mmio.c

  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
 18struct mux_mmio {
 19	struct regmap_field **fields;
 20	unsigned int *hardware_states;
 21};
 22
 23static int mux_mmio_get(struct mux_control *mux, int *state)
 24{
 25	struct mux_mmio *mux_mmio = mux_chip_priv(mux->chip);
 26	unsigned int index = mux_control_get_index(mux);
 27
 28	return regmap_field_read(mux_mmio->fields[index], state);
 29}
 30
 31static int mux_mmio_set(struct mux_control *mux, int state)
 32{
 33	struct mux_mmio *mux_mmio = mux_chip_priv(mux->chip);
 34	unsigned int index = mux_control_get_index(mux);
 35
 36	return regmap_field_write(mux_mmio->fields[index], state);
 37}
 38
 39static const struct mux_control_ops mux_mmio_ops = {
 40	.set = mux_mmio_set,
 41};
 42
 43static const struct of_device_id mux_mmio_dt_ids[] = {
 44	{ .compatible = "mmio-mux", },
 45	{ .compatible = "reg-mux", },
 46	{ /* sentinel */ }
 47};
 48MODULE_DEVICE_TABLE(of, mux_mmio_dt_ids);
 49
 50static const struct regmap_config mux_mmio_regmap_cfg = {
 51	.reg_bits = 32,
 52	.val_bits = 32,
 53	.reg_stride = 4,
 54};
 55
 56static int mux_mmio_probe(struct platform_device *pdev)
 57{
 58	struct device *dev = &pdev->dev;
 59	struct device_node *np = dev->of_node;
 60	struct mux_chip *mux_chip;
 61	struct mux_mmio *mux_mmio;
 62	struct regmap *regmap;
 63	void __iomem *base;
 64	int num_fields;
 65	int ret;
 66	int i;
 67
 68	if (of_device_is_compatible(np, "mmio-mux")) {
 69		regmap = syscon_node_to_regmap(np->parent);
 70	} else {
 71		base = devm_platform_ioremap_resource(pdev, 0);
 72		if (IS_ERR(base))
 73			regmap = ERR_PTR(-ENODEV);
 74		else
 75			regmap = devm_regmap_init_mmio(dev, base, &mux_mmio_regmap_cfg);
 76		/* Fallback to checking the parent node on "real" errors. */
 77		if (IS_ERR(regmap) && regmap != ERR_PTR(-EPROBE_DEFER)) {
 78			regmap = dev_get_regmap(dev->parent, NULL);
 79			if (!regmap)
 80				regmap = ERR_PTR(-ENODEV);
 81		}
 82	}
 83	if (IS_ERR(regmap))
 84		return dev_err_probe(dev, PTR_ERR(regmap),
 85				     "failed to get regmap\n");
 86
 87	ret = of_property_count_u32_elems(np, "mux-reg-masks");
 88	if (ret == 0 || ret % 2)
 89		ret = -EINVAL;
 90	if (ret < 0) {
 91		dev_err(dev, "mux-reg-masks property missing or invalid: %d\n",
 92			ret);
 93		return ret;
 94	}
 95	num_fields = ret / 2;
 96
 97	mux_chip = devm_mux_chip_alloc(dev, num_fields, sizeof(struct mux_mmio));
 98	if (IS_ERR(mux_chip))
 99		return PTR_ERR(mux_chip);
100
101	mux_mmio = mux_chip_priv(mux_chip);
102
103	mux_mmio->fields = devm_kmalloc(dev, num_fields * sizeof(*mux_mmio->fields), GFP_KERNEL);
104	if (!mux_mmio->fields)
105		return -ENOMEM;
106
107	mux_mmio->hardware_states = devm_kmalloc(dev, num_fields *
108						 sizeof(*mux_mmio->hardware_states), GFP_KERNEL);
109	if (!mux_mmio->hardware_states)
110		return -ENOMEM;
111
112	for (i = 0; i < num_fields; i++) {
113		struct mux_control *mux = &mux_chip->mux[i];
114		struct reg_field field;
115		s32 idle_state = MUX_IDLE_AS_IS;
116		u32 reg, mask;
117		int bits;
118
119		ret = of_property_read_u32_index(np, "mux-reg-masks",
120						 2 * i, &reg);
121		if (!ret)
122			ret = of_property_read_u32_index(np, "mux-reg-masks",
123							 2 * i + 1, &mask);
124		if (ret < 0) {
125			dev_err(dev, "bitfield %d: failed to read mux-reg-masks property: %d\n",
126				i, ret);
127			return ret;
128		}
129
130		field.reg = reg;
131		field.msb = fls(mask) - 1;
132		field.lsb = ffs(mask) - 1;
133
134		if (mask != GENMASK(field.msb, field.lsb)) {
135			dev_err(dev, "bitfield %d: invalid mask 0x%x\n",
136				i, mask);
137			return -EINVAL;
138		}
139
140		mux_mmio->fields[i] = devm_regmap_field_alloc(dev, regmap, field);
141		if (IS_ERR(mux_mmio->fields[i])) {
142			ret = PTR_ERR(mux_mmio->fields[i]);
143			dev_err(dev, "bitfield %d: failed to allocate: %d\n",
144				i, ret);
145			return ret;
146		}
147
148		bits = 1 + field.msb - field.lsb;
149		mux->states = 1 << bits;
150
151		of_property_read_u32_index(np, "idle-states", i,
152					   (u32 *)&idle_state);
153		if (idle_state != MUX_IDLE_AS_IS) {
154			if (idle_state < 0 || idle_state >= mux->states) {
155				dev_err(dev, "bitfield: %d: out of range idle state %d\n",
156					i, idle_state);
157				return -EINVAL;
158			}
159
160			mux->idle_state = idle_state;
161		}
162	}
163
164	mux_chip->ops = &mux_mmio_ops;
165
166	dev_set_drvdata(dev, mux_chip);
167
168	return devm_mux_chip_register(dev, mux_chip);
169}
170
171static int mux_mmio_suspend_noirq(struct device *dev)
172{
173	struct mux_chip *mux_chip = dev_get_drvdata(dev);
174	struct mux_mmio *mux_mmio = mux_chip_priv(mux_chip);
175	unsigned int state;
176	int ret, i;
177
178	for (i = 0; i < mux_chip->controllers; i++) {
179		ret = mux_mmio_get(&mux_chip->mux[i], &state);
180		if (ret) {
181			dev_err(dev, "control %u: error saving mux: %d\n", i, ret);
182			return ret;
183		}
184
185		mux_mmio->hardware_states[i] = state;
186	}
187
188	return 0;
189}
190
191static int mux_mmio_resume_noirq(struct device *dev)
192{
193	struct mux_chip *mux_chip = dev_get_drvdata(dev);
194	struct mux_mmio *mux_mmio = mux_chip_priv(mux_chip);
195	int ret, i;
196
197	for (i = 0; i < mux_chip->controllers; i++) {
198		ret = mux_mmio_set(&mux_chip->mux[i], mux_mmio->hardware_states[i]);
199		if (ret) {
200			dev_err(dev, "control %u: error restoring mux: %d\n", i, ret);
201			return ret;
202		}
203	}
204
205	return 0;
206}
207
208static DEFINE_NOIRQ_DEV_PM_OPS(mux_mmio_pm_ops, mux_mmio_suspend_noirq, mux_mmio_resume_noirq);
209
210static struct platform_driver mux_mmio_driver = {
211	.driver = {
212		.name = "mmio-mux",
213		.of_match_table	= mux_mmio_dt_ids,
214		.pm = pm_sleep_ptr(&mux_mmio_pm_ops),
215	},
216	.probe = mux_mmio_probe,
217};
218module_platform_driver(mux_mmio_driver);
219
220MODULE_DESCRIPTION("MMIO register bitfield-controlled multiplexer driver");
221MODULE_AUTHOR("Philipp Zabel <p.zabel@pengutronix.de>");
222MODULE_LICENSE("GPL v2");