[RFC PATCH] of: Fix DMA configuration for non-DT masters
Oza Oza
oza.oza at broadcom.com
Tue Mar 28 22:46:20 PDT 2017
On Wed, Mar 29, 2017 at 10:23 AM, Oza Oza <oza.oza at broadcom.com> wrote:
> On Wed, Mar 29, 2017 at 12:27 AM, Robin Murphy <robin.murphy at arm.com> wrote:
>> For PCI masters not represented in DT, we pass the OF node of their
>> associated host bridge to of_dma_configure(), such that they can inherit
>> the appropriate DMA configuration from whatever is described there.
>> Unfortunately, whilst this has worked for the "dma-coherent" property,
>> it turns out to miss the case where the host bridge node has a non-empty
>> "dma-ranges", since nobody is expecting the 'device' to be a bus itself.
>>
>> It transpires, though, that the de-facto interface since the prototype
>> change in 1f5c69aa51f9 ("of: Move of_dma_configure() to device.c to help
>> re-use") is very clear-cut: either the master_np argument is redundant
>> with dev->of_node, or dev->of_node is NULL and master_np is the relevant
>> parent bus. Let's ratify that behaviour, then teach the whole
>> of_dma_configure() pipeline to cope with both cases properly.
>>
>> Signed-off-by: Robin Murphy <robin.murphy at arm.com>
>> ---
>>
>> This is what I'd consider the better fix - rather than adding yet more
>> special cases - which will also make it simple to handle multiple
>> "dma-ranges" entries with minimal further disruption. The callers now
>> left passing dev->of_node as 'parent' are harmless, but look a bit silly
>> and clearly want cleaning up - I'd be partial to renaming the existing
>> function and having a single-argument wrapper for the 'normal' case, e.g.:
>>
>> static inline int of_dma_configure(struct device_node *dev)
>> {
>> return of_dma_configure_parent(dev, NULL);
>> }
>>
>> Thoughts?
>>
>> Robin.
>>
>> drivers/iommu/of_iommu.c | 7 ++++---
>> drivers/of/address.c | 37 +++++++++++++++++++++++++------------
>> drivers/of/device.c | 12 +++++++-----
>> include/linux/of_address.h | 7 ++++---
>> include/linux/of_device.h | 4 ++--
>> include/linux/of_iommu.h | 4 ++--
>> 6 files changed, 44 insertions(+), 27 deletions(-)
>>
>> diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c
>> index 2683e9fc0dcf..35aff07bb5eb 100644
>> --- a/drivers/iommu/of_iommu.c
>> +++ b/drivers/iommu/of_iommu.c
>> @@ -138,21 +138,22 @@ static const struct iommu_ops
>> }
>>
>> const struct iommu_ops *of_iommu_configure(struct device *dev,
>> - struct device_node *master_np)
>> + struct device_node *parent)
>> {
>> struct of_phandle_args iommu_spec;
>> - struct device_node *np;
>> + struct device_node *np, *master_np;
>> const struct iommu_ops *ops = NULL;
>> int idx = 0;
>>
>> if (dev_is_pci(dev))
>> - return of_pci_iommu_configure(to_pci_dev(dev), master_np);
>> + return of_pci_iommu_configure(to_pci_dev(dev), parent);
>>
>> /*
>> * We don't currently walk up the tree looking for a parent IOMMU.
>> * See the `Notes:' section of
>> * Documentation/devicetree/bindings/iommu/iommu.txt
>> */
>> + master_np = dev->of_node ? dev->of_node : parent;
>> while (!of_parse_phandle_with_args(master_np, "iommus",
>> "#iommu-cells", idx,
>> &iommu_spec)) {
>> diff --git a/drivers/of/address.c b/drivers/of/address.c
>> index 02b2903fe9d2..833bc17f5e55 100644
>> --- a/drivers/of/address.c
>> +++ b/drivers/of/address.c
>> @@ -808,6 +808,7 @@ EXPORT_SYMBOL(of_io_request_and_map);
>> /**
>> * of_dma_get_range - Get DMA range info
>> * @np: device node to get DMA range info
>> + * @parent: node of device's parent bus, if @np is NULL
>> * @dma_addr: pointer to store initial DMA address of DMA range
>> * @paddr: pointer to store initial CPU address of DMA range
>> * @size: pointer to store size of DMA range
>> @@ -822,36 +823,48 @@ EXPORT_SYMBOL(of_io_request_and_map);
>> * It returns -ENODEV if "dma-ranges" property was not found
>> * for this device in DT.
>> */
>> -int of_dma_get_range(struct device_node *np, u64 *dma_addr, u64 *paddr, u64 *size)
>> +int of_dma_get_range(struct device_node *np, struct device_node *parent,
>> + u64 *dma_addr, u64 *paddr, u64 *size)
>> {
>> - struct device_node *node = of_node_get(np);
>> + struct device_node *node;
>> const __be32 *ranges = NULL;
>> int len, naddr, nsize, pna;
>> int ret = 0;
>> u64 dmaaddr;
>>
>> - if (!node)
>> - return -EINVAL;
>> -
>> - while (1) {
>> + if (np) {
>> + node = of_node_get(np);
>> naddr = of_n_addr_cells(node);
>> nsize = of_n_size_cells(node);
>> node = of_get_next_parent(node);
>> - if (!node)
>> - break;
>> + } else if (parent) {
>> + node = of_node_get(parent);
>> + np = parent;
>> + if (of_property_read_u32(node, "#address-cells", &naddr))
>> + naddr = of_n_addr_cells(node);
>> + if (of_property_read_u32(node, "#size-cells", &nsize))
>> + nsize = of_n_size_cells(node);
>> + } else {
>> + return -EINVAL;
>> + }
>>
>> + while (node) {
>> ranges = of_get_property(node, "dma-ranges", &len);
>>
>> - /* Ignore empty ranges, they imply no translation required */
>> - if (ranges && len > 0)
>> - break;
>> -
>> /*
>> * At least empty ranges has to be defined for parent node if
>> * DMA is supported
>> */
>> if (!ranges)
>> break;
>> +
>> + /* Ignore empty ranges, they imply no translation required */
>> + if (len > 0)
>> + break;
>> +
>> + naddr = of_n_addr_cells(node);
>> + nsize = of_n_size_cells(node);
>> + node = of_get_next_parent(node);
>> }
>>
>> if (!ranges) {
>> diff --git a/drivers/of/device.c b/drivers/of/device.c
>> index 9bb8518b28f2..57ec5324ed6c 100644
>> --- a/drivers/of/device.c
>> +++ b/drivers/of/device.c
>> @@ -73,7 +73,8 @@ int of_device_add(struct platform_device *ofdev)
>> /**
>> * of_dma_configure - Setup DMA configuration
>> * @dev: Device to apply DMA configuration
>> - * @np: Pointer to OF node having DMA configuration
>> + * @parent: OF node of device's parent bus, if @dev is not
>> + * represented in DT (i.e. @dev->of_node is NULL)
>> *
>> * Try to get devices's DMA configuration from DT and update it
>> * accordingly.
>> @@ -82,13 +83,14 @@ int of_device_add(struct platform_device *ofdev)
>> * can use a platform bus notifier and handle BUS_NOTIFY_ADD_DEVICE events
>> * to fix up DMA configuration.
>> */
>> -void of_dma_configure(struct device *dev, struct device_node *np)
>> +void of_dma_configure(struct device *dev, struct device_node *parent)
>> {
>> u64 dma_addr, paddr, size;
>> int ret;
>> bool coherent;
>> unsigned long offset;
>> const struct iommu_ops *iommu;
>> + struct device_node *np = dev->of_node;
>>
>> /*
>> * Set default coherent_dma_mask to 32 bit. Drivers are expected to
>> @@ -104,7 +106,7 @@ void of_dma_configure(struct device *dev, struct device_node *np)
>> if (!dev->dma_mask)
>> dev->dma_mask = &dev->coherent_dma_mask;
>>
>> - ret = of_dma_get_range(np, &dma_addr, &paddr, &size);
>> + ret = of_dma_get_range(np, parent, &dma_addr, &paddr, &size);
>> if (ret < 0) {
>> dma_addr = offset = 0;
>> size = dev->coherent_dma_mask + 1;
>> @@ -132,11 +134,11 @@ void of_dma_configure(struct device *dev, struct device_node *np)
>> dev->coherent_dma_mask = DMA_BIT_MASK(ilog2(dma_addr + size));
>> *dev->dma_mask = dev->coherent_dma_mask;
>>
>> - coherent = of_dma_is_coherent(np);
>> + coherent = of_dma_is_coherent(np ? np : parent);
>> dev_dbg(dev, "device is%sdma coherent\n",
>> coherent ? " " : " not ");
>>
>> - iommu = of_iommu_configure(dev, np);
>> + iommu = of_iommu_configure(dev, parent);
>> dev_dbg(dev, "device is%sbehind an iommu\n",
>> iommu ? " " : " not ");
>>
>> diff --git a/include/linux/of_address.h b/include/linux/of_address.h
>> index 37864734ca50..f1a507f3ae57 100644
>> --- a/include/linux/of_address.h
>> +++ b/include/linux/of_address.h
>> @@ -52,8 +52,8 @@ extern int of_pci_range_parser_init(struct of_pci_range_parser *parser,
>> extern struct of_pci_range *of_pci_range_parser_one(
>> struct of_pci_range_parser *parser,
>> struct of_pci_range *range);
>> -extern int of_dma_get_range(struct device_node *np, u64 *dma_addr,
>> - u64 *paddr, u64 *size);
>> +extern int of_dma_get_range(struct device_node *np, struct device_node *parent,
>> + u64 *dma_addr, u64 *paddr, u64 *size);
>> extern bool of_dma_is_coherent(struct device_node *np);
>> #else /* CONFIG_OF_ADDRESS */
>> static inline void __iomem *of_io_request_and_map(struct device_node *device,
>> @@ -95,7 +95,8 @@ static inline struct of_pci_range *of_pci_range_parser_one(
>> return NULL;
>> }
>>
>> -static inline int of_dma_get_range(struct device_node *np, u64 *dma_addr,
>> +static inline int of_dma_get_range(struct device_node *np,
>> + struct device_node *parent, u64 *dma_addr,
>> u64 *paddr, u64 *size)
>> {
>> return -ENODEV;
>> diff --git a/include/linux/of_device.h b/include/linux/of_device.h
>> index c12dace043f3..bcd2b6fbeef3 100644
>> --- a/include/linux/of_device.h
>> +++ b/include/linux/of_device.h
>> @@ -55,7 +55,7 @@ static inline struct device_node *of_cpu_device_node_get(int cpu)
>> return of_node_get(cpu_dev->of_node);
>> }
>>
>> -void of_dma_configure(struct device *dev, struct device_node *np);
>> +void of_dma_configure(struct device *dev, struct device_node *parent);
>> #else /* CONFIG_OF */
>>
>> static inline int of_driver_match_device(struct device *dev,
>> @@ -103,7 +103,7 @@ static inline struct device_node *of_cpu_device_node_get(int cpu)
>> {
>> return NULL;
>> }
>> -static inline void of_dma_configure(struct device *dev, struct device_node *np)
>> +static inline void of_dma_configure(struct device *dev, struct device_node *parent)
>> {}
>> #endif /* CONFIG_OF */
>>
>> diff --git a/include/linux/of_iommu.h b/include/linux/of_iommu.h
>> index 13394ac83c66..c02b62e8e6ed 100644
>> --- a/include/linux/of_iommu.h
>> +++ b/include/linux/of_iommu.h
>> @@ -12,7 +12,7 @@ extern int of_get_dma_window(struct device_node *dn, const char *prefix,
>> size_t *size);
>>
>> extern const struct iommu_ops *of_iommu_configure(struct device *dev,
>> - struct device_node *master_np);
>> + struct device_node *parent);
>>
>> #else
>>
>> @@ -24,7 +24,7 @@ static inline int of_get_dma_window(struct device_node *dn, const char *prefix,
>> }
>>
>> static inline const struct iommu_ops *of_iommu_configure(struct device *dev,
>> - struct device_node *master_np)
>> + struct device_node *parent)
>> {
>> return NULL;
>> }
>> --
>> 2.11.0.dirty
>>
>
> pci and memory mapped device world is different. of course if you talk
> from iommu perspective, all the master are same for IOMMU
>
> but the original intention of the patch is to try to solve 2 problems.
> please refer to https://lkml.org/lkml/2017/3/29/10
>
> 1) expose generic API for pci world clients to configure their
> dma-ranges. right now there is none.
> 2) same API can be used by IOMMU to derive dma_mask.
>
> while the current patch posted to handle dma-ranges for both memory
> mapped and pci devices, which I think is overdoing.
>
> besides we have different configuration of dma-ranges based on iommu
> is enabled or not enabled.
> #define PCIE_DMA_RANGES dma-ranges = <0x43000000 0x00 0x80000000 0x00
> 0x80000000 0x00 0x80000000 \
> 0x43000000 0x08 0x00000000 0x08
> 0x00000000 0x08 0x00000000 \
> 0x43000000 0x80 0x00000000 0x80
> 0x00000000 0x40 0x00000000>;
> Not sure if this patch will consider above dma-ranges.
>
> my suggestion is to leave existing of_dma_get_range as is, and have
> new function for pci world as discussed in
> please refer to https://lkml.org/lkml/2017/3/29/10
>
> Regards,
> Oza.
also I see that, in case of multiple ranges of_dma_get_range doesnt handle that.
and also it is not meant to handle.
so with this patch will return wrong size and hence wrong dma_mask.
having said, I think it is better to separate pci world dma-ranges
function on of_pci.c
for which my discussion with Rob already, (same thread)
https://lkml.org/lkml/2017/3/29/10
Waiting for Rob's viewpoint on this.
Regards,
Oza.
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