drivers/nvmem/meson-efuse.c

   1 /*
   2  * Amlogic Meson GX eFuse Driver
   3  *
   4  * Copyright (c) 2016 Endless Computers, Inc.
   5  * Author: Carlo Caione <carlo@endlessm.com>
   6  *
   7  * This program is free software; you can redistribute it and/or modify it
   8  * under the terms of version 2 of the GNU General Public License as
   9  * published by the Free Software Foundation.
  10  *
  11  * This program is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
  14  * more details.
  15  */
  16
  17 #include <linux/clk.h>
  18 #include <linux/module.h>
  19 #include <linux/nvmem-provider.h>
  20 #include <linux/of.h>
  21 #include <linux/platform_device.h>
  22
  23 #include <linux/firmware/meson/meson_sm.h>
  24
  25 static int meson_efuse_read(void *context, unsigned int offset,
  26                             void *val, size_t bytes)
  27 {
  28         return meson_sm_call_read((u8 *)val, bytes, SM_EFUSE_READ, offset,
  29                                   bytes, 0, 0, 0);
  30 }
  31
  32 static int meson_efuse_write(void *context, unsigned int offset,
  33                              void *val, size_t bytes)
  34 {
  35         return meson_sm_call_write((u8 *)val, bytes, SM_EFUSE_WRITE, offset,
  36                                    bytes, 0, 0, 0);
  37 }
  38
  39 static const struct of_device_id meson_efuse_match[] = {
  40         { .compatible = "amlogic,meson-gxbb-efuse", },
  41         { /* sentinel */ },
  42 };
  43 MODULE_DEVICE_TABLE(of, meson_efuse_match);
  44
  45 static int meson_efuse_probe(struct platform_device *pdev)
  46 {
  47         struct device *dev = &pdev->dev;
  48         struct nvmem_device *nvmem;
  49         struct nvmem_config *econfig;
  50         struct clk *clk;
  51         unsigned int size;
  52         int ret;
  53
  54         clk = devm_clk_get(dev, NULL);
  55         if (IS_ERR(clk)) {
  56                 ret = PTR_ERR(clk);
  57                 if (ret != -EPROBE_DEFER)
  58                         dev_err(dev, "failed to get efuse gate");
  59                 return ret;
  60         }
  61
  62         ret = clk_prepare_enable(clk);
  63         if (ret) {
  64                 dev_err(dev, "failed to enable gate");
  65                 return ret;
  66         }
  67
  68         ret = devm_add_action_or_reset(dev,
  69                                        (void(*)(void *))clk_disable_unprepare,
  70                                        clk);
  71         if (ret) {
  72                 dev_err(dev, "failed to add disable callback");
  73                 return ret;
  74         }
  75
  76         if (meson_sm_call(SM_EFUSE_USER_MAX, &size, 0, 0, 0, 0, 0) < 0) {
  77                 dev_err(dev, "failed to get max user");
  78                 return -EINVAL;
  79         }
  80
  81         econfig = devm_kzalloc(dev, sizeof(*econfig), GFP_KERNEL);
  82         if (!econfig)
  83                 return -ENOMEM;
  84
  85         econfig->dev = dev;
  86         econfig->name = dev_name(dev);
  87         econfig->stride = 1;
  88         econfig->word_size = 1;
  89         econfig->reg_read = meson_efuse_read;
  90         econfig->reg_write = meson_efuse_write;
  91         econfig->size = size;
  92
  93         nvmem = devm_nvmem_register(&pdev->dev, econfig);
  94
  95         return PTR_ERR_OR_ZERO(nvmem);
  96 }
  97
  98 static struct platform_driver meson_efuse_driver = {
  99         .probe = meson_efuse_probe,
 100         .driver = {
 101                 .name = "meson-efuse",
 102                 .of_match_table = meson_efuse_match,
 103         },
 104 };
 105
 106 module_platform_driver(meson_efuse_driver);
 107
 108 MODULE_AUTHOR("Carlo Caione <carlo@endlessm.com>");
 109 MODULE_DESCRIPTION("Amlogic Meson GX NVMEM driver");
 110 MODULE_LICENSE("GPL v2");