[PATCH v2 4/5] mips: bmips: setup: make CBR address configurable

[Christian Marangi <ansuelsmth@xxxxxxxxx>]

Add support to provide CBR address from DT to handle broken
SoC/Bootloader that doesn't correctly init it. This permits to use the
RAC flush even in these condition.

To provide a CBR address from DT, the property "brcm,bmips-cbr-reg"
needs to be set in the "cpus" node. On DT init, this property presence
will be checked and will set the bmips_cbr_addr value accordingly. Also
bmips_rac_flush_disable will be set to false as RAC flush can be
correctly supported.

The CBR address from DT will be applied only if the CBR address from the
registers is 0, if the CBR address from the registers is not 0 and
is not equal to the one set in DT (if provided) a WARN is printed.

Also the DT CBR address is validated on being outside DRAM window.

To ALWAYS overwrite the CBR address the additional property
"brcm,bmips-broken-cbr-reg" needs to be set.

Signed-off-by: Christian Marangi <ansuelsmth@xxxxxxxxx>
---
 arch/mips/bmips/setup.c | 37 +++++++++++++++++++++++++++++++++++--
 1 file changed, 35 insertions(+), 2 deletions(-)

diff --git a/arch/mips/bmips/setup.c b/arch/mips/bmips/setup.c
index 5e024399222f..bf27b29c7a14 100644
--- a/arch/mips/bmips/setup.c
+++ b/arch/mips/bmips/setup.c
@@ -34,7 +34,11 @@
 #define REG_BCM6328_OTP		((void __iomem *)CKSEG1ADDR(0x1000062c))
 #define BCM6328_TP1_DISABLED	BIT(9)
 
-/* CBR addr doesn't change and we can cache it */
+/*
+ * CBR addr doesn't change and we can cache it.
+ * For broken SoC/Bootloader CBR addr might also be provided via DT
+ * with "brcm,bmips-cbr-reg" in the "cpus" node.
+ */
 void __iomem *bmips_cbr_addr __ro_after_init  __read_mostly;
 extern bool bmips_rac_flush_disable;
 
@@ -207,13 +211,42 @@ void __init plat_mem_setup(void)
 void __init device_tree_init(void)
 {
 	struct device_node *np;
+	u32 addr;
 
 	unflatten_and_copy_device_tree();
 
 	/* Disable SMP boot unless both CPUs are listed in DT and !disabled */
 	np = of_find_node_by_name(NULL, "cpus");
-	if (np && of_get_available_child_count(np) <= 1)
+	if (!np)
+		return;
+
+	if (of_get_available_child_count(np) <= 1)
 		bmips_smp_enabled = 0;
+
+	/* Check if DT provide a CBR address */
+	if (of_property_read_u32(np, "brcm,bmips-cbr-reg", &addr))
+		goto exit;
+
+	/* Make sure CBR address is outside DRAM window */
+	if (addr >= (u32)memblock_start_of_DRAM() &&
+	    addr < (u32)memblock_end_of_DRAM()) {
+		WARN(1, "DT CBR %x inside DRAM window. Ignoring DT CBR.\n",
+		     addr);
+		goto exit;
+	}
+
+	if (bmips_cbr_addr && addr != (u32)bmips_cbr_addr &&
+	    !of_property_read_bool(np, "brcm,bmips-broken-cbr-reg")) {
+		WARN(1, "register CBR %x differ from DT CBR %x. Ignoring DT CBR.\n",
+		     (u32)bmips_cbr_addr, addr);
+		goto exit;
+	}
+
+	bmips_cbr_addr = (void __iomem *)addr;
+	/* Since CBR is provided by DT, enable RAC flush */
+	bmips_rac_flush_disable = false;
+
+exit:
 	of_node_put(np);
 }
 
-- 
2.43.0