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 <log.h>
  10 #include <rtc.h>
  11
  12 static const u8 bootcount_magic = 0xbc;
  13
  14 struct bootcount_rtc_priv {
  15         struct udevice *rtc;
  16         u32 offset;
  17 };
  18
  19 static int bootcount_rtc_set(struct udevice *dev, const u32 a)
  20 {
  21         struct bootcount_rtc_priv *priv = dev_get_priv(dev);
  22         const u16 val = bootcount_magic << 8 | (a & 0xff);
  23
  24         if (rtc_write16(priv->rtc, priv->offset, val) < 0) {
  25                 debug("%s: rtc_write16 failed\n", __func__);
  26                 return -EIO;
  27         }
  28
  29         return 0;
  30 }
  31
  32 static int bootcount_rtc_get(struct udevice *dev, u32 *a)
  33 {
  34         struct bootcount_rtc_priv *priv = dev_get_priv(dev);
  35         u16 val;
  36
  37         if (rtc_read16(priv->rtc, priv->offset, &val) < 0) {
  38                 debug("%s: rtc_write16 failed\n", __func__);
  39                 return -EIO;
  40         }
  41
  42         if (val >> 8 == bootcount_magic) {
  43                 *a = val & 0xff;
  44                 return 0;
  45         }
  46
  47         debug("%s: bootcount magic does not match on %04x\n", __func__, val);
  48         return -EIO;
  49 }
  50
  51 static int bootcount_rtc_probe(struct udevice *dev)
  52 {
  53         struct ofnode_phandle_args phandle_args;
  54         struct bootcount_rtc_priv *priv = dev_get_priv(dev);
  55         struct udevice *rtc;
  56
  57         if (dev_read_phandle_with_args(dev, "rtc", NULL, 0, 0, &phandle_args)) {
  58                 debug("%s: rtc backing device not specified\n", dev->name);
  59                 return -ENOENT;
  60         }
  61
  62         if (uclass_get_device_by_ofnode(UCLASS_RTC, phandle_args.node, &rtc)) {
  63                 debug("%s: could not get backing device\n", dev->name);
  64                 return -ENODEV;
  65         }
  66
  67         priv->rtc = rtc;
  68         priv->offset = dev_read_u32_default(dev, "offset", 0);
  69
  70         return 0;
  71 }
  72
  73 static const struct bootcount_ops bootcount_rtc_ops = {
  74         .get = bootcount_rtc_get,
  75         .set = bootcount_rtc_set,
  76 };
  77
  78 static const struct udevice_id bootcount_rtc_ids[] = {
  79         { .compatible = "u-boot,bootcount-rtc" },
  80         { }
  81 };
  82
  83 U_BOOT_DRIVER(bootcount_rtc) = {
  84         .name   = "bootcount-rtc",
  85         .id     = UCLASS_BOOTCOUNT,
  86         .priv_auto_alloc_size = sizeof(struct bootcount_rtc_priv),
  87         .probe  = bootcount_rtc_probe,
  88         .of_match = bootcount_rtc_ids,
  89         .ops    = &bootcount_rtc_ops,
  90 };