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 
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, &reg);
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	= of_match_ptr(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