Re: [PATCH RFC V2 3/3] PCI: Add basic properties for dynamically generated PCI OF node

[Lizhi Hou <lizhi.hou@xxxxxxx>]

On 10/26/22 12:39, Rob Herring wrote:
> On Wed, Oct 12, 2022 at 11:14:00AM -0700, Lizhi Hou wrote:
> > This patch addes 'reg', 'compatible' and 'device_typ' properties for
> typo
>
> Please read submitting-patches.rst and what it says about 'This patch'.
Sure. And I will merge patch 2 and 3.
> > dynamically generated PCI device tree node
> >
> > Signed-off-by: Lizhi Hou <lizhi.hou@xxxxxxx>
> > Signed-off-by: Sonal Santan <sonal.santan@xxxxxxx>
> > Signed-off-by: Max Zhen <max.zhen@xxxxxxx>
> > Signed-off-by: Brian Xu <brian.xu@xxxxxxx>
> > ---
> >   drivers/pci/Makefile      |   1 +
> >   drivers/pci/of.c          |  10 ++-
> >   drivers/pci/of_property.c | 177 ++++++++++++++++++++++++++++++++++++++
> I don't think we need a separate file here and patches 2 and 3 should be
> combined. Patch 2 alone doesn't really make sense.
>
>
> >   drivers/pci/pci.h         |   3 +-
> >   4 files changed, 189 insertions(+), 2 deletions(-)
> >   create mode 100644 drivers/pci/of_property.c
> >
> > diff --git a/drivers/pci/Makefile b/drivers/pci/Makefile
> > index 2680e4c92f0a..cc8b4e01e29d 100644
> > --- a/drivers/pci/Makefile
> > +++ b/drivers/pci/Makefile
> > @@ -32,6 +32,7 @@ obj-$(CONFIG_PCI_P2PDMA)	+= p2pdma.o
> >   obj-$(CONFIG_XEN_PCIDEV_FRONTEND) += xen-pcifront.o
> >   obj-$(CONFIG_VGA_ARB)		+= vgaarb.o
> >   obj-$(CONFIG_PCI_DOE)		+= doe.o
> > +obj-$(CONFIG_PCI_DYNAMIC_OF_NODES) += of_property.o
> >   
> >   # Endpoint library must be initialized before its users
> >   obj-$(CONFIG_PCI_ENDPOINT)	+= endpoint/
> > diff --git a/drivers/pci/of.c b/drivers/pci/of.c
> > index 83e042f495a6..00d716589660 100644
> > --- a/drivers/pci/of.c
> > +++ b/drivers/pci/of.c
> > @@ -619,6 +619,7 @@ void of_pci_make_dev_node(struct pci_dev *pdev)
> >   {
> >   	struct device_node *parent, *dt_node;
> >   	const char *pci_type = "dev";
> > +	struct property *props;
> >   	char *full_name;
> >   
> >   	/*
> > @@ -645,10 +646,15 @@ void of_pci_make_dev_node(struct pci_dev *pdev)
> >   	if (!full_name)
> >   		goto failed;
> >   
> > -	dt_node = of_create_node(parent, full_name, NULL);
> > +	props = of_pci_props_create(pdev);
> > +	if (!props)
> > +		goto failed;
> > +
> > +	dt_node = of_create_node(parent, full_name, props);
> >   	if (!dt_node)
> >   		goto failed;
> >   
> > +	of_pci_props_destroy(props);
> >   	kfree(full_name);
> >   
> >   	pdev->dev.of_node = dt_node;
> > @@ -656,6 +662,8 @@ void of_pci_make_dev_node(struct pci_dev *pdev)
> >   	return;
> >   
> >   failed:
> > +	if (props)
> > +		of_pci_props_destroy(props);
> >   	kfree(full_name);
> >   }
> >   #endif
> > diff --git a/drivers/pci/of_property.c b/drivers/pci/of_property.c
> > new file mode 100644
> > index 000000000000..693a08323aa4
> > --- /dev/null
> > +++ b/drivers/pci/of_property.c
> > @@ -0,0 +1,177 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +/*
> > + * Copyright (C) 2022, Advanced Micro Devices, Inc.
> > + */
> > +
> > +#include <linux/pci.h>
> > +#include <linux/of.h>
> > +#include <linux/bitfield.h>
> > +#include <linux/bits.h>
> > +
> > +struct of_pci_prop {
> > +	char *name;
> > +	int (*prop_val)(struct pci_dev *pdev, void **val, u32 *len);
> > +};
> > +
> > +struct of_pci_addr_pair {
> > +	__be32		phys_hi;
> > +	__be32		phys_mid;
> > +	__be32		phys_lo;
> > +	__be32		size_hi;
> > +	__be32		size_lo;
> > +};
> > +
> > +#define OF_PCI_ADDR_SPACE_CONFIG	0x0
> > +#define OF_PCI_ADDR_SPACE_IO		0x1
> > +#define OF_PCI_ADDR_SPACE_MEM32		0x2
> > +#define OF_PCI_ADDR_SPACE_MEM64		0x3
> > +
> > +#define OF_PCI_ADDR_FIELD_SS		GENMASK(25, 24)
> > +#define OF_PCI_ADDR_FIELD_PREFETCH	BIT(30)
> > +#define OF_PCI_ADDR_FIELD_BUS		GENMASK(23, 16)
> > +#define OF_PCI_ADDR_FIELD_DEV		GENMASK(15, 11)
> > +#define OF_PCI_ADDR_FIELD_FUNC		GENMASK(10, 8)
> > +#define OF_PCI_ADDR_FIELD_REG		GENMASK(7, 0)
> > +
> > +#define OF_PCI_SIZE_HI			GENMASK_ULL(63, 32)
> > +#define OF_PCI_SIZE_LO			GENMASK_ULL(31, 0)
> > +
> > +#define OF_PCI_PROP_COMPAT_LEN_MAX	256
> > +static int of_pci_prop_device_type(struct pci_dev *pdev, void **val, u32 *len)
> > +{
> > +	if (!pci_is_bridge(pdev))
> > +		return 0;
> > +
> > +	*val = kasprintf(GFP_KERNEL, "pci");
> > +	if (!*val)
> > +		return -ENOMEM;
> > +
> > +	*len = strlen(*val) + 1;
> > +
> > +	return 0;
> > +}
> > +
> > +static int of_pci_prop_reg(struct pci_dev *pdev, void **val, u32 *len)
> > +{
> > +	struct of_pci_addr_pair *reg;
> > +	u32 reg_val, base_addr, ss;
> > +	resource_size_t sz;
> > +	int i = 1, resno;
> > +
> > +	reg = kzalloc(sizeof(*reg) * (PCI_STD_NUM_BARS + 1), GFP_KERNEL);
> > +	if (!reg)
> > +		return -ENOMEM;
> > +
> > +	reg_val = FIELD_PREP(OF_PCI_ADDR_FIELD_SS, OF_PCI_ADDR_SPACE_CONFIG) |
> > +		FIELD_PREP(OF_PCI_ADDR_FIELD_BUS, pdev->bus->number) |
> > +		FIELD_PREP(OF_PCI_ADDR_FIELD_DEV, PCI_SLOT(pdev->devfn)) |
> > +		FIELD_PREP(OF_PCI_ADDR_FIELD_FUNC, PCI_FUNC(pdev->devfn));
> > +	reg[0].phys_hi = cpu_to_be32(reg_val);
> > +
> > +	base_addr = PCI_BASE_ADDRESS_0;
> > +	for (resno = PCI_STD_RESOURCES; resno <= PCI_STD_RESOURCE_END;
> > +	     resno++, base_addr += 4) {
> > +		sz = pci_resource_len(pdev, resno);
> > +		if (!sz)
> > +			continue;
> > +
> > +		if (pci_resource_flags(pdev, resno) & IORESOURCE_IO)
> > +			ss = OF_PCI_ADDR_SPACE_IO;
> > +		else if (pci_resource_flags(pdev, resno) & IORESOURCE_MEM_64)
> > +			ss = OF_PCI_ADDR_SPACE_MEM64;
> > +		else
> > +			ss = OF_PCI_ADDR_SPACE_MEM32;
> > +
> > +		reg_val &= ~(OF_PCI_ADDR_FIELD_SS | OF_PCI_ADDR_FIELD_PREFETCH |
> > +				OF_PCI_ADDR_FIELD_REG);
> > +		reg_val |= FIELD_PREP(OF_PCI_ADDR_FIELD_SS, ss) |
> > +			FIELD_PREP(OF_PCI_ADDR_FIELD_REG, base_addr);
> > +		if (pci_resource_flags(pdev, resno) & IORESOURCE_PREFETCH)
> > +			reg_val |= OF_PCI_ADDR_FIELD_PREFETCH;
> > +		reg[i].phys_hi = cpu_to_be32(reg_val);
> > +		reg[i].size_hi = cpu_to_be32(FIELD_GET(OF_PCI_SIZE_HI, sz));
> > +		reg[i].size_lo = cpu_to_be32(FIELD_GET(OF_PCI_SIZE_LO, sz));
> > +		i++;
> > +	}
> > +
> > +	*val = reg;
> > +	*len = i * sizeof(*reg);
> > +
> > +	return 0;
> > +}
> > +
> > +static int of_pci_prop_compatible(struct pci_dev *pdev, void **val, u32 *len)
> > +{
> > +	char *compat;
> > +
> > +	compat = kzalloc(OF_PCI_PROP_COMPAT_LEN_MAX, GFP_KERNEL);
> The size here looks pretty arbitrary yet we should be able to calculate
> the worst case.
I will remove this.
> > +	if (!compat)
> > +		return -ENOMEM;
> > +
> > +	*val = compat;
> > +	if (pdev->subsystem_vendor) {
> > +		compat += sprintf(compat, "pci%x,%x.%x.%x.%x",
> > +				  pdev->vendor, pdev->device,
> > +				  pdev->subsystem_vendor,
> > +				  pdev->subsystem_device,
> > +				  pdev->revision) + 1;
> > +		compat += sprintf(compat, "pci%x,%x.%x.%x",
> > +				  pdev->vendor, pdev->device,
> > +				  pdev->subsystem_vendor,
> > +				  pdev->subsystem_device) + 1;
> > +		compat += sprintf(compat, "pci%x,%x",
> > +				  pdev->subsystem_vendor,
> > +				  pdev->subsystem_device) + 1;
> > +	}
> > +	compat += sprintf(compat, "pci%x,%x.%x",
> > +			  pdev->vendor, pdev->device, pdev->revision) + 1;
> > +	compat += sprintf(compat, "pci%x,%x", pdev->vendor, pdev->device) + 1;
> > +	compat += sprintf(compat, "pciclass,%06x", pdev->class) + 1;
> > +	compat += sprintf(compat, "pciclass,%04x", pdev->class >> 8) + 1;
> No checking/preventing overrunning the compat buffer?
>
> I don't think we need all these compatible strings. One with VID/PID and
> one with the class should be sufficient. But I'm not sure offhand what
> subsystem_vendor/device device is...
Ok. I will keep pci%x,%x, pciclass,%06x, pciclass,%04x.
> > +
> > +	*len = (u32)(compat - (char *)*val);
> > +
> > +	return 0;
> > +}
> > +
> > +struct of_pci_prop of_pci_props[] = {
> > +	{ .name = "device_type", .prop_val = of_pci_prop_device_type },
> This only only applies to bridge nodes.

In of_pci_prop_device_type, it returns immediately for pci endpoint.

To make it obvious, I will separate bridge and endpoint property arrays.

> > +	{ .name = "reg", .prop_val = of_pci_prop_reg },
> > +	{ .name = "compatible", .prop_val = of_pci_prop_compatible },
> > +	{},
> > +};
> > +
> > +struct property *of_pci_props_create(struct pci_dev *pdev)
> > +{
> > +	struct property *props, *pp;
> > +	void *val;
> > +	u32 len;
> > +	int i;
> > +
> > +	props = kcalloc(ARRAY_SIZE(of_pci_props), sizeof(*props), GFP_KERNEL);
> > +	if (!props)
> > +		return NULL;
> > +
> > +	pp = props;
> > +	for (i = 0; of_pci_props[i].name; i++) {
> > +		len = 0;
> > +		of_pci_props[i].prop_val(pdev, &val, &len);
> > +		if (!len)
> > +			continue;
> > +		props->name = of_pci_props[i].name;
> > +		props->value = val;
> > +		props->length = len;
> > +		props++;
> This creates an array of properties and then copies each one, and it
> also exposes the internals of 'struct property' which we want to make
> opaque. Neither of these is great.
>
> I'd rather see the of_changeset API expanded to handle specific types of
> properties. Something like this:
>
> of_changeset_add_prop_string(cset, node, "device_type", "pci");
> of_changeset_add_prop_string_array(cset, node, "compatible", compats, cnt);
> of_changeset_add_prop_u32_array(cset, node, "reg", reg, cnt);
>
> And perhaps these functions just wrap similar non-changeset functions
> that produce a struct property.
>
> IOW, it should be similar to the of_property_read_* APIs, but to
> set/add rather than get.
Okay. I will add above 3 APIs and use them to create properties.
> You are also missing 'ranges', '#address-cells, and '#size-cells' in
> bridge nodes.

I will add them. Do you have more in mind that I need to add with this 
patch?


Thanks,

Lizhi

> Rob