263 lines · c
1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * I2C multiplexer using a single register4 *5 * Copyright 2015 Freescale Semiconductor6 * York Sun <yorksun@freescale.com>7 */8 9#include <linux/i2c.h>10#include <linux/i2c-mux.h>11#include <linux/init.h>12#include <linux/io.h>13#include <linux/module.h>14#include <linux/of_address.h>15#include <linux/platform_data/i2c-mux-reg.h>16#include <linux/platform_device.h>17#include <linux/slab.h>18 19struct regmux {20 struct i2c_mux_reg_platform_data data;21};22 23static int i2c_mux_reg_set(const struct regmux *mux, unsigned int chan_id)24{25 if (!mux->data.reg)26 return -EINVAL;27 28 /*29 * Write to the register, followed by a read to ensure the write is30 * completed on a "posted" bus, for example PCI or write buffers.31 * The endianness of reading doesn't matter and the return data32 * is not used.33 */34 switch (mux->data.reg_size) {35 case 4:36 if (mux->data.little_endian)37 iowrite32(chan_id, mux->data.reg);38 else39 iowrite32be(chan_id, mux->data.reg);40 if (!mux->data.write_only)41 ioread32(mux->data.reg);42 break;43 case 2:44 if (mux->data.little_endian)45 iowrite16(chan_id, mux->data.reg);46 else47 iowrite16be(chan_id, mux->data.reg);48 if (!mux->data.write_only)49 ioread16(mux->data.reg);50 break;51 case 1:52 iowrite8(chan_id, mux->data.reg);53 if (!mux->data.write_only)54 ioread8(mux->data.reg);55 break;56 }57 58 return 0;59}60 61static int i2c_mux_reg_select(struct i2c_mux_core *muxc, u32 chan)62{63 struct regmux *mux = i2c_mux_priv(muxc);64 65 return i2c_mux_reg_set(mux, chan);66}67 68static int i2c_mux_reg_deselect(struct i2c_mux_core *muxc, u32 chan)69{70 struct regmux *mux = i2c_mux_priv(muxc);71 72 if (mux->data.idle_in_use)73 return i2c_mux_reg_set(mux, mux->data.idle);74 75 return 0;76}77 78#ifdef CONFIG_OF79static int i2c_mux_reg_probe_dt(struct regmux *mux,80 struct platform_device *pdev)81{82 struct device_node *np = pdev->dev.of_node;83 struct device_node *adapter_np, *child;84 struct i2c_adapter *adapter;85 struct resource res;86 unsigned *values;87 int i = 0;88 89 if (!np)90 return -ENODEV;91 92 adapter_np = of_parse_phandle(np, "i2c-parent", 0);93 if (!adapter_np) {94 dev_err(&pdev->dev, "Cannot parse i2c-parent\n");95 return -ENODEV;96 }97 adapter = of_find_i2c_adapter_by_node(adapter_np);98 of_node_put(adapter_np);99 if (!adapter)100 return -EPROBE_DEFER;101 102 mux->data.parent = i2c_adapter_id(adapter);103 put_device(&adapter->dev);104 105 mux->data.n_values = of_get_child_count(np);106 if (of_property_read_bool(np, "little-endian")) {107 mux->data.little_endian = true;108 } else if (of_property_read_bool(np, "big-endian")) {109 mux->data.little_endian = false;110 } else {111#if defined(__BYTE_ORDER) ? __BYTE_ORDER == __LITTLE_ENDIAN : \112 defined(__LITTLE_ENDIAN)113 mux->data.little_endian = true;114#elif defined(__BYTE_ORDER) ? __BYTE_ORDER == __BIG_ENDIAN : \115 defined(__BIG_ENDIAN)116 mux->data.little_endian = false;117#else118#error Endianness not defined?119#endif120 }121 mux->data.write_only = of_property_read_bool(np, "write-only");122 123 values = devm_kcalloc(&pdev->dev,124 mux->data.n_values, sizeof(*mux->data.values),125 GFP_KERNEL);126 if (!values)127 return -ENOMEM;128 129 for_each_child_of_node(np, child) {130 of_property_read_u32(child, "reg", values + i);131 i++;132 }133 mux->data.values = values;134 135 if (!of_property_read_u32(np, "idle-state", &mux->data.idle))136 mux->data.idle_in_use = true;137 138 /* map address from "reg" if exists */139 if (of_address_to_resource(np, 0, &res) == 0) {140 mux->data.reg_size = resource_size(&res);141 mux->data.reg = devm_ioremap_resource(&pdev->dev, &res);142 if (IS_ERR(mux->data.reg))143 return PTR_ERR(mux->data.reg);144 }145 146 return 0;147}148#else149static int i2c_mux_reg_probe_dt(struct regmux *mux,150 struct platform_device *pdev)151{152 return 0;153}154#endif155 156static int i2c_mux_reg_probe(struct platform_device *pdev)157{158 struct i2c_mux_core *muxc;159 struct regmux *mux;160 struct i2c_adapter *parent;161 struct resource *res;162 int i, ret, nr;163 164 mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);165 if (!mux)166 return -ENOMEM;167 168 if (dev_get_platdata(&pdev->dev)) {169 memcpy(&mux->data, dev_get_platdata(&pdev->dev),170 sizeof(mux->data));171 } else {172 ret = i2c_mux_reg_probe_dt(mux, pdev);173 if (ret < 0)174 return dev_err_probe(&pdev->dev, ret,175 "Error parsing device tree");176 }177 178 parent = i2c_get_adapter(mux->data.parent);179 if (!parent)180 return -EPROBE_DEFER;181 182 if (!mux->data.reg) {183 dev_info(&pdev->dev,184 "Register not set, using platform resource\n");185 mux->data.reg = devm_platform_get_and_ioremap_resource(pdev, 0, &res);186 if (IS_ERR(mux->data.reg)) {187 ret = PTR_ERR(mux->data.reg);188 goto err_put_parent;189 }190 mux->data.reg_size = resource_size(res);191 }192 193 if (mux->data.reg_size != 4 && mux->data.reg_size != 2 &&194 mux->data.reg_size != 1) {195 dev_err(&pdev->dev, "Invalid register size\n");196 ret = -EINVAL;197 goto err_put_parent;198 }199 200 muxc = i2c_mux_alloc(parent, &pdev->dev, mux->data.n_values, 0, 0,201 i2c_mux_reg_select, NULL);202 if (!muxc) {203 ret = -ENOMEM;204 goto err_put_parent;205 }206 muxc->priv = mux;207 208 platform_set_drvdata(pdev, muxc);209 210 if (mux->data.idle_in_use)211 muxc->deselect = i2c_mux_reg_deselect;212 213 for (i = 0; i < mux->data.n_values; i++) {214 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 err_del_mux_adapters;219 }220 221 dev_dbg(&pdev->dev, "%d port mux on %s adapter\n",222 mux->data.n_values, muxc->parent->name);223 224 return 0;225 226err_del_mux_adapters:227 i2c_mux_del_adapters(muxc);228err_put_parent:229 i2c_put_adapter(parent);230 231 return ret;232}233 234static void i2c_mux_reg_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_reg_of_match[] = {243 { .compatible = "i2c-mux-reg", },244 {},245};246MODULE_DEVICE_TABLE(of, i2c_mux_reg_of_match);247 248static struct platform_driver i2c_mux_reg_driver = {249 .probe = i2c_mux_reg_probe,250 .remove_new = i2c_mux_reg_remove,251 .driver = {252 .name = "i2c-mux-reg",253 .of_match_table = of_match_ptr(i2c_mux_reg_of_match),254 },255};256 257module_platform_driver(i2c_mux_reg_driver);258 259MODULE_DESCRIPTION("Register-based I2C multiplexer driver");260MODULE_AUTHOR("York Sun <yorksun@freescale.com>");261MODULE_LICENSE("GPL");262MODULE_ALIAS("platform:i2c-mux-reg");263