drivers/bootcount/rtc.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * (C) Copyright 2018 Theobroma Systems Design und Consulting GmbH
   4  */
   5
   6 #include <common.h>
   7 #include <bootcount.h>
   8 #include <dm.h>
   9 #include <rtc.h>
  10
  11 static const u8 bootcount_magic = 0xbc;
  12
  13 struct bootcount_rtc_priv {
  14         struct udevice *rtc;
  15         u32 offset;
  16 };
  17
  18 static int bootcount_rtc_set(struct udevice *dev, const u32 a)
  19 {
  20         struct bootcount_rtc_priv *priv = dev_get_priv(dev);
  21         const u16 val = bootcount_magic << 8 | (a & 0xff);
  22
  23         if (rtc_write16(priv->rtc, priv->offset, val) < 0) {
  24                 debug("%s: rtc_write16 failed\n", __func__);
  25                 return -EIO;
  26         }
  27
  28         return 0;
  29 }
  30
  31 static int bootcount_rtc_get(struct udevice *dev, u32 *a)
  32 {
  33         struct bootcount_rtc_priv *priv = dev_get_priv(dev);
  34         u16 val;
  35
  36         if (rtc_read16(priv->rtc, priv->offset, &val) < 0) {
  37                 debug("%s: rtc_write16 failed\n", __func__);
  38                 return -EIO;
  39         }
  40
  41         if (val >> 8 == bootcount_magic) {
  42                 *a = val & 0xff;
  43                 return 0;
  44         }
  45
  46         debug("%s: bootcount magic does not match on %04x\n", __func__, val);
  47         return -EIO;
  48 }
  49
  50 static int bootcount_rtc_probe(struct udevice *dev)
  51 {
  52         struct ofnode_phandle_args phandle_args;
  53         struct bootcount_rtc_priv *priv = dev_get_priv(dev);
  54         struct udevice *rtc;
  55
  56         if (dev_read_phandle_with_args(dev, "rtc", NULL, 0, 0, &phandle_args)) {
  57                 debug("%s: rtc backing device not specified\n", dev->name);
  58                 return -ENOENT;
  59         }
  60
  61         if (uclass_get_device_by_ofnode(UCLASS_RTC, phandle_args.node, &rtc)) {
  62                 debug("%s: could not get backing device\n", dev->name);
  63                 return -ENODEV;
  64         }
  65
  66         priv->rtc = rtc;
  67         priv->offset = dev_read_u32_default(dev, "offset", 0);
  68
  69         return 0;
  70 }
  71
  72 static const struct bootcount_ops bootcount_rtc_ops = {
  73         .get = bootcount_rtc_get,
  74         .set = bootcount_rtc_set,
  75 };
  76
  77 static const struct udevice_id bootcount_rtc_ids[] = {
  78         { .compatible = "u-boot,bootcount-rtc" },
  79         { }
  80 };
  81
  82 U_BOOT_DRIVER(bootcount_rtc) = {
  83         .name   = "bootcount-rtc",
  84         .id     = UCLASS_BOOTCOUNT,
  85         .priv_auto_alloc_size = sizeof(struct bootcount_rtc_priv),
  86         .probe  = bootcount_rtc_probe,
  87         .of_match = bootcount_rtc_ids,
  88         .ops    = &bootcount_rtc_ops,
  89 };