This would follow the convention for subject lines:
PCI: OF: Add of_pci_get_dma_ranges() for inbound DMA restrictions
On Fri, Aug 09, 2019 at 07:34:48PM +0200, marek.va...@gmail.com wrote:
> From: Oza Pawandeep <oza....@broadcom.com>
>
> The patch exports interface to PCIe RC drivers so that,
> Drivers can get their inbound memory configuration.
IIUC this interface (of_pci_get_dma_ranges()) is not used directly by
*drivers*; it is used by of_bus_pci_get_dma_ranges() in the next
patch, and it's called by the driver core via this path:
really_probe
pci_dma_configure # pci_bus_type.dma_configure
of_dma_configure
of_dma_get_range
bus->get_dma_ranges
of_bus_pci_get_dma_ranges # of_busses[0].get_dma_ranges
of_pci_get_dma_ranges
> It provides basis for IOVA reservations for inbound memory
> holes, if RC is not capable of addressing all the host memory,
> Specifically when IOMMU is enabled and on ARMv8 where 64bit IOVA
> could be allocated.
>
> It handles multiple inbound windows, and returns resources,
> and is left to the caller, how it wants to use them.
This should say exactly what the problem is, maybe even with a link to
a problem report. I assume it is something like "RC <X> cannot
address all of host memory, and if we happen to allocate a buffer
that's not addressable, DMA to the buffer fails". It'd be nice to
know what the failure looks like (SERR# asserted, panic, reboot, etc).
> Signed-off-by: Oza Pawandeep <oza....@broadcom.com>
> Signed-off-by: Marek Vasut <marek.vasut+rene...@gmail.com>
> Cc: Arnd Bergmann <a...@arndb.de>
> Cc: Geert Uytterhoeven <geert+rene...@glider.be>
> Cc: Lorenzo Pieralisi <lorenzo.pieral...@arm.com>
> Cc: Robin Murphy <robin.mur...@arm.com>
> Cc: Simon Horman <horms+rene...@verge.net.au>
> Cc: Wolfram Sang <w...@the-dreams.de>
> Cc: linux-renesas-soc@vger.kernel.org
> To: linux-...@vger.kernel.org
> ---
> drivers/pci/of.c | 96 ++++++++++++++++++++++++++++++++++++++++++
> include/linux/of_pci.h | 7 +++
> 2 files changed, 103 insertions(+)
>
> diff --git a/drivers/pci/of.c b/drivers/pci/of.c
> index bc7b27a28795..4018f1a26f6f 100644
> --- a/drivers/pci/of.c
> +++ b/drivers/pci/of.c
> @@ -347,6 +347,102 @@ int devm_of_pci_get_host_bridge_resources(struct device
> *dev,
> return err;
> }
> EXPORT_SYMBOL_GPL(devm_of_pci_get_host_bridge_resources);
> +
> +/**
> + * of_pci_get_dma_ranges - Parse PCI host bridge inbound resources from DT
> + * @np: device node of the host bridge having the dma-ranges property
> + * @resources: list where the range of resources will be added after DT
> parsing
> + *
> + * It is the caller's job to free the @resources list.
> + *
> + * This function will parse the "dma-ranges" property of a
> + * PCI host bridge device node and setup the resource mapping based
> + * on its content.
Rewrap this so it uses the whole width (75-78 columns).
> + * It returns zero if the range parsing has been successful or a standard
> error
> + * value if it failed.
> + */
> +
> +int of_pci_get_dma_ranges(struct device_node *dn, struct list_head
> *resources)
> +{
> + struct device_node *node = of_node_get(dn);
> + int rlen;
> + int pna = of_n_addr_cells(node);
> + const int na = 3, ns = 2;
> + int np = pna + na + ns;
> + int ret = 0;
> + struct resource *res;
> + const u32 *dma_ranges;
> + struct of_pci_range range;
> +
> + if (!node)
> + return -EINVAL;
> +
> + while (1) {
> + dma_ranges = of_get_property(node, "dma-ranges", &rlen);
> +
> + /* Ignore empty ranges, they imply no translation required. */
> + if (dma_ranges && rlen > 0)
> + break;
> +
> + /* no dma-ranges, they imply no translation required. */
Capitalize as you do other comments (s/no/No/).
> + if (!dma_ranges)
> + break;
> +
> + node = of_get_next_parent(node);
> +
> + if (!node)
> + break;
> + }
> +
> + if (!dma_ranges) {
> + pr_debug("pcie device has no dma-ranges defined for node(%s)\n",
This isn't PCIe-specific, so it should say "PCI".
> + dn->full_name);
> + ret = -EINVAL;
> + goto out;
> + }
> +
> + while ((rlen -= np * 4) >= 0) {
> + range.pci_space = be32_to_cpup((const __be32 *) &dma_ranges[0]);
> + range.pci_addr = of_read_number(dma_ranges + 1, ns);
> + range.cpu_addr = of_translate_dma_address(node,
> + dma_ranges + na);
> + range.size = of_read_number(dma_ranges + pna + na, ns);
> + range.flags = IORESOURCE_MEM;
> +
> + dma_ranges += np;
> +
> + /*
> + * 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) {
> + ret = -ENOMEM;
> + goto parse_failed;
> + }
> +
> + ret = of_pci_range_to_resource(&range, dn, res);
> + if (ret) {
> + kfree(res);
> + continue;
> + }
> +
> + pci_add_resource_offset(resources, res,
> + res->start - range.pci_addr);
> + }
> + return ret;
> +
> +parse_failed:
> + pci_free_resource_list(resources);
> +out:
> + of_node_put(node);
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(of_pci_get_dma_ranges);
I don't think this needs to be exported, does it? The only caller I
see (of_bus_pci_get_dma_ranges()) cannot be in a module.
> #endif /* CONFIG_OF_ADDRESS */
>
> #if IS_ENABLED(CONFIG_OF_IRQ)
> diff --git a/include/linux/of_pci.h b/include/linux/of_pci.h
> index 21a89c4880fa..02bff0587dd2 100644
> --- a/include/linux/of_pci.h
> +++ b/include/linux/of_pci.h
> @@ -13,6 +13,7 @@ struct device_node;
> struct device_node *of_pci_find_child_device(struct device_node *parent,
> unsigned int devfn);
> int of_pci_get_devfn(struct device_node *np);
> +int of_pci_get_dma_ranges(struct device_node *np, struct list_head
> *resources);
> void of_pci_check_probe_only(void);
> #else
> static inline struct device_node *of_pci_find_child_device(struct
> device_node *parent,
> @@ -26,6 +27,12 @@ static inline int of_pci_get_devfn(struct device_node *np)
> return -EINVAL;
> }
>
> +static inline int of_pci_get_dma_ranges(struct device_node *np,
> + struct list_head *resources)
> +{
> + return -EINVAL;
> +}
> +
> static inline void of_pci_check_probe_only(void) { }
> #endif
>
> --
> 2.20.1
>
