ARM: 8659/1: l2c: allow CA9 optimizations to be disabled

If a PL310 is added to a system, but the sideband signals are not
connected, some Cortex A9 optimizations cannot be used. In particular,
enabling Full Line of Zeros in the CA9 without sidebands connected will
crash the system since the CA9 will expect the L2C to perform operations,
yet the L2C never gets the commands. Early BRESP also does not work
without sideband signals.

Signed-off-by: Chris Brandt <chris.brandt@renesas.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

diff --git a/Documentation/devicetree/bindings/arm/l2c2x0.txt b/Documentation/devicetree/bindings/arm/l2c2x0.txt
index 917199f179658248baa37b7f84c20b737b3a5152..d9650c1788f4122199703abe8a89253dc6f1974f 100644 (file)
--- a/Documentation/devicetree/bindings/arm/l2c2x0.txt
+++ b/Documentation/devicetree/bindings/arm/l2c2x0.txt
@@ -90,6 +90,9 @@ Optional properties:
 - arm,standby-mode: L2 standby mode enable. Value <0> (forcibly disable),
   <1> (forcibly enable), property absent (OS specific behavior,
   preferably retain firmware settings)
+- arm,early-bresp-disable : Disable the CA9 optimization Early BRESP (PL310)
+- arm,full-line-zero-disable : Disable the CA9 optimization Full line of zero
+  write (PL310)
 
 Example:
 

diff --git a/arch/arm/mm/cache-l2x0.c b/arch/arm/mm/cache-l2x0.c
index 2290be390f87b15c48cd9cfc67a08386e1148999..808efbb89b88ce188828dead3b5081975d542deb 100644 (file)
--- a/arch/arm/mm/cache-l2x0.c
+++ b/arch/arm/mm/cache-l2x0.c
@@ -57,6 +57,9 @@ static unsigned long sync_reg_offset = L2X0_CACHE_SYNC;
 
 struct l2x0_regs l2x0_saved_regs;
 
+static bool l2x0_bresp_disable;
+static bool l2x0_flz_disable;
+
 /*
  * Common code for all cache controllers.
  */
@@ -620,7 +623,7 @@ static void __init l2c310_enable(void __iomem *base, unsigned num_lock)
        u32 aux = l2x0_saved_regs.aux_ctrl;
 
        if (rev >= L310_CACHE_ID_RTL_R2P0) {
-               if (cortex_a9) {
+               if (cortex_a9 && !l2x0_bresp_disable) {
                        aux |= L310_AUX_CTRL_EARLY_BRESP;
                        pr_info("L2C-310 enabling early BRESP for Cortex-A9\n");
                } else if (aux & L310_AUX_CTRL_EARLY_BRESP) {
@@ -629,7 +632,7 @@ static void __init l2c310_enable(void __iomem *base, unsigned num_lock)
                }
        }
 
-       if (cortex_a9) {
+       if (cortex_a9 && !l2x0_flz_disable) {
                u32 aux_cur = readl_relaxed(base + L2X0_AUX_CTRL);
                u32 acr = get_auxcr();
 
@@ -1200,6 +1203,12 @@ static void __init l2c310_of_parse(const struct device_node *np,
                *aux_mask &= ~L2C_AUX_CTRL_PARITY_ENABLE;
        }
 
+       if (of_property_read_bool(np, "arm,early-bresp-disable"))
+               l2x0_bresp_disable = true;
+
+       if (of_property_read_bool(np, "arm,full-line-zero-disable"))
+               l2x0_flz_disable = true;
+
        prefetch = l2x0_saved_regs.prefetch_ctrl;
 
        ret = of_property_read_u32(np, "arm,double-linefill", &val);