linux-kernel - Re: [PATCH v3 3/7] of: introduce of_dma_is

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Date:	Mon, 5 May 2014 17:45:48 -0400
From:	Santosh Shilimkar <santosh.shilimkar@...com>
To:	Rob Herring <robherring2@...il.com>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Russell King <linux@....linux.org.uk>,
	Arnd Bergmann <arnd@...db.de>, Olof Johansson <olof@...om.net>,
	Grant Likely <grant.likely@...aro.org>,
	Rob Herring <robh+dt@...nel.org>,
	Catalin Marinas <catalin.marinas@....com>,
	Linus Walleij <linus.walleij@...aro.org>,
	Grygorii Strashko <grygorii.strashko@...com>
Subject: Re: [PATCH v3 3/7] of: introduce of_dma_is_coherent() helper

On Thursday 01 May 2014 08:56 PM, Rob Herring wrote:
> On Thu, Apr 24, 2014 at 10:30 AM, Santosh Shilimkar
> <santosh.shilimkar@...com> wrote:
>> The of_dma_is_coherent() helper parses the given DT device
>> node to see if the "dma-coherent" property is supported and
>> returns true or false accordingly.
>>
>> If the arch is always coherent or always noncoherent, then the default
>> DMA ops has to be specified accordingly.
>>
>> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
>> Cc: Russell King <linux@....linux.org.uk>
>> Cc: Arnd Bergmann <arnd@...db.de>
>> Cc: Olof Johansson <olof@...om.net>
>> Cc: Grant Likely <grant.likely@...aro.org>
>> Cc: Rob Herring <robh+dt@...nel.org>
>> Cc: Catalin Marinas <catalin.marinas@....com>
>> Cc: Linus Walleij <linus.walleij@...aro.org>
>> Signed-off-by: Santosh Shilimkar <santosh.shilimkar@...com>
>> Signed-off-by: Grygorii Strashko <grygorii.strashko@...com>
>> ---
>>  drivers/of/platform.c       |   23 +++++++++++++++++++++++
>>  include/linux/of_platform.h |    6 ++++++
> 
> I thought I said this already, but this does not belong in these files
> as the function does not deal with platform devices. Probably
> address.c/of_address.h would be the best place.
> 
Updated patch with functions now moved to of_address.h/address.c

>From 08fb70715afe4adf203d24f1737dba7123c6713b Mon Sep 17 00:00:00 2001
From: Santosh Shilimkar <santosh.shilimkar@...com>
Date: Thu, 24 Apr 2014 11:30:03 -0400
Subject: [PATCH v3 3/7] of: introduce of_dma_is_coherent() helper

The of_dma_is_coherent() helper parses the given DT device
node to see if the "dma-coherent" property is supported and
returns true or false accordingly.

If the arch is always coherent or always noncoherent, then the default
DMA ops has to be specified accordingly.

Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Russell King <linux@....linux.org.uk>
Cc: Arnd Bergmann <arnd@...db.de>
Cc: Olof Johansson <olof@...om.net>
Cc: Grant Likely <grant.likely@...aro.org>
Cc: Rob Herring <robh+dt@...nel.org>
Cc: Catalin Marinas <catalin.marinas@....com>
Cc: Linus Walleij <linus.walleij@...aro.org>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@...com>
Signed-off-by: Grygorii Strashko <grygorii.strashko@...com>
---
 drivers/of/address.c       |   23 +++++++++++++++++++++++
 include/linux/of_address.h |    6 ++++++
 2 files changed, 29 insertions(+)

diff --git a/drivers/of/address.c b/drivers/of/address.c
index c54baee..d244b28 100644
--- a/drivers/of/address.c
+++ b/drivers/of/address.c
@@ -808,3 +808,26 @@ out:
 	return ret;
 }
 EXPORT_SYMBOL_GPL(of_dma_get_range);
+
+/**
+ * of_dma_is_coherent - Check if device is coherent
+ * @np:	device node
+ *
+ * It returns true if "dma-coherent" property was found
+ * for this device in DT.
+ */
+bool of_dma_is_coherent(struct device_node *np)
+{
+	struct device_node *node = of_node_get(np);
+
+	while (node) {
+		if (of_property_read_bool(node, "dma-coherent")) {
+			of_node_put(node);
+			return true;
+		}
+		node = of_get_next_parent(node);
+	}
+	of_node_put(node);
+	return false;
+}
+EXPORT_SYMBOL_GPL(of_dma_is_coherent);
\ No newline at end of file
diff --git a/include/linux/of_address.h b/include/linux/of_address.h
index 4d7b325..839a352 100644
--- a/include/linux/of_address.h
+++ b/include/linux/of_address.h
@@ -65,6 +65,7 @@ extern struct of_pci_range *of_pci_range_parser_one(
 					struct of_pci_range *range);
 extern int of_dma_get_range(struct device_node *np, u64 *dma_addr,
 				u64 *paddr, u64 *size);
+extern bool of_dma_is_coherent(struct device_node *np);
 #else /* CONFIG_OF_ADDRESS */
 static inline struct device_node *of_find_matching_node_by_address(
 					struct device_node *from,
@@ -98,6 +99,11 @@ static inline int of_dma_get_range(struct device_node *np, u64 *dma_addr,
 {
 	return -ENODEV;
 }
+
+static inline bool of_dma_is_coherent(struct device_node *np)
+{
+	return false;
+}
 #endif /* CONFIG_OF_ADDRESS */
 
 #ifdef CONFIG_OF
-- 
1.7.9.5

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