[PATCH v6 4/7] ARM: l2c: Add support for overriding prefetch settings

[Marek Szyprowski]

From: Tomasz Figa <t.figa@xxxxxxxxxxx>

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@xxxxxxxxxxx>
[mszyprow: rebased onto v3.18-rc1, added error messages when property value
 is missing]
Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
---
 Documentation/devicetree/bindings/arm/l2cc.txt | 10 +++++
 arch/arm/mm/cache-l2x0.c                       | 55 ++++++++++++++++++++++++++
 2 files changed, 65 insertions(+)

diff --git a/Documentation/devicetree/bindings/arm/l2cc.txt b/Documentation/devicetree/bindings/arm/l2cc.txt
index 292ef7ca3058..0dbabe9a6b0a 100644
--- a/Documentation/devicetree/bindings/arm/l2cc.txt
+++ b/Documentation/devicetree/bindings/arm/l2cc.txt
@@ -57,6 +57,16 @@ 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 ad981894de73..69cfa8359ed3 100644
--- a/arch/arm/mm/cache-l2x0.c
+++ b/arch/arm/mm/cache-l2x0.c
@@ -1163,6 +1163,9 @@ static void __init l2c310_of_parse(const struct device_node *np,
 	u32 tag[3] = { 0, 0, 0 };
 	u32 filter[2] = { 0, 0 };
 	u32 assoc;
+	u32 prefetch;
+	u32 val;
+	int ret;
 
 	of_property_read_u32_array(np, "arm,tag-latency", tag, ARRAY_SIZE(tag));
 	if (tag[0] && tag[1] && tag[2])
@@ -1204,6 +1207,58 @@ static void __init l2c310_of_parse(const struct device_node *np,
 		pr_err("PL310 OF: %d calculated, only 8 and 16 legal\n", assoc);
 		break;
 	}
+
+	prefetch = l2x0_saved_regs.prefetch_ctrl;
+
+	ret = of_property_read_u32(np, "arm,double-linefill", &val);
+	if (ret == 0) {
+		if (val)
+			prefetch |= L310_PREFETCH_CTRL_DBL_LINEFILL;
+		else
+			prefetch &= ~L310_PREFETCH_CTRL_DBL_LINEFILL;
+	} else if (ret != -EINVAL) {
+		pr_err("PL310 OF: missing value for arm,double-linefill property\n");
+	}
+
+	ret = of_property_read_u32(np, "arm,double-linefill-incr", &val);
+	if (ret == 0) {
+		if (val)
+			prefetch |= L310_PREFETCH_CTRL_DBL_LINEFILL_INCR;
+		else
+			prefetch &= ~L310_PREFETCH_CTRL_DBL_LINEFILL_INCR;
+	} else if (ret != -EINVAL) {
+		pr_err("PL310 OF: missing value for arm,double-linefill-incr property\n");
+	}
+
+	ret = of_property_read_u32(np, "arm,double-linefill-wrap", &val);
+	if (ret == 0) {
+		if (!val)
+			prefetch |= L310_PREFETCH_CTRL_DBL_LINEFILL_WRAP;
+		else
+			prefetch &= ~L310_PREFETCH_CTRL_DBL_LINEFILL_WRAP;
+	} else if (ret != -EINVAL) {
+		pr_err("PL310 OF: missing value for arm,double-linefill-wrap property\n");
+	}
+
+	ret = of_property_read_u32(np, "arm,prefetch-drop", &val);
+	if (ret == 0) {
+		if (val)
+			prefetch |= L310_PREFETCH_CTRL_PREFETCH_DROP;
+		else
+			prefetch &= ~L310_PREFETCH_CTRL_PREFETCH_DROP;
+	} else if (ret != -EINVAL) {
+		pr_err("PL310 OF: missing value for arm,prefetch-drop property\n");
+	}
+
+	ret = of_property_read_u32(np, "arm,prefetch-offset", &val);
+	if (ret == 0) {
+		prefetch &= ~L310_PREFETCH_CTRL_OFFSET_MASK;
+		prefetch |= val & L310_PREFETCH_CTRL_OFFSET_MASK;
+	} else if (ret != -EINVAL) {
+		pr_err("PL310 OF: missing value for arm,prefetch-offset property\n");
+	}
+
+	l2x0_saved_regs.prefetch_ctrl = prefetch;
 }
 
 static const struct l2c_init_data of_l2c310_data __initconst = {
-- 
1.9.2

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