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