diff options
Diffstat (limited to 'drivers/i2c/muxes/i2c-mux-mlxcpld.c')
| -rw-r--r-- | drivers/i2c/muxes/i2c-mux-mlxcpld.c | 194 |
1 files changed, 194 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..1a879f6a3 --- /dev/null +++ b/drivers/i2c/muxes/i2c-mux-mlxcpld.c @@ -0,0 +1,194 @@ +// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0 +/* + * Mellanox i2c mux driver + * + * Copyright (C) 2016-2020 Mellanox Technologies + */ + +#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/mlxcpld.h> +#include <linux/platform_device.h> +#include <linux/slab.h> + +/* mlxcpld_mux - mux control structure: + * @last_val - last selected register value or -1 if mux deselected + * @client - I2C device client + * @pdata: platform data + */ +struct mlxcpld_mux { + int last_val; + struct i2c_client *client; + struct mlxcpld_mux_plat_data pdata; +}; + +/* 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) + * + */ + +/* 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 mlxcpld_mux *mux, u32 val) +{ + struct i2c_client *client = mux->client; + union i2c_smbus_data data; + struct i2c_msg msg; + u8 buf[3]; + + switch (mux->pdata.reg_size) { + case 1: + data.byte = val; + return __i2c_smbus_xfer(adap, client->addr, client->flags, + I2C_SMBUS_WRITE, mux->pdata.sel_reg_addr, + I2C_SMBUS_BYTE_DATA, &data); + case 2: + buf[0] = mux->pdata.sel_reg_addr >> 8; + buf[1] = mux->pdata.sel_reg_addr; + buf[2] = val; + msg.addr = client->addr; + msg.buf = buf; + msg.len = mux->pdata.reg_size + 1; + msg.flags = 0; + return __i2c_transfer(adap, &msg, 1); + default: + return -EINVAL; + } +} + +static int mlxcpld_mux_select_chan(struct i2c_mux_core *muxc, u32 chan) +{ + struct mlxcpld_mux *mux = i2c_mux_priv(muxc); + u32 regval = chan; + int err = 0; + + if (mux->pdata.reg_size == 1) + regval += 1; + + /* Only select the channel if its different from the last channel */ + if (mux->last_val != regval) { + err = mlxcpld_mux_reg_write(muxc->parent, mux, regval); + mux->last_val = err < 0 ? -1 : regval; + } + + return err; +} + +static int mlxcpld_mux_deselect(struct i2c_mux_core *muxc, u32 chan) +{ + struct mlxcpld_mux *mux = i2c_mux_priv(muxc); + + /* Deselect active channel */ + mux->last_val = -1; + + return mlxcpld_mux_reg_write(muxc->parent, mux, 0); +} + +/* Probe/reomove functions */ +static int mlxcpld_mux_probe(struct platform_device *pdev) +{ + struct mlxcpld_mux_plat_data *pdata = dev_get_platdata(&pdev->dev); + struct i2c_client *client = to_i2c_client(pdev->dev.parent); + struct i2c_mux_core *muxc; + struct mlxcpld_mux *data; + int num, err; + u32 func; + + if (!pdata) + return -EINVAL; + + switch (pdata->reg_size) { + case 1: + func = I2C_FUNC_SMBUS_WRITE_BYTE_DATA; + break; + case 2: + func = I2C_FUNC_I2C; + break; + default: + return -EINVAL; + } + + if (!i2c_check_functionality(client->adapter, func)) + return -ENODEV; + + muxc = i2c_mux_alloc(client->adapter, &pdev->dev, pdata->num_adaps, + sizeof(*data), 0, mlxcpld_mux_select_chan, + mlxcpld_mux_deselect); + if (!muxc) + return -ENOMEM; + + platform_set_drvdata(pdev, muxc); + data = i2c_mux_priv(muxc); + data->client = client; + memcpy(&data->pdata, pdata, sizeof(*pdata)); + data->last_val = -1; /* force the first selection */ + + /* Create an adapter for each channel. */ + for (num = 0; num < pdata->num_adaps; num++) { + err = i2c_mux_add_adapter(muxc, 0, pdata->chan_ids[num], 0); + if (err) + goto virt_reg_failed; + } + + /* Notify caller when all channels' adapters are created. */ + if (pdata->completion_notify) + pdata->completion_notify(pdata->handle, muxc->parent, muxc->adapter); + + return 0; + +virt_reg_failed: + i2c_mux_del_adapters(muxc); + return err; +} + +static int mlxcpld_mux_remove(struct platform_device *pdev) +{ + struct i2c_mux_core *muxc = platform_get_drvdata(pdev); + + i2c_mux_del_adapters(muxc); + return 0; +} + +static struct platform_driver mlxcpld_mux_driver = { + .driver = { + .name = "i2c-mux-mlxcpld", + }, + .probe = mlxcpld_mux_probe, + .remove = mlxcpld_mux_remove, +}; + +module_platform_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"); |