Re: [PATCH v10 08/10] OF: PCI: Add support for parsing PCI host bridge resources from DT

[Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>]

On Mon, Sep 08, 2014 at 02:54:30PM +0100, Liviu Dudau wrote:
> Provide a function to parse the PCI DT ranges that can be used to
> create a pci_host_bridge structure together with its associated
> bus.
> 
> Cc: Bjorn Helgaas <bhelgaas@google.com>
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: Grant Likely <grant.likely@linaro.org>
> Cc: Rob Herring <robh+dt@kernel.org>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>
> ---
>  drivers/of/of_pci.c    | 102 +++++++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/of_pci.h |  11 ++++++
>  2 files changed, 113 insertions(+)
> 
> diff --git a/drivers/of/of_pci.c b/drivers/of/of_pci.c
> index a107edb..36701da 100644
> --- a/drivers/of/of_pci.c
> +++ b/drivers/of/of_pci.c
> @@ -1,7 +1,9 @@
>  #include <linux/kernel.h>
>  #include <linux/export.h>
>  #include <linux/of.h>
> +#include <linux/of_address.h>
>  #include <linux/of_pci.h>
> +#include <linux/slab.h>
>  
>  static inline int __of_pci_pci_compare(struct device_node *node,
>  				       unsigned int data)
> @@ -123,6 +125,106 @@ int of_pci_get_domain_nr(struct device_node *node, bool allocate_if_missing)
>  }
>  EXPORT_SYMBOL_GPL(of_pci_get_domain_nr);
>  
> +/**
> + * of_pci_get_host_bridge_resources - Parse PCI host bridge resources from DT
> + * @dev: device node of the host bridge having the range property
> + * @busno: bus number associated with the bridge root bus
> + * @bus_max: maximum number of busses for this bridge
> + * @resources: list where the range of resources will be added after DT parsing
> + * @io_base: pointer to a variable that will contain on return the physical
> + * address for the start of the I/O range.
> + *
> + * It is the callers job to free the @resources list.
> + *
> + * This function will parse the "ranges" property of a PCI host bridge device
> + * node and setup the resource mapping based on its content. It is expected
> + * that the property conforms with the Power ePAPR document.

You should also define what it returns and when.

> + *
> + */
> +int of_pci_get_host_bridge_resources(struct device_node *dev,
> +			unsigned char busno, unsigned char bus_max,
> +			struct list_head *resources, resource_size_t *io_base)
> +{
> +	struct resource *res;
> +	struct resource *bus_range;
> +	struct of_pci_range range;
> +	struct of_pci_range_parser parser;
> +	char range_type[4];
> +	int err;
> +
> +	bus_range = kzalloc(sizeof(*bus_range), GFP_KERNEL);
> +	if (!bus_range)
> +		return -ENOMEM;
> +
> +	pr_info("PCI host bridge %s ranges:\n", dev->full_name);
> +
> +	err = of_pci_parse_bus_range(dev, bus_range);
> +	if (err) {
> +		bus_range->start = busno;
> +		bus_range->end = bus_max;
> +		bus_range->flags = IORESOURCE_BUS;
> +		pr_info("  No bus range found for %s, using %pR\n",
> +			dev->full_name, &bus_range);
> +	} else {
> +		if (bus_range->end > bus_range->start + bus_max)
> +			bus_range->end = bus_range->start + bus_max;
> +	}
> +	pci_add_resource(resources, bus_range);

This means that eg in the PCI generic host controller I cannot "filter"
the bus resource, unless I remove it, "filter" it, and add it again.

I certainly can't filter a resource that has been already added without
removing it first.

Thoughts ?

> +
> +	/* Check for ranges property */
> +	err = of_pci_range_parser_init(&parser, dev);
> +	if (err)
> +		goto parse_failed;
> +
> +	pr_debug("Parsing ranges property...\n");
> +	for_each_of_pci_range(&parser, &range) {
> +		/* Read next ranges element */
> +		if ((range.flags & IORESOURCE_TYPE_BITS) == IORESOURCE_IO)
> +			snprintf(range_type, 4, " IO");
> +		else if ((range.flags & IORESOURCE_TYPE_BITS) == IORESOURCE_MEM)
> +			snprintf(range_type, 4, "MEM");
> +		else
> +			snprintf(range_type, 4, "err");
> +		pr_info("  %s %#010llx..%#010llx -> %#010llx\n", range_type,
> +			range.cpu_addr, range.cpu_addr + range.size - 1,
> +			range.pci_addr);
> +
> +		/*
> +		 * If we failed translation or got a zero-sized region
> +		 * then skip this range
> +		 */
> +		if (range.cpu_addr == OF_BAD_ADDR || range.size == 0)
> +			continue;
> +
> +		res = kzalloc(sizeof(struct resource), GFP_KERNEL);
> +		if (!res) {
> +			err = -ENOMEM;
> +			goto parse_failed;
> +		}
> +
> +		err = of_pci_range_to_resource(&range, dev, res);
> +		if (err) {
> +			kfree(res);

You might want to add a label to free res to make things more uniform.

> +			goto parse_failed;
> +		}
> +
> +		if (resource_type(res) == IORESOURCE_IO) {
> +			if (*io_base)

You do not zero io_base in the first place so you should ask the API
user to do that. Is 0 a valid value BTW ? If it is you've got to resort
to something else to detect multiple IO resources.

Lorenzo