Only upstream user of this binding is the raspberry pi 4 DT, where it's
used to pass along bootloader-provided info to Linux. We have instances
in barebox, where a previous stage bootloader passes along a memory
region with info for barebox to interpret. This could in future be
modelled as nvmem-rmem nodes. The binding is also quite handy for
debugging.
Signed-off-by: Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx>
---
drivers/nvmem/Kconfig | 6 ++++
drivers/nvmem/Makefile | 2 ++
drivers/nvmem/rmem.c | 67 ++++++++++++++++++++++++++++++++++++++++++
drivers/of/base.c | 21 ++++++++++---
fs/devfs-core.c | 2 +-
include/driver.h | 3 ++
6 files changed, 96 insertions(+), 5 deletions(-)
create mode 100644 drivers/nvmem/rmem.c
diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
index e4a72b1431a9..0d7c0b7b9e3d 100644
--- a/drivers/nvmem/Kconfig
+++ b/drivers/nvmem/Kconfig
@@ -9,6 +9,12 @@ menuconfig NVMEM
if NVMEM
+config NVMEM_RMEM
+ bool "Reserved Memory Based Driver Support"
+ help
+ This driver maps reserved memory into an nvmem device. It might be
+ useful to expose information left by firmware in memory.
+
config NVMEM_SNVS_LPGPR
tristate "Freescale SNVS LPGPR support"
select MFD_SYSCON
diff --git a/drivers/nvmem/Makefile b/drivers/nvmem/Makefile
index 617e3725a726..6330f3d6e681 100644
--- a/drivers/nvmem/Makefile
+++ b/drivers/nvmem/Makefile
@@ -5,6 +5,8 @@
obj-$(CONFIG_NVMEM) += nvmem_core.o
nvmem_core-y := core.o regmap.o
+obj-$(CONFIG_NVMEM_RMEM) += rmem.o
+
# Devices
obj-$(CONFIG_NVMEM_SNVS_LPGPR) += nvmem_snvs_lpgpr.o
nvmem_snvs_lpgpr-y := snvs_lpgpr.o
diff --git a/drivers/nvmem/rmem.c b/drivers/nvmem/rmem.c
new file mode 100644
index 000000000000..e103cec4482a
--- /dev/null
+++ b/drivers/nvmem/rmem.c
@@ -0,0 +1,67 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2020 Nicolas Saenz Julienne <nsaenzjulienne@xxxxxxx>
+ */
+
+#include <io.h>
+#include <driver.h>
+#include <linux/nvmem-provider.h>
+#include <init.h>
+
+struct rmem {
+ struct device_d *dev;
+ const struct resource *mem;
+};
+
+static int rmem_read(void *context, unsigned int offset,
+ void *val, size_t bytes)
+{
+ struct rmem *rmem = context;
+ return mem_copy(rmem->dev, val, (void *)rmem->mem->start + offset,
+ bytes, offset, 0);
+}
+
+static struct nvmem_bus rmem_nvmem_bus = {
+ .read = rmem_read,
+};
+
+static int rmem_probe(struct device_d *dev)
+{
+ struct nvmem_config config = { };
+ struct resource *mem;
+ struct rmem *priv;
+
+ mem = dev_request_mem_resource(dev, 0);
+ if (IS_ERR(mem))
+ return PTR_ERR(mem);
+
+ priv = kzalloc(sizeof(*priv), GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+
+ priv->mem = mem;
+
+ config.dev = priv->dev = dev;
+ config.priv = priv;
+ config.name = "rmem";
+ config.size = resource_size(mem);
+ config.bus = &rmem_nvmem_bus;
+
+ return PTR_ERR_OR_ZERO(nvmem_register(&config));
+}
+
+static const struct of_device_id rmem_match[] = {
+ { .compatible = "nvmem-rmem", },
+ { /* sentinel */ },
+};
+
+static struct driver_d rmem_driver = {
+ .name = "rmem",
+ .of_compatible = rmem_match,
+ .probe = rmem_probe,
+};
+device_platform_driver(rmem_driver);
+
+MODULE_AUTHOR("Nicolas Saenz Julienne <nsaenzjulienne@xxxxxxx>");
+MODULE_DESCRIPTION("Reserved Memory Based nvmem Driver");
+MODULE_LICENSE("GPL");
diff --git a/drivers/of/base.c b/drivers/of/base.c
index 193bae7fa017..015629e1e967 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -2331,9 +2331,14 @@ static void of_platform_device_create_root(struct device_node *np)
free(dev);
}
+static const struct of_device_id reserved_mem_matches[] = {
+ { .compatible = "nvmem-rmem" },
+ {}
+};
+
int of_probe(void)
{
- struct device_node *firmware;
+ struct device_node *node;
int ret;
if(!root_node)
@@ -2347,9 +2352,17 @@ int of_probe(void)
ret = of_probe_memory();
- firmware = of_find_node_by_path("/firmware");
- if (firmware)
- of_platform_populate(firmware, NULL, NULL);
+ /*
+ * Handle certain compatibles explicitly, since we don't want to create
+ * platform_devices for every node in /reserved-memory with a
+ * "compatible",
+ */
+ for_each_matching_node(node, reserved_mem_matches)
+ of_platform_device_create(node, NULL);
+
+ node = of_find_node_by_path("/firmware");
+ if (node)
+ of_platform_populate(node, NULL, NULL);
of_platform_device_create_root(root_node);
diff --git a/fs/devfs-core.c b/fs/devfs-core.c
index f804f969745c..30ad0e050835 100644
--- a/fs/devfs-core.c
+++ b/fs/devfs-core.c
@@ -529,7 +529,7 @@ void cdev_remove_loop(struct cdev *cdev)
free(cdev);
}
-static ssize_t mem_copy(struct device_d *dev, void *dst, const void *src,
+ssize_t mem_copy(struct device_d *dev, void *dst, const void *src,
resource_size_t count, resource_size_t offset,
unsigned long flags)
{
diff --git a/include/driver.h b/include/driver.h
index d84fe35d5063..c7f5903fcea0 100644
--- a/include/driver.h
+++ b/include/driver.h
@@ -347,6 +347,9 @@ struct cdev;
/* These are used by drivers which work with direct memory accesses */
ssize_t mem_read(struct cdev *cdev, void *buf, size_t count, loff_t offset, ulong flags);
ssize_t mem_write(struct cdev *cdev, const void *buf, size_t count, loff_t offset, ulong flags);
+ssize_t mem_copy(struct device_d *dev, void *dst, const void *src,
+ resource_size_t count, resource_size_t offset,
+ unsigned long flags);
int generic_memmap_ro(struct cdev *dev, void **map, int flags);
int generic_memmap_rw(struct cdev *dev, void **map, int flags);
--
2.29.2
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