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kernel os linux

i2c: I2C bus multiplexer driver pca954x

I2C driver for PCA954x I2C multiplexer series.

Signed-off-by: Michael Lawnick <ml.lawnick@gmx.de>
Acked-by: Rodolfo Giometti <giometti@linux.it>
Signed-off-by: Jean Delvare <khali@linux-fr.org>

authored by

Michael Lawnick and committed by
Jean Delvare
7f528135 0826374b

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drivers/i2c/Kconfig
··· 58 58 This support is also available as a module. If so, the module 59 59 will be called i2c-mux. 60 60 61 + source drivers/i2c/muxes/Kconfig 62 + 61 63 config I2C_HELPER_AUTO 62 64 bool "Autoselect pertinent helper modules" 63 65 default y
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drivers/i2c/Makefile
··· 7 7 obj-$(CONFIG_I2C_SMBUS) += i2c-smbus.o 8 8 obj-$(CONFIG_I2C_CHARDEV) += i2c-dev.o 9 9 obj-$(CONFIG_I2C_MUX) += i2c-mux.o 10 - obj-y += algos/ busses/ 10 + obj-y += algos/ busses/ muxes/ 11 11 12 12 ifeq ($(CONFIG_I2C_DEBUG_CORE),y) 13 13 EXTRA_CFLAGS += -DDEBUG
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drivers/i2c/muxes/Kconfig
··· 1 + # 2 + # Multiplexer I2C chip drivers configuration 3 + # 4 + 5 + menu "Multiplexer I2C Chip support" 6 + depends on I2C_MUX 7 + 8 + config I2C_MUX_PCA954x 9 + tristate "Philips PCA954x I2C Mux/switches" 10 + depends on EXPERIMENTAL 11 + help 12 + If you say yes here you get support for the Philips PCA954x 13 + I2C mux/switch devices. 14 + 15 + This driver can also be built as a module. If so, the module 16 + will be called pca954x. 17 + 18 + endmenu
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drivers/i2c/muxes/Makefile
··· 1 + # 2 + # Makefile for multiplexer I2C chip drivers. 3 + 4 + obj-$(CONFIG_I2C_MUX_PCA954x) += pca954x.o 5 + 6 + ifeq ($(CONFIG_I2C_DEBUG_BUS),y) 7 + EXTRA_CFLAGS += -DDEBUG 8 + endif
+301
drivers/i2c/muxes/pca954x.c
··· 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 __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 + 249 + virt_reg_failed: 250 + for (num--; num >= 0; num--) 251 + i2c_del_mux_adapter(data->virt_adaps[num]); 252 + exit_free: 253 + kfree(data); 254 + err: 255 + return ret; 256 + } 257 + 258 + static 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 + 276 + static 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 + 286 + static int __init pca954x_init(void) 287 + { 288 + return i2c_add_driver(&pca954x_driver); 289 + } 290 + 291 + static void __exit pca954x_exit(void) 292 + { 293 + i2c_del_driver(&pca954x_driver); 294 + } 295 + 296 + module_init(pca954x_init); 297 + module_exit(pca954x_exit); 298 + 299 + MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>"); 300 + MODULE_DESCRIPTION("PCA954x I2C mux/switch driver"); 301 + MODULE_LICENSE("GPL v2");
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include/linux/i2c/pca954x.h
··· 1 + /* 2 + * 3 + * pca954x.h - I2C multiplexer/switch support 4 + * 5 + * Copyright (c) 2008-2009 Rodolfo Giometti <giometti@linux.it> 6 + * Copyright (c) 2008-2009 Eurotech S.p.A. <info@eurotech.it> 7 + * Michael Lawnick <michael.lawnick.ext@nsn.com> 8 + * 9 + * This program is free software; you can redistribute it and/or modify 10 + * it under the terms of the GNU General Public License as published by 11 + * the Free Software Foundation; either version 2 of the License, or 12 + * (at your option) any later version. 13 + * 14 + * This program is distributed in the hope that it will be useful, 15 + * but WITHOUT ANY WARRANTY; without even the implied warranty of 16 + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 17 + * GNU General Public License for more details. 18 + * 19 + * You should have received a copy of the GNU General Public License 20 + * along with this program; if not, write to the Free Software 21 + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 22 + */ 23 + 24 + 25 + #ifndef _LINUX_I2C_PCA954X_H 26 + #define _LINUX_I2C_PCA954X_H 27 + 28 + /* Platform data for the PCA954x I2C multiplexers */ 29 + 30 + /* Per channel initialisation data: 31 + * @adap_id: bus number for the adapter. 0 = don't care 32 + * @deselect_on_exit: set this entry to 1, if your H/W needs deselection 33 + * of this channel after transaction. 34 + * 35 + */ 36 + struct pca954x_platform_mode { 37 + int adap_id; 38 + unsigned int deselect_on_exit:1; 39 + }; 40 + 41 + /* Per mux/switch data, used with i2c_register_board_info */ 42 + struct pca954x_platform_data { 43 + struct pca954x_platform_mode *modes; 44 + int num_modes; 45 + }; 46 + 47 + #endif /* _LINUX_I2C_PCA954X_H */