| 1 | // SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0 |
| 2 | /* |
| 3 | * Mellanox i2c mux driver |
| 4 | * |
| 5 | * Copyright (C) 2016-2020 Mellanox Technologies |
| 6 | */ |
| 7 | |
| 8 | #include <linux/device.h> |
| 9 | #include <linux/i2c.h> |
| 10 | #include <linux/i2c-mux.h> |
| 11 | #include <linux/io.h> |
| 12 | #include <linux/init.h> |
| 13 | #include <linux/module.h> |
| 14 | #include <linux/platform_data/mlxcpld.h> |
| 15 | #include <linux/platform_device.h> |
| 16 | #include <linux/slab.h> |
| 17 | |
| 18 | /* mlxcpld_mux - mux control structure: |
| 19 | * @last_val - last selected register value or -1 if mux deselected |
| 20 | * @client - I2C device client |
| 21 | * @pdata: platform data |
| 22 | */ |
| 23 | struct mlxcpld_mux { |
| 24 | int last_val; |
| 25 | struct i2c_client *client; |
| 26 | struct mlxcpld_mux_plat_data pdata; |
| 27 | }; |
| 28 | |
| 29 | /* MUX logic description. |
| 30 | * Driver can support different mux control logic, according to CPLD |
| 31 | * implementation. |
| 32 | * |
| 33 | * Connectivity schema. |
| 34 | * |
| 35 | * i2c-mlxcpld Digital Analog |
| 36 | * driver |
| 37 | * *--------* * -> mux1 (virt bus2) -> mux -> | |
| 38 | * | I2CLPC | i2c physical * -> mux2 (virt bus3) -> mux -> | |
| 39 | * | bridge | bus 1 *---------* | |
| 40 | * | logic |---------------------> * mux reg * | |
| 41 | * | in CPLD| *---------* | |
| 42 | * *--------* i2c-mux-mlxpcld ^ * -> muxn (virt busn) -> mux -> | |
| 43 | * | driver | | |
| 44 | * | *---------------* | Devices |
| 45 | * | * CPLD (i2c bus)* select | |
| 46 | * | * registers for *--------* |
| 47 | * | * mux selection * deselect |
| 48 | * | *---------------* |
| 49 | * | | |
| 50 | * <--------> <-----------> |
| 51 | * i2c cntrl Board cntrl reg |
| 52 | * reg space space (mux select, |
| 53 | * IO, LED, WD, info) |
| 54 | * |
| 55 | */ |
| 56 | |
| 57 | /* Write to mux register. Don't use i2c_transfer() and i2c_smbus_xfer() |
| 58 | * for this as they will try to lock adapter a second time. |
| 59 | */ |
| 60 | static int mlxcpld_mux_reg_write(struct i2c_adapter *adap, |
| 61 | struct mlxcpld_mux *mux, u32 val) |
| 62 | { |
| 63 | struct i2c_client *client = mux->client; |
| 64 | union i2c_smbus_data data; |
| 65 | struct i2c_msg msg; |
| 66 | u8 buf[3]; |
| 67 | |
| 68 | switch (mux->pdata.reg_size) { |
| 69 | case 1: |
| 70 | data.byte = val; |
| 71 | return __i2c_smbus_xfer(adap, client->addr, client->flags, |
| 72 | I2C_SMBUS_WRITE, mux->pdata.sel_reg_addr, |
| 73 | I2C_SMBUS_BYTE_DATA, &data); |
| 74 | case 2: |
| 75 | buf[0] = mux->pdata.sel_reg_addr >> 8; |
| 76 | buf[1] = mux->pdata.sel_reg_addr; |
| 77 | buf[2] = val; |
| 78 | msg.addr = client->addr; |
| 79 | msg.buf = buf; |
| 80 | msg.len = mux->pdata.reg_size + 1; |
| 81 | msg.flags = 0; |
| 82 | return __i2c_transfer(adap, &msg, 1); |
| 83 | default: |
| 84 | return -EINVAL; |
| 85 | } |
| 86 | } |
| 87 | |
| 88 | static int mlxcpld_mux_select_chan(struct i2c_mux_core *muxc, u32 chan) |
| 89 | { |
| 90 | struct mlxcpld_mux *mux = i2c_mux_priv(muxc); |
| 91 | u32 regval = chan; |
| 92 | int err = 0; |
| 93 | |
| 94 | if (mux->pdata.reg_size == 1) |
| 95 | regval += 1; |
| 96 | |
| 97 | /* Only select the channel if its different from the last channel */ |
| 98 | if (mux->last_val != regval) { |
| 99 | err = mlxcpld_mux_reg_write(muxc->parent, mux, regval); |
| 100 | mux->last_val = err < 0 ? -1 : regval; |
| 101 | } |
| 102 | |
| 103 | return err; |
| 104 | } |
| 105 | |
| 106 | static int mlxcpld_mux_deselect(struct i2c_mux_core *muxc, u32 chan) |
| 107 | { |
| 108 | struct mlxcpld_mux *mux = i2c_mux_priv(muxc); |
| 109 | |
| 110 | /* Deselect active channel */ |
| 111 | mux->last_val = -1; |
| 112 | |
| 113 | return mlxcpld_mux_reg_write(muxc->parent, mux, 0); |
| 114 | } |
| 115 | |
| 116 | /* Probe/reomove functions */ |
| 117 | static int mlxcpld_mux_probe(struct platform_device *pdev) |
| 118 | { |
| 119 | struct mlxcpld_mux_plat_data *pdata = dev_get_platdata(&pdev->dev); |
| 120 | struct i2c_client *client = to_i2c_client(pdev->dev.parent); |
| 121 | struct i2c_mux_core *muxc; |
| 122 | struct mlxcpld_mux *data; |
| 123 | int num, err; |
| 124 | u32 func; |
| 125 | |
| 126 | if (!pdata) |
| 127 | return -EINVAL; |
| 128 | |
| 129 | switch (pdata->reg_size) { |
| 130 | case 1: |
| 131 | func = I2C_FUNC_SMBUS_WRITE_BYTE_DATA; |
| 132 | break; |
| 133 | case 2: |
| 134 | func = I2C_FUNC_I2C; |
| 135 | break; |
| 136 | default: |
| 137 | return -EINVAL; |
| 138 | } |
| 139 | |
| 140 | if (!i2c_check_functionality(client->adapter, func)) |
| 141 | return -ENODEV; |
| 142 | |
| 143 | muxc = i2c_mux_alloc(client->adapter, &pdev->dev, pdata->num_adaps, |
| 144 | sizeof(*data), 0, mlxcpld_mux_select_chan, |
| 145 | mlxcpld_mux_deselect); |
| 146 | if (!muxc) |
| 147 | return -ENOMEM; |
| 148 | |
| 149 | platform_set_drvdata(pdev, muxc); |
| 150 | data = i2c_mux_priv(muxc); |
| 151 | data->client = client; |
| 152 | memcpy(&data->pdata, pdata, sizeof(*pdata)); |
| 153 | data->last_val = -1; /* force the first selection */ |
| 154 | |
| 155 | /* Create an adapter for each channel. */ |
| 156 | for (num = 0; num < pdata->num_adaps; num++) { |
| 157 | err = i2c_mux_add_adapter(muxc, 0, pdata->chan_ids[num]); |
| 158 | if (err) |
| 159 | goto virt_reg_failed; |
| 160 | } |
| 161 | |
| 162 | /* Notify caller when all channels' adapters are created. */ |
| 163 | if (pdata->completion_notify) |
| 164 | pdata->completion_notify(pdata->handle, muxc->parent, muxc->adapter); |
| 165 | |
| 166 | return 0; |
| 167 | |
| 168 | virt_reg_failed: |
| 169 | i2c_mux_del_adapters(muxc); |
| 170 | return err; |
| 171 | } |
| 172 | |
| 173 | static void mlxcpld_mux_remove(struct platform_device *pdev) |
| 174 | { |
| 175 | struct i2c_mux_core *muxc = platform_get_drvdata(pdev); |
| 176 | |
| 177 | i2c_mux_del_adapters(muxc); |
| 178 | } |
| 179 | |
| 180 | static struct platform_driver mlxcpld_mux_driver = { |
| 181 | .driver = { |
| 182 | .name = "i2c-mux-mlxcpld", |
| 183 | }, |
| 184 | .probe = mlxcpld_mux_probe, |
| 185 | .remove_new = mlxcpld_mux_remove, |
| 186 | }; |
| 187 | |
| 188 | module_platform_driver(mlxcpld_mux_driver); |
| 189 | |
| 190 | MODULE_AUTHOR("Michael Shych <michaels@mellanox.com>"); |
| 191 | MODULE_DESCRIPTION("Mellanox I2C-CPLD-MUX driver"); |
| 192 | MODULE_LICENSE("Dual BSD/GPL"); |
| 193 | MODULE_ALIAS("platform:i2c-mux-mlxcpld"); |