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   1 From 5d8e6e6c10a3d37486d263b16ddc15991a7e4a88 Mon Sep 17 00:00:00 2001
   2 From: Michael Walle <michael@walle.cc>
   3 Date: Mon, 6 Feb 2023 13:43:46 +0000
   4 Subject: [PATCH] nvmem: core: add an index parameter to the cell
   5
   6 Sometimes a cell can represend multiple values. For example, a base
   7 ethernet address stored in the NVMEM can be expanded into multiple
   8 discreet ones by adding an offset.
   9
  10 For this use case, introduce an index parameter which is then used to
  11 distiguish between values. This parameter will then be passed to the
  12 post process hook which can then use it to create different values
  13 during reading.
  14
  15 At the moment, there is only support for the device tree path. You can
  16 add the index to the phandle, e.g.
  17
  18   &net {
  19           nvmem-cells = <&base_mac_address 2>;
  20           nvmem-cell-names = "mac-address";
  21   };
  22
  23   &nvmem_provider {
  24           base_mac_address: base-mac-address@0 {
  25                   #nvmem-cell-cells = <1>;
  26                   reg = <0 6>;
  27           };
  28   };
  29
  30 Signed-off-by: Michael Walle <michael@walle.cc>
  31 Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
  32 Link: https://lore.kernel.org/r/20230206134356.839737-13-srinivas.kandagatla@linaro.org
  33 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  34 ---
  35  drivers/nvmem/core.c           | 37 ++++++++++++++++++++++++----------
  36  drivers/nvmem/imx-ocotp.c      |  4 ++--
  37  include/linux/nvmem-provider.h |  4 ++--
  38  3 files changed, 30 insertions(+), 15 deletions(-)
  39
  40 --- a/drivers/nvmem/core.c
  41 +++ b/drivers/nvmem/core.c
  42 @@ -60,6 +60,7 @@ struct nvmem_cell_entry {
  43  struct nvmem_cell {
  44         struct nvmem_cell_entry *entry;
  45         const char              *id;
  46 +       int                     index;
  47  };
  48
  49  static DEFINE_MUTEX(nvmem_mutex);
  50 @@ -1122,7 +1123,8 @@ struct nvmem_device *devm_nvmem_device_g
  51  }
  52  EXPORT_SYMBOL_GPL(devm_nvmem_device_get);
  53
  54 -static struct nvmem_cell *nvmem_create_cell(struct nvmem_cell_entry *entry, const char *id)
  55 +static struct nvmem_cell *nvmem_create_cell(struct nvmem_cell_entry *entry,
  56 +                                           const char *id, int index)
  57  {
  58         struct nvmem_cell *cell;
  59         const char *name = NULL;
  60 @@ -1141,6 +1143,7 @@ static struct nvmem_cell *nvmem_create_c
  61
  62         cell->id = name;
  63         cell->entry = entry;
  64 +       cell->index = index;
  65
  66         return cell;
  67  }
  68 @@ -1179,7 +1182,7 @@ nvmem_cell_get_from_lookup(struct device
  69                                 __nvmem_device_put(nvmem);
  70                                 cell = ERR_PTR(-ENOENT);
  71                         } else {
  72 -                               cell = nvmem_create_cell(cell_entry, con_id);
  73 +                               cell = nvmem_create_cell(cell_entry, con_id, 0);
  74                                 if (IS_ERR(cell))
  75                                         __nvmem_device_put(nvmem);
  76                         }
  77 @@ -1227,15 +1230,27 @@ struct nvmem_cell *of_nvmem_cell_get(str
  78         struct nvmem_device *nvmem;
  79         struct nvmem_cell_entry *cell_entry;
  80         struct nvmem_cell *cell;
  81 +       struct of_phandle_args cell_spec;
  82         int index = 0;
  83 +       int cell_index = 0;
  84 +       int ret;
  85
  86         /* if cell name exists, find index to the name */
  87         if (id)
  88                 index = of_property_match_string(np, "nvmem-cell-names", id);
  89
  90 -       cell_np = of_parse_phandle(np, "nvmem-cells", index);
  91 -       if (!cell_np)
  92 -               return ERR_PTR(-ENOENT);
  93 +       ret = of_parse_phandle_with_optional_args(np, "nvmem-cells",
  94 +                                                 "#nvmem-cell-cells",
  95 +                                                 index, &cell_spec);
  96 +       if (ret)
  97 +               return ERR_PTR(ret);
  98 +
  99 +       if (cell_spec.args_count > 1)
 100 +               return ERR_PTR(-EINVAL);
 101 +
 102 +       cell_np = cell_spec.np;
 103 +       if (cell_spec.args_count)
 104 +               cell_index = cell_spec.args[0];
 105
 106         nvmem_np = of_get_parent(cell_np);
 107         if (!nvmem_np) {
 108 @@ -1257,7 +1272,7 @@ struct nvmem_cell *of_nvmem_cell_get(str
 109                 return ERR_PTR(-ENOENT);
 110         }
 111
 112 -       cell = nvmem_create_cell(cell_entry, id);
 113 +       cell = nvmem_create_cell(cell_entry, id, cell_index);
 114         if (IS_ERR(cell))
 115                 __nvmem_device_put(nvmem);
 116
 117 @@ -1410,8 +1425,8 @@ static void nvmem_shift_read_buffer_in_p
 118  }
 119
 120  static int __nvmem_cell_read(struct nvmem_device *nvmem,
 121 -                     struct nvmem_cell_entry *cell,
 122 -                     void *buf, size_t *len, const char *id)
 123 +                            struct nvmem_cell_entry *cell,
 124 +                            void *buf, size_t *len, const char *id, int index)
 125  {
 126         int rc;
 127
 128 @@ -1425,7 +1440,7 @@ static int __nvmem_cell_read(struct nvme
 129                 nvmem_shift_read_buffer_in_place(cell, buf);
 130
 131         if (nvmem->cell_post_process) {
 132 -               rc = nvmem->cell_post_process(nvmem->priv, id,
 133 +               rc = nvmem->cell_post_process(nvmem->priv, id, index,
 134                                               cell->offset, buf, cell->bytes);
 135                 if (rc)
 136                         return rc;
 137 @@ -1460,7 +1475,7 @@ void *nvmem_cell_read(struct nvmem_cell
 138         if (!buf)
 139                 return ERR_PTR(-ENOMEM);
 140
 141 -       rc = __nvmem_cell_read(nvmem, cell->entry, buf, len, cell->id);
 142 +       rc = __nvmem_cell_read(nvmem, cell->entry, buf, len, cell->id, cell->index);
 143         if (rc) {
 144                 kfree(buf);
 145                 return ERR_PTR(rc);
 146 @@ -1773,7 +1788,7 @@ ssize_t nvmem_device_cell_read(struct nv
 147         if (rc)
 148                 return rc;
 149
 150 -       rc = __nvmem_cell_read(nvmem, &cell, buf, &len, NULL);
 151 +       rc = __nvmem_cell_read(nvmem, &cell, buf, &len, NULL, 0);
 152         if (rc)
 153                 return rc;
 154
 155 --- a/drivers/nvmem/imx-ocotp.c
 156 +++ b/drivers/nvmem/imx-ocotp.c
 157 @@ -222,8 +222,8 @@ read_end:
 158         return ret;
 159  }
 160
 161 -static int imx_ocotp_cell_pp(void *context, const char *id, unsigned int offset,
 162 -                            void *data, size_t bytes)
 163 +static int imx_ocotp_cell_pp(void *context, const char *id, int index,
 164 +                            unsigned int offset, void *data, size_t bytes)
 165  {
 166         struct ocotp_priv *priv = context;
 167
 168 --- a/include/linux/nvmem-provider.h
 169 +++ b/include/linux/nvmem-provider.h
 170 @@ -20,8 +20,8 @@ typedef int (*nvmem_reg_read_t)(void *pr
 171  typedef int (*nvmem_reg_write_t)(void *priv, unsigned int offset,
 172                                  void *val, size_t bytes);
 173  /* used for vendor specific post processing of cell data */
 174 -typedef int (*nvmem_cell_post_process_t)(void *priv, const char *id, unsigned int offset,
 175 -                                         void *buf, size_t bytes);
 176 +typedef int (*nvmem_cell_post_process_t)(void *priv, const char *id, int index,
 177 +                                        unsigned int offset, void *buf, size_t bytes);
 178
 179  enum nvmem_type {
 180         NVMEM_TYPE_UNKNOWN = 0,