Message-ID: <YwoNdUPoSKKHhzxx@yilunxu-OptiPlex-7050>
Date:   Sat, 27 Aug 2022 20:26:29 +0800
From:   Xu Yilun <yilun.xu@...el.com>
To:     Nava kishore Manne <nava.kishore.manne@....com>
Cc:     git@....com, robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org,
        michal.simek@...inx.com, mdf@...nel.org, hao.wu@...el.com,
        trix@...hat.com, p.zabel@...gutronix.de,
        gregkh@...uxfoundation.org, ronak.jain@...inx.com,
        rajan.vaja@...inx.com, abhyuday.godhasara@...inx.com,
        piyush.mehta@...inx.com, lakshmi.sai.krishna.potthuri@...inx.com,
        harsha.harsha@...inx.com, linus.walleij@...aro.org,
        nava.manne@...inx.com, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-fpga@...r.kernel.org
Subject: Re: [PATCH 4/4] fpga: zynqmp: Add afi config driver

On 2022-08-24 at 09:25:42 +0530, Nava kishore Manne wrote:
> Add zynqmp AXI FIFO interface(AFI) config driver. This is useful for the
> configuration of the PS-PL interface on Zynq US+ MPSoC platform.

Please help illustrate how to use the device for FPGA reprogramming, why
it should be implemented as an FPGA bridge.

>From the code I actually didn't see any operation that gates the
fpga-region from other part of the machine.

> 
> Signed-off-by: Nava kishore Manne <nava.kishore.manne@....com>
> ---
>  MAINTAINERS               |   6 ++
>  drivers/fpga/Kconfig      |  13 +++
>  drivers/fpga/Makefile     |   1 +
>  drivers/fpga/zynqmp-afi.c | 211 ++++++++++++++++++++++++++++++++++++++
>  4 files changed, 231 insertions(+)
>  create mode 100644 drivers/fpga/zynqmp-afi.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 20ffac651214..957e753e6406 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -8032,6 +8032,12 @@ F:	Documentation/fpga/
>  F:	drivers/fpga/
>  F:	include/linux/fpga/
>  
> +FPGA ZYNQMP PS-PL BRIDGE DRIVER
> +M:	Nava kishore Manne <nava.kishore.manne@....com>
> +S:	Supported
> +F:	Documentation/devicetree/bindings/fpga/xlnx,zynqmp-afi-fpga.yaml
> +F:	drivers/fpga/zynqmp-afi.c
> +
>  INTEL MAX10 BMC SECURE UPDATES
>  M:	Russ Weight <russell.h.weight@...el.com>
>  L:	linux-fpga@...r.kernel.org
> diff --git a/drivers/fpga/Kconfig b/drivers/fpga/Kconfig
> index 6c416955da53..c08794d30fb5 100644
> --- a/drivers/fpga/Kconfig
> +++ b/drivers/fpga/Kconfig
> @@ -130,6 +130,19 @@ config XILINX_PR_DECOUPLER
>  	  reconfiguration, preventing the system deadlock that can
>  	  occur if AXI transactions are interrupted by DFX.
>  
> +config ZYNQMP_AFI
> +	tristate "Xilinx ZYNQMP AFI support"
> +	depends on FPGA_BRIDGE
> +	help
> +	  Say Y to enable drivers to handle the PS-PL clocks configurations
> +	  and PS-PL Bus-width. Xilinx Zynq US+ MPSoC connect the PS to the
> +	  programmable logic (PL) through the AXI port. This AXI port helps
> +	  to establish the data path between the PS and PL.
> +	  In-order to establish the proper communication path between PS and PL,
> +	  the AXI port data path should be configured with the proper Bus-width
> +	  values and it will also handles the PS-PL reset signals to reset the
> +	  PL domain.

Same concern, please describe its relationship to FPGA reprogramming.

> +
>  config FPGA_REGION
>  	tristate "FPGA Region"
>  	depends on FPGA_BRIDGE
> diff --git a/drivers/fpga/Makefile b/drivers/fpga/Makefile
> index 42ae8b58abce..94cfe60972db 100644
> --- a/drivers/fpga/Makefile
> +++ b/drivers/fpga/Makefile
> @@ -31,6 +31,7 @@ obj-$(CONFIG_FPGA_BRIDGE)		+= fpga-bridge.o
>  obj-$(CONFIG_SOCFPGA_FPGA_BRIDGE)	+= altera-hps2fpga.o altera-fpga2sdram.o
>  obj-$(CONFIG_ALTERA_FREEZE_BRIDGE)	+= altera-freeze-bridge.o
>  obj-$(CONFIG_XILINX_PR_DECOUPLER)	+= xilinx-pr-decoupler.o
> +obj-$(CONFIG_ZYNQMP_AFI)		+= zynqmp-afi.o
>  
>  # High Level Interfaces
>  obj-$(CONFIG_FPGA_REGION)		+= fpga-region.o
> diff --git a/drivers/fpga/zynqmp-afi.c b/drivers/fpga/zynqmp-afi.c
> new file mode 100644
> index 000000000000..bc975d304039
> --- /dev/null
> +++ b/drivers/fpga/zynqmp-afi.c
> @@ -0,0 +1,211 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2022 Xilinx, Inc.
> + */
> +
> +#include <linux/err.h>
> +#include <linux/firmware/xlnx-zynqmp.h>
> +#include <linux/fpga/fpga-bridge.h>
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/reset.h>
> +#include <linux/slab.h>
> +
> +/* Registers and special values for doing register-based operations */
> +#define AFI_RDCHAN_CTRL_OFFSET	0x00
> +#define AFI_WRCHAN_CTRL_OFFSET	0x14
> +#define AFI_BUSWIDTH_MASK	BIT(0)
> +
> +/**
> + * struct zynqmp_afi - AFI register description.
> + * @dev: device that owns this.
> + * @of_node: Device Tree overlay.
> + * @resets: Pointer to the reset control for ps-pl resets.
> + */
> +struct zynqmp_afi {
> +	struct device *dev;
> +	struct device_node *of_node;
> +	struct reset_control *resets;
> +};
> +
> +/**
> + * struct zynqmp_afi_configreg - AFI configuration registers info.
> + * @reg:	Name of the AFI configuration register.
> + * @id:		Register index value.
> + */
> +struct zynqmp_afi_configreg {
> +	char *reg;
> +	u32 id;
> +};
> +
> +static struct zynqmp_afi_configreg afi_cfgreg[] = {
> +	{.reg = "xlnx,afi-fm0-rd-bus-width",	.id = AFIFM0_RDCTRL},
> +	{.reg = "xlnx,afi-fm1-rd-bus-width",	.id = AFIFM1_RDCTRL},
> +	{.reg = "xlnx,afi-fm2-rd-bus-width",	.id = AFIFM2_RDCTRL},
> +	{.reg = "xlnx,afi-fm3-rd-bus-width",	.id = AFIFM3_RDCTRL},
> +	{.reg = "xlnx,afi-fm4-rd-bus-width",	.id = AFIFM4_RDCTRL},
> +	{.reg = "xlnx,afi-fm5-rd-bus-width",	.id = AFIFM5_RDCTRL},
> +	{.reg = "xlnx,afi-fm6-rd-bus-width",	.id = AFIFM6_RDCTRL},
> +	{.reg = "xlnx,afi-fm0-wr-bus-width",	.id = AFIFM0_WRCTRL},
> +	{.reg = "xlnx,afi-fm1-wr-bus-width",	.id = AFIFM1_WRCTRL},
> +	{.reg = "xlnx,afi-fm2-wr-bus-width",	.id = AFIFM2_WRCTRL},
> +	{.reg = "xlnx,afi-fm3-wr-bus-width",	.id = AFIFM3_WRCTRL},
> +	{.reg = "xlnx,afi-fm4-wr-bus-width",	.id = AFIFM4_WRCTRL},
> +	{.reg = "xlnx,afi-fm5-wr-bus-width",	.id = AFIFM5_WRCTRL},
> +	{.reg = "xlnx,afi-fm6-wr-bus-width",	.id = AFIFM6_WRCTRL},
> +	{.reg = "xlnx,afi-fs-ss0-bus-width",	.id = AFIFS},
> +	{.reg = "xlnx,afi-fs-ss2-bus-width",	.id = AFIFS_SS2},
> +	{}
> +};
> +
> +static int zynqmp_afi_config(struct zynqmp_afi *afi_data)
> +{
> +	struct zynqmp_afi_configreg *cfgptr = afi_cfgreg;
> +	struct device_node *np = afi_data->of_node;
> +	u32 afi_ss0_val, afi_ss1_val, bus_width;
> +	int ret;
> +
> +	while (cfgptr->reg) {
> +		ret = of_property_read_u32(np, cfgptr->reg, &bus_width);
> +		if (!ret) {
> +			if (cfgptr->id == AFIFS_SS2) {
> +				if (bus_width == 32)
> +					ret = zynqmp_pm_afi(AFIFS_SS2,
> +							    AFIFS_SS_BUS_WIDTH_32_CONFIG_VAL);
> +				else if (bus_width == 64)
> +					ret = zynqmp_pm_afi(AFIFS_SS2,
> +							    AFIFS_SS0_SS2_BUS_WIDTH_64_CONFIG_VAL);
> +				else if (bus_width == 128)
> +					ret = zynqmp_pm_afi(AFIFS_SS2,
> +							    AFIFS_SS0_SS2_BUS_WIDTH_128_CONFIG_VAL);
> +				else
> +					return -EINVAL;
> +			} else if (cfgptr->id == AFIFS) {
> +				if (bus_width == 32)
> +					afi_ss0_val = AFIFS_SS_BUS_WIDTH_32_CONFIG_VAL;
> +				else if (bus_width == 64)
> +					afi_ss0_val = AFIFS_SS0_SS2_BUS_WIDTH_64_CONFIG_VAL;
> +				else if (bus_width == 128)
> +					afi_ss0_val = AFIFS_SS0_SS2_BUS_WIDTH_128_CONFIG_VAL;
> +				else
> +					return -EINVAL;
> +
> +				ret = of_property_read_u32(np, "xlnx,afi-fs-ss1-bus-width",
> +							   &bus_width);
> +				if (!ret) {
> +					if (bus_width == 32)
> +						afi_ss1_val = AFIFS_SS_BUS_WIDTH_32_CONFIG_VAL;
> +					else if (bus_width == 64)
> +						afi_ss1_val = AFIFS_SS1_BUS_WIDTH_64_CONFIG_VAL;
> +					else if (bus_width == 128)
> +						afi_ss1_val = AFIFS_SS1_BUS_WIDTH_128_CONFIG_VAL;
> +					else
> +						return -EINVAL;
> +
> +					ret = zynqmp_pm_afi(AFIFS, afi_ss1_val | afi_ss0_val);
> +				}
> +			} else {
> +				if (bus_width == 32)
> +					ret = zynqmp_pm_afi(cfgptr->id,
> +							    AFIFM_BUS_WIDTH_32_CONFIG_VAL);
> +				else if (bus_width == 64)
> +					ret = zynqmp_pm_afi(cfgptr->id,
> +							    AFIFM_BUS_WIDTH_64_CONFIG_VAL);
> +				else if (bus_width == 128)
> +					ret = zynqmp_pm_afi(cfgptr->id,
> +							    AFIFM_BUS_WIDTH_128_CONFIG_VAL);
> +				else
> +					return -EINVAL;
> +			}
> +		}
> +		cfgptr++;
> +	}
> +
> +	return 0;
> +}
> +
> +static int zynqmp_afi_enable_set(struct fpga_bridge *bridge, bool enable)
> +{
> +	struct device_node *overlay = bridge->info->overlay;
> +	struct zynqmp_afi *priv = bridge->priv;
> +	int ret = 0;
> +
> +	if (enable) {
> +		reset_control_reset(priv->resets);
> +		return 0;
> +	}
> +
> +	of_node_get(overlay);
> +	priv->of_node =
> +	of_find_node_with_property(overlay,
> +				   "xlnx,afi-fm0-rd-bus-width");

I'm a little confused here. The fpga_image_info.overlay is for
fpga-region, but from your binding doc this property is for this afi
device. You want to add another overlay targeting afi dev node during
reprograming?

> +	if (priv->of_node)
> +		ret = zynqmp_afi_config(priv);
> +	of_node_put(priv->of_node);
> +
> +	return ret;
> +}
> +
> +static const struct fpga_bridge_ops zynqmp_afi_br_ops = {
> +	.enable_set = zynqmp_afi_enable_set,
> +};
> +
> +static const struct of_device_id zynqmp_afi_of_match[] = {
> +	{ .compatible =  "xlnx,zynqmp-afi-fpga" },
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(of, zynqmp_afi_of_match);
> +
> +static int zynqmp_afi_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct zynqmp_afi *priv;
> +	struct fpga_bridge *br;
> +
> +	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	priv->dev = dev;
> +
> +	priv->resets = devm_reset_control_array_get_optional_exclusive(&pdev->dev);
> +	if (IS_ERR(priv->resets))
> +		return PTR_ERR(priv->resets);
> +
> +	br = fpga_bridge_register(dev, "Xilinx ZynqMP AFI",
> +				  &zynqmp_afi_br_ops, priv);
> +	if (IS_ERR(br)) {
> +		dev_err(dev, "unable to register Xilinx ZynqMP AFI");

Need a "\n" at the end?

Thanks,
Yilun

> +		return PTR_ERR(br);
> +	}
> +
> +	platform_set_drvdata(pdev, br);
> +
> +	return 0;
> +}
> +
> +static int zynqmp_afi_remove(struct platform_device *pdev)
> +{
> +	struct fpga_bridge *bridge = platform_get_drvdata(pdev);
> +
> +	fpga_bridge_unregister(bridge);
> +
> +	return 0;
> +}
> +
> +static struct platform_driver zynqmp_afi_driver = {
> +	.probe = zynqmp_afi_probe,
> +	.remove = zynqmp_afi_remove,
> +	.driver = {
> +		.name = "zynqmp_afi",
> +		.of_match_table = of_match_ptr(zynqmp_afi_of_match),
> +	},
> +};
> +
> +module_platform_driver(zynqmp_afi_driver);
> +
> +MODULE_DESCRIPTION("ZYNQMP FPGA AXI FIFO interface configuration module");
> +MODULE_AUTHOR("Nava kishore Manne <nava.kishore.manne@....com>");
> +MODULE_LICENSE("GPL");
> -- 
> 2.25.1
> 

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