linux-kernel - [PATCH v3 4/7] ARM: l2c: Add support for overriding prefetch settings

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Date:	Thu, 17 Jul 2014 18:38:59 +0200
From:	Tomasz Figa <t.figa@...sung.com>
To:	linux-samsung-soc@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	Kukjin Kim <kgene.kim@...sung.com>,
	Russell King - ARM Linux <linux@....linux.org.uk>,
	lauraa@...eaurora.org, linux-omap@...r.kernel.org,
	linus.walleij@...aro.org, santosh.shilimkar@...com,
	tony@...mide.com, drake@...lessm.com,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	Tomasz Figa <tomasz.figa@...il.com>, loeliger@...il.com,
	Tomasz Figa <t.figa@...sung.com>
Subject: [PATCH v3 4/7] ARM: l2c: Add support for overriding prefetch settings

Firmware on certain boards (e.g. ODROID-U3) can leave incorrect L2C prefetch
settings configured in registers leading to crashes if L2C is enabled
without overriding them. This patch introduces bindings to enable
prefetch settings to be specified from DT and necessary support in the
driver.

Signed-off-by: Tomasz Figa <t.figa@...sung.com>
---
 Documentation/devicetree/bindings/arm/l2cc.txt | 10 +++++++
 arch/arm/mm/cache-l2x0.c                       | 39 ++++++++++++++++++++++++++
 2 files changed, 49 insertions(+)

diff --git a/Documentation/devicetree/bindings/arm/l2cc.txt b/Documentation/devicetree/bindings/arm/l2cc.txt
index af527ee..3443d2d 100644
--- a/Documentation/devicetree/bindings/arm/l2cc.txt
+++ b/Documentation/devicetree/bindings/arm/l2cc.txt
@@ -47,6 +47,16 @@ Optional properties:
 - cache-id-part: cache id part number to be used if it is not present
   on hardware
 - wt-override: If present then L2 is forced to Write through mode
+- arm,double-linefill : Override double linefill enable setting. Enable if
+  non-zero, disable if zero.
+- arm,double-linefill-incr : Override double linefill on INCR read. Enable
+  if non-zero, disable if zero.
+- arm,double-linefill-wrap : Override double linefill on WRAP read. Enable
+  if non-zero, disable if zero.
+- arm,prefetch-drop : Override prefetch drop enable setting. Enable if non-zero,
+  disable if zero.
+- arm,prefetch-offset : Override prefetch offset value. Valid values are
+  0-7, 15, 23, and 31.
 
 Example:
 
diff --git a/arch/arm/mm/cache-l2x0.c b/arch/arm/mm/cache-l2x0.c
index 21a625a0..6274803 100644
--- a/arch/arm/mm/cache-l2x0.c
+++ b/arch/arm/mm/cache-l2x0.c
@@ -1055,6 +1055,8 @@ static void __init l2c310_of_parse(const struct device_node *np,
 	u32 data[3] = { 0, 0, 0 };
 	u32 tag[3] = { 0, 0, 0 };
 	u32 filter[2] = { 0, 0 };
+	u32 prefetch;
+	u32 val;
 
 	of_property_read_u32_array(np, "arm,tag-latency", tag, ARRAY_SIZE(tag));
 	if (tag[0] && tag[1] && tag[2])
@@ -1079,6 +1081,43 @@ static void __init l2c310_of_parse(const struct device_node *np,
 		l2x0_saved_regs.filter_start = (filter[0] & ~(SZ_1M - 1))
 					| L310_ADDR_FILTER_EN;
 	}
+
+	prefetch = l2x0_saved_regs.prefetch_ctrl;
+
+	if (!of_property_read_u32(np, "arm,double-linefill", &val)) {
+		if (val)
+			prefetch |= L310_PREFETCH_CTRL_DBL_LINEFILL;
+		else
+			prefetch &= ~L310_PREFETCH_CTRL_DBL_LINEFILL;
+	}
+
+	if (!of_property_read_u32(np, "arm,double-linefill-incr", &val)) {
+		if (val)
+			prefetch |= L310_PREFETCH_CTRL_DBL_LINEFILL_INCR;
+		else
+			prefetch &= ~L310_PREFETCH_CTRL_DBL_LINEFILL_INCR;
+	}
+
+	if (!of_property_read_u32(np, "arm,double-linefill-wrap", &val)) {
+		if (!val)
+			prefetch |= L310_PREFETCH_CTRL_DBL_LINEFILL_WRAP;
+		else
+			prefetch &= ~L310_PREFETCH_CTRL_DBL_LINEFILL_WRAP;
+	}
+
+	if (!of_property_read_u32(np, "arm,prefetch-drop", &val)) {
+		if (val)
+			prefetch |= L310_PREFETCH_CTRL_PREFETCH_DROP;
+		else
+			prefetch &= ~L310_PREFETCH_CTRL_PREFETCH_DROP;
+	}
+
+	if (!of_property_read_u32(np, "arm,prefetch-offset", &val)) {
+		prefetch &= ~L310_PREFETCH_CTRL_OFFSET_MASK;
+		prefetch |= val & L310_PREFETCH_CTRL_OFFSET_MASK;
+	}
+
+	l2x0_saved_regs.prefetch_ctrl = prefetch;
 }
 
 static const struct l2c_init_data of_l2c310_data __initconst = {
-- 
1.9.3

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