target/linux/generic/pending-4.14/497-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 diff --git a/drivers/mtd/Kconfig b/drivers/mtd/Kconfig
  45 index 5a2d71729b9a..de18bc568e3e 100644
  46 --- a/drivers/mtd/Kconfig
  47 +++ b/drivers/mtd/Kconfig
  48 @@ -342,4 +342,6 @@ source "drivers/mtd/spi-nor/Kconfig"
  49
  50  source "drivers/mtd/ubi/Kconfig"
  51
  52 +source "drivers/mtd/composite/Kconfig"
  53 +
  54  endif # MTD
  55 diff --git a/drivers/mtd/Makefile b/drivers/mtd/Makefile
  56 index d6f8f625e1ff..a6c5f134c35d 100644
  57 --- a/drivers/mtd/Makefile
  58 +++ b/drivers/mtd/Makefile
  59 @@ -36,3 +36,6 @@ obj-y         += chips/ lpddr/ maps/ devices/ nand/ onenand/ tests/
  60
  61  obj-$(CONFIG_MTD_SPI_NOR)      += spi-nor/
  62  obj-$(CONFIG_MTD_UBI)          += ubi/
  63 +
  64 +# Composite drivers must be loaded last
  65 +obj-y          += composite/
  66 diff --git a/drivers/mtd/composite/Kconfig b/drivers/mtd/composite/Kconfig
  67 new file mode 100644
  68 index 000000000000..0490fc0284bb
  69 --- /dev/null
  70 +++ b/drivers/mtd/composite/Kconfig
  71 @@ -0,0 +1,12 @@
  72 +menu "Composite MTD device drivers"
  73 +       depends on MTD!=n
  74 +
  75 +config MTD_VIRT_CONCAT
  76 +       tristate "Virtual concat MTD device"
  77 +       help
  78 +         This driver allows creation of a virtual MTD concat device, which
  79 +         concatenates multiple underlying MTD devices to a single device.
  80 +         This is required by some SoC boards where multiple memory banks are
  81 +         used as one device with partitions spanning across device boundaries.
  82 +
  83 +endmenu
  84 diff --git a/drivers/mtd/composite/Makefile b/drivers/mtd/composite/Makefile
  85 new file mode 100644
  86 index 000000000000..8421a0a30606
  87 --- /dev/null
  88 +++ b/drivers/mtd/composite/Makefile
  89 @@ -0,0 +1,6 @@
  90 +# SPDX-License-Identifier: GPL-2.0
  91 +#
  92 +# linux/drivers/mtd/composite/Makefile
  93 +#
  94 +
  95 +obj-$(CONFIG_MTD_VIRT_CONCAT)   += virt_concat.o
  96 diff --git a/drivers/mtd/composite/virt_concat.c b/drivers/mtd/composite/virt_concat.c
  97 new file mode 100644
  98 index 000000000000..bfd432188c35
  99 --- /dev/null
 100 +++ b/drivers/mtd/composite/virt_concat.c
 101 @@ -0,0 +1,128 @@
 102 +// SPDX-License-Identifier: GPL-2.0+
 103 +/*
 104 + * Virtual concat MTD device driver
 105 + *
 106 + * Copyright (C) 2018 Bernhard Frauendienst
 107 + * Author: Bernhard Frauendienst, kernel@nospam.obeliks.de
 108 + */
 109 +
 110 +#include <linux/module.h>
 111 +#include <linux/device.h>
 112 +#include <linux/mtd/concat.h>
 113 +#include <linux/mtd/mtd.h>
 114 +#include <linux/mtd/partitions.h>
 115 +#include <linux/of.h>
 116 +#include <linux/of_platform.h>
 117 +#include <linux/slab.h>
 118 +
 119 +/*
 120 + * struct of_virt_concat - platform device driver data.
 121 + * @cmtd the final mtd_concat device
 122 + * @num_devices the number of devices in @devices
 123 + * @devices points to an array of devices already loaded
 124 + */
 125 +struct of_virt_concat {
 126 +       struct mtd_info *cmtd;
 127 +       int num_devices;
 128 +       struct mtd_info **devices;
 129 +};
 130 +
 131 +static int virt_concat_remove(struct platform_device *pdev)
 132 +{
 133 +       struct of_virt_concat *info;
 134 +       int i;
 135 +
 136 +       info = platform_get_drvdata(pdev);
 137 +       if (!info)
 138 +               return 0;
 139 +
 140 +       // unset data for when this is called after a probe error
 141 +       platform_set_drvdata(pdev, NULL);
 142 +
 143 +       if (info->cmtd) {
 144 +               mtd_device_unregister(info->cmtd);
 145 +               mtd_concat_destroy(info->cmtd);
 146 +       }
 147 +
 148 +       if (info->devices) {
 149 +               for (i = 0; i < info->num_devices; i++)
 150 +                       put_mtd_device(info->devices[i]);
 151 +       }
 152 +
 153 +       return 0;
 154 +}
 155 +
 156 +static int virt_concat_probe(struct platform_device *pdev)
 157 +{
 158 +       struct device_node *node = pdev->dev.of_node;
 159 +       struct of_phandle_iterator it;
 160 +       struct of_virt_concat *info;
 161 +       struct mtd_info *mtd;
 162 +       int err = 0, count;
 163 +
 164 +       count = of_count_phandle_with_args(node, "devices", NULL);
 165 +       if (count <= 0)
 166 +               return -EINVAL;
 167 +
 168 +       info = devm_kzalloc(&pdev->dev, sizeof(*info), GFP_KERNEL);
 169 +       if (!info)
 170 +               return -ENOMEM;
 171 +       info->devices = devm_kcalloc(&pdev->dev, count,
 172 +                                    sizeof(*(info->devices)), GFP_KERNEL);
 173 +       if (!info->devices) {
 174 +               err = -ENOMEM;
 175 +               goto err_remove;
 176 +       }
 177 +
 178 +       platform_set_drvdata(pdev, info);
 179 +
 180 +       of_for_each_phandle(&it, err, node, "devices", NULL, 0) {
 181 +               mtd = get_mtd_device_by_node(it.node);
 182 +               if (IS_ERR(mtd)) {
 183 +                       of_node_put(it.node);
 184 +                       err = -EPROBE_DEFER;
 185 +                       goto err_remove;
 186 +               }
 187 +
 188 +               info->devices[info->num_devices++] = mtd;
 189 +       }
 190 +
 191 +       info->cmtd = mtd_concat_create(info->devices, info->num_devices,
 192 +                                      dev_name(&pdev->dev));
 193 +       if (!info->cmtd) {
 194 +               err = -ENXIO;
 195 +               goto err_remove;
 196 +       }
 197 +
 198 +       info->cmtd->dev.parent = &pdev->dev;
 199 +       mtd_set_of_node(info->cmtd, node);
 200 +       mtd_device_register(info->cmtd, NULL, 0);
 201 +
 202 +       return 0;
 203 +
 204 +err_remove:
 205 +       virt_concat_remove(pdev);
 206 +
 207 +       return err;
 208 +}
 209 +
 210 +static const struct of_device_id virt_concat_of_match[] = {
 211 +       { .compatible = "mtd-concat", },
 212 +       { /* sentinel */ }
 213 +};
 214 +MODULE_DEVICE_TABLE(of, virt_concat_of_match);
 215 +
 216 +static struct platform_driver virt_concat_driver = {
 217 +       .probe = virt_concat_probe,
 218 +       .remove = virt_concat_remove,
 219 +       .driver  = {
 220 +               .name   = "virt-mtdconcat",
 221 +               .of_match_table = virt_concat_of_match,
 222 +       },
 223 +};
 224 +
 225 +module_platform_driver(virt_concat_driver);
 226 +
 227 +MODULE_LICENSE("GPL v2");
 228 +MODULE_AUTHOR("Bernhard Frauendienst <kernel@nospam.obeliks.de>");
 229 +MODULE_DESCRIPTION("Virtual concat MTD device driver");
 230 --
 231 2.18.0
 232