target/linux/generic/pending-4.19/497-mtd-mtdconcat-add-dt-driver-for-concat-devices.patch

   1 From e53f712d8eac71f54399b61038ccf87d2cee99d7 Mon Sep 17 00:00:00 2001
   2 From: Bernhard Frauendienst <kernel@nospam.obeliks.de>
   3 Date: Sat, 25 Aug 2018 12:35:22 +0200
   4 Subject: [PATCH 497/497] mtd: mtdconcat: add dt driver for concat devices
   5
   6 Some mtd drivers like physmap variants have support for concatenating
   7 multiple mtd devices, but there is no generic way to define such a
   8 concat device from within the device tree.
   9
  10 This is useful for some SoC boards that use multiple flash chips as
  11 memory banks of a single mtd device, with partitions spanning chip
  12 borders.
  13
  14 This commit adds a driver for creating virtual mtd-concat devices. They
  15 must have a compatible = "mtd-concat" line, and define a list of devices
  16 to concat in the 'devices' property, for example:
  17
  18 flash {
  19   compatible = "mtd-concat";
  20
  21   devices = <&flash0 &flash1>;
  22
  23   partitions {
  24     ...
  25   };
  26 };
  27
  28 The driver is added to the very end of the mtd Makefile to increase the
  29 likelyhood of all child devices already being loaded at the time of
  30 probing, preventing unnecessary deferred probes.
  31
  32 Signed-off-by: Bernhard Frauendienst <kernel@nospam.obeliks.de>
  33 ---
  34  drivers/mtd/Kconfig                 |   2 +
  35  drivers/mtd/Makefile                |   3 +
  36  drivers/mtd/composite/Kconfig       |  12 +++
  37  drivers/mtd/composite/Makefile      |   6 ++
  38  drivers/mtd/composite/virt_concat.c | 128 ++++++++++++++++++++++++++++
  39  5 files changed, 151 insertions(+)
  40  create mode 100644 drivers/mtd/composite/Kconfig
  41  create mode 100644 drivers/mtd/composite/Makefile
  42  create mode 100644 drivers/mtd/composite/virt_concat.c
  43
  44 --- a/drivers/mtd/Kconfig
  45 +++ b/drivers/mtd/Kconfig
  46 @@ -374,4 +374,6 @@ source "drivers/mtd/spi-nor/Kconfig"
  47
  48  source "drivers/mtd/ubi/Kconfig"
  49
  50 +source "drivers/mtd/composite/Kconfig"
  51 +
  52  endif # MTD
  53 --- a/drivers/mtd/Makefile
  54 +++ b/drivers/mtd/Makefile
  55 @@ -39,3 +39,6 @@ obj-y         += chips/ lpddr/ maps/ devices/ n
  56
  57  obj-$(CONFIG_MTD_SPI_NOR)      += spi-nor/
  58  obj-$(CONFIG_MTD_UBI)          += ubi/
  59 +
  60 +# Composite drivers must be loaded last
  61 +obj-y          += composite/
  62 --- /dev/null
  63 +++ b/drivers/mtd/composite/Kconfig
  64 @@ -0,0 +1,12 @@
  65 +menu "Composite MTD device drivers"
  66 +       depends on MTD!=n
  67 +
  68 +config MTD_VIRT_CONCAT
  69 +       tristate "Virtual concat MTD device"
  70 +       help
  71 +         This driver allows creation of a virtual MTD concat device, which
  72 +         concatenates multiple underlying MTD devices to a single device.
  73 +         This is required by some SoC boards where multiple memory banks are
  74 +         used as one device with partitions spanning across device boundaries.
  75 +
  76 +endmenu
  77 --- /dev/null
  78 +++ b/drivers/mtd/composite/Makefile
  79 @@ -0,0 +1,6 @@
  80 +# SPDX-License-Identifier: GPL-2.0
  81 +#
  82 +# linux/drivers/mtd/composite/Makefile
  83 +#
  84 +
  85 +obj-$(CONFIG_MTD_VIRT_CONCAT)   += virt_concat.o
  86 --- /dev/null
  87 +++ b/drivers/mtd/composite/virt_concat.c
  88 @@ -0,0 +1,128 @@
  89 +// SPDX-License-Identifier: GPL-2.0+
  90 +/*
  91 + * Virtual concat MTD device driver
  92 + *
  93 + * Copyright (C) 2018 Bernhard Frauendienst
  94 + * Author: Bernhard Frauendienst, kernel@nospam.obeliks.de
  95 + */
  96 +
  97 +#include <linux/module.h>
  98 +#include <linux/device.h>
  99 +#include <linux/mtd/concat.h>
 100 +#include <linux/mtd/mtd.h>
 101 +#include <linux/mtd/partitions.h>
 102 +#include <linux/of.h>
 103 +#include <linux/of_platform.h>
 104 +#include <linux/slab.h>
 105 +
 106 +/*
 107 + * struct of_virt_concat - platform device driver data.
 108 + * @cmtd the final mtd_concat device
 109 + * @num_devices the number of devices in @devices
 110 + * @devices points to an array of devices already loaded
 111 + */
 112 +struct of_virt_concat {
 113 +       struct mtd_info *cmtd;
 114 +       int num_devices;
 115 +       struct mtd_info **devices;
 116 +};
 117 +
 118 +static int virt_concat_remove(struct platform_device *pdev)
 119 +{
 120 +       struct of_virt_concat *info;
 121 +       int i;
 122 +
 123 +       info = platform_get_drvdata(pdev);
 124 +       if (!info)
 125 +               return 0;
 126 +
 127 +       // unset data for when this is called after a probe error
 128 +       platform_set_drvdata(pdev, NULL);
 129 +
 130 +       if (info->cmtd) {
 131 +               mtd_device_unregister(info->cmtd);
 132 +               mtd_concat_destroy(info->cmtd);
 133 +       }
 134 +
 135 +       if (info->devices) {
 136 +               for (i = 0; i < info->num_devices; i++)
 137 +                       put_mtd_device(info->devices[i]);
 138 +       }
 139 +
 140 +       return 0;
 141 +}
 142 +
 143 +static int virt_concat_probe(struct platform_device *pdev)
 144 +{
 145 +       struct device_node *node = pdev->dev.of_node;
 146 +       struct of_phandle_iterator it;
 147 +       struct of_virt_concat *info;
 148 +       struct mtd_info *mtd;
 149 +       int err = 0, count;
 150 +
 151 +       count = of_count_phandle_with_args(node, "devices", NULL);
 152 +       if (count <= 0)
 153 +               return -EINVAL;
 154 +
 155 +       info = devm_kzalloc(&pdev->dev, sizeof(*info), GFP_KERNEL);
 156 +       if (!info)
 157 +               return -ENOMEM;
 158 +       info->devices = devm_kcalloc(&pdev->dev, count,
 159 +                                    sizeof(*(info->devices)), GFP_KERNEL);
 160 +       if (!info->devices) {
 161 +               err = -ENOMEM;
 162 +               goto err_remove;
 163 +       }
 164 +
 165 +       platform_set_drvdata(pdev, info);
 166 +
 167 +       of_for_each_phandle(&it, err, node, "devices", NULL, 0) {
 168 +               mtd = get_mtd_device_by_node(it.node);
 169 +               if (IS_ERR(mtd)) {
 170 +                       of_node_put(it.node);
 171 +                       err = -EPROBE_DEFER;
 172 +                       goto err_remove;
 173 +               }
 174 +
 175 +               info->devices[info->num_devices++] = mtd;
 176 +       }
 177 +
 178 +       info->cmtd = mtd_concat_create(info->devices, info->num_devices,
 179 +                                      dev_name(&pdev->dev));
 180 +       if (!info->cmtd) {
 181 +               err = -ENXIO;
 182 +               goto err_remove;
 183 +       }
 184 +
 185 +       info->cmtd->dev.parent = &pdev->dev;
 186 +       mtd_set_of_node(info->cmtd, node);
 187 +       mtd_device_register(info->cmtd, NULL, 0);
 188 +
 189 +       return 0;
 190 +
 191 +err_remove:
 192 +       virt_concat_remove(pdev);
 193 +
 194 +       return err;
 195 +}
 196 +
 197 +static const struct of_device_id virt_concat_of_match[] = {
 198 +       { .compatible = "mtd-concat", },
 199 +       { /* sentinel */ }
 200 +};
 201 +MODULE_DEVICE_TABLE(of, virt_concat_of_match);
 202 +
 203 +static struct platform_driver virt_concat_driver = {
 204 +       .probe = virt_concat_probe,
 205 +       .remove = virt_concat_remove,
 206 +       .driver  = {
 207 +               .name   = "virt-mtdconcat",
 208 +               .of_match_table = virt_concat_of_match,
 209 +       },
 210 +};
 211 +
 212 +module_platform_driver(virt_concat_driver);
 213 +
 214 +MODULE_LICENSE("GPL v2");
 215 +MODULE_AUTHOR("Bernhard Frauendienst <kernel@nospam.obeliks.de>");
 216 +MODULE_DESCRIPTION("Virtual concat MTD device driver");