diff options
Diffstat (limited to 'drivers/i2c/muxes/i2c-mux-mlxcpld.c')
| -rw-r--r-- | drivers/i2c/muxes/i2c-mux-mlxcpld.c | 201 |
1 files changed, 201 insertions, 0 deletions
diff --git a/drivers/i2c/muxes/i2c-mux-mlxcpld.c b/drivers/i2c/muxes/i2c-mux-mlxcpld.c new file mode 100644 index 000000000..f2bf3e57e --- /dev/null +++ b/drivers/i2c/muxes/i2c-mux-mlxcpld.c @@ -0,0 +1,201 @@ +/* + * drivers/i2c/muxes/i2c-mux-mlxcpld.c + * Copyright (c) 2016 Mellanox Technologies. All rights reserved. + * Copyright (c) 2016 Michael Shych <michaels@mellanox.com> + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are met: + * + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. Neither the names of the copyright holders nor the names of its + * contributors may be used to endorse or promote products derived from + * this software without specific prior written permission. + * + * Alternatively, this software may be distributed under the terms of the + * GNU General Public License ("GPL") version 2 as published by the Free + * Software Foundation. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" + * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE + * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR + * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF + * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS + * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN + * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGE. + */ + +#include <linux/device.h> +#include <linux/i2c.h> +#include <linux/i2c-mux.h> +#include <linux/io.h> +#include <linux/init.h> +#include <linux/module.h> +#include <linux/platform_data/x86/mlxcpld.h> +#include <linux/platform_device.h> +#include <linux/slab.h> + +#define CPLD_MUX_MAX_NCHANS 8 + +/* mlxcpld_mux - mux control structure: + * @last_chan - last register value + * @client - I2C device client + */ +struct mlxcpld_mux { + u8 last_chan; + struct i2c_client *client; +}; + +/* MUX logic description. + * Driver can support different mux control logic, according to CPLD + * implementation. + * + * Connectivity schema. + * + * i2c-mlxcpld Digital Analog + * driver + * *--------* * -> mux1 (virt bus2) -> mux -> | + * | I2CLPC | i2c physical * -> mux2 (virt bus3) -> mux -> | + * | bridge | bus 1 *---------* | + * | logic |---------------------> * mux reg * | + * | in CPLD| *---------* | + * *--------* i2c-mux-mlxpcld ^ * -> muxn (virt busn) -> mux -> | + * | driver | | + * | *---------------* | Devices + * | * CPLD (i2c bus)* select | + * | * registers for *--------* + * | * mux selection * deselect + * | *---------------* + * | | + * <--------> <-----------> + * i2c cntrl Board cntrl reg + * reg space space (mux select, + * IO, LED, WD, info) + * + */ + +static const struct i2c_device_id mlxcpld_mux_id[] = { + { "mlxcpld_mux_module", 0 }, + { } +}; +MODULE_DEVICE_TABLE(i2c, mlxcpld_mux_id); + +/* Write to mux register. Don't use i2c_transfer() and i2c_smbus_xfer() + * for this as they will try to lock adapter a second time. + */ +static int mlxcpld_mux_reg_write(struct i2c_adapter *adap, + struct i2c_client *client, u8 val) +{ + struct mlxcpld_mux_plat_data *pdata = dev_get_platdata(&client->dev); + union i2c_smbus_data data = { .byte = val }; + + return __i2c_smbus_xfer(adap, client->addr, client->flags, + I2C_SMBUS_WRITE, pdata->sel_reg_addr, + I2C_SMBUS_BYTE_DATA, &data); +} + +static int mlxcpld_mux_select_chan(struct i2c_mux_core *muxc, u32 chan) +{ + struct mlxcpld_mux *data = i2c_mux_priv(muxc); + struct i2c_client *client = data->client; + u8 regval = chan + 1; + int err = 0; + + /* Only select the channel if its different from the last channel */ + if (data->last_chan != regval) { + err = mlxcpld_mux_reg_write(muxc->parent, client, regval); + data->last_chan = err < 0 ? 0 : regval; + } + + return err; +} + +static int mlxcpld_mux_deselect(struct i2c_mux_core *muxc, u32 chan) +{ + struct mlxcpld_mux *data = i2c_mux_priv(muxc); + struct i2c_client *client = data->client; + + /* Deselect active channel */ + data->last_chan = 0; + + return mlxcpld_mux_reg_write(muxc->parent, client, data->last_chan); +} + +/* Probe/reomove functions */ +static int mlxcpld_mux_probe(struct i2c_client *client, + const struct i2c_device_id *id) +{ + struct i2c_adapter *adap = to_i2c_adapter(client->dev.parent); + struct mlxcpld_mux_plat_data *pdata = dev_get_platdata(&client->dev); + struct i2c_mux_core *muxc; + int num, force; + struct mlxcpld_mux *data; + int err; + + if (!pdata) + return -EINVAL; + + if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_WRITE_BYTE_DATA)) + return -ENODEV; + + muxc = i2c_mux_alloc(adap, &client->dev, CPLD_MUX_MAX_NCHANS, + sizeof(*data), 0, mlxcpld_mux_select_chan, + mlxcpld_mux_deselect); + if (!muxc) + return -ENOMEM; + + data = i2c_mux_priv(muxc); + i2c_set_clientdata(client, muxc); + data->client = client; + data->last_chan = 0; /* force the first selection */ + + /* Create an adapter for each channel. */ + for (num = 0; num < CPLD_MUX_MAX_NCHANS; num++) { + if (num >= pdata->num_adaps) + /* discard unconfigured channels */ + break; + + force = pdata->adap_ids[num]; + + err = i2c_mux_add_adapter(muxc, force, num, 0); + if (err) + goto virt_reg_failed; + } + + return 0; + +virt_reg_failed: + i2c_mux_del_adapters(muxc); + return err; +} + +static int mlxcpld_mux_remove(struct i2c_client *client) +{ + struct i2c_mux_core *muxc = i2c_get_clientdata(client); + + i2c_mux_del_adapters(muxc); + return 0; +} + +static struct i2c_driver mlxcpld_mux_driver = { + .driver = { + .name = "mlxcpld-mux", + }, + .probe = mlxcpld_mux_probe, + .remove = mlxcpld_mux_remove, + .id_table = mlxcpld_mux_id, +}; + +module_i2c_driver(mlxcpld_mux_driver); + +MODULE_AUTHOR("Michael Shych (michaels@mellanox.com)"); +MODULE_DESCRIPTION("Mellanox I2C-CPLD-MUX driver"); +MODULE_LICENSE("Dual BSD/GPL"); +MODULE_ALIAS("platform:i2c-mux-mlxcpld"); |