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.h>
14 #include <linux/platform_device.h>
15 #include <linux/property.h>
16 #include <linux/regmap.h>
17
mux_mmio_set(struct mux_control * mux,int state)18 static 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
25 static const struct mux_control_ops mux_mmio_ops = {
26 .set = mux_mmio_set,
27 };
28
29 static const struct of_device_id mux_mmio_dt_ids[] = {
30 { .compatible = "mmio-mux", },
31 { .compatible = "reg-mux", },
32 { /* sentinel */ }
33 };
34 MODULE_DEVICE_TABLE(of, mux_mmio_dt_ids);
35
mux_mmio_probe(struct platform_device * pdev)36 static int mux_mmio_probe(struct platform_device *pdev)
37 {
38 struct device *dev = &pdev->dev;
39 struct device_node *np = dev->of_node;
40 struct regmap_field **fields;
41 struct mux_chip *mux_chip;
42 struct regmap *regmap;
43 int num_fields;
44 int ret;
45 int i;
46
47 if (of_device_is_compatible(np, "mmio-mux"))
48 regmap = syscon_node_to_regmap(np->parent);
49 else
50 regmap = dev_get_regmap(dev->parent, NULL) ?: ERR_PTR(-ENODEV);
51 if (IS_ERR(regmap)) {
52 ret = PTR_ERR(regmap);
53 dev_err(dev, "failed to get regmap: %d\n", ret);
54 return ret;
55 }
56
57 ret = of_property_count_u32_elems(np, "mux-reg-masks");
58 if (ret == 0 || ret % 2)
59 ret = -EINVAL;
60 if (ret < 0) {
61 dev_err(dev, "mux-reg-masks property missing or invalid: %d\n",
62 ret);
63 return ret;
64 }
65 num_fields = ret / 2;
66
67 mux_chip = devm_mux_chip_alloc(dev, num_fields, num_fields *
68 sizeof(*fields));
69 if (IS_ERR(mux_chip))
70 return PTR_ERR(mux_chip);
71
72 fields = mux_chip_priv(mux_chip);
73
74 for (i = 0; i < num_fields; i++) {
75 struct mux_control *mux = &mux_chip->mux[i];
76 struct reg_field field;
77 s32 idle_state = MUX_IDLE_AS_IS;
78 u32 reg, mask;
79 int bits;
80
81 ret = of_property_read_u32_index(np, "mux-reg-masks",
82 2 * i, ®);
83 if (!ret)
84 ret = of_property_read_u32_index(np, "mux-reg-masks",
85 2 * i + 1, &mask);
86 if (ret < 0) {
87 dev_err(dev, "bitfield %d: failed to read mux-reg-masks property: %d\n",
88 i, ret);
89 return ret;
90 }
91
92 field.reg = reg;
93 field.msb = fls(mask) - 1;
94 field.lsb = ffs(mask) - 1;
95
96 if (mask != GENMASK(field.msb, field.lsb)) {
97 dev_err(dev, "bitfield %d: invalid mask 0x%x\n",
98 i, mask);
99 return -EINVAL;
100 }
101
102 fields[i] = devm_regmap_field_alloc(dev, regmap, field);
103 if (IS_ERR(fields[i])) {
104 ret = PTR_ERR(fields[i]);
105 dev_err(dev, "bitfield %d: failed allocate: %d\n",
106 i, ret);
107 return ret;
108 }
109
110 bits = 1 + field.msb - field.lsb;
111 mux->states = 1 << bits;
112
113 of_property_read_u32_index(np, "idle-states", i,
114 (u32 *)&idle_state);
115 if (idle_state != MUX_IDLE_AS_IS) {
116 if (idle_state < 0 || idle_state >= mux->states) {
117 dev_err(dev, "bitfield: %d: out of range idle state %d\n",
118 i, idle_state);
119 return -EINVAL;
120 }
121
122 mux->idle_state = idle_state;
123 }
124 }
125
126 mux_chip->ops = &mux_mmio_ops;
127
128 return devm_mux_chip_register(dev, mux_chip);
129 }
130
131 static struct platform_driver mux_mmio_driver = {
132 .driver = {
133 .name = "mmio-mux",
134 .of_match_table = mux_mmio_dt_ids,
135 },
136 .probe = mux_mmio_probe,
137 };
138 module_platform_driver(mux_mmio_driver);
139
140 MODULE_DESCRIPTION("MMIO register bitfield-controlled multiplexer driver");
141 MODULE_AUTHOR("Philipp Zabel <p.zabel@pengutronix.de>");
142 MODULE_LICENSE("GPL v2");
143