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/pm.h> 46 #include <linux/slab.h> 47 48 #define PCA954X_MAX_NCHANS 8 49 50 enum pca_type { 51 pca_9540, 52 pca_9542, 53 pca_9543, 54 pca_9544, 55 pca_9545, 56 pca_9546, 57 pca_9547, 58 pca_9548, 59 }; 60 61 struct pca954x { 62 enum pca_type type; 63 struct i2c_adapter *virt_adaps[PCA954X_MAX_NCHANS]; 64 65 u8 last_chan; /* last register value */ 66 }; 67 68 struct chip_desc { 69 u8 nchans; 70 u8 enable; /* used for muxes only */ 71 enum muxtype { 72 pca954x_ismux = 0, 73 pca954x_isswi 74 } muxtype; 75 }; 76 77 /* Provide specs for the PCA954x types we know about */ 78 static const struct chip_desc chips[] = { 79 [pca_9540] = { 80 .nchans = 2, 81 .enable = 0x4, 82 .muxtype = pca954x_ismux, 83 }, 84 [pca_9543] = { 85 .nchans = 2, 86 .muxtype = pca954x_isswi, 87 }, 88 [pca_9544] = { 89 .nchans = 4, 90 .enable = 0x4, 91 .muxtype = pca954x_ismux, 92 }, 93 [pca_9545] = { 94 .nchans = 4, 95 .muxtype = pca954x_isswi, 96 }, 97 [pca_9547] = { 98 .nchans = 8, 99 .enable = 0x8, 100 .muxtype = pca954x_ismux, 101 }, 102 [pca_9548] = { 103 .nchans = 8, 104 .muxtype = pca954x_isswi, 105 }, 106 }; 107 108 static const struct i2c_device_id pca954x_id[] = { 109 { "pca9540", pca_9540 }, 110 { "pca9542", pca_9540 }, 111 { "pca9543", pca_9543 }, 112 { "pca9544", pca_9544 }, 113 { "pca9545", pca_9545 }, 114 { "pca9546", pca_9545 }, 115 { "pca9547", pca_9547 }, 116 { "pca9548", pca_9548 }, 117 { } 118 }; 119 MODULE_DEVICE_TABLE(i2c, pca954x_id); 120 121 /* Write to mux register. Don't use i2c_transfer()/i2c_smbus_xfer() 122 for this as they will try to lock adapter a second time */ 123 static int pca954x_reg_write(struct i2c_adapter *adap, 124 struct i2c_client *client, u8 val) 125 { 126 int ret = -ENODEV; 127 128 if (adap->algo->master_xfer) { 129 struct i2c_msg msg; 130 char buf[1]; 131 132 msg.addr = client->addr; 133 msg.flags = 0; 134 msg.len = 1; 135 buf[0] = val; 136 msg.buf = buf; 137 ret = __i2c_transfer(adap, &msg, 1); 138 } else { 139 union i2c_smbus_data data; 140 ret = adap->algo->smbus_xfer(adap, client->addr, 141 client->flags, 142 I2C_SMBUS_WRITE, 143 val, I2C_SMBUS_BYTE, &data); 144 } 145 146 return ret; 147 } 148 149 static int pca954x_select_chan(struct i2c_adapter *adap, 150 void *client, u32 chan) 151 { 152 struct pca954x *data = i2c_get_clientdata(client); 153 const struct chip_desc *chip = &chips[data->type]; 154 u8 regval; 155 int ret = 0; 156 157 /* we make switches look like muxes, not sure how to be smarter */ 158 if (chip->muxtype == pca954x_ismux) 159 regval = chan | chip->enable; 160 else 161 regval = 1 << chan; 162 163 /* Only select the channel if its different from the last channel */ 164 if (data->last_chan != regval) { 165 ret = pca954x_reg_write(adap, client, regval); 166 data->last_chan = regval; 167 } 168 169 return ret; 170 } 171 172 static int pca954x_deselect_mux(struct i2c_adapter *adap, 173 void *client, u32 chan) 174 { 175 struct pca954x *data = i2c_get_clientdata(client); 176 177 /* Deselect active channel */ 178 data->last_chan = 0; 179 return pca954x_reg_write(adap, client, data->last_chan); 180 } 181 182 /* 183 * I2C init/probing/exit functions 184 */ 185 static int pca954x_probe(struct i2c_client *client, 186 const struct i2c_device_id *id) 187 { 188 struct i2c_adapter *adap = to_i2c_adapter(client->dev.parent); 189 struct pca954x_platform_data *pdata = dev_get_platdata(&client->dev); 190 struct device_node *of_node = client->dev.of_node; 191 bool idle_disconnect_dt; 192 struct gpio_desc *gpio; 193 int num, force, class; 194 struct pca954x *data; 195 int ret; 196 197 if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE)) 198 return -ENODEV; 199 200 data = devm_kzalloc(&client->dev, sizeof(struct pca954x), GFP_KERNEL); 201 if (!data) 202 return -ENOMEM; 203 204 i2c_set_clientdata(client, data); 205 206 /* Get the mux out of reset if a reset GPIO is specified. */ 207 gpio = devm_gpiod_get_optional(&client->dev, "reset", GPIOD_OUT_LOW); 208 if (IS_ERR(gpio)) 209 return PTR_ERR(gpio); 210 211 /* Write the mux register at addr to verify 212 * that the mux is in fact present. This also 213 * initializes the mux to disconnected state. 214 */ 215 if (i2c_smbus_write_byte(client, 0) < 0) { 216 dev_warn(&client->dev, "probe failed\n"); 217 return -ENODEV; 218 } 219 220 data->type = id->driver_data; 221 data->last_chan = 0; /* force the first selection */ 222 223 idle_disconnect_dt = of_node && 224 of_property_read_bool(of_node, "i2c-mux-idle-disconnect"); 225 226 /* Now create an adapter for each channel */ 227 for (num = 0; num < chips[data->type].nchans; num++) { 228 bool idle_disconnect_pd = false; 229 230 force = 0; /* dynamic adap number */ 231 class = 0; /* no class by default */ 232 if (pdata) { 233 if (num < pdata->num_modes) { 234 /* force static number */ 235 force = pdata->modes[num].adap_id; 236 class = pdata->modes[num].class; 237 } else 238 /* discard unconfigured channels */ 239 break; 240 idle_disconnect_pd = pdata->modes[num].deselect_on_exit; 241 } 242 243 data->virt_adaps[num] = 244 i2c_add_mux_adapter(adap, &client->dev, client, 245 force, num, class, pca954x_select_chan, 246 (idle_disconnect_pd || idle_disconnect_dt) 247 ? pca954x_deselect_mux : NULL); 248 249 if (data->virt_adaps[num] == NULL) { 250 ret = -ENODEV; 251 dev_err(&client->dev, 252 "failed to register multiplexed adapter" 253 " %d as bus %d\n", num, force); 254 goto virt_reg_failed; 255 } 256 } 257 258 dev_info(&client->dev, 259 "registered %d multiplexed busses for I2C %s %s\n", 260 num, chips[data->type].muxtype == pca954x_ismux 261 ? "mux" : "switch", client->name); 262 263 return 0; 264 265 virt_reg_failed: 266 for (num--; num >= 0; num--) 267 i2c_del_mux_adapter(data->virt_adaps[num]); 268 return ret; 269 } 270 271 static int pca954x_remove(struct i2c_client *client) 272 { 273 struct pca954x *data = i2c_get_clientdata(client); 274 const struct chip_desc *chip = &chips[data->type]; 275 int i; 276 277 for (i = 0; i < chip->nchans; ++i) 278 if (data->virt_adaps[i]) { 279 i2c_del_mux_adapter(data->virt_adaps[i]); 280 data->virt_adaps[i] = NULL; 281 } 282 283 return 0; 284 } 285 286 #ifdef CONFIG_PM_SLEEP 287 static int pca954x_resume(struct device *dev) 288 { 289 struct i2c_client *client = to_i2c_client(dev); 290 struct pca954x *data = i2c_get_clientdata(client); 291 292 data->last_chan = 0; 293 return i2c_smbus_write_byte(client, 0); 294 } 295 #endif 296 297 static SIMPLE_DEV_PM_OPS(pca954x_pm, NULL, pca954x_resume); 298 299 static struct i2c_driver pca954x_driver = { 300 .driver = { 301 .name = "pca954x", 302 .pm = &pca954x_pm, 303 }, 304 .probe = pca954x_probe, 305 .remove = pca954x_remove, 306 .id_table = pca954x_id, 307 }; 308 309 module_i2c_driver(pca954x_driver); 310 311 MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>"); 312 MODULE_DESCRIPTION("PCA954x I2C mux/switch driver"); 313 MODULE_LICENSE("GPL v2"); 314