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
36 static const struct regmap_config mux_mmio_regmap_cfg = {
37 .reg_bits = 32,
38 .val_bits = 32,
39 .reg_stride = 4,
40 };
41
mux_mmio_probe(struct platform_device * pdev)42 static int mux_mmio_probe(struct platform_device *pdev)
43 {
44 struct device *dev = &pdev->dev;
45 struct device_node *np = dev->of_node;
46 struct regmap_field **fields;
47 struct mux_chip *mux_chip;
48 struct regmap *regmap;
49 void __iomem *base;
50 int num_fields;
51 int ret;
52 int i;
53
54 if (of_device_is_compatible(np, "mmio-mux")) {
55 regmap = syscon_node_to_regmap(np->parent);
56 } else {
57 base = devm_platform_ioremap_resource(pdev, 0);
58 if (IS_ERR(base))
59 regmap = ERR_PTR(-ENODEV);
60 else
61 regmap = regmap_init_mmio(dev, base, &mux_mmio_regmap_cfg);
62 /* Fallback to checking the parent node on "real" errors. */
63 if (IS_ERR(regmap) && regmap != ERR_PTR(-EPROBE_DEFER)) {
64 regmap = dev_get_regmap(dev->parent, NULL);
65 if (!regmap)
66 regmap = ERR_PTR(-ENODEV);
67 }
68 }
69 if (IS_ERR(regmap))
70 return dev_err_probe(dev, PTR_ERR(regmap),
71 "failed to get regmap\n");
72
73 ret = of_property_count_u32_elems(np, "mux-reg-masks");
74 if (ret == 0 || ret % 2)
75 ret = -EINVAL;
76 if (ret < 0) {
77 dev_err(dev, "mux-reg-masks property missing or invalid: %d\n",
78 ret);
79 return ret;
80 }
81 num_fields = ret / 2;
82
83 mux_chip = devm_mux_chip_alloc(dev, num_fields, num_fields *
84 sizeof(*fields));
85 if (IS_ERR(mux_chip))
86 return PTR_ERR(mux_chip);
87
88 fields = mux_chip_priv(mux_chip);
89
90 for (i = 0; i < num_fields; i++) {
91 struct mux_control *mux = &mux_chip->mux[i];
92 struct reg_field field;
93 s32 idle_state = MUX_IDLE_AS_IS;
94 u32 reg, mask;
95 int bits;
96
97 ret = of_property_read_u32_index(np, "mux-reg-masks",
98 2 * i, ®);
99 if (!ret)
100 ret = of_property_read_u32_index(np, "mux-reg-masks",
101 2 * i + 1, &mask);
102 if (ret < 0) {
103 dev_err(dev, "bitfield %d: failed to read mux-reg-masks property: %d\n",
104 i, ret);
105 return ret;
106 }
107
108 field.reg = reg;
109 field.msb = fls(mask) - 1;
110 field.lsb = ffs(mask) - 1;
111
112 if (mask != GENMASK(field.msb, field.lsb)) {
113 dev_err(dev, "bitfield %d: invalid mask 0x%x\n",
114 i, mask);
115 return -EINVAL;
116 }
117
118 fields[i] = devm_regmap_field_alloc(dev, regmap, field);
119 if (IS_ERR(fields[i])) {
120 ret = PTR_ERR(fields[i]);
121 dev_err(dev, "bitfield %d: failed to allocate: %d\n",
122 i, ret);
123 return ret;
124 }
125
126 bits = 1 + field.msb - field.lsb;
127 mux->states = 1 << bits;
128
129 of_property_read_u32_index(np, "idle-states", i,
130 (u32 *)&idle_state);
131 if (idle_state != MUX_IDLE_AS_IS) {
132 if (idle_state < 0 || idle_state >= mux->states) {
133 dev_err(dev, "bitfield: %d: out of range idle state %d\n",
134 i, idle_state);
135 return -EINVAL;
136 }
137
138 mux->idle_state = idle_state;
139 }
140 }
141
142 mux_chip->ops = &mux_mmio_ops;
143
144 return devm_mux_chip_register(dev, mux_chip);
145 }
146
147 static struct platform_driver mux_mmio_driver = {
148 .driver = {
149 .name = "mmio-mux",
150 .of_match_table = mux_mmio_dt_ids,
151 },
152 .probe = mux_mmio_probe,
153 };
154 module_platform_driver(mux_mmio_driver);
155
156 MODULE_DESCRIPTION("MMIO register bitfield-controlled multiplexer driver");
157 MODULE_AUTHOR("Philipp Zabel <p.zabel@pengutronix.de>");
158 MODULE_LICENSE("GPL v2");
159