linux-kernel - [PATCH v5 3/4] mips: bmips: setup: make CBR address configurable

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Date: Sat, 11 May 2024 15:03:47 +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>,
	linux-mips@...r.kernel.org,
	devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v5 3/4] 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 "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 overwrite the cached one and the
one set in the CBR register will be ignored.

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

Signed-off-by: Christian Marangi <ansuelsmth@...il.com>
Acked-by: Florian Fainelli <florian.fainelli@...adcom.com>
---
 arch/mips/bmips/setup.c      | 24 +++++++++++++++++++++++-
 arch/mips/kernel/smp-bmips.c |  6 +++++-
 2 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/arch/mips/bmips/setup.c b/arch/mips/bmips/setup.c
index dba789ec75b3..c7d83f0c7b05 100644
--- a/arch/mips/bmips/setup.c
+++ b/arch/mips/bmips/setup.c
@@ -205,13 +205,35 @@ 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;
+	}
+
+	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);
 }
 
diff --git a/arch/mips/kernel/smp-bmips.c b/arch/mips/kernel/smp-bmips.c
index 555a5b449ca8..20e2fb10022d 100644
--- a/arch/mips/kernel/smp-bmips.c
+++ b/arch/mips/kernel/smp-bmips.c
@@ -46,7 +46,11 @@ int bmips_smp_enabled = 1;
 int bmips_cpu_offset;
 cpumask_t bmips_booted_mask;
 unsigned long bmips_tp1_irqs = IE_IRQ1;
-/* 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 __read_mostly;
 
 #define RESET_FROM_KSEG0		0x80080800
-- 
2.43.0