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 <khali@linux-fr.org>. 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/module.h> 39 #include <linux/init.h> 40 #include <linux/slab.h> 41 #include <linux/device.h> 42 #include <linux/i2c.h> 43 #include <linux/i2c-mux.h> 44 45 #include <linux/i2c/pca954x.h> 46 47 #define PCA954X_MAX_NCHANS 8 48 49 enum pca_type { 50 pca_9540, 51 pca_9542, 52 pca_9543, 53 pca_9544, 54 pca_9545, 55 pca_9546, 56 pca_9547, 57 pca_9548, 58 }; 59 60 struct pca954x { 61 enum pca_type type; 62 struct i2c_adapter *virt_adaps[PCA954X_MAX_NCHANS]; 63 64 u8 last_chan; /* last register value */ 65 }; 66 67 struct chip_desc { 68 u8 nchans; 69 u8 enable; /* used for muxes only */ 70 enum muxtype { 71 pca954x_ismux = 0, 72 pca954x_isswi 73 } muxtype; 74 }; 75 76 /* Provide specs for the PCA954x types we know about */ 77 static const struct chip_desc chips[] = { 78 [pca_9540] = { 79 .nchans = 2, 80 .enable = 0x4, 81 .muxtype = pca954x_ismux, 82 }, 83 [pca_9543] = { 84 .nchans = 2, 85 .muxtype = pca954x_isswi, 86 }, 87 [pca_9544] = { 88 .nchans = 4, 89 .enable = 0x4, 90 .muxtype = pca954x_ismux, 91 }, 92 [pca_9545] = { 93 .nchans = 4, 94 .muxtype = pca954x_isswi, 95 }, 96 [pca_9547] = { 97 .nchans = 8, 98 .enable = 0x8, 99 .muxtype = pca954x_ismux, 100 }, 101 [pca_9548] = { 102 .nchans = 8, 103 .muxtype = pca954x_isswi, 104 }, 105 }; 106 107 static const struct i2c_device_id pca954x_id[] = { 108 { "pca9540", pca_9540 }, 109 { "pca9542", pca_9540 }, 110 { "pca9543", pca_9543 }, 111 { "pca9544", pca_9544 }, 112 { "pca9545", pca_9545 }, 113 { "pca9546", pca_9545 }, 114 { "pca9547", pca_9547 }, 115 { "pca9548", pca_9548 }, 116 { } 117 }; 118 MODULE_DEVICE_TABLE(i2c, pca954x_id); 119 120 /* Write to mux register. Don't use i2c_transfer()/i2c_smbus_xfer() 121 for this as they will try to lock adapter a second time */ 122 static int pca954x_reg_write(struct i2c_adapter *adap, 123 struct i2c_client *client, u8 val) 124 { 125 int ret = -ENODEV; 126 127 if (adap->algo->master_xfer) { 128 struct i2c_msg msg; 129 char buf[1]; 130 131 msg.addr = client->addr; 132 msg.flags = 0; 133 msg.len = 1; 134 buf[0] = val; 135 msg.buf = buf; 136 ret = adap->algo->master_xfer(adap, &msg, 1); 137 } else { 138 union i2c_smbus_data data; 139 ret = adap->algo->smbus_xfer(adap, client->addr, 140 client->flags, 141 I2C_SMBUS_WRITE, 142 val, I2C_SMBUS_BYTE, &data); 143 } 144 145 return ret; 146 } 147 148 static int pca954x_select_chan(struct i2c_adapter *adap, 149 void *client, u32 chan) 150 { 151 struct pca954x *data = i2c_get_clientdata(client); 152 const struct chip_desc *chip = &chips[data->type]; 153 u8 regval; 154 int ret = 0; 155 156 /* we make switches look like muxes, not sure how to be smarter */ 157 if (chip->muxtype == pca954x_ismux) 158 regval = chan | chip->enable; 159 else 160 regval = 1 << chan; 161 162 /* Only select the channel if its different from the last channel */ 163 if (data->last_chan != regval) { 164 ret = pca954x_reg_write(adap, client, regval); 165 data->last_chan = regval; 166 } 167 168 return ret; 169 } 170 171 static int pca954x_deselect_mux(struct i2c_adapter *adap, 172 void *client, u32 chan) 173 { 174 struct pca954x *data = i2c_get_clientdata(client); 175 176 /* Deselect active channel */ 177 data->last_chan = 0; 178 return pca954x_reg_write(adap, client, data->last_chan); 179 } 180 181 /* 182 * I2C init/probing/exit functions 183 */ 184 static int pca954x_probe(struct i2c_client *client, 185 const struct i2c_device_id *id) 186 { 187 struct i2c_adapter *adap = to_i2c_adapter(client->dev.parent); 188 struct pca954x_platform_data *pdata = dev_get_platdata(&client->dev); 189 int num, force, class; 190 struct pca954x *data; 191 int ret = -ENODEV; 192 193 if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE)) 194 goto err; 195 196 data = kzalloc(sizeof(struct pca954x), GFP_KERNEL); 197 if (!data) { 198 ret = -ENOMEM; 199 goto err; 200 } 201 202 i2c_set_clientdata(client, data); 203 204 /* Write the mux register at addr to verify 205 * that the mux is in fact present. This also 206 * initializes the mux to disconnected state. 207 */ 208 if (i2c_smbus_write_byte(client, 0) < 0) { 209 dev_warn(&client->dev, "probe failed\n"); 210 goto exit_free; 211 } 212 213 data->type = id->driver_data; 214 data->last_chan = 0; /* force the first selection */ 215 216 /* Now create an adapter for each channel */ 217 for (num = 0; num < chips[data->type].nchans; num++) { 218 force = 0; /* dynamic adap number */ 219 class = 0; /* no class by default */ 220 if (pdata) { 221 if (num < pdata->num_modes) { 222 /* force static number */ 223 force = pdata->modes[num].adap_id; 224 class = pdata->modes[num].class; 225 } else 226 /* discard unconfigured channels */ 227 break; 228 } 229 230 data->virt_adaps[num] = 231 i2c_add_mux_adapter(adap, &client->dev, client, 232 force, num, class, pca954x_select_chan, 233 (pdata && pdata->modes[num].deselect_on_exit) 234 ? pca954x_deselect_mux : NULL); 235 236 if (data->virt_adaps[num] == NULL) { 237 ret = -ENODEV; 238 dev_err(&client->dev, 239 "failed to register multiplexed adapter" 240 " %d as bus %d\n", num, force); 241 goto virt_reg_failed; 242 } 243 } 244 245 dev_info(&client->dev, 246 "registered %d multiplexed busses for I2C %s %s\n", 247 num, chips[data->type].muxtype == pca954x_ismux 248 ? "mux" : "switch", client->name); 249 250 return 0; 251 252 virt_reg_failed: 253 for (num--; num >= 0; num--) 254 i2c_del_mux_adapter(data->virt_adaps[num]); 255 exit_free: 256 kfree(data); 257 err: 258 return ret; 259 } 260 261 static int pca954x_remove(struct i2c_client *client) 262 { 263 struct pca954x *data = i2c_get_clientdata(client); 264 const struct chip_desc *chip = &chips[data->type]; 265 int i; 266 267 for (i = 0; i < chip->nchans; ++i) 268 if (data->virt_adaps[i]) { 269 i2c_del_mux_adapter(data->virt_adaps[i]); 270 data->virt_adaps[i] = NULL; 271 } 272 273 kfree(data); 274 return 0; 275 } 276 277 static struct i2c_driver pca954x_driver = { 278 .driver = { 279 .name = "pca954x", 280 .owner = THIS_MODULE, 281 }, 282 .probe = pca954x_probe, 283 .remove = pca954x_remove, 284 .id_table = pca954x_id, 285 }; 286 287 module_i2c_driver(pca954x_driver); 288 289 MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>"); 290 MODULE_DESCRIPTION("PCA954x I2C mux/switch driver"); 291 MODULE_LICENSE("GPL v2"); 292