs-lynx.o
> diff --git a/drivers/net/pcs/pcs-xpcs-plat.c b/drivers/net/pcs/pcs-xpcs-plat.c
> index e78a233fb198d940951064a71e8597c6c666bc9d..e013a5253a22651220e62352d03faabc3a3c3658 100644
> --- a/drivers/net/pcs/pcs-xpcs-plat.c
> +++ b/drivers/net/pcs/pcs-xpcs-plat.c
> @@ -20,6 +20,7 @@
>  #include <linux/sizes.h>
>  
>  #include "pcs-xpcs.h"
> +#include "pcs-xpcs-qcom.h"
>  
>  /* Page select register for the indirect MMIO CSRs access */
>  #define DW_VR_CSR_VIEWPORT		0xff
> @@ -239,8 +240,14 @@ static int xpcs_mmio_write_c45(struct mii_bus *bus, int addr, int dev,
>  		return xpcs_mmio_write_reg_direct(pxpcs, dev, reg, val);
>  }
>  
> +static const struct dw_xpcs_plat_ops xpcs_qcom_ops = {
> +	.reg_read = xpcs_qcom_reg_read,
> +	.reg_write = xpcs_qcom_reg_write,
> +};
> +
>  static struct dw_xpcs_plat *xpcs_plat_create_data(struct platform_device *pdev)
>  {
> +	const struct dw_xpcs_info *info;
>  	struct dw_xpcs_plat *pxpcs;
>  
>  	pxpcs = devm_kzalloc(&pdev->dev, sizeof(*pxpcs), GFP_KERNEL);
> @@ -248,6 +255,12 @@ static struct dw_xpcs_plat *xpcs_plat_create_data(struct platform_device *pdev)
>  		return ERR_PTR(-ENOMEM);
>  
>  	pxpcs->pdev = pdev;
> +	info = device_get_match_data(&pdev->dev);
> +	if (!info)
> +		return ERR_PTR(-EINVAL);
> +
> +	if (info->pcs == QCOM_NORD_XPCS_ID)
> +		pxpcs->ops = &xpcs_qcom_ops;
>  
>  	dev_set_drvdata(&pdev->dev, pxpcs);
>  
> @@ -285,7 +298,7 @@ static int xpcs_plat_init_res(struct dw_xpcs_plat *pxpcs)
>  	else
>  		spc_size = pxpcs->reg_width * SZ_2M;
>  
> -	if (resource_size(res) < spc_size) {
> +	if (!pxpcs->ops && resource_size(res) < spc_size) {
>  		dev_err(dev, "Invalid reg-space size\n");
>  		return -EINVAL;
>  	}
> @@ -452,8 +465,10 @@ DW_XPCS_INFO_DECLARE(xpcs_pma_gen4_3g, DW_XPCS_ID_NATIVE, DW_XPCS_PMA_GEN4_3G_ID
>  DW_XPCS_INFO_DECLARE(xpcs_pma_gen4_6g, DW_XPCS_ID_NATIVE, DW_XPCS_PMA_GEN4_6G_ID);
>  DW_XPCS_INFO_DECLARE(xpcs_pma_gen5_10g, DW_XPCS_ID_NATIVE, DW_XPCS_PMA_GEN5_10G_ID);
>  DW_XPCS_INFO_DECLARE(xpcs_pma_gen5_12g, DW_XPCS_ID_NATIVE, DW_XPCS_PMA_GEN5_12G_ID);
> +DW_XPCS_INFO_DECLARE(xpcs_qcom_nord, QCOM_NORD_XPCS_ID, DW_XPCS_PMA_ID_NATIVE);
>  
>  static const struct of_device_id xpcs_of_ids[] = {
> +	{ .compatible = "qcom,nord-dw-xpcs", .data = &xpcs_qcom_nord },
>  	{ .compatible = "snps,dw-xpcs", .data = &xpcs_generic },
>  	{ .compatible = "snps,dw-xpcs-gen1-3g", .data = &xpcs_pma_gen1_3g },
>  	{ .compatible = "snps,dw-xpcs-gen2-3g", .data = &xpcs_pma_gen2_3g },
> diff --git a/drivers/net/pcs/pcs-xpcs-qcom.c b/drivers/net/pcs/pcs-xpcs-qcom.c
> new file mode 100644
> index 0000000000000000000000000000000000000000..63c95c951454819b62eb3fd00abcc6b529e2004b
> --- /dev/null
> +++ b/drivers/net/pcs/pcs-xpcs-qcom.c
> @@ -0,0 +1,86 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Qualcomm DesignWare XPCS platform helpers
> + *
> + * Copyright (c) 2026 Qualcomm Innovation Center, Inc. All rights reserved.
> + */
> +
> +#include <linux/io.h>
> +#include <linux/mdio.h>
> +#include <linux/platform_device.h>
> +#include <linux/pm_runtime.h>
> +
> +#include "pcs-xpcs.h"
> +#include "pcs-xpcs-qcom.h"
> +
> +/* Qualcomm Nord direct MMIO XPCS windows. */
> +#define QCOM_XPCS_SR_XS_BASE		0x0000
> +#define QCOM_XPCS_VR_XS_BASE		0x2000
> +#define QCOM_XPCS_SR_PMA_BASE		0x3000
> +#define QCOM_XPCS_SR_MII_BASE		0x4000
> +#define QCOM_XPCS_VR_MII_BASE		0x5000
> +
> +static int xpcs_qcom_reg_offset(int dev, int reg)
> +{
> +	switch (dev) {
> +	case MDIO_MMD_PCS:
> +		if (reg & DW_VENDOR)
> +			return QCOM_XPCS_VR_XS_BASE +
> +			       ((reg & ~DW_VENDOR) << 2);
> +
> +		return QCOM_XPCS_SR_XS_BASE + (reg << 2);
> +
> +	case MDIO_MMD_PMAPMD:
> +		return QCOM_XPCS_SR_PMA_BASE + (reg << 2);
> +
> +	case MDIO_MMD_VEND2:
> +		if (reg >= DW_VENDOR)
> +			return QCOM_XPCS_VR_MII_BASE +
> +			       ((reg - DW_VENDOR) << 2);
> +
> +		return QCOM_XPCS_SR_MII_BASE + (reg << 2);
> +
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +}

This seems to be the real difference with respect to the
xpcs_mmio_read_reg_direct()/xpcs_mmio_write_reg_direct(), right?
Maybe a different approach (simpler but probably less flexible is to make
xpcs_mmio_addr_format() SoC dependent. What do you think?

> +
> +int xpcs_qcom_reg_read(struct platform_device *pdev, void __iomem *reg_base,
> +		       int dev, int reg)
> +{
> +	int offset, ret;
> +
> +	offset = xpcs_qcom_reg_offset(dev, reg);
> +	if (offset < 0)
> +		return offset;
> +
> +	ret = pm_runtime_resume_and_get(&pdev->dev);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = readl(reg_base + offset) & 0xffff;
> +
> +	pm_runtime_put(&pdev->dev);
> +
> +	return ret;
> +}
> +
> +int xpcs_qcom_reg_write(struct platform_device *pdev, void __iomem *reg_base,
> +			int dev, int reg, u16 val)
> +{
> +	int offset, ret;
> +
> +	offset = xpcs_qcom_reg_offset(dev, reg);
> +	if (offset < 0)
> +		return offset;
> +
> +	ret = pm_runtime_resume_and_get(&pdev->dev);
> +	if (ret < 0)
> +		return ret;
> +
> +	writel(val, reg_base + offset);
> +
> +	pm_runtime_put(&pdev->dev);
> +
> +	return 0;
> +}
> diff --git a/drivers/net/pcs/pcs-xpcs-qcom.h b/drivers/net/pcs/pcs-xpcs-qcom.h
> new file mode 100644
> index 0000000000000000000000000000000000000000..a1084f6a10a96baa8ba0d192ee64cdaed90da125
> --- /dev/null
> +++ b/drivers/net/pcs/pcs-xpcs-qcom.h
> @@ -0,0 +1,16 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +
> +#ifndef __PCS_XPCS_QCOM_H
> +#define __PCS_XPCS_QCOM_H
> +
> +#include <linux/io.h>
> +#include <linux/types.h>
> +
> +struct platform_device;
> +
> +int xpcs_qcom_reg_read(struct platform_device *pdev, void __iomem *reg_base,
> +		       int dev, int reg);
> +int xpcs_qcom_reg_write(struct platform_device *pdev, void __iomem *reg_base,
> +			int dev, int reg, u16 val);
> +
> +#endif /* __PCS_XPCS_QCOM_H */
> diff --git a/drivers/net/pcs/pcs-xpcs.c b/drivers/net/pcs/pcs-xpcs.c
> index 7f5c7a275630f2b064e4b9abdd6c3619e9346cec..1f556b4f7c44f06f24a2f724734d3a7d71424de3 100644
> --- a/drivers/net/pcs/pcs-xpcs.c
> +++ b/drivers/net/pcs/pcs-xpcs.c
> @@ -1571,6 +1571,15 @@ static const struct dw_xpcs_compat nxp_sja1110_xpcs_compat[] = {
>  	}
>  };
>  
> +static const struct dw_xpcs_compat qcom_nord_xpcs_compat[] = {
> +	{
> +		.interface = PHY_INTERFACE_MODE_USXGMII,
> +		.supported = xpcs_usxgmii_features,
> +		.an_mode = DW_AN_C37_USXGMII,
> +	}, {
> +	}
> +};
> +
>  static const struct dw_xpcs_desc xpcs_desc_list[] = {
>  	{
>  		.id = DW_XPCS_ID,
> @@ -1584,6 +1593,10 @@ static const struct dw_xpcs_desc xpcs_desc_list[] = {
>  		.id = NXP_SJA1110_XPCS_ID,
>  		.mask = DW_XPCS_ID_MASK,
>  		.compat = nxp_sja1110_xpcs_compat,
> +	}, {
> +		.id = QCOM_NORD_XPCS_ID,
> +		.mask = DW_XPCS_ID_MASK,
> +		.compat = qcom_nord_xpcs_compat,
>  	},

I guess this part is supposed to be part of patch 2/9, right?

Regards,
Lorenzo

>  };
>  
> diff --git a/include/linux/pcs/pcs-xpcs.h b/include/linux/pcs/pcs-xpcs.h
> index 4ea995b70150e33e1e1a47cc7aa324c53742fbdc..0f69e14b2a4c8d17b59a570debd14a77ab040182 100644
> --- a/include/linux/pcs/pcs-xpcs.h
> +++ b/include/linux/pcs/pcs-xpcs.h
> @@ -26,6 +26,7 @@ enum dw_xpcs_pcs_id {
>  	DW_XPCS_ID_NATIVE = 0,
>  	NXP_SJA1105_XPCS_ID = 0x00000010,
>  	NXP_SJA1110_XPCS_ID = 0x00000020,
> +	QCOM_NORD_XPCS_ID = 0x00000030,
>  	DW_XPCS_ID = 0x7996ced0,
>  	DW_XPCS_ID_MASK = 0xffffffff,
>  };
> 
> -- 
> 2.34.1
>

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