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Date: Mon, 29 Apr 2024 13:00:26 -0400
From: Frank Li <Frank.li@nxp.com>
To: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Cc: Richard Zhu <hongxing.zhu@nxp.com>,
	Lucas Stach <l.stach@pengutronix.de>,
	Lorenzo Pieralisi <lpieralisi@kernel.org>,
	Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= <kw@linux.com>,
	Rob Herring <robh@kernel.org>, Bjorn Helgaas <bhelgaas@google.com>,
	Shawn Guo <shawnguo@kernel.org>,
	Sascha Hauer <s.hauer@pengutronix.de>,
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	Fabio Estevam <festevam@gmail.com>,
	NXP Linux Team <linux-imx@nxp.com>,
	Philipp Zabel <p.zabel@pengutronix.de>,
	Liam Girdwood <lgirdwood@gmail.com>,
	Mark Brown <broonie@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Conor Dooley <conor+dt@kernel.org>, linux-pci@vger.kernel.org,
	imx@lists.linux.dev, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, bpf@vger.kernel.org,
	devicetree@vger.kernel.org
Subject: Re: [PATCH v3 08/11] PCI: imx: Config look up table(LUT) to support
 MSI ITS and IOMMU for i.MX95
Message-ID: <Zi/SKgO6TkrCcsj3@lizhi-Precision-Tower-5810>
References: <20240402-pci2_upstream-v3-0-803414bdb430@nxp.com>
 <20240402-pci2_upstream-v3-8-803414bdb430@nxp.com>
 <20240427113643.GM1981@thinkpad>
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On Sat, Apr 27, 2024 at 05:06:43PM +0530, Manivannan Sadhasivam wrote:
> PCI: imx6: Add support for configuring BDF to SID mapping for i.MX95
> 
> On Tue, Apr 02, 2024 at 10:33:44AM -0400, Frank Li wrote:
> > i.MX95 need config LUT to convert bpf to stream id. IOMMU and ITS use the
> 
> Did you mean BDF? Here and everywhere.
> 
> > same stream id. Check msi-map and smmu-map and make sure the same PCI bpf
> > map to the same stream id. Then config LUT related registers.
> > 
> 
> These DT properties not documented in the binding.
> 
> > Signed-off-by: Frank Li <Frank.Li@nxp.com>
> > ---
> >  drivers/pci/controller/dwc/pcie-imx.c | 175 ++++++++++++++++++++++++++++++++++
> >  1 file changed, 175 insertions(+)
> > 
> > diff --git a/drivers/pci/controller/dwc/pcie-imx.c b/drivers/pci/controller/dwc/pcie-imx.c
> > index af0f960f28757..653d8e8ee1abc 100644
> > --- a/drivers/pci/controller/dwc/pcie-imx.c
> > +++ b/drivers/pci/controller/dwc/pcie-imx.c
> > @@ -55,6 +55,22 @@
> >  #define IMX95_PE0_GEN_CTRL_3			0x1058
> >  #define IMX95_PCIE_LTSSM_EN			BIT(0)
> >  
> > +#define IMX95_PE0_LUT_ACSCTRL			0x1008
> > +#define IMX95_PEO_LUT_RWA			BIT(16)
> > +#define IMX95_PE0_LUT_ENLOC			GENMASK(4, 0)
> > +
> > +#define IMX95_PE0_LUT_DATA1			0x100c
> > +#define IMX95_PE0_LUT_VLD			BIT(31)
> > +#define IMX95_PE0_LUT_DAC_ID			GENMASK(10, 8)
> > +#define IMX95_PE0_LUT_STREAM_ID			GENMASK(5, 0)
> > +
> > +#define IMX95_PE0_LUT_DATA2			0x1010
> > +#define IMX95_PE0_LUT_REQID			GENMASK(31, 16)
> > +#define IMX95_PE0_LUT_MASK			GENMASK(15, 0)
> > +
> > +#define IMX95_SID_MASK				GENMASK(5, 0)
> > +#define IMX95_MAX_LUT				32
> > +
> >  #define to_imx_pcie(x)	dev_get_drvdata((x)->dev)
> >  
> >  enum imx_pcie_variants {
> > @@ -217,6 +233,159 @@ static int imx95_pcie_init_phy(struct imx_pcie *imx_pcie)
> >  	return 0;
> >  }
> >  
> > +static int imx_pcie_update_lut(struct imx_pcie *imx_pcie, int index, u16 reqid, u16 mask, u8 sid)
> > +{
> > +	struct dw_pcie *pci = imx_pcie->pci;
> > +	struct device *dev = pci->dev;
> > +	u32 data1, data2;
> > +
> > +	if (sid >= 64) {
> > +		dev_err(dev, "Too big stream id: %d\n", sid);
> 
> 'Invalid SID for index (%d): %d\n', index, sid
> 
> > +		return -EINVAL;
> > +	}
> > +
> > +	data1 = FIELD_PREP(IMX95_PE0_LUT_DAC_ID, 0);
> > +	data1 |= FIELD_PREP(IMX95_PE0_LUT_STREAM_ID, sid);
> > +	data1 |= IMX95_PE0_LUT_VLD;
> > +
> > +	regmap_write(imx_pcie->iomuxc_gpr, IMX95_PE0_LUT_DATA1, data1);
> > +
> > +	data2 = mask;
> > +	data2 |= FIELD_PREP(IMX95_PE0_LUT_REQID, reqid);
> > +
> > +	regmap_write(imx_pcie->iomuxc_gpr, IMX95_PE0_LUT_DATA2, data2);
> > +
> > +	regmap_write(imx_pcie->iomuxc_gpr, IMX95_PE0_LUT_ACSCTRL, index);
> > +
> > +	return 0;
> > +}
> > +
> > +struct imx_of_map {
> 
> imx_iommu_map
> 
> > +	u32 bdf;
> > +	u32 phandle;
> > +	u32 sid;
> > +	u32 sid_len;
> > +};
> > +
> > +static int imx_check_msi_and_smmmu(struct imx_pcie *imx_pcie,
> > +				   struct imx_of_map *msi_map, u32 msi_size, u32 msi_map_mask,
> > +				   struct imx_of_map *smmu_map, u32 smmu_size, u32 smmu_map_mask)
> > +{
> > +	struct dw_pcie *pci = imx_pcie->pci;
> > +	struct device *dev = pci->dev;
> > +	int i;
> > +
> 
> 	if (!msi_map || !smmu_map)
> 		return 0;
> 
> > +	if (msi_map && smmu_map) {
> > +		if (msi_size != smmu_size)
> > +			return -EINVAL;
> > +		if (msi_map_mask != smmu_map_mask)
> > +			return -EINVAL;
> 
> 	if (msi_size != smmu_size || msi_map_mask != smmu_map_mask)
> 		return -EINVAL;
> 
> > +
> > +		for (i = 0; i < msi_size / sizeof(*msi_map); i++) {
> > +			if (msi_map->bdf != smmu_map->bdf) {
> > +				dev_err(dev, "bdf setting is not match\n");
> 
> 'BDF mismatch between msi-map and iommu-map'
> 
> > +				return -EINVAL;
> > +			}
> > +			if ((msi_map->sid & IMX95_SID_MASK) != smmu_map->sid) {
> > +				dev_err(dev, "sid setting is not match\n");
> 
> 'SID mismatch between msi-map and iommu-map'
> 
> > +				return -EINVAL;
> > +			}
> > +			if ((msi_map->sid_len & IMX95_SID_MASK) != smmu_map->sid_len) {
> > +				dev_err(dev, "sid_len setting is not match\n");
> 
> 'SID length  mismatch between msi-map and iommu-map'
> 
> > +				return -EINVAL;
> > +			}
> > +		}
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +/*
> > + * Simple static config lut according to dts settings DAC index and stream ID used as a match result
> > + * of LUT pre-allocated and used by PCIes.
> > + *
> 
> Please reword the above sentence.

How about:

"A straightforward static configuration lookup table (LUT) is established
based on the stream ID specified in the DTS settings."

> 
> > + * Currently stream ID from 32-64 for PCIe.
> > + * 32-40: first PCI bus.
> > + * 40-48: second PCI bus.
> 
> I believe this is an SoC specific info. So better not add it here. It belongs to
> DT.
> 
> > + *
> > + * DAC_ID is index of TRDC.DAC index, start from 2 at iMX95.
> > + * ITS [pci(2bit): streamid(6bits)]
> > + *	pci 0 is 0
> > + *	pci 1 is 3
> > + */
> > +static int imx_pcie_config_sid(struct imx_pcie *imx_pcie)
> > +{
> > +	struct imx_of_map *msi_map = NULL, *smmu_map = NULL, *cur;
> > +	int i, j, lut_index, nr_map, msi_size = 0, smmu_size = 0;
> > +	u32 msi_map_mask = 0xffff, smmu_map_mask = 0xffff;
> > +	struct dw_pcie *pci = imx_pcie->pci;
> > +	struct device *dev = pci->dev;
> > +	u32 mask;
> > +	int size;
> > +
> > +	of_get_property(dev->of_node, "msi-map", &msi_size);
> > +	if (msi_size) {
> 
> You mentioned in the commit message that msi-map and iommu-map needs to be the
> same for this SoC. But here you are just ignoring the absence of 'msi-map'
> property.

If msi-map not exist, it will be fail back to use DWC's msi controller
insteand of ITS.

Do you think need comments here for that?

> 
> > +		msi_map = devm_kzalloc(dev, msi_size, GFP_KERNEL);
> > +		if (!msi_map)
> > +			return -ENOMEM;
> > +
> > +		if (of_property_read_u32_array(dev->of_node, "msi-map", (u32 *)msi_map,
> > +					       msi_size / sizeof(u32)))
> > +			return -EINVAL;
> > +
> > +		of_property_read_u32(dev->of_node, "msi-map-mask", &msi_map_mask);
> > +	}
> > +
> > +	cur = msi_map;
> > +	size = msi_size;
> > +	mask = msi_map_mask;
> > +
> > +	of_get_property(dev->of_node, "iommu-map", &smmu_size);
> 
> Same comment as above.

If iommu-map was not exist, it will work without iommu. the combination
as below (4 cases).
			not-exist          exit
msi-map                   dw-msi           its
iommu-map		  by-pass-mmu	   smmu

Require stream id must be the same only when both msi-map and iommu exist.

> 
> > +	if (smmu_size) {
> > +		smmu_map = devm_kzalloc(dev, smmu_size, GFP_KERNEL);
> > +		if (!smmu_map)
> > +			return -ENOMEM;
> > +
> > +		if (of_property_read_u32_array(dev->of_node, "iommu-map", (u32 *)smmu_map,
> > +					       smmu_size / sizeof(u32)))
> > +			return -EINVAL;
> > +
> > +		of_property_read_u32(dev->of_node, "iommu_map_mask", &smmu_map_mask);
> > +	}
> > +
> > +	if (imx_check_msi_and_smmmu(imx_pcie, msi_map, msi_size, msi_map_mask,
> > +				     smmu_map, smmu_size, smmu_map_mask))
> > +		return -EINVAL;
> > +
> 
> Hmm, so you want to continue even if the 'msi-map' and 'iommu-map' properties
> don't exist i.e., for old platforms?

imx_check_msi_and_smmmu() will return 0 when smmu_map is null.

> 
> > +	if (!cur) {
> > +		cur = smmu_map;
> > +		size = smmu_size;
> > +		mask = smmu_map_mask;
> > +	}
> > +
> > +	nr_map = size / (sizeof(*cur));
> > +
> > +	lut_index = 0;
> 
> Just initialize it while defining itself.
> 
> > +	for (i = 0; i < nr_map; i++) {
> > +		for (j = 0; j < cur->sid_len; j++) {
> > +			imx_pcie_update_lut(imx_pcie, lut_index, cur->bdf + j, mask,
> > +					    (cur->sid + j) & IMX95_SID_MASK);
> > +			lut_index++;
> > +		}
> > +		cur++;
> > +
> > +		if (lut_index >= IMX95_MAX_LUT) {
> > +			dev_err(dev, "its-map/iommu-map exceed HW limiation\n");
> 
> 'Too many msi-map/iommu-map entries'
> 
> But I think you can just continue to use the allowed entries.
> 
> > +			return -EINVAL;
> > +		}
> > +	}
> > +
> > +	devm_kfree(dev, smmu_map);
> > +	devm_kfree(dev, msi_map);
> 
> Please don't explicitly free the devm_ managed resources unless really needed.
> Else don't use devm_ at all.

It'd better use auto clean up function __free(kfree) here.
> 
> > +
> > +	return 0;
> > +}
> > +
> >  static void imx_pcie_configure_type(struct imx_pcie *imx_pcie)
> >  {
> >  	const struct imx_pcie_drvdata *drvdata = imx_pcie->drvdata;
> > @@ -950,6 +1119,12 @@ static int imx_pcie_host_init(struct dw_pcie_rp *pp)
> >  		goto err_phy_off;
> >  	}
> >  
> > +	ret = imx_pcie_config_sid(imx_pcie);
> > +	if (ret < 0) {
> > +		dev_err(dev, "failed to config sid:%d\n", ret);
> 
> 'Failed to config BDF to SID mapping: %d\n'
> 
> - Mani
> 
> -- 
> மணிவண்ணன் சதாசிவம்