1// SPDX-License-Identifier: GPL-2.0
2/*
3 * MMIO register bitfield-controlled multiplexer driver
4 *
5 * Copyright (C) 2017 Pengutronix, Philipp Zabel <kernel@pengutronix.de>
6 */
7
8#include <linux/bitops.h>
9#include <linux/err.h>
10#include <linux/mfd/syscon.h>
11#include <linux/module.h>
12#include <linux/mux/driver.h>
13#include <linux/of_platform.h>
14#include <linux/platform_device.h>
15#include <linux/property.h>
16#include <linux/regmap.h>
17
18static int mux_mmio_set(struct mux_control *mux, int state)
19{
20 struct regmap_field **fields = mux_chip_priv(mux->chip);
21
22 return regmap_field_write(fields[mux_control_get_index(mux)], state);
23}
24
25static const struct mux_control_ops mux_mmio_ops = {
26 .set = mux_mmio_set,
27};
28
29static const struct of_device_id mux_mmio_dt_ids[] = {
30 { .compatible = "mmio-mux", },
31 { /* sentinel */ }
32};
33MODULE_DEVICE_TABLE(of, mux_mmio_dt_ids);
34
35static int mux_mmio_probe(struct platform_device *pdev)
36{
37 struct device *dev = &pdev->dev;
38 struct device_node *np = dev->of_node;
39 struct regmap_field **fields;
40 struct mux_chip *mux_chip;
41 struct regmap *regmap;
42 int num_fields;
43 int ret;
44 int i;
45
46 regmap = syscon_node_to_regmap(np->parent);
47 if (IS_ERR(regmap)) {
48 ret = PTR_ERR(regmap);
49 dev_err(dev, "failed to get regmap: %d\n", ret);
50 return ret;
51 }
52
53 ret = of_property_count_u32_elems(np, "mux-reg-masks");
54 if (ret == 0 || ret % 2)
55 ret = -EINVAL;
56 if (ret < 0) {
57 dev_err(dev, "mux-reg-masks property missing or invalid: %d\n",
58 ret);
59 return ret;
60 }
61 num_fields = ret / 2;
62
63 mux_chip = devm_mux_chip_alloc(dev, num_fields, num_fields *
64 sizeof(*fields));
65 if (IS_ERR(mux_chip))
66 return PTR_ERR(mux_chip);
67
68 fields = mux_chip_priv(mux_chip);
69
70 for (i = 0; i < num_fields; i++) {
71 struct mux_control *mux = &mux_chip->mux[i];
72 struct reg_field field;
73 s32 idle_state = MUX_IDLE_AS_IS;
74 u32 reg, mask;
75 int bits;
76
77 ret = of_property_read_u32_index(np, "mux-reg-masks",
78 2 * i, &reg);
79 if (!ret)
80 ret = of_property_read_u32_index(np, "mux-reg-masks",
81 2 * i + 1, &mask);
82 if (ret < 0) {
83 dev_err(dev, "bitfield %d: failed to read mux-reg-masks property: %d\n",
84 i, ret);
85 return ret;
86 }
87
88 field.reg = reg;
89 field.msb = fls(mask) - 1;
90 field.lsb = ffs(mask) - 1;
91
92 if (mask != GENMASK(field.msb, field.lsb)) {
93 dev_err(dev, "bitfield %d: invalid mask 0x%x\n",
94 i, mask);
95 return -EINVAL;
96 }
97
98 fields[i] = devm_regmap_field_alloc(dev, regmap, field);
99 if (IS_ERR(fields[i])) {
100 ret = PTR_ERR(fields[i]);
101 dev_err(dev, "bitfield %d: failed allocate: %d\n",
102 i, ret);
103 return ret;
104 }
105
106 bits = 1 + field.msb - field.lsb;
107 mux->states = 1 << bits;
108
109 of_property_read_u32_index(np, "idle-states", i,
110 (u32 *)&idle_state);
111 if (idle_state != MUX_IDLE_AS_IS) {
112 if (idle_state < 0 || idle_state >= mux->states) {
113 dev_err(dev, "bitfield: %d: out of range idle state %d\n",
114 i, idle_state);
115 return -EINVAL;
116 }
117
118 mux->idle_state = idle_state;
119 }
120 }
121
122 mux_chip->ops = &mux_mmio_ops;
123
124 return devm_mux_chip_register(dev, mux_chip);
125}
126
127static struct platform_driver mux_mmio_driver = {
128 .driver = {
129 .name = "mmio-mux",
130 .of_match_table = of_match_ptr(mux_mmio_dt_ids),
131 },
132 .probe = mux_mmio_probe,
133};
134module_platform_driver(mux_mmio_driver);
135
136MODULE_DESCRIPTION("MMIO register bitfield-controlled multiplexer driver");
137MODULE_AUTHOR("Philipp Zabel <p.zabel@pengutronix.de>");
138MODULE_LICENSE("GPL v2");
139