Hi everybody,
when porting my router board from a mach-file based OpenWRT target to a
device-tree based target, I found that there is no generic way to create
a mtd_concat device from within the dts. The following patches attempt
to provide that possibility.
This is a second roll of that patch series, the first one can be seen at
[1]. Apologies for not including the correct recipients in the first
roll.
In this first discussion, concerns were raised that a driver for a
"virtual" device like this might have no place in the device tree
system. However, I would argue that this very similar to specifying the
partitions of a mtd device, which can also done in the device tree. In
fact, I believe this is the only way to be able to specify the
partitions of such a concat device in the dts file (but I'm happy to be
corrected if I'm mistaken).
I have made the example in the dt-binding documentation a little bit
more expressive in this detail.
In this second roll I have also addressed all issues that reviewers have
brought up so far, hopefully to their satisfaction.
Best Regards
Bernhard
[1] http://lists.infradead.org/pipermail/linux-mtd/2018-September/083832.html
Bernhard Frauendienst (3):
mtd: core: add get_mtd_device_by_node
dt-bindings: add bindings for mtd-concat devices
mtd: mtdconcat: add dt driver for concat devices
.../devicetree/bindings/mtd/mtd-concat.txt | 36 +++++
drivers/mtd/Kconfig | 2 +
drivers/mtd/Makefile | 3 +
drivers/mtd/composite/Kconfig | 12 ++
drivers/mtd/composite/Makefile | 7 +
drivers/mtd/composite/virt_concat.c | 128 ++++++++++++++++++
drivers/mtd/mtdcore.c | 38 ++++++
include/linux/mtd/mtd.h | 2 +
8 files changed, 228 insertions(+)
create mode 100644 Documentation/devicetree/bindings/mtd/mtd-concat.txt
create mode 100644 drivers/mtd/composite/Kconfig
create mode 100644 drivers/mtd/composite/Makefile
create mode 100644 drivers/mtd/composite/virt_concat.c
--
2.17.1
Some mtd drivers like physmap variants have support for concatenating
multiple mtd devices, but there is no generic way to define such a
concat device from within the device tree.
This is useful for some SoC boards that use multiple flash chips as
memory banks of a single mtd device, with partitions spanning chip
borders.
This commit adds a driver for creating virtual mtd-concat devices. They
must have a compatible = "mtd-concat" line, and define a list of devices
to concat in the 'devices' property, for example:
flash {
compatible = "mtd-concat";
devices = <&flash0 &flash1>;
partitions {
...
};
};
The driver is added to the very end of the mtd Makefile to increase the
likelyhood of all child devices already being loaded at the time of
probing, preventing unnecessary deferred probes.
Signed-off-by: Bernhard Frauendienst <[email protected]>
---
drivers/mtd/Kconfig | 2 +
drivers/mtd/Makefile | 3 +
drivers/mtd/composite/Kconfig | 12 +++
drivers/mtd/composite/Makefile | 7 ++
drivers/mtd/composite/virt_concat.c | 128 ++++++++++++++++++++++++++++
5 files changed, 152 insertions(+)
create mode 100644 drivers/mtd/composite/Kconfig
create mode 100644 drivers/mtd/composite/Makefile
create mode 100644 drivers/mtd/composite/virt_concat.c
diff --git a/drivers/mtd/Kconfig b/drivers/mtd/Kconfig
index c77f537323ec..6345d886d458 100644
--- a/drivers/mtd/Kconfig
+++ b/drivers/mtd/Kconfig
@@ -339,4 +339,6 @@ source "drivers/mtd/spi-nor/Kconfig"
source "drivers/mtd/ubi/Kconfig"
+source "drivers/mtd/composite/Kconfig"
+
endif # MTD
diff --git a/drivers/mtd/Makefile b/drivers/mtd/Makefile
index 93473d215a38..57af7190b063 100644
--- a/drivers/mtd/Makefile
+++ b/drivers/mtd/Makefile
@@ -36,3 +36,6 @@ obj-y += chips/ lpddr/ maps/ devices/ nand/ tests/
obj-$(CONFIG_MTD_SPI_NOR) += spi-nor/
obj-$(CONFIG_MTD_UBI) += ubi/
+
+# Composite drivers must be loaded last
+obj-y += composite/
diff --git a/drivers/mtd/composite/Kconfig b/drivers/mtd/composite/Kconfig
new file mode 100644
index 000000000000..0490fc0284bb
--- /dev/null
+++ b/drivers/mtd/composite/Kconfig
@@ -0,0 +1,12 @@
+menu "Composite MTD device drivers"
+ depends on MTD!=n
+
+config MTD_VIRT_CONCAT
+ tristate "Virtual concat MTD device"
+ help
+ This driver allows creation of a virtual MTD concat device, which
+ concatenates multiple underlying MTD devices to a single device.
+ This is required by some SoC boards where multiple memory banks are
+ used as one device with partitions spanning across device boundaries.
+
+endmenu
diff --git a/drivers/mtd/composite/Makefile b/drivers/mtd/composite/Makefile
new file mode 100644
index 000000000000..7f4bdeee0e0a
--- /dev/null
+++ b/drivers/mtd/composite/Makefile
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# linux/drivers/mtd/composite/Makefile
+#
+
+obj-$(CONFIG_MTD_VIRT_CONCAT) += virt_concat.o
+
diff --git a/drivers/mtd/composite/virt_concat.c b/drivers/mtd/composite/virt_concat.c
new file mode 100644
index 000000000000..76918d4ef07f
--- /dev/null
+++ b/drivers/mtd/composite/virt_concat.c
@@ -0,0 +1,128 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Virtual concat MTD device driver
+ *
+ * Copyright (C) 2018 Bernhard Frauendienst
+ * Author: Bernhard Frauendienst, [email protected]
+ */
+
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/mtd/concat.h>
+#include <linux/mtd/mtd.h>
+#include <linux/mtd/partitions.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/slab.h>
+
+/*
+ * struct of_virt_concat - platform device driver data.
+ * @cmtd the final mtd_concat device
+ * @num_devices the number of devices in @devices
+ * @devices array of devices already loaded
+ */
+struct of_virt_concat {
+ struct mtd_info *cmtd;
+ int num_devices;
+ struct mtd_info **devices;
+};
+
+static int virt_concat_remove(struct platform_device *pdev)
+{
+ struct of_virt_concat *info;
+ int i;
+
+ info = platform_get_drvdata(pdev);
+ if (!info)
+ return 0;
+
+ // unset data for when this is called after a probe error
+ platform_set_drvdata(pdev, NULL);
+
+ if (info->cmtd) {
+ mtd_device_unregister(info->cmtd);
+ mtd_concat_destroy(info->cmtd);
+ }
+
+ if (info->devices) {
+ for (i = 0; i < info->num_devices; i++)
+ put_mtd_device(info->devices[i]);
+ }
+
+ return 0;
+}
+
+static int virt_concat_probe(struct platform_device *pdev)
+{
+ struct device_node *node = pdev->dev.of_node;
+ struct of_phandle_iterator it;
+ struct of_virt_concat *info;
+ struct mtd_info *mtd;
+ int err = 0, count;
+
+ count = of_count_phandle_with_args(node, "devices", NULL);
+ if (count <= 0)
+ return -EINVAL;
+
+ info = devm_kzalloc(&pdev->dev, sizeof(*info), GFP_KERNEL);
+ if (!info)
+ return -ENOMEM;
+ info->devices = devm_kcalloc(&pdev->dev, count,
+ sizeof(*(info->devices)), GFP_KERNEL);
+ if (!info->devices) {
+ err = -ENOMEM;
+ goto err_remove;
+ }
+
+ platform_set_drvdata(pdev, info);
+
+ of_for_each_phandle(&it, err, node, "devices", NULL, 0) {
+ mtd = get_mtd_device_by_node(it.node);
+ if (IS_ERR(mtd)) {
+ of_node_put(it.node);
+ err = -EPROBE_DEFER;
+ goto err_remove;
+ }
+
+ info->devices[info->num_devices++] = mtd;
+ }
+
+ info->cmtd = mtd_concat_create(info->devices, info->num_devices,
+ dev_name(&pdev->dev));
+ if (!info->cmtd) {
+ err = -ENXIO;
+ goto err_remove;
+ }
+
+ info->cmtd->dev.parent = &pdev->dev;
+ mtd_set_of_node(info->cmtd, node);
+ mtd_device_register(info->cmtd, NULL, 0);
+
+ return 0;
+
+err_remove:
+ virt_concat_remove(pdev);
+
+ return err;
+}
+
+static const struct of_device_id virt_concat_of_match[] = {
+ { .compatible = "mtd-concat", },
+ { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, virt_concat_of_match);
+
+static struct platform_driver virt_concat_driver = {
+ .probe = virt_concat_probe,
+ .remove = virt_concat_remove,
+ .driver = {
+ .name = "virt-mtdconcat",
+ .of_match_table = virt_concat_of_match,
+ },
+};
+
+module_platform_driver(virt_concat_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Bernhard Frauendienst <[email protected]>");
+MODULE_DESCRIPTION("Virtual concat MTD device driver");
--
2.17.1
Add function to retrieve a mtd device by its OF node. Since drivers can
assign arbitrary names to mtd devices in the absence of a label
property, there is no other reliable way to retrieve a mtd device for a
given OF node.
Signed-off-by: Bernhard Frauendienst <[email protected]>
Reviewed-by: Miquel Raynal <[email protected]>
---
drivers/mtd/mtdcore.c | 38 ++++++++++++++++++++++++++++++++++++++
include/linux/mtd/mtd.h | 2 ++
2 files changed, 40 insertions(+)
diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index 97ac219c082e..87dd63926bc9 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -926,6 +926,44 @@ struct mtd_info *get_mtd_device_nm(const char *name)
}
EXPORT_SYMBOL_GPL(get_mtd_device_nm);
+/**
+ * get_mtd_device_by_node - obtain a validated handle for an MTD device
+ * by of_node
+ * @of_node: OF node of MTD device to open
+ *
+ * This function returns MTD device description structure in case of
+ * success and an error code in case of failure.
+ */
+struct mtd_info *get_mtd_device_by_node(const struct device_node *of_node)
+{
+ int err = -ENODEV;
+ struct mtd_info *mtd = NULL, *other;
+
+ mutex_lock(&mtd_table_mutex);
+
+ mtd_for_each_device(other) {
+ if (of_node == other->dev.of_node) {
+ mtd = other;
+ break;
+ }
+ }
+
+ if (!mtd)
+ goto out_unlock;
+
+ err = __get_mtd_device(mtd);
+ if (err)
+ goto out_unlock;
+
+ mutex_unlock(&mtd_table_mutex);
+ return mtd;
+
+out_unlock:
+ mutex_unlock(&mtd_table_mutex);
+ return ERR_PTR(err);
+}
+EXPORT_SYMBOL_GPL(get_mtd_device_by_node);
+
void put_mtd_device(struct mtd_info *mtd)
{
mutex_lock(&mtd_table_mutex);
diff --git a/include/linux/mtd/mtd.h b/include/linux/mtd/mtd.h
index cd0be91bdefa..fe71358f8eaa 100644
--- a/include/linux/mtd/mtd.h
+++ b/include/linux/mtd/mtd.h
@@ -570,6 +570,8 @@ extern struct mtd_info *get_mtd_device(struct mtd_info *mtd, int num);
extern int __get_mtd_device(struct mtd_info *mtd);
extern void __put_mtd_device(struct mtd_info *mtd);
extern struct mtd_info *get_mtd_device_nm(const char *name);
+extern struct mtd_info *get_mtd_device_by_node(
+ const struct device_node *of_node);
extern void put_mtd_device(struct mtd_info *mtd);
--
2.17.1
Signed-off-by: Bernhard Frauendienst <[email protected]>
---
.../devicetree/bindings/mtd/mtd-concat.txt | 36 +++++++++++++++++++
1 file changed, 36 insertions(+)
create mode 100644 Documentation/devicetree/bindings/mtd/mtd-concat.txt
diff --git a/Documentation/devicetree/bindings/mtd/mtd-concat.txt b/Documentation/devicetree/bindings/mtd/mtd-concat.txt
new file mode 100644
index 000000000000..2daf3157b163
--- /dev/null
+++ b/Documentation/devicetree/bindings/mtd/mtd-concat.txt
@@ -0,0 +1,36 @@
+Virtual MTD concat device
+
+Requires properties:
+- devices: list of phandles to mtd nodes that should be concatenated
+
+Example:
+
+&spi {
+ flash0: flash@0 {
+ ...
+ };
+ flash1: flash@1 {
+ ...
+ };
+};
+
+flash {
+ compatible = "mtd-concat";
+
+ devices = <&flash0 &flash1>;
+
+ partitions {
+ compatible = "fixed-partitions";
+
+ partition@0 {
+ label = "boot";
+ reg = <0x0000000 0x0040000>;
+ read-only;
+ };
+
+ partition@40000 {
+ label = "firmware";
+ reg = <0x0040000 0x1fc0000>;
+ };
+ }
+}
--
2.17.1
Apologies, again, I seem not to be able to handle git-send-mail
correctly, the cover letter got lost in operation (using get_maintainers
on a cover letter is not a good idea). Here it is again:
Hi everybody,
when porting my router board from a mach-file based OpenWRT target to a
device-tree based target, I found that there is no generic way to create
a mtd_concat device from within the dts. The following patches attempt
to provide that possibility.
This is a second roll of that patch series, the first one can be seen at
[1]. Apologies for not including the correct recipients in the first
roll.
In this first discussion, concerns were raised that a driver for a
"virtual" device like this might have no place in the device tree
system. However, I would argue that this very similar to specifying the
partitions of a mtd device, which can also done in the device tree. In
fact, I believe this is the only way to be able to specify the
partitions of such a concat device in the dts file (but I'm happy to be
corrected if I'm mistaken).
I have made the example in the dt-binding documentation a little bit
more expressive in this detail.
In this second roll I have also addressed all issues that reviewers have
brought up so far, hopefully to their satisfaction.
Best Regards
Bernhard
[1]
http://lists.infradead.org/pipermail/linux-mtd/2018-September/083832.html
Bernhard Frauendienst (3):
mtd: core: add get_mtd_device_by_node
dt-bindings: add bindings for mtd-concat devices
mtd: mtdconcat: add dt driver for concat devices
.../devicetree/bindings/mtd/mtd-concat.txt | 36 +++++
drivers/mtd/Kconfig | 2 +
drivers/mtd/Makefile | 3 +
drivers/mtd/composite/Kconfig | 12 ++
drivers/mtd/composite/Makefile | 7 +
drivers/mtd/composite/virt_concat.c | 128 ++++++++++++++++++
drivers/mtd/mtdcore.c | 38 ++++++
include/linux/mtd/mtd.h | 2 +
8 files changed, 228 insertions(+)
create mode 100644 Documentation/devicetree/bindings/mtd/mtd-concat.txt
create mode 100644 drivers/mtd/composite/Kconfig
create mode 100644 drivers/mtd/composite/Makefile
create mode 100644 drivers/mtd/composite/virt_concat.c
--
2.17.1
Hello,
it looks like I didn't even manage to correctly CC the device tree
maintainers and list, which was the main reason for sending out this
second roll. This is getting embarrassing, but I guess I will simply
prepare a 3rd roll and try even harder to send it to the right people
this time (without relying on any script magic).
Of course I'm happy to include any suggestions you have in the meantime.
Sorry for the disturbance!
Best regards,
Bernhard
Am 07.09.2018 um 20:12 schrieb Bernhard Frauendienst:
> Apologies, again, I seem not to be able to handle git-send-mail > correctly, the cover letter got lost in operation (using
get_maintainers > on a cover letter is not a good idea). Here it is
again: > > > Hi everybody, > > when porting my router board from a
mach-file based OpenWRT target to a > device-tree based target, I found
that there is no generic way to create > a mtd_concat device from within
the dts. The following patches attempt > to provide that possibility. >
> This is a second roll of that patch series, the first one can be seen
at > [1]. Apologies for not including the correct recipients in the
first > roll. > > In this first discussion, concerns were raised that a
driver for a > "virtual" device like this might have no place in the
device tree > system. However, I would argue that this very similar to
specifying the > partitions of a mtd device, which can also done in the
device tree. In > fact, I believe this is the only way to be able to
specify the > partitions of such a concat device in the dts file (but
I'm happy to be > corrected if I'm mistaken). > I have made the example
in the dt-binding documentation a little bit > more expressive in this
detail. > > In this second roll I have also addressed all issues that
reviewers have > brought up so far, hopefully to their satisfaction. > >
Best Regards > Bernhard > > [1]
http://lists.infradead.org/pipermail/linux-mtd/2018-September/083832.html
> > > Bernhard Frauendienst (3): > mtd: core: add
get_mtd_device_by_node > dt-bindings: add bindings for mtd-concat
devices > mtd: mtdconcat: add dt driver for concat devices > >
.../devicetree/bindings/mtd/mtd-concat.txt | 36 +++++ >
drivers/mtd/Kconfig | 2 + > drivers/mtd/Makefile | 3 + >
drivers/mtd/composite/Kconfig | 12 ++ > drivers/mtd/composite/Makefile |
7 + > drivers/mtd/composite/virt_concat.c | 128 ++++++++++++++++++ >
drivers/mtd/mtdcore.c | 38 ++++++ > include/linux/mtd/mtd.h | 2 + > 8
files changed, 228 insertions(+) > create mode 100644
Documentation/devicetree/bindings/mtd/mtd-concat.txt > create mode
100644 drivers/mtd/composite/Kconfig > create mode 100644
drivers/mtd/composite/Makefile > create mode 100644
drivers/mtd/composite/virt_concat.c >