linux-kernel - [PATCH 4/6] mips: bmips: setup: make CBR address configurable

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Date: Fri,  3 May 2024 15:54:04 +0200
From: Christian Marangi <ansuelsmth@...il.com>
To: Hauke Mehrtens <hauke@...ke-m.de>,
	Rafał Miłecki <zajec5@...il.com>,
	Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Florian Fainelli <florian.fainelli@...adcom.com>,
	Broadcom internal kernel review list <bcm-kernel-feedback-list@...adcom.com>,
	Christian Marangi <ansuelsmth@...il.com>,
	Álvaro Fernández Rojas <noltari@...il.com>,
	linux-mips@...r.kernel.org,
	devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Daniel González Cabanelas <dgcbueu@...il.com>
Subject: [PATCH 4/6] mips: bmips: setup: make CBR address configurable

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 "mips-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.

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

Signed-off-by: Christian Marangi <ansuelsmth@...il.com>
---
 arch/mips/bmips/setup.c | 30 +++++++++++++++++++++++++++---
 1 file changed, 27 insertions(+), 3 deletions(-)

diff --git a/arch/mips/bmips/setup.c b/arch/mips/bmips/setup.c
index 18561d426f89..bef84677248e 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 "mips-cbr-reg" in the "cpus" node.
+ */
 void __iomem *bmips_cbr_addr;
 extern bool bmips_rac_flush_disable;
 
@@ -212,8 +216,28 @@ void __init device_tree_init(void)
 
 	/* 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)
-		bmips_smp_enabled = 0;
+	if (np) {
+		u32 addr;
+
+		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, "mips-cbr-reg", &addr)) {
+			if (!of_property_read_bool(np, "mips-broken-cbr-reg") &&
+			    bmips_cbr_addr && addr != (u32)bmips_cbr_addr) {
+				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