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
 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	{ .compatible = "reg-mux", },
 32	{ /* sentinel */ }
 33};
 34MODULE_DEVICE_TABLE(of, mux_mmio_dt_ids);
 35
 36static 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 = device_node_to_regmap(np);
 51		/* Fallback to checking the parent node on "real" errors. */
 52		if (IS_ERR(regmap) && regmap != ERR_PTR(-EPROBE_DEFER)) {
 53			regmap = dev_get_regmap(dev->parent, NULL);
 54			if (!regmap)
 55				regmap = ERR_PTR(-ENODEV);
 56		}
 57	}
 58	if (IS_ERR(regmap))
 59		return dev_err_probe(dev, PTR_ERR(regmap),
 60				     "failed to get regmap\n");
 61
 62	ret = of_property_count_u32_elems(np, "mux-reg-masks");
 63	if (ret == 0 || ret % 2)
 64		ret = -EINVAL;
 65	if (ret < 0) {
 66		dev_err(dev, "mux-reg-masks property missing or invalid: %d\n",
 67			ret);
 68		return ret;
 69	}
 70	num_fields = ret / 2;
 71
 72	mux_chip = devm_mux_chip_alloc(dev, num_fields, num_fields *
 73				       sizeof(*fields));
 74	if (IS_ERR(mux_chip))
 75		return PTR_ERR(mux_chip);
 76
 77	fields = mux_chip_priv(mux_chip);
 78
 79	for (i = 0; i < num_fields; i++) {
 80		struct mux_control *mux = &mux_chip->mux[i];
 81		struct reg_field field;
 82		s32 idle_state = MUX_IDLE_AS_IS;
 83		u32 reg, mask;
 84		int bits;
 85
 86		ret = of_property_read_u32_index(np, "mux-reg-masks",
 87						 2 * i, &reg);
 88		if (!ret)
 89			ret = of_property_read_u32_index(np, "mux-reg-masks",
 90							 2 * i + 1, &mask);
 91		if (ret < 0) {
 92			dev_err(dev, "bitfield %d: failed to read mux-reg-masks property: %d\n",
 93				i, ret);
 94			return ret;
 95		}
 96
 97		field.reg = reg;
 98		field.msb = fls(mask) - 1;
 99		field.lsb = ffs(mask) - 1;
100
101		if (mask != GENMASK(field.msb, field.lsb)) {
102			dev_err(dev, "bitfield %d: invalid mask 0x%x\n",
103				i, mask);
104			return -EINVAL;
105		}
106
107		fields[i] = devm_regmap_field_alloc(dev, regmap, field);
108		if (IS_ERR(fields[i])) {
109			ret = PTR_ERR(fields[i]);
110			dev_err(dev, "bitfield %d: failed allocate: %d\n",
111				i, ret);
112			return ret;
113		}
114
115		bits = 1 + field.msb - field.lsb;
116		mux->states = 1 << bits;
117
118		of_property_read_u32_index(np, "idle-states", i,
119					   (u32 *)&idle_state);
120		if (idle_state != MUX_IDLE_AS_IS) {
121			if (idle_state < 0 || idle_state >= mux->states) {
122				dev_err(dev, "bitfield: %d: out of range idle state %d\n",
123					i, idle_state);
124				return -EINVAL;
125			}
126
127			mux->idle_state = idle_state;
128		}
129	}
130
131	mux_chip->ops = &mux_mmio_ops;
132
133	return devm_mux_chip_register(dev, mux_chip);
134}
135
136static struct platform_driver mux_mmio_driver = {
137	.driver = {
138		.name = "mmio-mux",
139		.of_match_table	= mux_mmio_dt_ids,
140	},
141	.probe = mux_mmio_probe,
142};
143module_platform_driver(mux_mmio_driver);
144
145MODULE_DESCRIPTION("MMIO register bitfield-controlled multiplexer driver");
146MODULE_AUTHOR("Philipp Zabel <p.zabel@pengutronix.de>");
147MODULE_LICENSE("GPL v2");