Re: [PATCH v2 5/7] ARM: of: introduce common routine for DMA configuration

by arm_dt_dma_configure() as following:
 - call of_get_dma_range() and get supported DMA range info
   (dma_addr, cpu_addr, dma_size);
 - if "not found" then fill dma_mask as DMA_BIT_MASK(32)
   (this is default behaviour);
 - if "failed" then clean up dma_mask (DMA not supported)
 - if ok then update devices DMA configuration:
      set dma_mask to (dma_addr + dma_size - 1)
      set dma_pfn_offset to PFN_DOWN(cpu_addr - dma_addr)

Cc: Russell King <linux-lFZ/pmaqli7XmaaqVzeoHQ@public.gmane.org>
Cc: Arnd Bergmann <redacted>
Cc: Olof Johansson <redacted>
Cc: Grant Likely <redacted>
Cc: Rob Herring <redacted>
Signed-off-by: Grygorii Strashko <redacted>
Signed-off-by: Santosh Shilimkar <redacted>
---
 arch/arm/include/asm/prom.h |    3 +++
 arch/arm/kernel/devtree.c   |   61 +++++++++++++++++++++++++++++++++++++++++++
 drivers/of/platform.c       |    5 +++-
 include/linux/of.h          |    2 +-
 4 files changed, 69 insertions(+), 2 deletions(-)

diff --git a/arch/arm/include/asm/prom.h b/arch/arm/include/asm/prom.h
index b681575..1acb732 100644
--- a/arch/arm/include/asm/prom.h
+++ b/arch/arm/include/asm/prom.h

@@ -11,11 +11,13 @@
 #ifndef __ASMARM_PROM_H
 #define __ASMARM_PROM_H

+struct device;
 #ifdef CONFIG_OF

 extern const struct machine_desc *setup_machine_fdt(unsigned int dt_phys);
 extern void arm_dt_memblock_reserve(void);
 extern void __init arm_dt_init_cpu_maps(void);
+extern void arm_dt_dma_configure(struct device *dev);

 #else /* CONFIG_OF */

@@ -26,6 +28,7 @@ static inline const struct machine_desc *setup_machine_fdt(unsigned int dt_phys)

 static inline void arm_dt_memblock_reserve(void) { }
 static inline void arm_dt_init_cpu_maps(void) { }
+static inline void arm_dt_dma_configure(struct device *dev) { }

 #endif /* CONFIG_OF */
 #endif /* ASMARM_PROM_H */

diff --git a/arch/arm/kernel/devtree.c b/arch/arm/kernel/devtree.c
index f751714..926b5dd 100644
--- a/arch/arm/kernel/devtree.c
+++ b/arch/arm/kernel/devtree.c

@@ -18,6 +18,9 @@
 #include <linux/of_fdt.h>
 #include <linux/of_irq.h>
 #include <linux/of_platform.h>
+#include <linux/of_dma.h>
+#include <linux/dma-mapping.h>
+#include <linux/slab.h>

 #include <asm/cputype.h>
 #include <asm/setup.h>

@@ -235,3 +238,61 @@ const struct machine_desc * __init setup_machine_fdt(unsigned int dt_phys)

        return mdesc;
 }
+
+void arm_dt_dma_configure(struct device *dev)

+{
+       dma_addr_t dma_addr;
+       phys_addr_t paddr, size;
+       dma_addr_t dma_mask;
+       int ret;
+
+       /*
+        * if dma-ranges property doesn't exist - use 32 bits DMA mask
+        * by default and don't set skip archdata.dma_pfn_offset
+        */
+       ret = of_dma_get_range(dev->of_node, &dma_addr, &paddr, &size);
+       if (ret == -ENODEV) {
+               dev->coherent_dma_mask = DMA_BIT_MASK(32);
+               if (!dev->dma_mask)
+                       dev->dma_mask = &dev->coherent_dma_mask;
+               return;
+       }
+
+       /* if failed - disable DMA for device */
+       if (ret < 0) {
+               dev_err(dev, "failed to configure DMA\n");
+               return;
+       }
+
+       /* DMA ranges found. Calculate and set dma_pfn_offset */
+       dev->archdata.dma_pfn_offset = PFN_DOWN(paddr - dma_addr);
+
+       /* Configure DMA mask */
+       dev->dma_mask = kmalloc(sizeof(*dev->dma_mask), GFP_KERNEL);

+       if (!dev->dma_mask)
+               return;
+
+       dma_mask = dma_addr + size - 1;
+
+       ret = arm_dma_set_mask(dev, dma_mask);
+       if (ret < 0) {
+               dev_err(dev, "failed to set DMA mask %#08x\n", dma_mask);
+               kfree(dev->dma_mask);
+               dev->dma_mask = NULL;
+               return;
+       }
+
+       dev_dbg(dev, "dma_pfn_offset(%#08lx) dma_mask(%#016llx)\n",
+               dev->archdata.dma_pfn_offset, *dev->dma_mask);
+
+       if (of_dma_is_coherent(dev->of_node)) {
+               set_dma_ops(dev, &arm_coherent_dma_ops);

+               dev_dbg(dev, "device is dma coherent\n");
+       }
+
+       ret = dma_set_coherent_mask(dev, dma_mask);
+       if (ret < 0) {
+               dev_err(dev, "failed to set coherent DMA mask %#08x\n",
+                       dma_mask);
+       }
+}

diff --git a/drivers/of/platform.c b/drivers/of/platform.c
index 404d1da..97d5533 100644
--- a/drivers/of/platform.c
+++ b/drivers/of/platform.c

@@ -213,10 +213,13 @@ static struct platform_device *of_platform_device_create_pdata(

 #if defined(CONFIG_MICROBLAZE)
        dev->archdata.dma_mask = 0xffffffffUL;

-#endif
+#elif defined(CONFIG_ARM_LPAE)
+       arm_dt_dma_configure(&dev->dev);
+#else
        dev->dev.coherent_dma_mask = DMA_BIT_MASK(32);
        if (!dev->dev.dma_mask)
                dev->dev.dma_mask = &dev->dev.coherent_dma_mask;
+#endif
        dev->dev.bus = &platform_bus_type;
        dev->dev.platform_data = platform_data;

diff --git a/include/linux/of.h b/include/linux/of.h
index 70c64ba..a321058 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h

@@ -136,7 +136,7 @@ static inline unsigned long of_read_ulong(const __be32 *cell, int size)
        return of_read_number(cell, size);
 }

-#if defined(CONFIG_SPARC)
+#if defined(CONFIG_SPARC) || defined(CONFIG_ARM_LPAE)
 #include <asm/prom.h>