linux-kernel - [PATCH 3/3] misc: SRAM: Add option to map SRAM to allow code execution

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Date:   Thu, 27 Oct 2016 13:56:12 -0500
From:   Dave Gerlach <d-gerlach@...com>
To:     Arnd Bergmann <arnd@...db.de>,
        Russell King <linux@....linux.org.uk>,
        Dan Williams <dan.j.williams@...el.com>
CC:     <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <linux-omap@...r.kernel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Shawn Guo <shawnguo@...nel.org>,
        Tony Lindgren <tony@...mide.com>,
        Alexandre Belloni <alexandre.belloni@...e-electrons.com>,
        Nishanth Menon <nm@...com>, Dave Gerlach <d-gerlach@...com>
Subject: [PATCH 3/3] misc: SRAM: Add option to map SRAM to allow code execution

Allow option for mapping SRAM as executable. DT node can specify
"memory-exec" and "memory-exec-nocache" to also map it as non-cached.
This is useful for platforms using the sram driver that need to run
PM code from sram like several ARM platforms.

Signed-off-by: Dave Gerlach <d-gerlach@...com>
---
 Documentation/devicetree/bindings/sram/sram.txt | 2 ++
 drivers/misc/sram.c                             | 7 +++++++
 2 files changed, 9 insertions(+)

diff --git a/Documentation/devicetree/bindings/sram/sram.txt b/Documentation/devicetree/bindings/sram/sram.txt
index add48f09015e..8eac557204e5 100644
--- a/Documentation/devicetree/bindings/sram/sram.txt
+++ b/Documentation/devicetree/bindings/sram/sram.txt
@@ -29,6 +29,8 @@ 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.
+- memory-exec : map range to allow code execution
+- memory-exec-nocache : map range to allow code execution and also non-cached
 
 Required properties in the area nodes:
 
diff --git a/drivers/misc/sram.c b/drivers/misc/sram.c
index f84b53d6ce50..a9ba1be115bb 100644
--- a/drivers/misc/sram.c
+++ b/drivers/misc/sram.c
@@ -362,6 +362,13 @@ static int sram_probe(struct platform_device *pdev)
 
 	if (of_property_read_bool(pdev->dev.of_node, "no-memory-wc"))
 		sram->virt_base = devm_ioremap(sram->dev, res->start, size);
+	else if (of_property_read_bool(pdev->dev.of_node, "memory-exec"))
+		sram->virt_base = devm_memremap(sram->dev, res->start, size,
+						MEMREMAP_EXEC);
+	else if (of_property_read_bool(pdev->dev.of_node,
+				       "memory-exec-nocache"))
+		sram->virt_base = devm_memremap(sram->dev, res->start, size,
+						MEMREMAP_EXEC_NOCACHE);
 	else
 		sram->virt_base = devm_ioremap_wc(sram->dev, res->start, size);
 	if (!sram->virt_base)
-- 
2.9.3