linux-kernel - [PATCH 2/5] of: reserved_mem: Implement alloc-{bottom-up,top-down}

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Message-Id: <20230510-dt-resv-bottom-up-v1-2-3bf68873dbed@gerhold.net>
Date:   Mon, 15 May 2023 12:12:17 +0200
From:   Stephan Gerhold <stephan@...hold.net>
To:     Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>
Cc:     Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        devicetree@...r.kernel.org, devicetree-spec@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        Stephan Gerhold <stephan@...hold.net>
Subject: [PATCH 2/5] of: reserved_mem: Implement alloc-{bottom-up,top-down}

Use memblock_set_bottom_up() to specify an explicit allocation order for
dynamic reservations with "alloc-ranges". Since the default value varies
between architectures the previous value is saved and restored after
trying the allocations.

If neither alloc-bottom-up or alloc-top-down are specified the previous
implementation-defined allocation order is preserved.

Signed-off-by: Stephan Gerhold <stephan@...hold.net>
---
 drivers/of/of_reserved_mem.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
index 948efa9f99e3..6443140deacf 100644
--- a/drivers/of/of_reserved_mem.c
+++ b/drivers/of/of_reserved_mem.c
@@ -89,7 +89,7 @@ static int __init __reserved_mem_alloc_size(unsigned long node,
 	phys_addr_t base = 0, align = 0, size;
 	int len;
 	const __be32 *prop;
-	bool nomap;
+	bool nomap, prev_bottom_up;
 	int ret;
 
 	prop = of_get_flat_dt_prop(node, "size", &len);
@@ -130,6 +130,12 @@ static int __init __reserved_mem_alloc_size(unsigned long node,
 			return -EINVAL;
 		}
 
+		prev_bottom_up = memblock_bottom_up();
+		if (of_get_flat_dt_prop(node, "alloc-bottom-up", NULL))
+			memblock_set_bottom_up(true);
+		if (of_get_flat_dt_prop(node, "alloc-top-down", NULL))
+			memblock_set_bottom_up(false);
+
 		base = 0;
 
 		while (len > 0) {
@@ -148,6 +154,7 @@ static int __init __reserved_mem_alloc_size(unsigned long node,
 			len -= t_len;
 		}
 
+		memblock_set_bottom_up(prev_bottom_up);
 	} else {
 		ret = early_init_dt_alloc_reserved_memory_arch(size, align,
 							0, 0, nomap, &base);

-- 
2.40.1