linux-kernel - [PATCH v5 net-next 01/10] misc: sram: add optional ioremap without write combining

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Message-Id: <1457604558-1121-2-git-send-email-gregory.clement@free-electrons.com>
Date:	Thu, 10 Mar 2016 11:09:09 +0100
From:	Gregory CLEMENT <gregory.clement@...e-electrons.com>
To:	"David S. Miller" <davem@...emloft.net>,
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
	Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
	Florian Fainelli <f.fainelli@...il.com>
Cc:	Jason Cooper <jason@...edaemon.net>, Andrew Lunn <andrew@...n.ch>,
	Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>,
	Gregory CLEMENT <gregory.clement@...e-electrons.com>,
	linux-arm-kernel@...ts.infradead.org,
	Lior Amsalem <alior@...vell.com>,
	Nadav Haklai <nadavh@...vell.com>,
	Marcin Wojtas <mw@...ihalf.com>,
	Simon Guinot <simon.guinot@...uanux.org>,
	Russell King - ARM Linux <linux@....linux.org.uk>,
	Willy Tarreau <w@....eu>, Timor Kardashov <timork@...vell.com>,
	Dmitri Epshtein <dima@...vell.com>,
	Sebastian Careba <nitroshift@...oo.com>
Subject: [PATCH v5 net-next 01/10] misc: sram: add optional ioremap without write combining

From: Marcin Wojtas <mw@...ihalf.com>

Some SRAM users may require non-bufferable access to the memory, which is
impossible, because devm_ioremap_wc() is used for setting sram->virt_base.

This commit adds optional flag 'no-memory-wc', which allow to choose remap
method, using DT property. Documentation is updated accordingly.

Signed-off-by: Marcin Wojtas <mw@...ihalf.com>
---
 Documentation/devicetree/bindings/sram/sram.txt | 5 +++++
 drivers/misc/sram.c                             | 5 ++++-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/sram/sram.txt b/Documentation/devicetree/bindings/sram/sram.txt
index 42ee9438b771..227e3a341af1 100644
--- a/Documentation/devicetree/bindings/sram/sram.txt
+++ b/Documentation/devicetree/bindings/sram/sram.txt
@@ -25,6 +25,11 @@ Required properties in the sram node:
 - ranges : standard definition, should translate from local addresses
            within the sram to bus addresses
 
+Optional properties in the sram node:
+
+- no-memory-wc : the flag indicating, that SRAM memory region has not to
+                 be remapped as write combining. WC is used by default.
+
 Required properties in the area nodes:
 
 - reg : iomem address range, relative to the SRAM range
diff --git a/drivers/misc/sram.c b/drivers/misc/sram.c
index 736dae715dbf..69cdabea9c03 100644
--- a/drivers/misc/sram.c
+++ b/drivers/misc/sram.c
@@ -360,7 +360,10 @@ static int sram_probe(struct platform_device *pdev)
 		return -EBUSY;
 	}
 
-	sram->virt_base = devm_ioremap_wc(sram->dev, res->start, size);
+	if (of_property_read_bool(pdev->dev.of_node, "no-memory-wc"))
+		sram->virt_base = devm_ioremap(sram->dev, res->start, size);
+	else
+		sram->virt_base = devm_ioremap_wc(sram->dev, res->start, size);
 	if (IS_ERR(sram->virt_base))
 		return PTR_ERR(sram->virt_base);
 
-- 
2.5.0