drivers/bootcount/bootcount_syscon.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (c) Vaisala Oyj. All rights reserved.
   4  */
   5
   6 #include <common.h>
   7 #include <bootcount.h>
   8 #include <dm.h>
   9 #include <dm/device_compat.h>
  10 #include <linux/ioport.h>
  11 #include <regmap.h>
  12 #include <syscon.h>
  13
  14 #define BYTES_TO_BITS(bytes) ((bytes) << 3)
  15 #define GEN_REG_MASK(val_size, val_addr)                                       \
  16         (GENMASK(BYTES_TO_BITS(val_size) - 1, 0)                               \
  17          << (!!((val_addr) == 0x02) * BYTES_TO_BITS(2)))
  18 #define GET_DEFAULT_VALUE(val_size)                                            \
  19         (CONFIG_SYS_BOOTCOUNT_MAGIC >>                                         \
  20          (BYTES_TO_BITS((sizeof(u32) - (val_size)))))
  21
  22 /**
  23  * struct bootcount_syscon_priv - driver's private data
  24  *
  25  * @regmap: syscon regmap
  26  * @reg_addr: register address used to store the bootcount value
  27  * @size: size of the bootcount value (2 or 4 bytes)
  28  * @magic: magic used to validate/save the bootcount value
  29  * @magic_mask: magic value bitmask
  30  * @reg_mask: mask used to identify the location of the bootcount value
  31  * in the register when 2 bytes length is used
  32  * @shift: value used to extract the botcount value from the register
  33  */
  34 struct bootcount_syscon_priv {
  35         struct regmap *regmap;
  36         fdt_addr_t reg_addr;
  37         fdt_size_t size;
  38         u32 magic;
  39         u32 magic_mask;
  40         u32 reg_mask;
  41         int shift;
  42 };
  43
  44 static int bootcount_syscon_set(struct udevice *dev, const u32 val)
  45 {
  46         struct bootcount_syscon_priv *priv = dev_get_priv(dev);
  47         u32 regval;
  48
  49         if ((val & priv->magic_mask) != 0)
  50                 return -EINVAL;
  51
  52         regval = (priv->magic & priv->magic_mask) | (val & ~priv->magic_mask);
  53
  54         if (priv->size == 2) {
  55                 regval &= 0xffff;
  56                 regval |= (regval & 0xffff) << BYTES_TO_BITS(priv->size);
  57         }
  58
  59         debug("%s: Prepare to write reg value: 0x%08x with register mask: 0x%08x\n",
  60               __func__, regval, priv->reg_mask);
  61
  62         return regmap_update_bits(priv->regmap, priv->reg_addr, priv->reg_mask,
  63                                   regval);
  64 }
  65
  66 static int bootcount_syscon_get(struct udevice *dev, u32 *val)
  67 {
  68         struct bootcount_syscon_priv *priv = dev_get_priv(dev);
  69         u32 regval;
  70         int ret;
  71
  72         ret = regmap_read(priv->regmap, priv->reg_addr, &regval);
  73         if (ret)
  74                 return ret;
  75
  76         regval &= priv->reg_mask;
  77         regval >>= priv->shift;
  78
  79         if ((regval & priv->magic_mask) == (priv->magic & priv->magic_mask)) {
  80                 *val = regval & ~priv->magic_mask;
  81         } else {
  82                 dev_err(dev, "%s: Invalid bootcount magic\n", __func__);
  83                 return -EINVAL;
  84         }
  85
  86         debug("%s: Read bootcount value: 0x%08x from regval: 0x%08x\n",
  87               __func__, *val, regval);
  88         return 0;
  89 }
  90
  91 static int bootcount_syscon_of_to_plat(struct udevice *dev)
  92 {
  93         struct bootcount_syscon_priv *priv = dev_get_priv(dev);
  94         fdt_addr_t bootcount_offset;
  95         fdt_size_t reg_size;
  96
  97         priv->regmap = syscon_regmap_lookup_by_phandle(dev, "syscon");
  98         if (IS_ERR(priv->regmap)) {
  99                 dev_err(dev, "%s: Unable to find regmap (%ld)\n", __func__,
 100                         PTR_ERR(priv->regmap));
 101                 return PTR_ERR(priv->regmap);
 102         }
 103
 104         priv->reg_addr = dev_read_addr_size_name(dev, "syscon_reg", &reg_size);
 105         if (priv->reg_addr == FDT_ADDR_T_NONE) {
 106                 dev_err(dev, "%s: syscon_reg address not found\n", __func__);
 107                 return -EINVAL;
 108         }
 109         if (reg_size != 4) {
 110                 dev_err(dev, "%s: Unsupported register size: %pa\n", __func__,
 111                         &reg_size);
 112                 return -EINVAL;
 113         }
 114
 115         bootcount_offset = dev_read_addr_size_name(dev, "offset", &priv->size);
 116         if (bootcount_offset == FDT_ADDR_T_NONE) {
 117                 dev_err(dev, "%s: offset configuration not found\n", __func__);
 118                 return -EINVAL;
 119         }
 120         if (bootcount_offset + priv->size > reg_size) {
 121                 dev_err(dev,
 122                         "%s: Bootcount value doesn't fit in the reserved space\n",
 123                         __func__);
 124                 return -EINVAL;
 125         }
 126         if (priv->size != 2 && priv->size != 4) {
 127                 dev_err(dev,
 128                         "%s: Driver supports only 2 and 4 bytes bootcount size\n",
 129                         __func__);
 130                 return -EINVAL;
 131         }
 132
 133         priv->magic = GET_DEFAULT_VALUE(priv->size);
 134         priv->magic_mask = GENMASK(BYTES_TO_BITS(priv->size) - 1,
 135                                    BYTES_TO_BITS(priv->size >> 1));
 136         priv->shift = !!(bootcount_offset == 0x02) * BYTES_TO_BITS(priv->size);
 137         priv->reg_mask = GEN_REG_MASK(priv->size, bootcount_offset);
 138
 139         return 0;
 140 }
 141
 142 static const struct bootcount_ops bootcount_syscon_ops = {
 143         .get = bootcount_syscon_get,
 144         .set = bootcount_syscon_set,
 145 };
 146
 147 static const struct udevice_id bootcount_syscon_ids[] = {
 148         { .compatible = "u-boot,bootcount-syscon" },
 149         {}
 150 };
 151
 152 U_BOOT_DRIVER(bootcount_syscon) = {
 153         .name = "bootcount-syscon",
 154         .id = UCLASS_BOOTCOUNT,
 155         .of_to_plat = bootcount_syscon_of_to_plat,
 156         .priv_auto = sizeof(struct bootcount_syscon_priv),
 157         .of_match = bootcount_syscon_ids,
 158         .ops = &bootcount_syscon_ops,
 159 };