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.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_gpio.h> 45 #include <linux/slab.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 struct device_node *np = client->dev.of_node; 190 int num, force, class; 191 struct pca954x *data; 192 int ret; 193 194 if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE)) 195 return -ENODEV; 196 197 data = devm_kzalloc(&client->dev, sizeof(struct pca954x), GFP_KERNEL); 198 if (!data) 199 return -ENOMEM; 200 201 i2c_set_clientdata(client, data); 202 203 if (IS_ENABLED(CONFIG_OF) && np) { 204 enum of_gpio_flags flags; 205 int gpio; 206 207 /* Get the mux out of reset if a reset GPIO is specified. */ 208 gpio = of_get_named_gpio_flags(np, "reset-gpio", 0, &flags); 209 if (gpio_is_valid(gpio)) { 210 ret = devm_gpio_request_one(&client->dev, gpio, 211 flags & OF_GPIO_ACTIVE_LOW ? 212 GPIOF_OUT_INIT_HIGH : GPIOF_OUT_INIT_LOW, 213 "pca954x reset"); 214 if (ret < 0) 215 return ret; 216 } 217 } 218 219 /* Write the mux register at addr to verify 220 * that the mux is in fact present. This also 221 * initializes the mux to disconnected state. 222 */ 223 if (i2c_smbus_write_byte(client, 0) < 0) { 224 dev_warn(&client->dev, "probe failed\n"); 225 return -ENODEV; 226 } 227 228 data->type = id->driver_data; 229 data->last_chan = 0; /* force the first selection */ 230 231 /* Now create an adapter for each channel */ 232 for (num = 0; num < chips[data->type].nchans; num++) { 233 force = 0; /* dynamic adap number */ 234 class = 0; /* no class by default */ 235 if (pdata) { 236 if (num < pdata->num_modes) { 237 /* force static number */ 238 force = pdata->modes[num].adap_id; 239 class = pdata->modes[num].class; 240 } else 241 /* discard unconfigured channels */ 242 break; 243 } 244 245 data->virt_adaps[num] = 246 i2c_add_mux_adapter(adap, &client->dev, client, 247 force, num, class, pca954x_select_chan, 248 (pdata && pdata->modes[num].deselect_on_exit) 249 ? pca954x_deselect_mux : NULL); 250 251 if (data->virt_adaps[num] == NULL) { 252 ret = -ENODEV; 253 dev_err(&client->dev, 254 "failed to register multiplexed adapter" 255 " %d as bus %d\n", num, force); 256 goto virt_reg_failed; 257 } 258 } 259 260 dev_info(&client->dev, 261 "registered %d multiplexed busses for I2C %s %s\n", 262 num, chips[data->type].muxtype == pca954x_ismux 263 ? "mux" : "switch", client->name); 264 265 return 0; 266 267 virt_reg_failed: 268 for (num--; num >= 0; num--) 269 i2c_del_mux_adapter(data->virt_adaps[num]); 270 return ret; 271 } 272 273 static int pca954x_remove(struct i2c_client *client) 274 { 275 struct pca954x *data = i2c_get_clientdata(client); 276 const struct chip_desc *chip = &chips[data->type]; 277 int i; 278 279 for (i = 0; i < chip->nchans; ++i) 280 if (data->virt_adaps[i]) { 281 i2c_del_mux_adapter(data->virt_adaps[i]); 282 data->virt_adaps[i] = NULL; 283 } 284 285 return 0; 286 } 287 288 static struct i2c_driver pca954x_driver = { 289 .driver = { 290 .name = "pca954x", 291 .owner = THIS_MODULE, 292 }, 293 .probe = pca954x_probe, 294 .remove = pca954x_remove, 295 .id_table = pca954x_id, 296 }; 297 298 module_i2c_driver(pca954x_driver); 299 300 MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>"); 301 MODULE_DESCRIPTION("PCA954x I2C mux/switch driver"); 302 MODULE_LICENSE("GPL v2"); 303