On Sat, Sep 8, 2018 at 8:20 AM Bernhard Frauendienst <kernel@xxxxxxxxxxxxxxxxx> wrote: > > 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. That is the generic way, but I suppose that only works for parallel memory mapped devices. So is it just spi-nor that you need to support? Can we just make reg take multiple chip selects just like the existing support takes multiple reg entries? > 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 <kernel@xxxxxxxxxxxxxxxxx> > --- > 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..8421a0a30606 > --- /dev/null > +++ b/drivers/mtd/composite/Makefile > @@ -0,0 +1,6 @@ > +# 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, kernel@xxxxxxxxxxxxxxxxx > + */ > + > +#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 points to an 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 <kernel@xxxxxxxxxxxxxxxxx>"); > +MODULE_DESCRIPTION("Virtual concat MTD device driver"); > -- > 2.18.0 >