1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * I2C multiplexer using a single register 4 * 5 * Copyright 2015 Freescale Semiconductor 6 * 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 19 struct regmux { 20 struct i2c_mux_reg_platform_data data; 21 }; 22 23 static 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 is 30 * completed on a "posted" bus, for example PCI or write buffers. 31 * The endianness of reading doesn't matter and the return data 32 * 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 else 39 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 else 47 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 61 static 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 68 static 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_OF 79 static 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 #else 118 #error Endianness not defined? 119 #endif 120 } 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 #else 149 static int i2c_mux_reg_probe_dt(struct regmux *mux, 150 struct platform_device *pdev) 151 { 152 return 0; 153 } 154 #endif 155 156 static 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 unsigned int class; 163 int i, ret, nr; 164 165 mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL); 166 if (!mux) 167 return -ENOMEM; 168 169 if (dev_get_platdata(&pdev->dev)) { 170 memcpy(&mux->data, dev_get_platdata(&pdev->dev), 171 sizeof(mux->data)); 172 } else { 173 ret = i2c_mux_reg_probe_dt(mux, pdev); 174 if (ret < 0) 175 return dev_err_probe(&pdev->dev, ret, 176 "Error parsing device tree"); 177 } 178 179 parent = i2c_get_adapter(mux->data.parent); 180 if (!parent) 181 return -EPROBE_DEFER; 182 183 if (!mux->data.reg) { 184 dev_info(&pdev->dev, 185 "Register not set, using platform resource\n"); 186 mux->data.reg = devm_platform_get_and_ioremap_resource(pdev, 0, &res); 187 if (IS_ERR(mux->data.reg)) { 188 ret = PTR_ERR(mux->data.reg); 189 goto err_put_parent; 190 } 191 mux->data.reg_size = resource_size(res); 192 } 193 194 if (mux->data.reg_size != 4 && mux->data.reg_size != 2 && 195 mux->data.reg_size != 1) { 196 dev_err(&pdev->dev, "Invalid register size\n"); 197 ret = -EINVAL; 198 goto err_put_parent; 199 } 200 201 muxc = i2c_mux_alloc(parent, &pdev->dev, mux->data.n_values, 0, 0, 202 i2c_mux_reg_select, NULL); 203 if (!muxc) { 204 ret = -ENOMEM; 205 goto err_put_parent; 206 } 207 muxc->priv = mux; 208 209 platform_set_drvdata(pdev, muxc); 210 211 if (mux->data.idle_in_use) 212 muxc->deselect = i2c_mux_reg_deselect; 213 214 for (i = 0; i < mux->data.n_values; i++) { 215 nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0; 216 class = mux->data.classes ? mux->data.classes[i] : 0; 217 218 ret = i2c_mux_add_adapter(muxc, nr, mux->data.values[i], class); 219 if (ret) 220 goto err_del_mux_adapters; 221 } 222 223 dev_dbg(&pdev->dev, "%d port mux on %s adapter\n", 224 mux->data.n_values, muxc->parent->name); 225 226 return 0; 227 228 err_del_mux_adapters: 229 i2c_mux_del_adapters(muxc); 230 err_put_parent: 231 i2c_put_adapter(parent); 232 233 return ret; 234 } 235 236 static int i2c_mux_reg_remove(struct platform_device *pdev) 237 { 238 struct i2c_mux_core *muxc = platform_get_drvdata(pdev); 239 240 i2c_mux_del_adapters(muxc); 241 i2c_put_adapter(muxc->parent); 242 243 return 0; 244 } 245 246 static const struct of_device_id i2c_mux_reg_of_match[] = { 247 { .compatible = "i2c-mux-reg", }, 248 {}, 249 }; 250 MODULE_DEVICE_TABLE(of, i2c_mux_reg_of_match); 251 252 static struct platform_driver i2c_mux_reg_driver = { 253 .probe = i2c_mux_reg_probe, 254 .remove = i2c_mux_reg_remove, 255 .driver = { 256 .name = "i2c-mux-reg", 257 .of_match_table = of_match_ptr(i2c_mux_reg_of_match), 258 }, 259 }; 260 261 module_platform_driver(i2c_mux_reg_driver); 262 263 MODULE_DESCRIPTION("Register-based I2C multiplexer driver"); 264 MODULE_AUTHOR("York Sun <yorksun@freescale.com>"); 265 MODULE_LICENSE("GPL"); 266 MODULE_ALIAS("platform:i2c-mux-reg"); 267