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Message-Id: <20260107-mtd-memregion-v3-4-f9fc9107b992@bootlin.com>
Date: Wed, 07 Jan 2026 14:04:55 +0100
From: Gregory CLEMENT <gregory.clement@...tlin.com>
To: Rob Herring <robh@...nel.org>, Linus Walleij <linus.walleij@...aro.org>,
Miquel Raynal <miquel.raynal@...tlin.com>,
Richard Weinberger <richard@....at>, Vignesh Raghavendra <vigneshr@...com>,
Krzysztof Kozlowski <krzk+dt@...nel.org>,
Conor Dooley <conor+dt@...nel.org>
Cc: Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
Vladimir Kondratiev <vladimir.kondratiev@...ileye.com>,
Benoît Monin <benoit.monin@...tlin.com>,
Théo Lebrun <theo.lebrun@...tlin.com>,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, linux-mtd@...ts.infradead.org,
Gregory CLEMENT <gregory.clement@...tlin.com>
Subject: [PATCH v3 4/4] mtd: physmap: Add support for RAM reserved memory
regions
MTD fixed-partitions can now be exposed for reserved RAM regions, not
just ROM reg regions. This is achieved by using the new compatible
property (mtd-mem or mtd-memro) previously introduced in the reserved
memory region node.
Based on the work of Muhammad Musa <muhammad.musa@...el.com>
Signed-off-by: Gregory CLEMENT <gregory.clement@...tlin.com>
---
drivers/mtd/maps/physmap-core.c | 73 +++++++++++++++++++++++++++++++++--------
drivers/of/platform.c | 2 ++
2 files changed, 62 insertions(+), 13 deletions(-)
diff --git a/drivers/mtd/maps/physmap-core.c b/drivers/mtd/maps/physmap-core.c
index 2bd7a1af898c9..cc7d08a413c78 100644
--- a/drivers/mtd/maps/physmap-core.c
+++ b/drivers/mtd/maps/physmap-core.c
@@ -39,6 +39,7 @@
#include <linux/mtd/cfi_endian.h>
#include <linux/io.h>
#include <linux/of.h>
+#include <linux/of_reserved_mem.h>
#include <linux/pm_runtime.h>
#include <linux/gpio/consumer.h>
@@ -263,6 +264,14 @@ static const struct of_device_id of_flash_match[] = {
.type = "rom",
.compatible = "direct-mapped"
},
+ {
+ .compatible = "mtd-mem",
+ .data = "map_ram",
+ },
+ {
+ .compatible = "mtd-memro",
+ .data = "map_rom",
+ },
{ /* sentinel */ },
};
MODULE_DEVICE_TABLE(of, of_flash_match);
@@ -348,10 +357,19 @@ static int physmap_flash_of_init(struct platform_device *dev)
map_indirect = of_property_read_bool(dp, "no-unaligned-direct-access");
- err = of_property_read_u32(dp, "bank-width", &bankwidth);
- if (err) {
- dev_err(&dev->dev, "Can't get bank width from device tree\n");
- return err;
+ if ((of_device_is_compatible(dp, "mtd-mem")) ||
+ (of_device_is_compatible(dp, "mtd-memro"))) {
+ /*
+ * When using reserved memory region from DRAM we use
+ * the defaullt 32 bits acces
+ */
+ bankwidth = 4;
+ } else {
+ err = of_property_read_u32(dp, "bank-width", &bankwidth);
+ if (err) {
+ dev_err(&dev->dev, "Can't get bank width from device tree\n");
+ return err;
+ }
}
if (of_property_read_bool(dp, "big-endian"))
@@ -446,8 +464,9 @@ static int physmap_flash_pdata_init(struct platform_device *dev)
static int physmap_flash_probe(struct platform_device *dev)
{
struct physmap_flash_info *info;
- int err = 0;
- int i;
+ struct resource *res_array;
+ int err = 0, is_rsvd_mem = 0, nreg = 0;
+ int i, curr_reg;
if (!dev->dev.of_node && !dev_get_platdata(&dev->dev))
return -EINVAL;
@@ -459,9 +478,13 @@ static int physmap_flash_probe(struct platform_device *dev)
while (platform_get_resource(dev, IORESOURCE_MEM, info->nmaps))
info->nmaps++;
- if (!info->nmaps)
- return -ENODEV;
-
+ if (!info->nmaps) {
+ info->nmaps = of_reserved_mem_region_total_count(dev->dev.of_node);
+ if (info->nmaps > 0)
+ is_rsvd_mem = 1;
+ else
+ return -ENODEV;
+ }
info->maps = devm_kzalloc(&dev->dev,
sizeof(*info->maps) * info->nmaps,
GFP_KERNEL);
@@ -503,7 +526,23 @@ static int physmap_flash_probe(struct platform_device *dev)
for (i = 0; i < info->nmaps; i++) {
struct resource *res;
- info->maps[i].virt = devm_platform_get_and_ioremap_resource(dev, i, &res);
+ if (is_rsvd_mem) {
+ if (nreg <= i) {
+ int cnt = of_reserved_mem_region_to_resource_array(&dev->dev,
+ dev->dev.of_node, i, &res_array);
+ if (cnt < 0) {
+ err = cnt;
+ goto err_out;
+ }
+ nreg += cnt;
+ curr_reg = 0;
+ }
+ res = &res_array[curr_reg++];
+ info->maps[i].virt = devm_ioremap_resource(&dev->dev, res);
+ } else {
+ info->maps[i].virt = devm_platform_get_and_ioremap_resource(dev, i, &res);
+ }
+
if (IS_ERR(info->maps[i].virt)) {
err = PTR_ERR(info->maps[i].virt);
goto err_out;
@@ -519,9 +558,17 @@ static int physmap_flash_probe(struct platform_device *dev)
info->maps[i].phys = res->start;
info->win_order = fls64(resource_size(res)) - 1;
- info->maps[i].size = BIT(info->win_order +
- (info->gpios ?
- info->gpios->ndescs : 0));
+ /* When using a memory region, the size is not necessarily a
+ * power of 2, so win_order is not applicable. Since GPIOs are
+ * unavailable in this context, directly using the region's size
+ * is safe.
+ */
+ if (is_rsvd_mem)
+ info->maps[i].size = resource_size(res);
+ else
+ info->maps[i].size = BIT(info->win_order +
+ (info->gpios ?
+ info->gpios->ndescs : 0));
info->maps[i].map_priv_1 = (unsigned long)dev;
diff --git a/drivers/of/platform.c b/drivers/of/platform.c
index f77cb19973a5d..23ea5a723aa7f 100644
--- a/drivers/of/platform.c
+++ b/drivers/of/platform.c
@@ -496,6 +496,8 @@ static const struct of_device_id reserved_mem_matches[] = {
{ .compatible = "ramoops" },
{ .compatible = "nvmem-rmem" },
{ .compatible = "google,open-dice" },
+ { .compatible = "mtd-memro" },
+ { .compatible = "mtd-mem" },
{}
};
--
2.51.0
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