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 == -EPROBE_DEFER) 175 return ret; 176 177 if (ret < 0) { 178 dev_err(&pdev->dev, "Error parsing device tree"); 179 return ret; 180 } 181 } 182 183 parent = i2c_get_adapter(mux->data.parent); 184 if (!parent) 185 return -EPROBE_DEFER; 186 187 if (!mux->data.reg) { 188 dev_info(&pdev->dev, 189 "Register not set, using platform resource\n"); 190 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 191 mux->data.reg_size = resource_size(res); 192 mux->data.reg = devm_ioremap_resource(&pdev->dev, res); 193 if (IS_ERR(mux->data.reg)) { 194 ret = PTR_ERR(mux->data.reg); 195 goto err_put_parent; 196 } 197 } 198 199 if (mux->data.reg_size != 4 && mux->data.reg_size != 2 && 200 mux->data.reg_size != 1) { 201 dev_err(&pdev->dev, "Invalid register size\n"); 202 ret = -EINVAL; 203 goto err_put_parent; 204 } 205 206 muxc = i2c_mux_alloc(parent, &pdev->dev, mux->data.n_values, 0, 0, 207 i2c_mux_reg_select, NULL); 208 if (!muxc) { 209 ret = -ENOMEM; 210 goto err_put_parent; 211 } 212 muxc->priv = mux; 213 214 platform_set_drvdata(pdev, muxc); 215 216 if (mux->data.idle_in_use) 217 muxc->deselect = i2c_mux_reg_deselect; 218 219 for (i = 0; i < mux->data.n_values; i++) { 220 nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0; 221 class = mux->data.classes ? mux->data.classes[i] : 0; 222 223 ret = i2c_mux_add_adapter(muxc, nr, mux->data.values[i], class); 224 if (ret) 225 goto err_del_mux_adapters; 226 } 227 228 dev_dbg(&pdev->dev, "%d port mux on %s adapter\n", 229 mux->data.n_values, muxc->parent->name); 230 231 return 0; 232 233 err_del_mux_adapters: 234 i2c_mux_del_adapters(muxc); 235 err_put_parent: 236 i2c_put_adapter(parent); 237 238 return ret; 239 } 240 241 static int i2c_mux_reg_remove(struct platform_device *pdev) 242 { 243 struct i2c_mux_core *muxc = platform_get_drvdata(pdev); 244 245 i2c_mux_del_adapters(muxc); 246 i2c_put_adapter(muxc->parent); 247 248 return 0; 249 } 250 251 static const struct of_device_id i2c_mux_reg_of_match[] = { 252 { .compatible = "i2c-mux-reg", }, 253 {}, 254 }; 255 MODULE_DEVICE_TABLE(of, i2c_mux_reg_of_match); 256 257 static struct platform_driver i2c_mux_reg_driver = { 258 .probe = i2c_mux_reg_probe, 259 .remove = i2c_mux_reg_remove, 260 .driver = { 261 .name = "i2c-mux-reg", 262 .of_match_table = of_match_ptr(i2c_mux_reg_of_match), 263 }, 264 }; 265 266 module_platform_driver(i2c_mux_reg_driver); 267 268 MODULE_DESCRIPTION("Register-based I2C multiplexer driver"); 269 MODULE_AUTHOR("York Sun <yorksun@freescale.com>"); 270 MODULE_LICENSE("GPL"); 271 MODULE_ALIAS("platform:i2c-mux-reg"); 272