Re: [PATCH 3/3] fpga: versal-fpga: Add versal fpga manager driver

[Moritz Fischer]

Hi Nava,

On Fri, Jan 22, 2021 at 10:34:15AM +0000, Nava kishore Manne wrote:
> Hi Moritz,
> 
> 	Thanks for the review.
> Please find my response inline.
> 
> > -----Original Message-----
> > From: Moritz Fischer <mdf@xxxxxxxxxx>
> > Sent: Tuesday, January 19, 2021 6:03 AM
> > To: Nava kishore Manne <navam@xxxxxxxxxx>
> > Cc: mdf@xxxxxxxxxx; trix@xxxxxxxxxx; robh+dt@xxxxxxxxxx; Michal Simek
> > <michals@xxxxxxxxxx>; linux-fpga@xxxxxxxxxxxxxxx;
> > devicetree@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; linux-
> > kernel@xxxxxxxxxxxxxxx; git <git@xxxxxxxxxx>; chinnikishore369@xxxxxxxxx;
> > Appana Durga Kedareswara Rao <appanad@xxxxxxxxxx>
> > Subject: Re: [PATCH 3/3] fpga: versal-fpga: Add versal fpga manager driver
> > 
> > Hi Nava,
> > 
> > On Mon, Jan 18, 2021 at 08:13:18AM +0530, Nava kishore Manne wrote:
> > > This patch adds driver for versal fpga manager.
> > Nit: Add support for Xilinx Versal FPGA manager
> 
> Will fix in v2.
> 
> > >
> > > PDI source type can be DDR, OCM, QSPI flash etc..
> > No idea what PDI is :)
> 
> Programmable device image (PDI). 
> This file is generated by Xilinx Vivado tool and it contains configuration data objects.
> 
> > > But driver allocates memory always from DDR, Since driver supports
> > > only DDR source type.
> > >
> > > Signed-off-by: Appana Durga Kedareswara rao
> > > <appana.durga.rao@xxxxxxxxxx>
> > > Signed-off-by: Nava kishore Manne <nava.manne@xxxxxxxxxx>
> > > ---
> > >  drivers/fpga/Kconfig       |   8 ++
> > >  drivers/fpga/Makefile      |   1 +
> > >  drivers/fpga/versal-fpga.c | 149
> > > +++++++++++++++++++++++++++++++++++++
> > >  3 files changed, 158 insertions(+)
> > >  create mode 100644 drivers/fpga/versal-fpga.c
> > >
> > > diff --git a/drivers/fpga/Kconfig b/drivers/fpga/Kconfig index
> > > 5645226ca3ce..9f779c3a6739 100644
> > > --- a/drivers/fpga/Kconfig
> > > +++ b/drivers/fpga/Kconfig
> > > @@ -216,4 +216,12 @@ config FPGA_MGR_ZYNQMP_FPGA
> > >  	  to configure the programmable logic(PL) through PS
> > >  	  on ZynqMP SoC.
> > >
> > > +config FPGA_MGR_VERSAL_FPGA
> > > +        tristate "Xilinx Versal FPGA"
> > > +        depends on ARCH_ZYNQMP || COMPILE_TEST
> > > +        help
> > > +          Select this option to enable FPGA manager driver support for
> > > +          Xilinx Versal SOC. This driver uses the versal soc firmware
> > > +          interface to load programmable logic(PL) images
> > > +          on versal soc.
> > >  endif # FPGA
> > > diff --git a/drivers/fpga/Makefile b/drivers/fpga/Makefile index
> > > d8e21dfc6778..40c9adb6a644 100644
> > > --- a/drivers/fpga/Makefile
> > > +++ b/drivers/fpga/Makefile
> > > @@ -18,6 +18,7 @@ obj-$(CONFIG_FPGA_MGR_TS73XX)		+=
> > ts73xx-fpga.o
> > >  obj-$(CONFIG_FPGA_MGR_XILINX_SPI)	+= xilinx-spi.o
> > >  obj-$(CONFIG_FPGA_MGR_ZYNQ_FPGA)	+= zynq-fpga.o
> > >  obj-$(CONFIG_FPGA_MGR_ZYNQMP_FPGA)	+= zynqmp-fpga.o
> > > +obj-$(CONFIG_FPGA_MGR_VERSAL_FPGA)      += versal-fpga.o
> > >  obj-$(CONFIG_ALTERA_PR_IP_CORE)         += altera-pr-ip-core.o
> > >  obj-$(CONFIG_ALTERA_PR_IP_CORE_PLAT)    += altera-pr-ip-core-plat.o
> > >
> > > diff --git a/drivers/fpga/versal-fpga.c b/drivers/fpga/versal-fpga.c
> > > new file mode 100644 index 000000000000..2a42aa78b182
> > > --- /dev/null
> > > +++ b/drivers/fpga/versal-fpga.c
> > > @@ -0,0 +1,149 @@
> > > +// SPDX-License-Identifier: GPL-2.0+
> > > +/*
> > > + * Copyright (C) 2021 Xilinx, Inc.
> > > + */
> > > +
> > > +#include <linux/dma-mapping.h>
> > > +#include <linux/fpga/fpga-mgr.h>
> > > +#include <linux/io.h>
> > > +#include <linux/kernel.h>
> > > +#include <linux/module.h>
> > > +#include <linux/of_address.h>
> > > +#include <linux/string.h>
> > > +#include <linux/firmware/xlnx-zynqmp.h>
> > > +
> > > +/* Constant Definitions */
> > > +#define PDI_SOURCE_TYPE	0xF
> > > +
> > > +/**
> > > + * struct versal_fpga_priv - Private data structure
> > > + * @dev:	Device data structure
> > > + * @flags:	flags which is used to identify the PL Image type
> > > + */
> > > +struct versal_fpga_priv {
> > > +	struct device *dev;
> > > +	u32 flags;
> > This seems unused ... please introduce them when/if you start using them.
> 
> Will fix in v2.
> 
> > > +};
> > > +
> > > +static int versal_fpga_ops_write_init(struct fpga_manager *mgr,
> > > +				      struct fpga_image_info *info,
> > > +				      const char *buf, size_t size) {
> > > +	struct versal_fpga_priv *priv;
> > > +
> > > +	priv = mgr->priv;
> > > +	priv->flags = info->flags;
> > ? What uses this ? It seems this function could just be 'return 0' right now.
> 
> Will fix in v2.
> 
> > > +
> > > +	return 0;
> > > +}
> > > +
> > > +static int versal_fpga_ops_write(struct fpga_manager *mgr,
> > > +				 const char *buf, size_t size)
> > > +{
> > > +	struct versal_fpga_priv *priv;
> > > +	dma_addr_t dma_addr = 0;
> > > +	char *kbuf;
> > > +	int ret;
> > > +
> > > +	priv = mgr->priv;
> > > +
> > > +	kbuf = dma_alloc_coherent(priv->dev, size, &dma_addr,
> > GFP_KERNEL);
> > > +	if (!kbuf)
> > > +		return -ENOMEM;
> > > +
> > > +	memcpy(kbuf, buf, size);
> > > +
> > > +	wmb(); /* ensure all writes are done before initiate FW call */
> > > +
> > > +	ret = zynqmp_pm_load_pdi(PDI_SOURCE_TYPE, dma_addr);
> > > +
> > > +	dma_free_coherent(priv->dev, size, kbuf, dma_addr);
> > > +
> > > +	return ret;
> > > +}
> > > +
> > > +static int versal_fpga_ops_write_complete(struct fpga_manager *mgr,
> > > +					  struct fpga_image_info *info)
> > > +{
> > > +	return 0;
> > > +}
> > > +
> > > +static enum fpga_mgr_states versal_fpga_ops_state(struct fpga_manager
> > > +*mgr) {
> > > +	return FPGA_MGR_STATE_OPERATING;
> > Is that always the case? Shouldn't that be FPGA_MGR_STATE_UNKNOWN?
> 
> For Versal SoC base PDI is always configured prior to Linux boot up. So I make the fpga state as OPERATING.
> Please let know if it is not a proper implementation will think about the alternate solution. 

So you're saying I can't boot a Versal SoC without a PDI / Bitstream
loaded? Interesting :)
> 
> > > +}
> > > +
> > > +static const struct fpga_manager_ops versal_fpga_ops = {
> > > +	.state = versal_fpga_ops_state,
> > > +	.write_init = versal_fpga_ops_write_init,
> > > +	.write = versal_fpga_ops_write,
> > > +	.write_complete = versal_fpga_ops_write_complete, };
> > > +
> > > +static int versal_fpga_probe(struct platform_device *pdev) {
> > > +	struct device *dev = &pdev->dev;
> > > +	struct versal_fpga_priv *priv;
> > > +	struct fpga_manager *mgr;
> > > +	int err, ret;
> > Please pick one, err or ret. 'err' seems unused?
> 
> Will fix in v2.
> 
> > > +
> > > +	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> > > +	if (!priv)
> > > +		return -ENOMEM;
> > > +
> > > +	priv->dev = dev;
> > > +	ret = dma_set_mask_and_coherent(&pdev->dev,
> > DMA_BIT_MASK(32));
> > > +	if (ret < 0) {
> > > +		dev_err(dev, "no usable DMA configuration");
> > Nit: "no usable DMA configuration\n"
> 
> Will fix in v2.
> 
> > > +		return ret;
> > > +	}
> > > +
> > > +	mgr = devm_fpga_mgr_create(dev, "Xilinx Versal FPGA Manager",
> > > +				   &versal_fpga_ops, priv);
> > > +	if (!mgr)
> > > +		return -ENOMEM;
> > > +
> > > +	platform_set_drvdata(pdev, mgr);
> > > +
> > 
> > Replace this part:
> > > +	err = fpga_mgr_register(mgr);
> > > +	if (err) {
> > > +		dev_err(dev, "unable to register FPGA manager");
> > > +		fpga_mgr_free(mgr);
> > > +		return err;
> > > +	}
> > 
> > with:
> > 	return devm_fpga_mgr_register(mgr);
> > 
> > I tried to get rid of the boilerplate, since every driver repeats it (and above
> > calling fpga_mgr_free(mgr) on a devm_fpga_mgr_create() created FPGA
> > manager is wrong?) :)
> 
> Thanks for pointing it. Will fix in v2.
> 
> > > +
> > > +	return 0;
> > > +}
> > > +
> > 
> > Then
> > > +static int versal_fpga_remove(struct platform_device *pdev) {
> > > +	struct fpga_manager *mgr = platform_get_drvdata(pdev);
> > > +
> > > +	fpga_mgr_unregister(mgr);
> > > +	fpga_mgr_free(mgr);
> > > +
> > > +	return 0;
> > > +}
> > drop this since cleanup is now automatic.
> 
> Thanks for pointing it. Will fix in v2.
> 
> > > +
> > > +static const struct of_device_id versal_fpga_of_match[] = {
> > > +	{ .compatible = "xlnx,versal-fpga", },
> > > +	{},
> > > +};
> > > +
> > Nit: Drop the newline
> 
> Will fix in v2.
> 
> > > +MODULE_DEVICE_TABLE(of, versal_fpga_of_match);
> > > +
> > > +static struct platform_driver versal_fpga_driver = {
> > > +	.probe = versal_fpga_probe,
> > > +	.remove = versal_fpga_remove,
> > > +	.driver = {
> > > +		.name = "versal_fpga_manager",
> > > +		.of_match_table = of_match_ptr(versal_fpga_of_match),
> > > +	},
> > > +};
> > > +
> > Nit: Drop the newline
> 
> Will fix in v2.
> 
> Regards,
> Navakishore.
- Moritz