[PATCH v11 6/9] ARM: l2c: Add support for overriding prefetch settings

Marek Szyprowski
2015-01-05T12:20:31Z

From: Tomasz Figa <t.figa@samsung.com>

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@samsung.com>
[mszyprow: rebased onto v3.18-rc1, added error message when prefetch related
dt property has been provided without any value]
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
---
Documentation/devicetree/bindings/arm/l2cc.txt | 10 +++++
arch/arm/mm/cache-l2x0.c | 54 ++++++++++++++++++++++++++
2 files changed, 64 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 dcde6086a228..e7f1bd90dde6 100644
--- a/arch/arm/mm/cache-l2x0.c
+++ b/arch/arm/mm/cache-l2x0.c
@@ -1169,6 +1169,8 @@ 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));
@@ -1214,6 +1216,58 @@ static void __init l2c310_of_parse(const struct device_node *np,
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("L2C-310 OF arm,double-linefill property value is missing\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("L2C-310 OF arm,double-linefill-incr property value is missing\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("L2C-310 OF arm,double-linefill-wrap property value is missing\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("L2C-310 OF arm,prefetch-drop property value is missing\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("L2C-310 OF arm,prefetch-offset property value is missing\n");
+ }
+
+ l2x0_saved_regs.prefetch_ctrl = prefetch;
}

static const struct l2c_init_data of_l2c310_data __initconst = {
--
1.9.2