/* * I2C multiplexer * * Copyright (c) 2008-2009 Rodolfo Giometti * Copyright (c) 2008-2009 Eurotech S.p.A. * * This module supports the PCA954x series of I2C multiplexer/switch chips * made by Philips Semiconductors. * This includes the: * PCA9540, PCA9542, PCA9543, PCA9544, PCA9545, PCA9546, PCA9547 * and PCA9548. * * These chips are all controlled via the I2C bus itself, and all have a * single 8-bit register. The upstream "parent" bus fans out to two, * four, or eight downstream busses or channels; which of these * are selected is determined by the chip type and register contents. A * mux can select only one sub-bus at a time; a switch can select any * combination simultaneously. * * Based on: * pca954x.c from Kumar Gala * Copyright (C) 2006 * * Based on: * pca954x.c from Ken Harrenstien * Copyright (C) 2004 Google, Inc. (Ken Harrenstien) * * Based on: * i2c-virtual_cb.c from Brian Kuschak * and * pca9540.c from Jean Delvare . * * This file is licensed under the terms of the GNU General Public * License version 2. This program is licensed "as is" without any * warranty of any kind, whether express or implied. */ #include #include #include #include #include #include #include #define PCA954X_MAX_NCHANS 8 enum pca_type { pca_9540, pca_9542, pca_9543, pca_9544, pca_9545, pca_9546, pca_9547, pca_9548, }; struct pca954x { enum pca_type type; struct i2c_adapter *virt_adaps[PCA954X_MAX_NCHANS]; u8 last_chan; /* last register value */ }; struct chip_desc { u8 nchans; u8 enable; /* used for muxes only */ enum muxtype { pca954x_ismux = 0, pca954x_isswi } muxtype; }; /* Provide specs for the PCA954x types we know about */ static const struct chip_desc chips[] = { [pca_9540] = { .nchans = 2, .enable = 0x4, .muxtype = pca954x_ismux, }, [pca_9543] = { .nchans = 2, .muxtype = pca954x_isswi, }, [pca_9544] = { .nchans = 4, .enable = 0x4, .muxtype = pca954x_ismux, }, [pca_9545] = { .nchans = 4, .muxtype = pca954x_isswi, }, [pca_9547] = { .nchans = 8, .enable = 0x8, .muxtype = pca954x_ismux, }, [pca_9548] = { .nchans = 8, .muxtype = pca954x_isswi, }, }; static const struct i2c_device_id pca954x_id[] = { { "pca9540", pca_9540 }, { "pca9542", pca_9540 }, { "pca9543", pca_9543 }, { "pca9544", pca_9544 }, { "pca9545", pca_9545 }, { "pca9546", pca_9545 }, { "pca9547", pca_9547 }, { "pca9548", pca_9548 }, { } }; MODULE_DEVICE_TABLE(i2c, pca954x_id); /* Write to mux register. Don't use i2c_transfer()/i2c_smbus_xfer() for this as they will try to lock adapter a second time */ static int pca954x_reg_write(struct i2c_adapter *adap, struct i2c_client *client, u8 val) { int ret = -ENODEV; if (adap->algo->master_xfer) { struct i2c_msg msg; char buf[1]; msg.addr = client->addr; msg.flags = 0; msg.len = 1; buf[0] = val; msg.buf = buf; ret = adap->algo->master_xfer(adap, &msg, 1); } else { union i2c_smbus_data data; ret = adap->algo->smbus_xfer(adap, client->addr, client->flags, I2C_SMBUS_WRITE, val, I2C_SMBUS_BYTE, &data); } return ret; } static int pca954x_select_chan(struct i2c_adapter *adap, void *client, u32 chan) { struct pca954x *data = i2c_get_clientdata(client); const struct chip_desc *chip = &chips[data->type]; u8 regval; int ret = 0; /* we make switches look like muxes, not sure how to be smarter */ if (chip->muxtype == pca954x_ismux) regval = chan | chip->enable; else regval = 1 << chan; /* Only select the channel if its different from the last channel */ if (data->last_chan != regval) { ret = pca954x_reg_write(adap, client, regval); data->last_chan = regval; } return ret; } static int pca954x_deselect_mux(struct i2c_adapter *adap, void *client, u32 chan) { struct pca954x *data = i2c_get_clientdata(client); /* Deselect active channel */ data->last_chan = 0; return pca954x_reg_write(adap, client, data->last_chan); } /* * I2C init/probing/exit functions */ static int pca954x_probe(struct i2c_client *client, const struct i2c_device_id *id) { struct i2c_adapter *adap = to_i2c_adapter(client->dev.parent); struct pca954x_platform_data *pdata = client->dev.platform_data; int num, force, class; struct pca954x *data; int ret = -ENODEV; if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE)) goto err; data = kzalloc(sizeof(struct pca954x), GFP_KERNEL); if (!data) { ret = -ENOMEM; goto err; } i2c_set_clientdata(client, data); /* Write the mux register at addr to verify * that the mux is in fact present. This also * initializes the mux to disconnected state. */ if (i2c_smbus_write_byte(client, 0) < 0) { dev_warn(&client->dev, "probe failed\n"); goto exit_free; } data->type = id->driver_data; data->last_chan = 0; /* force the first selection */ /* Now create an adapter for each channel */ for (num = 0; num < chips[data->type].nchans; num++) { force = 0; /* dynamic adap number */ class = 0; /* no class by default */ if (pdata) { if (num < pdata->num_modes) { /* force static number */ force = pdata->modes[num].adap_id; class = pdata->modes[num].class; } else /* discard unconfigured channels */ break; } data->virt_adaps[num] = i2c_add_mux_adapter(adap, &client->dev, client, force, num, class, pca954x_select_chan, (pdata && pdata->modes[num].deselect_on_exit) ? pca954x_deselect_mux : NULL); if (data->virt_adaps[num] == NULL) { ret = -ENODEV; dev_err(&client->dev, "failed to register multiplexed adapter" " %d as bus %d\n", num, force); goto virt_reg_failed; } } dev_info(&client->dev, "registered %d multiplexed busses for I2C %s %s\n", num, chips[data->type].muxtype == pca954x_ismux ? "mux" : "switch", client->name); return 0; virt_reg_failed: for (num--; num >= 0; num--) i2c_del_mux_adapter(data->virt_adaps[num]); exit_free: kfree(data); err: return ret; } static int pca954x_remove(struct i2c_client *client) { struct pca954x *data = i2c_get_clientdata(client); const struct chip_desc *chip = &chips[data->type]; int i; for (i = 0; i < chip->nchans; ++i) if (data->virt_adaps[i]) { i2c_del_mux_adapter(data->virt_adaps[i]); data->virt_adaps[i] = NULL; } kfree(data); return 0; } static struct i2c_driver pca954x_driver = { .driver = { .name = "pca954x", .owner = THIS_MODULE, }, .probe = pca954x_probe, .remove = pca954x_remove, .id_table = pca954x_id, }; module_i2c_driver(pca954x_driver); MODULE_AUTHOR("Rodolfo Giometti "); MODULE_DESCRIPTION("PCA954x I2C mux/switch driver"); MODULE_LICENSE("GPL v2");