Message-ID: <Z1HPs2/PBZY4iq/1@lizhi-Precision-Tower-5810>
Date: Thu, 5 Dec 2024 11:07:15 -0500
From: Frank Li <Frank.li@....com>
To: Lorenzo Pieralisi <lpieralisi@...nel.org>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>, Richard Zhu <hongxing.zhu@....com>,
	Lucas Stach <l.stach@...gutronix.de>,
	Krzysztof Wilczyński <kw@...ux.com>,
	Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
	Rob Herring <robh@...nel.org>, Shawn Guo <shawnguo@...nel.org>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Pengutronix Kernel Team <kernel@...gutronix.de>,
	Fabio Estevam <festevam@...il.com>, linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	imx@...ts.linux.dev, alyssa@...enzweig.io, bpf@...r.kernel.org,
	broonie@...nel.org, jgg@...pe.ca, joro@...tes.org,
	lgirdwood@...il.com, maz@...nel.org, p.zabel@...gutronix.de,
	robin.murphy@....com, will@...nel.org
Subject: Re: [PATCH v7 2/2] PCI: imx6: Add IOMMU and ITS MSI support for
 i.MX95

On Thu, Dec 05, 2024 at 11:25:07AM +0100, Lorenzo Pieralisi wrote:
> On Tue, Dec 03, 2024 at 06:27:16PM -0500, Frank Li wrote:
> > For the i.MX95, configuration of a LUT is necessary to convert Bus Device
> > Function (BDF) to stream IDs, which are utilized by both IOMMU and ITS.
> > This involves examining the msi-map and smmu-map to ensure consistent
>
> This involves checking msi-map and iommu-map device tree properties
> to...
>
> > mapping of PCI BDF to the same stream IDs. Subsequently, LUT-related
> > registers are configured. In the absence of an msi-map, the built-in MSI
> > controller is utilized as a fallback.
> >
> > Register a PCI bus callback function to handle enable_device() and
> > disable_device() operations, setting up the LUT whenever a new PCI device
> > is enabled.
> >
> > Acked-by: Richard Zhu <hongxing.zhu@....com>
> > Signed-off-by: Frank Li <Frank.Li@....com>
> > ---
> > Change from v5 to v6
> > - change comment rid to RID
> > - some mini change according to mani's feedback
> >
> > Change from v4 to v5
> > - rework commt message
> > - add comment for mutex
> > - s/reqid/rid/
> > - keep only one loop when enable lut
> > - add warning when try to add duplicate rid
> > - Replace hardcode 0xffff with IMX95_PE0_LUT_MASK
> > - Fix some error message
> >
> > Change from v3 to v4
> > - Check target value at of_map_id().
> > - of_node_put() for target.
> > - add case for msi-map exist, but rid entry is not exist.
> >
> > Change from v2 to v3
> > - Use the "target" argument of of_map_id()
> > - Check if rid already in lut table when enable device
> >
> > change from v1 to v2
> > - set callback to pci_host_bridge instead pci->ops.
> > ---
> >  drivers/pci/controller/dwc/pci-imx6.c | 183 +++++++++++++++++++++++++++++++++-
> >  1 file changed, 182 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
> > index c8d5c90aa4d45..ac5caa7b05075 100644
> > --- a/drivers/pci/controller/dwc/pci-imx6.c
> > +++ b/drivers/pci/controller/dwc/pci-imx6.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 {
> > @@ -87,6 +103,7 @@ enum imx_pcie_variants {
> >   * workaround suspend resume on some devices which are affected by this errata.
> >   */
> >  #define IMX_PCIE_FLAG_BROKEN_SUSPEND		BIT(9)
> > +#define IMX_PCIE_FLAG_HAS_LUT			BIT(10)
> >
> >  #define imx_check_flag(pci, val)	(pci->drvdata->flags & val)
> >
> > @@ -139,6 +156,9 @@ struct imx_pcie {
> >  	struct device		*pd_pcie_phy;
> >  	struct phy		*phy;
> >  	const struct imx_pcie_drvdata *drvdata;
> > +
> > +	/* Ensure that only one device's LUT is configured at any given time */
> > +	struct mutex		lock;
> >  };
> >
> >  /* Parameters for the waiting for PCIe PHY PLL to lock on i.MX7 */
> > @@ -930,6 +950,159 @@ static void imx_pcie_stop_link(struct dw_pcie *pci)
> >  	imx_pcie_ltssm_disable(dev);
> >  }
> >
> > +static int imx_pcie_add_lut(struct imx_pcie *imx_pcie, u16 rid, u8 sid)
> > +{
> > +	struct dw_pcie *pci = imx_pcie->pci;
> > +	struct device *dev = pci->dev;
> > +	u32 data1, data2;
> > +	int free = -1;
> > +	int i;
> > +
> > +	if (sid >= 64) {
> > +		dev_err(dev, "Invalid SID for index %d\n", sid);
> > +		return -EINVAL;
> > +	}
> > +
> > +	guard(mutex)(&imx_pcie->lock);
> > +
> > +	/*
> > +	 * Iterate through all LUT entries to check for duplicate RID and
> > +	 * identify the first available entry. Configure this available entry
> > +	 * immediately after verification to avoid rescanning it.
> > +	 */
> > +	for (i = 0; i < IMX95_MAX_LUT; i++) {
> > +		regmap_write(imx_pcie->iomuxc_gpr, IMX95_PE0_LUT_ACSCTRL, IMX95_PEO_LUT_RWA | i);
> > +		regmap_read(imx_pcie->iomuxc_gpr, IMX95_PE0_LUT_DATA1, &data1);
> > +
> > +		if (!(data1 & IMX95_PE0_LUT_VLD)) {
> > +			if (free < 0)
> > +				free = i;
> > +			continue;
> > +		}
> > +
> > +		regmap_read(imx_pcie->iomuxc_gpr, IMX95_PE0_LUT_DATA2, &data2);
> > +
> > +		/* Do not add duplicate RID */
> > +		if (rid == FIELD_GET(IMX95_PE0_LUT_REQID, data2)) {
> > +			dev_warn(dev, "Existing LUT entry available for RID (%d)", rid);
> > +			return 0;
> > +		}
> > +	}
> > +
> > +	if (free < 0) {
> > +		dev_err(dev, "LUT entry is not available\n");
> > +		return -ENOSPC;
> > +	}
> > +
> > +	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 = IMX95_PE0_LUT_MASK; /* Match all bits of RID */
> > +	data2 |= FIELD_PREP(IMX95_PE0_LUT_REQID, rid);
> > +	regmap_write(imx_pcie->iomuxc_gpr, IMX95_PE0_LUT_DATA2, data2);
> > +
> > +	regmap_write(imx_pcie->iomuxc_gpr, IMX95_PE0_LUT_ACSCTRL, free);
> > +
> > +	return 0;
> > +}
> > +
> > +static void imx_pcie_remove_lut(struct imx_pcie *imx_pcie, u16 rid)
> > +{
> > +	u32 data2;
> > +	int i;
> > +
> > +	guard(mutex)(&imx_pcie->lock);
> > +
> > +	for (i = 0; i < IMX95_MAX_LUT; i++) {
> > +		regmap_write(imx_pcie->iomuxc_gpr, IMX95_PE0_LUT_ACSCTRL, IMX95_PEO_LUT_RWA | i);
> > +		regmap_read(imx_pcie->iomuxc_gpr, IMX95_PE0_LUT_DATA2, &data2);
> > +		if (FIELD_GET(IMX95_PE0_LUT_REQID, data2) == rid) {
> > +			regmap_write(imx_pcie->iomuxc_gpr, IMX95_PE0_LUT_DATA1, 0);
> > +			regmap_write(imx_pcie->iomuxc_gpr, IMX95_PE0_LUT_DATA2, 0);
> > +			regmap_write(imx_pcie->iomuxc_gpr, IMX95_PE0_LUT_ACSCTRL, i);
> > +
> > +			break;
> > +		}
> > +	}
> > +}
> > +
> > +static int imx_pcie_enable_device(struct pci_host_bridge *bridge, struct pci_dev *pdev)
> > +{
> > +	struct imx_pcie *imx_pcie = to_imx_pcie(to_dw_pcie_from_pp(bridge->sysdata));
> > +	u32 sid_i, sid_m, rid = pci_dev_id(pdev);
> > +	struct device_node *target;
> > +	struct device *dev;
> > +	int err_i, err_m;
> > +
> > +	dev = imx_pcie->pci->dev;
> > +
> > +	target = NULL;
> > +	err_i = of_map_id(dev->of_node, rid, "iommu-map", "iommu-map-mask", &target, &sid_i);
> > +	if (target)
> > +		of_node_put(target);
> > +	else
> > +		err_i = -EINVAL;
>
> Why ? If target == NULL err_i is already set to a negative value ?

When no "iommu-map" exist, target == NULL, but err_i is 0.
See below err_m table.

>
> > +
> > +	target = NULL;
> > +	err_m = of_map_id(dev->of_node, rid, "msi-map", "msi-map-mask", &target, &sid_m);
> > +
> > +	/*
> > +	 * Return failure if msi-map exist and no entry for RID because dwc common
> > +	 * driver will skip setting up built-in MSI controller if msi-map existed.
>
> This is not ideal - to depend on the DWC common driver behaviour.



>
> > +	 *
> > +	 *   err_m      target
> > +	 *	0	NULL		Return failure, function not work.
> > +	 *      !0      NULL		msi-map not exist, use built-in MSI.
> 					^^^^
> "function not work" does not mean anything, sorry. What is it meant to
> say ?

RID is exeed what msi-map'r ranges for example

 RID	MSI   stream ID size
<0x100, &its, 0x8, 	0x1>

If RID is 0x101,  err_m is 0, target is NULL. sid_m will be 0x101, it is
wrong, because max streamID width is 5bits.

So it should return failure for this case.

>
> !=0
>
> > +	 *	0	!NULL		Find one entry.
> > +	 *	!0	!NULL		Invalidate case.
>
> "Find one entry", "Invalidate case", I don't understand what they mean.

Find one entry means get one streamID, as above example, RID = 0x100,
sid will be 0x8.

Invalidate case means never happen, this case doesn't exist.

>
> !=0 !=NULL
>
> > +	 */
> > +	if (!err_m && !target)
> > +		return -EINVAL;
> > +	else if (target)
> > +		of_node_put(target); /* Find entry for RID in msi-map */
> > +
> > +	/*
> > +	 * msi-map        iommu-map
> > +	 *   Y                Y            ITS + SMMU, require the same sid
> > +	 *   Y                N            ITS
> > +	 *   N                Y            DWC MSI Ctrl + SMMU
> > +	 *   N                N            DWC MSI Ctrl
> > +	 */
> > +	if (!err_i && !err_m)
> > +		if ((sid_i & IMX95_SID_MASK) != (sid_m & IMX95_SID_MASK)) {
>
> Here you mask sid_i
>
> > +			dev_err(dev, "iommu-map and msi-map entries mismatch!\n");
> > +			return -EINVAL;
> > +		}
> > +
> > +	/*
> > +	 * Both iommu-map and msi-map not exist, use dwc built-in MSI
> > +	 * controller, do nothing here.
> > +	 */
> > +	if (err_i && err_m)
> > +		return 0;
> > +
> > +	if (!err_i)
> > +		return imx_pcie_add_lut(imx_pcie, rid, sid_i);
>
> Here you don't ?

Okay, only need mask sid_m.

>
> Moreover - this would also cater for the case where (!err_i && !err_m) is
> true ?
>
> Probably cleaner to do:
> 	u32 sid;
>
> 	if (err_i && err_m)
> 		return 0;
>
> 	if (!err_i && !err_m) {
> 		if ((sid_i & IMX95_SID_MASK) != (sid_m & IMX95_SID_MASK)) {
> 			dev_err(dev, "iommu-map and msi-map entries mismatch!\n");
> 			return -EINVAL;
> 		}
> 	}
>
> 	if (!err_i)
> 		sid = sid_i & IMX95_SID_MASK;
> 	else if (!err_m)
> 		sid = sid_m & IMX95_SID_MASK;
>
> 	return imx_pcie_add_lut(imx_pcie, rid, sid);

Okay.

> > +	else if (!err_m)
> > +		/*
> > +		 * Hardware auto add 2 bits controller id ahead of stream ID,
> > +		 * so mask this 2bits to get stream ID.
> > +		 */
> > +		return imx_pcie_add_lut(imx_pcie, rid, sid_m & IMX95_SID_MASK);
> > +
> > +	return 0;
>
> return 0; is dead code AFAICS.
>
> > +}
> > +
> > +static void imx_pcie_disable_device(struct pci_host_bridge *bridge, struct pci_dev *pdev)
> > +{
> > +	struct imx_pcie *imx_pcie;
> > +
> > +	imx_pcie = to_imx_pcie(to_dw_pcie_from_pp(bridge->sysdata));
> > +	imx_pcie_remove_lut(imx_pcie, pci_dev_id(pdev));
> > +}
> > +
> >  static int imx_pcie_host_init(struct dw_pcie_rp *pp)
> >  {
> >  	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> > @@ -946,6 +1119,11 @@ static int imx_pcie_host_init(struct dw_pcie_rp *pp)
> >  		}
> >  	}
> >
> > +	if (pp->bridge && imx_check_flag(imx_pcie, IMX_PCIE_FLAG_HAS_LUT)) {
> > +		pp->bridge->enable_device = imx_pcie_enable_device;
> > +		pp->bridge->disable_device = imx_pcie_disable_device;
> > +	}
> > +
> >  	imx_pcie_assert_core_reset(imx_pcie);
> >
> >  	if (imx_pcie->drvdata->init_phy)
> > @@ -1330,6 +1508,8 @@ static int imx_pcie_probe(struct platform_device *pdev)
> >  	imx_pcie->pci = pci;
> >  	imx_pcie->drvdata = of_device_get_match_data(dev);
> >
> > +	mutex_init(&imx_pcie->lock);
> > +
> >  	/* Find the PHY if one is defined, only imx7d uses it */
> >  	np = of_parse_phandle(node, "fsl,imx7d-pcie-phy", 0);
> >  	if (np) {
> > @@ -1627,7 +1807,8 @@ static const struct imx_pcie_drvdata drvdata[] = {
> >  	},
> >  	[IMX95] = {
> >  		.variant = IMX95,
> > -		.flags = IMX_PCIE_FLAG_HAS_SERDES,
> > +		.flags = IMX_PCIE_FLAG_HAS_SERDES |
> > +			 IMX_PCIE_FLAG_HAS_LUT,
> >  		.clk_names = imx8mq_clks,
> >  		.clks_cnt = ARRAY_SIZE(imx8mq_clks),
> >  		.ltssm_off = IMX95_PE0_GEN_CTRL_3,
> >
> > --
> > 2.34.1
> >

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