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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * I2C multiplexer using GPIO API4 *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 i2c83 * 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 else193 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_new = 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");263