1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Amlogic Meson Reset Controller driver
4 *
5 * Copyright (c) 2018 BayLibre, SAS.
6 * Author: Neil Armstrong <narmstrong@baylibre.com>
7 */
8
9 #include <common.h>
10 #include <dm.h>
11 #include <reset-uclass.h>
12 #include <regmap.h>
13
14 #define REG_COUNT 8
15 #define BITS_PER_REG 32
16 #define LEVEL_OFFSET 0x7c
17
18 struct meson_reset_priv {
19 struct regmap *regmap;
20 };
21
meson_reset_request(struct reset_ctl * reset_ctl)22 static int meson_reset_request(struct reset_ctl *reset_ctl)
23 {
24 if (reset_ctl->id > (REG_COUNT * BITS_PER_REG))
25 return -EINVAL;
26
27 return 0;
28 }
29
meson_reset_free(struct reset_ctl * reset_ctl)30 static int meson_reset_free(struct reset_ctl *reset_ctl)
31 {
32 return 0;
33 }
34
meson_reset_level(struct reset_ctl * reset_ctl,bool assert)35 static int meson_reset_level(struct reset_ctl *reset_ctl, bool assert)
36 {
37 struct meson_reset_priv *priv = dev_get_priv(reset_ctl->dev);
38 uint bank = reset_ctl->id / BITS_PER_REG;
39 uint offset = reset_ctl->id % BITS_PER_REG;
40 uint reg_offset = LEVEL_OFFSET + (bank << 2);
41 uint val;
42
43 regmap_read(priv->regmap, reg_offset, &val);
44 if (assert)
45 val &= ~BIT(offset);
46 else
47 val |= BIT(offset);
48 regmap_write(priv->regmap, reg_offset, val);
49
50 return 0;
51 }
52
meson_reset_assert(struct reset_ctl * reset_ctl)53 static int meson_reset_assert(struct reset_ctl *reset_ctl)
54 {
55 return meson_reset_level(reset_ctl, true);
56 }
57
meson_reset_deassert(struct reset_ctl * reset_ctl)58 static int meson_reset_deassert(struct reset_ctl *reset_ctl)
59 {
60 return meson_reset_level(reset_ctl, false);
61 }
62
63 struct reset_ops meson_reset_ops = {
64 .request = meson_reset_request,
65 .free = meson_reset_free,
66 .rst_assert = meson_reset_assert,
67 .rst_deassert = meson_reset_deassert,
68 };
69
70 static const struct udevice_id meson_reset_ids[] = {
71 { .compatible = "amlogic,meson-gxbb-reset" },
72 { }
73 };
74
meson_reset_probe(struct udevice * dev)75 static int meson_reset_probe(struct udevice *dev)
76 {
77 struct meson_reset_priv *priv = dev_get_priv(dev);
78
79 return regmap_init_mem(dev_ofnode(dev), &priv->regmap);
80 }
81
82 U_BOOT_DRIVER(meson_reset) = {
83 .name = "meson_reset",
84 .id = UCLASS_RESET,
85 .of_match = meson_reset_ids,
86 .probe = meson_reset_probe,
87 .ops = &meson_reset_ops,
88 .priv_auto_alloc_size = sizeof(struct meson_reset_priv),
89 };
90