1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * I2C multiplexer using GPIO API
  4 *
  5 * Peter Korsgaard <peter.korsgaard@barco.com>
  6 */
  7
  8#include <linux/bits.h>
  9#include <linux/delay.h>
 10#include <linux/gpio/consumer.h>
 11#include <linux/gpio/driver.h>
 12#include <linux/i2c.h>
 13#include <linux/i2c-mux.h>
 14#include <linux/module.h>
 15#include <linux/overflow.h>
 16#include <linux/platform_data/i2c-mux-gpio.h>
 17#include <linux/platform_device.h>
 18#include <linux/slab.h>
 19
 20struct gpiomux {
 21	struct i2c_mux_gpio_platform_data data;
 22	int ngpios;
 23	struct gpio_desc **gpios;
 24};
 25
 26static void i2c_mux_gpio_set(const struct gpiomux *mux, unsigned int val)
 27{
 28	DECLARE_BITMAP(values, BITS_PER_TYPE(val));
 29
 30	values[0] = val;
 31
 32	gpiod_set_array_value_cansleep(mux->ngpios, mux->gpios, NULL, values);
 33}
 34
 35static int i2c_mux_gpio_select(struct i2c_mux_core *muxc, u32 chan)
 36{
 37	struct gpiomux *mux = i2c_mux_priv(muxc);
 38
 39	i2c_mux_gpio_set(mux, chan);
 40
 41	if (mux->data.settle_time)
 42		fsleep(mux->data.settle_time);
 43
 44	return 0;
 45}
 46
 47static int i2c_mux_gpio_deselect(struct i2c_mux_core *muxc, u32 chan)
 48{
 49	struct gpiomux *mux = i2c_mux_priv(muxc);
 50
 51	i2c_mux_gpio_set(mux, mux->data.idle);
 52
 53	return 0;
 54}
 55
 56static int i2c_mux_gpio_probe_fw(struct gpiomux *mux,
 57				 struct platform_device *pdev)
 58{
 59	struct device *dev = &pdev->dev;
 60	struct fwnode_handle *fwnode = dev_fwnode(dev);
 61	struct device_node *np = dev->of_node;
 62	struct device_node *adapter_np;
 63	struct i2c_adapter *adapter = NULL;
 64	struct fwnode_handle *child;
 65	unsigned int *values;
 66	int rc, i = 0;
 67
 68	if (is_of_node(fwnode)) {
 69		if (!np)
 70			return -ENODEV;
 71
 72		adapter_np = of_parse_phandle(np, "i2c-parent", 0);
 73		if (!adapter_np) {
 74			dev_err(&pdev->dev, "Cannot parse i2c-parent\n");
 75			return -ENODEV;
 76		}
 77		adapter = of_find_i2c_adapter_by_node(adapter_np);
 78		of_node_put(adapter_np);
 79
 80	} else if (is_acpi_node(fwnode)) {
 81		/*
 82		 * In ACPI land the mux should be a direct child of the i2c
 83		 * bus it muxes.
 84		 */
 85		acpi_handle dev_handle = ACPI_HANDLE(dev->parent);
 86
 87		adapter = i2c_acpi_find_adapter_by_handle(dev_handle);
 88	}
 89
 90	if (!adapter)
 91		return -EPROBE_DEFER;
 92
 93	mux->data.parent = i2c_adapter_id(adapter);
 94	put_device(&adapter->dev);
 95
 96	mux->data.n_values = device_get_child_node_count(dev);
 97	values = devm_kcalloc(dev,
 98			      mux->data.n_values, sizeof(*mux->data.values),
 99			      GFP_KERNEL);
100	if (!values) {
101		dev_err(dev, "Cannot allocate values array");
102		return -ENOMEM;
103	}
104
105	device_for_each_child_node(dev, child) {
106		if (is_of_node(child)) {
107			fwnode_property_read_u32(child, "reg", values + i);
108		} else if (is_acpi_node(child)) {
109			rc = acpi_get_local_address(ACPI_HANDLE_FWNODE(child), values + i);
110			if (rc) {
111				fwnode_handle_put(child);
112				return dev_err_probe(dev, rc, "Cannot get address\n");
113			}
114		}
115
116		i++;
117	}
118	mux->data.values = values;
119
120	if (device_property_read_u32(dev, "idle-state", &mux->data.idle))
121		mux->data.idle = I2C_MUX_GPIO_NO_IDLE;
122
123	device_property_read_u32(dev, "settle-time-us", &mux->data.settle_time);
124
125	return 0;
126}
127
128static int i2c_mux_gpio_probe(struct platform_device *pdev)
129{
130	struct i2c_mux_core *muxc;
131	struct gpiomux *mux;
132	struct i2c_adapter *parent;
133	struct i2c_adapter *root;
134	unsigned int initial_state;
135	int i, ngpios, ret;
136
137	mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
138	if (!mux)
139		return -ENOMEM;
140
141	if (!dev_get_platdata(&pdev->dev)) {
142		ret = i2c_mux_gpio_probe_fw(mux, pdev);
143		if (ret < 0)
144			return ret;
145	} else {
146		memcpy(&mux->data, dev_get_platdata(&pdev->dev),
147			sizeof(mux->data));
148	}
149
150	ngpios = gpiod_count(&pdev->dev, "mux");
151	if (ngpios <= 0) {
152		dev_err(&pdev->dev, "no valid gpios provided\n");
153		return ngpios ?: -EINVAL;
154	}
155	mux->ngpios = ngpios;
156
157	parent = i2c_get_adapter(mux->data.parent);
158	if (!parent)
159		return -EPROBE_DEFER;
160
161	muxc = i2c_mux_alloc(parent, &pdev->dev, mux->data.n_values,
162			     array_size(ngpios, sizeof(*mux->gpios)), 0,
163			     i2c_mux_gpio_select, NULL);
164	if (!muxc) {
165		ret = -ENOMEM;
166		goto alloc_failed;
167	}
168	mux->gpios = muxc->priv;
169	muxc->priv = mux;
170
171	platform_set_drvdata(pdev, muxc);
172
173	root = i2c_root_adapter(&parent->dev);
174
175	muxc->mux_locked = true;
176
177	if (mux->data.idle != I2C_MUX_GPIO_NO_IDLE) {
178		initial_state = mux->data.idle;
179		muxc->deselect = i2c_mux_gpio_deselect;
180	} else {
181		initial_state = mux->data.values[0];
182	}
183
184	for (i = 0; i < ngpios; i++) {
185		struct gpio_device *gdev;
186		struct device *dev;
187		struct gpio_desc *gpiod;
188		enum gpiod_flags flag;
189
190		if (initial_state & BIT(i))
191			flag = GPIOD_OUT_HIGH;
192		else
193			flag = GPIOD_OUT_LOW;
194		gpiod = devm_gpiod_get_index(&pdev->dev, "mux", i, flag);
195		if (IS_ERR(gpiod)) {
196			ret = PTR_ERR(gpiod);
197			goto alloc_failed;
198		}
199
200		mux->gpios[i] = gpiod;
201
202		if (!muxc->mux_locked)
203			continue;
204
205		gdev = gpiod_to_gpio_device(gpiod);
206		dev = gpio_device_to_device(gdev);
207		muxc->mux_locked = i2c_root_adapter(dev) == root;
208	}
209
210	if (muxc->mux_locked)
211		dev_info(&pdev->dev, "mux-locked i2c mux\n");
212
213	for (i = 0; i < mux->data.n_values; i++) {
214		u32 nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0;
215
216		ret = i2c_mux_add_adapter(muxc, nr, mux->data.values[i]);
217		if (ret)
218			goto add_adapter_failed;
219	}
220
221	dev_info(&pdev->dev, "%d port mux on %s adapter\n",
222		 mux->data.n_values, parent->name);
223
224	return 0;
225
226add_adapter_failed:
227	i2c_mux_del_adapters(muxc);
228alloc_failed:
229	i2c_put_adapter(parent);
230
231	return ret;
232}
233
234static void i2c_mux_gpio_remove(struct platform_device *pdev)
235{
236	struct i2c_mux_core *muxc = platform_get_drvdata(pdev);
237
238	i2c_mux_del_adapters(muxc);
239	i2c_put_adapter(muxc->parent);
240}
241
242static const struct of_device_id i2c_mux_gpio_of_match[] = {
243	{ .compatible = "i2c-mux-gpio", },
244	{},
245};
246MODULE_DEVICE_TABLE(of, i2c_mux_gpio_of_match);
247
248static struct platform_driver i2c_mux_gpio_driver = {
249	.probe	= i2c_mux_gpio_probe,
250	.remove = i2c_mux_gpio_remove,
251	.driver	= {
252		.name	= "i2c-mux-gpio",
253		.of_match_table = i2c_mux_gpio_of_match,
254	},
255};
256
257module_platform_driver(i2c_mux_gpio_driver);
258
259MODULE_DESCRIPTION("GPIO-based I2C multiplexer driver");
260MODULE_AUTHOR("Peter Korsgaard <peter.korsgaard@barco.com>");
261MODULE_LICENSE("GPL");
262MODULE_ALIAS("platform:i2c-mux-gpio");