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