1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * I2C multiplexer using GPIO API 4 * 5 * Peter Korsgaard <peter.korsgaard@barco.com> 6 */ 7 8 #include <linux/i2c.h> 9 #include <linux/i2c-mux.h> 10 #include <linux/overflow.h> 11 #include <linux/platform_data/i2c-mux-gpio.h> 12 #include <linux/platform_device.h> 13 #include <linux/module.h> 14 #include <linux/slab.h> 15 #include <linux/bits.h> 16 #include <linux/gpio/consumer.h> 17 #include <linux/gpio/driver.h> 18 19 struct gpiomux { 20 struct i2c_mux_gpio_platform_data data; 21 int ngpios; 22 struct gpio_desc **gpios; 23 }; 24 25 static void i2c_mux_gpio_set(const struct gpiomux *mux, unsigned int val) 26 { 27 DECLARE_BITMAP(values, BITS_PER_TYPE(val)); 28 29 values[0] = val; 30 31 gpiod_set_array_value_cansleep(mux->ngpios, mux->gpios, NULL, values); 32 } 33 34 static int i2c_mux_gpio_select(struct i2c_mux_core *muxc, u32 chan) 35 { 36 struct gpiomux *mux = i2c_mux_priv(muxc); 37 38 i2c_mux_gpio_set(mux, chan); 39 40 return 0; 41 } 42 43 static int i2c_mux_gpio_deselect(struct i2c_mux_core *muxc, u32 chan) 44 { 45 struct gpiomux *mux = i2c_mux_priv(muxc); 46 47 i2c_mux_gpio_set(mux, mux->data.idle); 48 49 return 0; 50 } 51 52 static int i2c_mux_gpio_probe_fw(struct gpiomux *mux, 53 struct platform_device *pdev) 54 { 55 struct device *dev = &pdev->dev; 56 struct fwnode_handle *fwnode = dev_fwnode(dev); 57 struct device_node *np = dev->of_node; 58 struct device_node *adapter_np; 59 struct i2c_adapter *adapter = NULL; 60 struct fwnode_handle *child; 61 unsigned int *values; 62 int rc, i = 0; 63 64 if (is_of_node(fwnode)) { 65 if (!np) 66 return -ENODEV; 67 68 adapter_np = of_parse_phandle(np, "i2c-parent", 0); 69 if (!adapter_np) { 70 dev_err(&pdev->dev, "Cannot parse i2c-parent\n"); 71 return -ENODEV; 72 } 73 adapter = of_find_i2c_adapter_by_node(adapter_np); 74 of_node_put(adapter_np); 75 76 } else if (is_acpi_node(fwnode)) { 77 /* 78 * In ACPI land the mux should be a direct child of the i2c 79 * bus it muxes. 80 */ 81 acpi_handle dev_handle = ACPI_HANDLE(dev->parent); 82 83 adapter = i2c_acpi_find_adapter_by_handle(dev_handle); 84 } 85 86 if (!adapter) 87 return -EPROBE_DEFER; 88 89 mux->data.parent = i2c_adapter_id(adapter); 90 put_device(&adapter->dev); 91 92 mux->data.n_values = device_get_child_node_count(dev); 93 values = devm_kcalloc(dev, 94 mux->data.n_values, sizeof(*mux->data.values), 95 GFP_KERNEL); 96 if (!values) { 97 dev_err(dev, "Cannot allocate values array"); 98 return -ENOMEM; 99 } 100 101 device_for_each_child_node(dev, child) { 102 if (is_of_node(child)) { 103 fwnode_property_read_u32(child, "reg", values + i); 104 } else if (is_acpi_node(child)) { 105 rc = acpi_get_local_address(ACPI_HANDLE_FWNODE(child), values + i); 106 if (rc) { 107 fwnode_handle_put(child); 108 return dev_err_probe(dev, rc, "Cannot get address\n"); 109 } 110 } 111 112 i++; 113 } 114 mux->data.values = values; 115 116 if (device_property_read_u32(dev, "idle-state", &mux->data.idle)) 117 mux->data.idle = I2C_MUX_GPIO_NO_IDLE; 118 119 return 0; 120 } 121 122 static int i2c_mux_gpio_probe(struct platform_device *pdev) 123 { 124 struct i2c_mux_core *muxc; 125 struct gpiomux *mux; 126 struct i2c_adapter *parent; 127 struct i2c_adapter *root; 128 unsigned int initial_state; 129 int i, ngpios, ret; 130 131 mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL); 132 if (!mux) 133 return -ENOMEM; 134 135 if (!dev_get_platdata(&pdev->dev)) { 136 ret = i2c_mux_gpio_probe_fw(mux, pdev); 137 if (ret < 0) 138 return ret; 139 } else { 140 memcpy(&mux->data, dev_get_platdata(&pdev->dev), 141 sizeof(mux->data)); 142 } 143 144 ngpios = gpiod_count(&pdev->dev, "mux"); 145 if (ngpios <= 0) { 146 dev_err(&pdev->dev, "no valid gpios provided\n"); 147 return ngpios ?: -EINVAL; 148 } 149 mux->ngpios = ngpios; 150 151 parent = i2c_get_adapter(mux->data.parent); 152 if (!parent) 153 return -EPROBE_DEFER; 154 155 muxc = i2c_mux_alloc(parent, &pdev->dev, mux->data.n_values, 156 array_size(ngpios, sizeof(*mux->gpios)), 0, 157 i2c_mux_gpio_select, NULL); 158 if (!muxc) { 159 ret = -ENOMEM; 160 goto alloc_failed; 161 } 162 mux->gpios = muxc->priv; 163 muxc->priv = mux; 164 165 platform_set_drvdata(pdev, muxc); 166 167 root = i2c_root_adapter(&parent->dev); 168 169 muxc->mux_locked = true; 170 171 if (mux->data.idle != I2C_MUX_GPIO_NO_IDLE) { 172 initial_state = mux->data.idle; 173 muxc->deselect = i2c_mux_gpio_deselect; 174 } else { 175 initial_state = mux->data.values[0]; 176 } 177 178 for (i = 0; i < ngpios; i++) { 179 struct gpio_device *gdev; 180 struct device *dev; 181 struct gpio_desc *gpiod; 182 enum gpiod_flags flag; 183 184 if (initial_state & BIT(i)) 185 flag = GPIOD_OUT_HIGH; 186 else 187 flag = GPIOD_OUT_LOW; 188 gpiod = devm_gpiod_get_index(&pdev->dev, "mux", i, flag); 189 if (IS_ERR(gpiod)) { 190 ret = PTR_ERR(gpiod); 191 goto alloc_failed; 192 } 193 194 mux->gpios[i] = gpiod; 195 196 if (!muxc->mux_locked) 197 continue; 198 199 gdev = gpiod_to_gpio_device(gpiod); 200 dev = gpio_device_to_device(gdev); 201 muxc->mux_locked = i2c_root_adapter(dev) == root; 202 } 203 204 if (muxc->mux_locked) 205 dev_info(&pdev->dev, "mux-locked i2c mux\n"); 206 207 for (i = 0; i < mux->data.n_values; i++) { 208 u32 nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0; 209 210 ret = i2c_mux_add_adapter(muxc, nr, mux->data.values[i]); 211 if (ret) 212 goto add_adapter_failed; 213 } 214 215 dev_info(&pdev->dev, "%d port mux on %s adapter\n", 216 mux->data.n_values, parent->name); 217 218 return 0; 219 220 add_adapter_failed: 221 i2c_mux_del_adapters(muxc); 222 alloc_failed: 223 i2c_put_adapter(parent); 224 225 return ret; 226 } 227 228 static void i2c_mux_gpio_remove(struct platform_device *pdev) 229 { 230 struct i2c_mux_core *muxc = platform_get_drvdata(pdev); 231 232 i2c_mux_del_adapters(muxc); 233 i2c_put_adapter(muxc->parent); 234 } 235 236 static const struct of_device_id i2c_mux_gpio_of_match[] = { 237 { .compatible = "i2c-mux-gpio", }, 238 {}, 239 }; 240 MODULE_DEVICE_TABLE(of, i2c_mux_gpio_of_match); 241 242 static struct platform_driver i2c_mux_gpio_driver = { 243 .probe = i2c_mux_gpio_probe, 244 .remove_new = i2c_mux_gpio_remove, 245 .driver = { 246 .name = "i2c-mux-gpio", 247 .of_match_table = i2c_mux_gpio_of_match, 248 }, 249 }; 250 251 module_platform_driver(i2c_mux_gpio_driver); 252 253 MODULE_DESCRIPTION("GPIO-based I2C multiplexer driver"); 254 MODULE_AUTHOR("Peter Korsgaard <peter.korsgaard@barco.com>"); 255 MODULE_LICENSE("GPL"); 256 MODULE_ALIAS("platform:i2c-mux-gpio"); 257