[PATCH] leon, l2cache: workaround for scrubber

[Daniel Hellstrom]

From: Martin Aberg <maberg at gaisler.com>

This is a workaround for a L2CACHE scrubber corner case described in GR740
User's Manual, Version 1.10, section 43.2.30.

The issue affects some version of the L2CACHE. However, since the performance
impact of the workaround is marginal, special device probing logic has been
avoided. In addition, this update does not affect users who enable the L2CACHE
and scrubber before RTEMS is started.
---
 bsps/sparc/shared/l2c/l2c.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/bsps/sparc/shared/l2c/l2c.c b/bsps/sparc/shared/l2c/l2c.c
index 7b17f8b..89b0f40 100644
--- a/bsps/sparc/shared/l2c/l2c.c
+++ b/bsps/sparc/shared/l2c/l2c.c
@@ -241,6 +241,8 @@
 /*
  * L2CACHE ACCESS CONTROL register fields 
  */
+#define L2C_ACCCTRL_DSC (0x1 << L2C_ACCCTRL_DSC_BIT)
+#define L2C_ACCCTRL_SH (0x1 << L2C_ACCCTRL_SH_BIT)
 #define L2C_ACCCTRL_SPLITQ (0x1 << L2C_ACCCTRL_SPLITQ_BIT)
 #define L2C_ACCCTRL_NHM (0x1 << L2C_ACCCTRL_NHM_BIT)
 #define L2C_ACCCTRL_BERR (0x1 << L2C_ACCCTRL_BERR_BIT)
@@ -251,6 +253,8 @@
 #define L2C_ACCCTRL_DBPWS (0x1 << L2C_ACCCTRL_DBPWS_BIT)
 #define L2C_ACCCTRL_SPLIT (0x1 << L2C_ACCCTRL_SPLIT_BIT)
 
+#define L2C_ACCCTRL_DSC_BIT 14
+#define L2C_ACCCTRL_SH_BIT 13
 #define L2C_ACCCTRL_SPLITQ_BIT 10
 #define L2C_ACCCTRL_NHM_BIT 9
 #define L2C_ACCCTRL_BERR_BIT 8
@@ -672,6 +676,10 @@ STATIC INLINE int l2cache_reg_scrub_enable(int delay)
 {
 	struct l2cache_priv *priv = l2cachepriv;
 
+	unsigned int accc = REG_READ(&priv->regs->access_control);
+	REG_WRITE(&priv->regs->access_control,
+			accc | L2C_ACCCTRL_DSC | L2C_ACCCTRL_SH);
+
 	unsigned int ctrl = REG_READ(&priv->regs->scrub_control_status);
 	REG_WRITE(&priv->regs->scrub_delay, 
 			(delay << L2C_SCRUB_DEL_BIT) & L2C_SCRUB_DEL);
-- 
2.7.4