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 49enum 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 60struct 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 67struct 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 */ 77static 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 107static 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}; 118MODULE_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 */ 122static 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 148static 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 171static 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 */ 184static int __devinit 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 = client->dev.platform_data; 189 int num, force; 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 /* Read the mux register at addr to verify 205 * that the mux is in fact present. 206 */ 207 if (i2c_smbus_read_byte(client) < 0) { 208 dev_warn(&client->dev, "probe failed\n"); 209 goto exit_free; 210 } 211 212 data->type = id->driver_data; 213 data->last_chan = 0; /* force the first selection */ 214 215 /* Now create an adapter for each channel */ 216 for (num = 0; num < chips[data->type].nchans; num++) { 217 force = 0; /* dynamic adap number */ 218 if (pdata) { 219 if (num < pdata->num_modes) 220 /* force static number */ 221 force = pdata->modes[num].adap_id; 222 else 223 /* discard unconfigured channels */ 224 break; 225 } 226 227 data->virt_adaps[num] = 228 i2c_add_mux_adapter(adap, client, 229 force, num, pca954x_select_chan, 230 (pdata && pdata->modes[num].deselect_on_exit) 231 ? pca954x_deselect_mux : NULL); 232 233 if (data->virt_adaps[num] == NULL) { 234 ret = -ENODEV; 235 dev_err(&client->dev, 236 "failed to register multiplexed adapter" 237 " %d as bus %d\n", num, force); 238 goto virt_reg_failed; 239 } 240 } 241 242 dev_info(&client->dev, 243 "registered %d multiplexed busses for I2C %s %s\n", 244 num, chips[data->type].muxtype == pca954x_ismux 245 ? "mux" : "switch", client->name); 246 247 return 0; 248 249virt_reg_failed: 250 for (num--; num >= 0; num--) 251 i2c_del_mux_adapter(data->virt_adaps[num]); 252exit_free: 253 kfree(data); 254err: 255 return ret; 256} 257 258static int __devexit pca954x_remove(struct i2c_client *client) 259{ 260 struct pca954x *data = i2c_get_clientdata(client); 261 const struct chip_desc *chip = &chips[data->type]; 262 int i, err; 263 264 for (i = 0; i < chip->nchans; ++i) 265 if (data->virt_adaps[i]) { 266 err = i2c_del_mux_adapter(data->virt_adaps[i]); 267 if (err) 268 return err; 269 data->virt_adaps[i] = NULL; 270 } 271 272 kfree(data); 273 return 0; 274} 275 276static struct i2c_driver pca954x_driver = { 277 .driver = { 278 .name = "pca954x", 279 .owner = THIS_MODULE, 280 }, 281 .probe = pca954x_probe, 282 .remove = __devexit_p(pca954x_remove), 283 .id_table = pca954x_id, 284}; 285 286static int __init pca954x_init(void) 287{ 288 return i2c_add_driver(&pca954x_driver); 289} 290 291static void __exit pca954x_exit(void) 292{ 293 i2c_del_driver(&pca954x_driver); 294} 295 296module_init(pca954x_init); 297module_exit(pca954x_exit); 298 299MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>"); 300MODULE_DESCRIPTION("PCA954x I2C mux/switch driver"); 301MODULE_LICENSE("GPL v2"); 302