1 /* 2 * I2C multiplexer 3 * 4 * Copyright (c) 2008-2009 Rodolfo Giometti <giometti@linux.it> 5 * Copyright (c) 2008-2009 Eurotech S.p.A. <info@eurotech.it> 6 * 7 * This module supports the PCA954x series of I2C multiplexer/switch chips 8 * made by Philips Semiconductors. 9 * This includes the: 10 * PCA9540, PCA9542, PCA9543, PCA9544, PCA9545, PCA9546, PCA9547 11 * and PCA9548. 12 * 13 * These chips are all controlled via the I2C bus itself, and all have a 14 * single 8-bit register. The upstream "parent" bus fans out to two, 15 * four, or eight downstream busses or channels; which of these 16 * are selected is determined by the chip type and register contents. A 17 * mux can select only one sub-bus at a time; a switch can select any 18 * combination simultaneously. 19 * 20 * Based on: 21 * pca954x.c from Kumar Gala <galak@kernel.crashing.org> 22 * Copyright (C) 2006 23 * 24 * Based on: 25 * pca954x.c from Ken Harrenstien 26 * Copyright (C) 2004 Google, Inc. (Ken Harrenstien) 27 * 28 * Based on: 29 * i2c-virtual_cb.c from Brian Kuschak <bkuschak@yahoo.com> 30 * and 31 * pca9540.c from Jean Delvare <jdelvare@suse.de>. 32 * 33 * This file is licensed under the terms of the GNU General Public 34 * License version 2. This program is licensed "as is" without any 35 * warranty of any kind, whether express or implied. 36 */ 37 38 #include <linux/device.h> 39 #include <linux/gpio/consumer.h> 40 #include <linux/i2c.h> 41 #include <linux/i2c-mux.h> 42 #include <linux/i2c/pca954x.h> 43 #include <linux/module.h> 44 #include <linux/of.h> 45 #include <linux/of_device.h> 46 #include <linux/pm.h> 47 #include <linux/slab.h> 48 49 #define PCA954X_MAX_NCHANS 8 50 51 enum pca_type { 52 pca_9540, 53 pca_9542, 54 pca_9543, 55 pca_9544, 56 pca_9545, 57 pca_9546, 58 pca_9547, 59 pca_9548, 60 }; 61 62 struct chip_desc { 63 u8 nchans; 64 u8 enable; /* used for muxes only */ 65 enum muxtype { 66 pca954x_ismux = 0, 67 pca954x_isswi 68 } muxtype; 69 }; 70 71 struct pca954x { 72 const struct chip_desc *chip; 73 74 u8 last_chan; /* last register value */ 75 u8 deselect; 76 struct i2c_client *client; 77 }; 78 79 /* Provide specs for the PCA954x types we know about */ 80 static const struct chip_desc chips[] = { 81 [pca_9540] = { 82 .nchans = 2, 83 .enable = 0x4, 84 .muxtype = pca954x_ismux, 85 }, 86 [pca_9543] = { 87 .nchans = 2, 88 .muxtype = pca954x_isswi, 89 }, 90 [pca_9544] = { 91 .nchans = 4, 92 .enable = 0x4, 93 .muxtype = pca954x_ismux, 94 }, 95 [pca_9545] = { 96 .nchans = 4, 97 .muxtype = pca954x_isswi, 98 }, 99 [pca_9547] = { 100 .nchans = 8, 101 .enable = 0x8, 102 .muxtype = pca954x_ismux, 103 }, 104 [pca_9548] = { 105 .nchans = 8, 106 .muxtype = pca954x_isswi, 107 }, 108 }; 109 110 static const struct i2c_device_id pca954x_id[] = { 111 { "pca9540", pca_9540 }, 112 { "pca9542", pca_9540 }, 113 { "pca9543", pca_9543 }, 114 { "pca9544", pca_9544 }, 115 { "pca9545", pca_9545 }, 116 { "pca9546", pca_9545 }, 117 { "pca9547", pca_9547 }, 118 { "pca9548", pca_9548 }, 119 { } 120 }; 121 MODULE_DEVICE_TABLE(i2c, pca954x_id); 122 123 #ifdef CONFIG_OF 124 static const struct of_device_id pca954x_of_match[] = { 125 { .compatible = "nxp,pca9540", .data = &chips[pca_9540] }, 126 { .compatible = "nxp,pca9542", .data = &chips[pca_9542] }, 127 { .compatible = "nxp,pca9543", .data = &chips[pca_9543] }, 128 { .compatible = "nxp,pca9544", .data = &chips[pca_9544] }, 129 { .compatible = "nxp,pca9545", .data = &chips[pca_9545] }, 130 { .compatible = "nxp,pca9546", .data = &chips[pca_9546] }, 131 { .compatible = "nxp,pca9547", .data = &chips[pca_9547] }, 132 { .compatible = "nxp,pca9548", .data = &chips[pca_9548] }, 133 {} 134 }; 135 #endif 136 137 /* Write to mux register. Don't use i2c_transfer()/i2c_smbus_xfer() 138 for this as they will try to lock adapter a second time */ 139 static int pca954x_reg_write(struct i2c_adapter *adap, 140 struct i2c_client *client, u8 val) 141 { 142 int ret = -ENODEV; 143 144 if (adap->algo->master_xfer) { 145 struct i2c_msg msg; 146 char buf[1]; 147 148 msg.addr = client->addr; 149 msg.flags = 0; 150 msg.len = 1; 151 buf[0] = val; 152 msg.buf = buf; 153 ret = __i2c_transfer(adap, &msg, 1); 154 } else { 155 union i2c_smbus_data data; 156 ret = adap->algo->smbus_xfer(adap, client->addr, 157 client->flags, 158 I2C_SMBUS_WRITE, 159 val, I2C_SMBUS_BYTE, &data); 160 } 161 162 return ret; 163 } 164 165 static int pca954x_select_chan(struct i2c_mux_core *muxc, u32 chan) 166 { 167 struct pca954x *data = i2c_mux_priv(muxc); 168 struct i2c_client *client = data->client; 169 const struct chip_desc *chip = data->chip; 170 u8 regval; 171 int ret = 0; 172 173 /* we make switches look like muxes, not sure how to be smarter */ 174 if (chip->muxtype == pca954x_ismux) 175 regval = chan | chip->enable; 176 else 177 regval = 1 << chan; 178 179 /* Only select the channel if its different from the last channel */ 180 if (data->last_chan != regval) { 181 ret = pca954x_reg_write(muxc->parent, client, regval); 182 data->last_chan = ret ? 0 : regval; 183 } 184 185 return ret; 186 } 187 188 static int pca954x_deselect_mux(struct i2c_mux_core *muxc, u32 chan) 189 { 190 struct pca954x *data = i2c_mux_priv(muxc); 191 struct i2c_client *client = data->client; 192 193 if (!(data->deselect & (1 << chan))) 194 return 0; 195 196 /* Deselect active channel */ 197 data->last_chan = 0; 198 return pca954x_reg_write(muxc->parent, client, data->last_chan); 199 } 200 201 /* 202 * I2C init/probing/exit functions 203 */ 204 static int pca954x_probe(struct i2c_client *client, 205 const struct i2c_device_id *id) 206 { 207 struct i2c_adapter *adap = to_i2c_adapter(client->dev.parent); 208 struct pca954x_platform_data *pdata = dev_get_platdata(&client->dev); 209 struct device_node *of_node = client->dev.of_node; 210 bool idle_disconnect_dt; 211 struct gpio_desc *gpio; 212 int num, force, class; 213 struct i2c_mux_core *muxc; 214 struct pca954x *data; 215 const struct of_device_id *match; 216 int ret; 217 218 if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE)) 219 return -ENODEV; 220 221 muxc = i2c_mux_alloc(adap, &client->dev, 222 PCA954X_MAX_NCHANS, sizeof(*data), 0, 223 pca954x_select_chan, pca954x_deselect_mux); 224 if (!muxc) 225 return -ENOMEM; 226 data = i2c_mux_priv(muxc); 227 228 i2c_set_clientdata(client, muxc); 229 data->client = client; 230 231 /* Get the mux out of reset if a reset GPIO is specified. */ 232 gpio = devm_gpiod_get_optional(&client->dev, "reset", GPIOD_OUT_LOW); 233 if (IS_ERR(gpio)) 234 return PTR_ERR(gpio); 235 236 /* Write the mux register at addr to verify 237 * that the mux is in fact present. This also 238 * initializes the mux to disconnected state. 239 */ 240 if (i2c_smbus_write_byte(client, 0) < 0) { 241 dev_warn(&client->dev, "probe failed\n"); 242 return -ENODEV; 243 } 244 245 match = of_match_device(of_match_ptr(pca954x_of_match), &client->dev); 246 if (match) 247 data->chip = of_device_get_match_data(&client->dev); 248 else 249 data->chip = &chips[id->driver_data]; 250 251 data->last_chan = 0; /* force the first selection */ 252 253 idle_disconnect_dt = of_node && 254 of_property_read_bool(of_node, "i2c-mux-idle-disconnect"); 255 256 /* Now create an adapter for each channel */ 257 for (num = 0; num < data->chip->nchans; num++) { 258 bool idle_disconnect_pd = false; 259 260 force = 0; /* dynamic adap number */ 261 class = 0; /* no class by default */ 262 if (pdata) { 263 if (num < pdata->num_modes) { 264 /* force static number */ 265 force = pdata->modes[num].adap_id; 266 class = pdata->modes[num].class; 267 } else 268 /* discard unconfigured channels */ 269 break; 270 idle_disconnect_pd = pdata->modes[num].deselect_on_exit; 271 data->deselect |= (idle_disconnect_pd 272 || idle_disconnect_dt) << num; 273 } 274 275 ret = i2c_mux_add_adapter(muxc, force, num, class); 276 277 if (ret) { 278 dev_err(&client->dev, 279 "failed to register multiplexed adapter" 280 " %d as bus %d\n", num, force); 281 goto virt_reg_failed; 282 } 283 } 284 285 dev_info(&client->dev, 286 "registered %d multiplexed busses for I2C %s %s\n", 287 num, data->chip->muxtype == pca954x_ismux 288 ? "mux" : "switch", client->name); 289 290 return 0; 291 292 virt_reg_failed: 293 i2c_mux_del_adapters(muxc); 294 return ret; 295 } 296 297 static int pca954x_remove(struct i2c_client *client) 298 { 299 struct i2c_mux_core *muxc = i2c_get_clientdata(client); 300 301 i2c_mux_del_adapters(muxc); 302 return 0; 303 } 304 305 #ifdef CONFIG_PM_SLEEP 306 static int pca954x_resume(struct device *dev) 307 { 308 struct i2c_client *client = to_i2c_client(dev); 309 struct i2c_mux_core *muxc = i2c_get_clientdata(client); 310 struct pca954x *data = i2c_mux_priv(muxc); 311 312 data->last_chan = 0; 313 return i2c_smbus_write_byte(client, 0); 314 } 315 #endif 316 317 static SIMPLE_DEV_PM_OPS(pca954x_pm, NULL, pca954x_resume); 318 319 static struct i2c_driver pca954x_driver = { 320 .driver = { 321 .name = "pca954x", 322 .pm = &pca954x_pm, 323 .of_match_table = of_match_ptr(pca954x_of_match), 324 }, 325 .probe = pca954x_probe, 326 .remove = pca954x_remove, 327 .id_table = pca954x_id, 328 }; 329 330 module_i2c_driver(pca954x_driver); 331 332 MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>"); 333 MODULE_DESCRIPTION("PCA954x I2C mux/switch driver"); 334 MODULE_LICENSE("GPL v2"); 335