1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Theobroma Systems Mule I2C device multiplexer 4 * 5 * Copyright (C) 2024 Theobroma Systems Design und Consulting GmbH 6 */ 7 8 #include <linux/i2c-mux.h> 9 #include <linux/i2c.h> 10 #include <linux/module.h> 11 #include <linux/of.h> 12 #include <linux/platform_device.h> 13 #include <linux/property.h> 14 #include <linux/regmap.h> 15 16 #define MULE_I2C_MUX_CONFIG_REG 0xff 17 #define MULE_I2C_MUX_DEFAULT_DEV 0x0 18 19 struct mule_i2c_reg_mux { 20 struct regmap *regmap; 21 }; 22 23 static int mule_i2c_mux_select(struct i2c_mux_core *muxc, u32 dev) 24 { 25 struct mule_i2c_reg_mux *mux = muxc->priv; 26 27 return regmap_write(mux->regmap, MULE_I2C_MUX_CONFIG_REG, dev); 28 } 29 30 static int mule_i2c_mux_deselect(struct i2c_mux_core *muxc, u32 dev) 31 { 32 return mule_i2c_mux_select(muxc, MULE_I2C_MUX_DEFAULT_DEV); 33 } 34 35 static void mule_i2c_mux_remove(void *data) 36 { 37 struct i2c_mux_core *muxc = data; 38 39 i2c_mux_del_adapters(muxc); 40 41 mule_i2c_mux_deselect(muxc, MULE_I2C_MUX_DEFAULT_DEV); 42 } 43 44 static int mule_i2c_mux_probe(struct platform_device *pdev) 45 { 46 struct device *mux_dev = &pdev->dev; 47 struct mule_i2c_reg_mux *priv; 48 struct i2c_client *client; 49 struct i2c_mux_core *muxc; 50 unsigned int readback; 51 int ndev, ret; 52 bool old_fw; 53 54 /* Count devices on the mux */ 55 ndev = of_get_child_count(mux_dev->of_node); 56 dev_dbg(mux_dev, "%d devices on the mux\n", ndev); 57 58 client = to_i2c_client(mux_dev->parent); 59 60 muxc = i2c_mux_alloc(client->adapter, mux_dev, ndev, sizeof(*priv), 61 I2C_MUX_LOCKED, mule_i2c_mux_select, mule_i2c_mux_deselect); 62 if (!muxc) 63 return -ENOMEM; 64 65 priv = i2c_mux_priv(muxc); 66 67 priv->regmap = dev_get_regmap(mux_dev->parent, NULL); 68 if (!priv->regmap) 69 return dev_err_probe(mux_dev, -ENODEV, 70 "No parent i2c register map\n"); 71 72 platform_set_drvdata(pdev, muxc); 73 74 /* 75 * MULE_I2C_MUX_DEFAULT_DEV is guaranteed to exist on all old and new 76 * mule fw. Mule fw without mux support will accept write ops to the 77 * config register, but readback returns 0xff (register not updated). 78 */ 79 ret = mule_i2c_mux_select(muxc, MULE_I2C_MUX_DEFAULT_DEV); 80 if (ret) 81 return dev_err_probe(mux_dev, ret, 82 "Failed to write config register\n"); 83 84 ret = regmap_read(priv->regmap, MULE_I2C_MUX_CONFIG_REG, &readback); 85 if (ret) 86 return dev_err_probe(mux_dev, ret, 87 "Failed to read config register\n"); 88 89 old_fw = (readback != MULE_I2C_MUX_DEFAULT_DEV); 90 91 ret = devm_add_action_or_reset(mux_dev, mule_i2c_mux_remove, muxc); 92 if (ret) 93 return dev_err_probe(mux_dev, ret, 94 "Failed to register mux remove\n"); 95 96 /* Create device adapters */ 97 for_each_child_of_node_scoped(mux_dev->of_node, dev) { 98 u32 reg; 99 100 ret = of_property_read_u32(dev, "reg", ®); 101 if (ret) 102 return dev_err_probe(mux_dev, ret, 103 "No reg property found for %s\n", 104 of_node_full_name(dev)); 105 106 if (old_fw && reg != 0) { 107 dev_warn(mux_dev, 108 "Mux is not supported, please update Mule FW\n"); 109 continue; 110 } 111 112 ret = mule_i2c_mux_select(muxc, reg); 113 if (ret) { 114 dev_warn(mux_dev, 115 "Device %d not supported, please update Mule FW\n", reg); 116 continue; 117 } 118 119 ret = i2c_mux_add_adapter(muxc, 0, reg); 120 if (ret) 121 return ret; 122 } 123 124 mule_i2c_mux_deselect(muxc, MULE_I2C_MUX_DEFAULT_DEV); 125 126 return 0; 127 } 128 129 static const struct of_device_id mule_i2c_mux_of_match[] = { 130 { .compatible = "tsd,mule-i2c-mux", }, 131 {}, 132 }; 133 MODULE_DEVICE_TABLE(of, mule_i2c_mux_of_match); 134 135 static struct platform_driver mule_i2c_mux_driver = { 136 .driver = { 137 .name = "mule-i2c-mux", 138 .of_match_table = mule_i2c_mux_of_match, 139 }, 140 .probe = mule_i2c_mux_probe, 141 }; 142 143 module_platform_driver(mule_i2c_mux_driver); 144 145 MODULE_AUTHOR("Farouk Bouabid <farouk.bouabid@cherry.de>"); 146 MODULE_DESCRIPTION("I2C mux driver for Theobroma Systems Mule"); 147 MODULE_LICENSE("GPL"); 148