[RFC PATCH 1/2] common: dma-mapping: introduce dma_get_parent_cfg() helper
From: Murali Karicheri <hidden>
Date: 2014-12-17 18:02:55
Also in:
linux-pci, lkml
Subsystem:
dma mapping helpers, driver core, kobjects, debugfs and sysfs, the rest · Maintainers:
Marek Szyprowski, Greg Kroah-Hartman, "Rafael J. Wysocki", Danilo Krummrich, Linus Torvalds
Now, in Kernel, parent device's DMA parameters has to be applied to the child as is - to enable DMA support for the device. Usually this is happened in places where parent device manually instantiates child device such as in drivers/pci/probe.c (pci_device_add() for example). Now DMA configuration is represented in device data structure not only by DMA mask and DMA params, it also includes dma_pfn_offset at least. Hence introduce common dma_get_parent_cfg() helper to apply dma configuration from parent to child, and use __weak to allow arch to override it if needed. Signed-off-by: Murali Karicheri <redacted> --- drivers/base/dma-mapping.c | 18 ++++++++++++++++++ include/linux/dma-mapping.h | 3 +++ 2 files changed, 21 insertions(+)
diff --git a/drivers/base/dma-mapping.c b/drivers/base/dma-mapping.c
index 9e8bbdd..5322426 100644
--- a/drivers/base/dma-mapping.c
+++ b/drivers/base/dma-mapping.c@@ -339,3 +339,21 @@ void dma_common_free_remap(void *cpu_addr, size_t size, unsigned long vm_flags) vunmap(cpu_addr); } #endif + +int __weak dma_get_parent_cfg(struct device *dev, struct device *parent) +{ + struct device *temp = parent; + + if (!temp) + temp = dev->parent; + + if (temp && is_device_dma_capable(temp)) { + dev->dma_mask = temp->dma_mask; + dev->coherent_dma_mask = temp->coherent_dma_mask; + dev->dma_parms = temp->dma_parms; + dev->dma_pfn_offset = temp->dma_pfn_offset; + return 0; + } + return -EINVAL; +} +EXPORT_SYMBOL(dma_get_parent_cfg);
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index d5d3881..eb080d6 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h@@ -127,6 +127,9 @@ static inline int dma_coerce_mask_and_coherent(struct device *dev, u64 mask) return dma_set_mask_and_coherent(dev, mask); } +extern int __weak dma_get_parent_cfg(struct device *dev, + struct device *parent); + extern u64 dma_get_required_mask(struct device *dev); #ifndef set_arch_dma_coherent_ops
--
1.7.9.5