How does the kernel determine the resource flags of a device node in a device tree?

I further narrowed down the issue.

My top-level structure is this:

struct test_pcie {

struct platform_device *pdev;

void __iomem *axi_slave_base_1;

void __iomem *axi_slave_base_2;

void __iomem *axi_slave_base_3;

int irq;

u8 root_bus_nr;

struct irq_domain *irq_domain;

struct resource bus_range;

struct list_head resources;

};

When I register the driver, I printed out what resources i.e. list of 'struct resource' it has, and it's types. I wrote a dump() function which lists out the resources.

void dump_resources (struct platform_device *dev)

{

int i;

for (i = 0; i < dev->num_resources; i++) {

struct resource *r = &dev->resource[i];

if (r->name != NULL)

printk("%s: r->name=%s, r->type=%lx\n", __FUNCTION__, r->name, resource_type(r));

}

}

I passed "pointer_to_struct_pcie->pdev" to dump_resources and this is what I got:

[ 17.078754] dump_resources: r->name=axi_slave_1, r->type=0x200

[ 17.084833] dump_resources: r->name=axi_slave_2, r->type=0x200

[ 17.090722] dump_resources: r->name=axi_slave_3, r->type=0x200

[ 17.096531] dump_resources: r->name=/sopc@0/pcie@0x000000000, r->type=0x400

So, in the beginning, the driver has 4 resources, out of which 3 are of IORESOURCE_MEM type (r->type=0x200), and 1 is of IORESOURCE_BUS type (r->type=0x400).

The 3 IORESOURCE_MEM type resources i.e. axi_slave_1, axi_slave_2, axi_slave_3 are listed under the device node of "/sopc@0/pcie@0x000000000" (IORESOURCE_BUS type) as can be evidenced from the DTS file.

The problem comes when I try to parse the ranges inside the "/sopc@0/pcie@0x000000000" device node, with the call to altera_pcie_parse_request_of_pci_ranges() which calls of_pci_get_host_bridge_resources(np, 0, 0xff, &pcie->resources, NULL), and then loops each of the pcie->resources obtained until it hits a IORESOURCE_MEM type resource. In the loop, I printed out each resource name in the list, but I found that it has ONLY one resource in the list:

resource_list_for_each_entry(win, &pcie->resources) {

struct resource *parent, *res = win->res;

printk("resource: name=%s, flags=0x%lx\n", res->name, res->flags);

switch (resource_type(res)) {

case IORESOURCE_MEM:

parent = &iomem_resource;

res_valid |= !(res->flags & IORESOURCE_PREFETCH);

printk("res_valid = %d\n", res_valid);

break;

default:

continue;

}

if (!res_valid) {

dev_err(dev, "non-prefetchable memory resource required\n");

err = -EINVAL;

goto out_release_res;

}

The output I got was:

[ 17.183229] resource: name=pcie, flags=0x1000

This resource "pcie" is nothing but the device node that encapsulates the sub-resources under it viz. axi_slave_1, axi_slave_2, axi_slave_3. The flags 0x1000 show the "pcie" device node as IORESOURCE_BUS type, so it doesn't fall into "case IORESOURCE_MEM" but rather into "case default" and exits. This clearly shows that axi_slave_1, axi_slave_2, axi_slave_3 are not part of "pcie->resources" list. While the device node seems to have been mapped, the sub-resources under it seem to have been not mapped.

So, I feel I need to dig into of_pci_get_host_bridge_resources(np, 0, 0xff, &pcie->resources, NULL) and check why pcie->resources contains only one resource i.e the top-level "pcie" device node, but not the sub-resources under it. But in the beginning, when I register the driver, I could see the top-level resource as well as it's sub-resources, as given in the prints above.

If someone has got clue already as to what might have gone wrong or what is needed to be done, please answer.