On Fri, Mar 04, 2022 at 09:23:01PM -0800, Lizhi Hou wrote:
> This patch enables PCIe device to uses flattened device tree to describe
> apertures in its PCIe BARs. The aperture address consists of PCIe BAR index
> and offset.
>
> For this kind of device, the driver probe routine calls the new added
> interface to create a device tree node. This device tree node is attached
> under system device tree root. Then the driver may load the flatten device
> tree overlay and attach it under this node. And the node also contains
> 'ranges' property which is used to translate aperture address(BAR index
> and offset) to CPU address.
>
This is the devicetree support for the PCI endpoint subsystem. Hence, the
code should live under drivers/pci/endpoint/.
But let's first settle on the structure of the devicetree binding first.
Thanks,
Mani
> Signed-off-by: Sonal Santan <sonal.santan@xxxxxxxxxx>
> Signed-off-by: Max Zhen <max.zhen@xxxxxxxxxx>
> Signed-off-by: Lizhi Hou <lizhi.hou@xxxxxxxxxx>
> ---
> drivers/pci/of.c | 180 +++++++++++++++++++++++++++++++++++++++++
> include/linux/of_pci.h | 15 ++++
> 2 files changed, 195 insertions(+)
>
> diff --git a/drivers/pci/of.c b/drivers/pci/of.c
> index cb2e8351c2cc..198f08351070 100644
> --- a/drivers/pci/of.c
> +++ b/drivers/pci/of.c
> @@ -605,6 +605,186 @@ int devm_of_pci_bridge_init(struct device *dev, struct pci_host_bridge *bridge)
> return pci_parse_request_of_pci_ranges(dev, bridge);
> }
>
> +#if IS_ENABLED(CONFIG_OF_DYNAMIC)
> +
> +static void devm_of_pci_destroy_bus_endpoint(struct device *dev, void *res)
> +{
> + struct device_node *node = res;
> +
> + of_detach_node(node);
> +}
> +
> +static int of_ep_add_property(struct device *dev, struct property **proplist, const char *name,
> + const int length, void *value)
> +{
> + struct property *new;
> +
> + new = devm_kzalloc(dev, sizeof(*new), GFP_KERNEL);
> + if (!new)
> + return -ENOMEM;
> +
> + new->name = devm_kstrdup(dev, name, GFP_KERNEL);
> + if (!new->name)
> + return -ENOMEM;
> +
> + new->value = devm_kmalloc(dev, length, GFP_KERNEL);
> + if (!new->value)
> + return -ENOMEM;
> +
> + memcpy(new->value, value, length);
> + new->length = length;
> + new->next = *proplist;
> + *proplist = new;
> +
> + return 0;
> +}
> +
> +static struct device_node *of_ep_alloc_node(struct pci_dev *pdev, const char *name)
> +{
> + struct device_node *node;
> + char *full_name;
> +
> + node = devres_alloc(devm_of_pci_destroy_bus_endpoint, sizeof(*node), GFP_KERNEL);
> + if (!node)
> + return NULL;
> +
> + full_name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "/%s@%llx", name,
> + (u64)pci_resource_start(pdev, 0));
> + if (!full_name)
> + return NULL;
> +
> + node->parent = of_root;
> + node->full_name = full_name;
> + of_node_set_flag(node, OF_DYNAMIC);
> + of_node_init(node);
> +
> + return node;
> +}
> +
> +/**
> + * devm_of_pci_create_bus_endpoint - Create a device node for the given pci device.
> + * @pdev: PCI device pointer.
> + *
> + * For PCI device which uses flattened device tree to describe apertures in its BARs,
> + * a device node for the given pci device is required. Then the flattened device tree
> + * overlay from the device can be applied to the base tree.
> + * The device node is under root node and act like bus node. It contains a "ranges"
> + * property which is used for address translation of its children. Each child node
> + * corresponds an aperture and use BAR index and offset as its address.
> +
> + * Returns 0 on success or a negative error-code on failure.
> + */
> +int devm_of_pci_create_bus_endpoint(struct pci_dev *pdev)
> +{
> + struct property *proplist = NULL;
> + struct device *dev = &pdev->dev;
> + int range_ncells, addr_ncells;
> + struct device_node *node;
> + void *prop = NULL;
> + u32 *range_cell;
> + __be32 val;
> + int i, ret;
> +
> + node = of_ep_alloc_node(pdev, "pci-ep-bus");
> + if (!node)
> + return -ENOMEM;
> +
> + /* the endpoint node works as 'simple-bus' to translate aperture addresses. */
> + prop = "simple-bus";
> + ret = of_ep_add_property(dev, &proplist, "compatible", strlen(prop) + 1, prop);
> + if (ret)
> + goto cleanup;
> +
> + /* The address and size cells of nodes underneath are 2 */
> + val = cpu_to_be32(2);
> + ret = of_ep_add_property(dev, &proplist, "#address-cells", sizeof(u32), &val);
> + if (ret)
> + goto cleanup;
> +
> + ret = of_ep_add_property(dev, &proplist, "#size-cells", sizeof(u32), &val);
> + if (ret)
> + goto cleanup;
> +
> + /* child address format: 0xIooooooo oooooooo, I = bar index, o = offset on bar */
> + addr_ncells = of_n_addr_cells(node);
> + if (addr_ncells > 2) {
> + /* does not support number of address cells greater than 2 */
> + ret = -EINVAL;
> + goto cleanup;
> + }
> +
> + /* range cells include <node addr cells> <child addr cells> <child size cells> */
> + range_ncells = addr_ncells + 4;
> + prop = kzalloc(range_ncells * sizeof(u32) * PCI_STD_NUM_BARS, GFP_KERNEL);
> + if (!prop) {
> + ret = -ENOMEM;
> + goto cleanup;
> + }
> +
> + range_cell = prop;
> + for (i = 0; i < PCI_STD_NUM_BARS; i++) {
> + if (!pci_resource_len(pdev, i))
> + continue;
> + /* highest 4 bits of address are bar index */
> + *(__be64 *)range_cell = cpu_to_be64((u64)i << 60);
> + range_cell += 2;
> + if (addr_ncells == 2)
> + *(__be64 *)range_cell = cpu_to_be64((u64)pci_resource_start(pdev, i));
> + else
> + *(__be32 *)range_cell = cpu_to_be32((u32)pci_resource_start(pdev, i));
> +
> + range_cell += addr_ncells;
> + *(__be64 *)range_cell = cpu_to_be64((u64)pci_resource_len(pdev, i));
> + range_cell += 2;
> + }
> +
> + /* error out if there is not PCI BAR been found */
> + if ((void *)range_cell == prop) {
> + ret = -EINVAL;
> + goto cleanup;
> + }
> +
> + ret = of_ep_add_property(dev, &proplist, "ranges", (void *)range_cell - prop, prop);
> + kfree(prop);
> + if (ret)
> + goto cleanup;
> +
> + node->properties = proplist;
> + ret = of_attach_node(node);
> + if (ret)
> + goto cleanup;
> +
> + devres_add(dev, node);
> +
> + return 0;
> +
> +cleanup:
> + kfree(prop);
> + if (node)
> + devres_free(node);
> +
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(devm_of_pci_create_bus_endpoint);
> +
> +struct device_node *of_pci_find_bus_endpoint(struct pci_dev *pdev)
> +{
> + struct device_node *dn;
> + char *path;
> +
> + path = kasprintf(GFP_KERNEL, "/pci-ep-bus@%llx",
> + (u64)pci_resource_start(pdev, 0));
> + if (!path)
> + return NULL;
> +
> + dn = of_find_node_by_path(path);
> + kfree(path);
> +
> + return dn;
> +}
> +EXPORT_SYMBOL_GPL(of_pci_find_bus_endpoint);
> +#endif /* CONFIG_OF_DYNAMIC */
> +
> #endif /* CONFIG_PCI */
>
> /**
> diff --git a/include/linux/of_pci.h b/include/linux/of_pci.h
> index 29658c0ee71f..c1d86be321b2 100644
> --- a/include/linux/of_pci.h
> +++ b/include/linux/of_pci.h
> @@ -38,4 +38,19 @@ of_irq_parse_and_map_pci(const struct pci_dev *dev, u8 slot, u8 pin)
> }
> #endif
>
> +#if IS_ENABLED(CONFIG_OF_DYNAMIC) && IS_ENABLED(CONFIG_PCI)
> +int devm_of_pci_create_bus_endpoint(struct pci_dev *pdev);
> +struct device_node *of_pci_find_bus_endpoint(struct pci_dev *pdev);
> +#else
> +static inline int devm_of_pci_create_bus_endpoint(struct pci_dev *pdev)
> +{
> + return -EINVAL;
> +}
> +
> +static inline struct device_node *of_pci_find_bus_endpoint(struct pci_dev *pdev)
> +{
> + return NULL;
> +}
> +#endif
> +
> #endif
> --
> 2.27.0
>
--
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