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 /* FIXME: stop poking around inside gpiolib */ 18 #include "../../gpio/gpiolib.h" 19 20 struct gpiomux { 21 struct i2c_mux_gpio_platform_data data; 22 int ngpios; 23 struct gpio_desc **gpios; 24 }; 25 26 static void i2c_mux_gpio_set(const struct gpiomux *mux, unsigned val) 27 { 28 DECLARE_BITMAP(values, BITS_PER_TYPE(val)); 29 30 values[0] = val; 31 32 gpiod_set_array_value_cansleep(mux->ngpios, mux->gpios, NULL, values); 33 } 34 35 static int i2c_mux_gpio_select(struct i2c_mux_core *muxc, u32 chan) 36 { 37 struct gpiomux *mux = i2c_mux_priv(muxc); 38 39 i2c_mux_gpio_set(mux, chan); 40 41 return 0; 42 } 43 44 static int i2c_mux_gpio_deselect(struct i2c_mux_core *muxc, u32 chan) 45 { 46 struct gpiomux *mux = i2c_mux_priv(muxc); 47 48 i2c_mux_gpio_set(mux, mux->data.idle); 49 50 return 0; 51 } 52 53 static int i2c_mux_gpio_probe_fw(struct gpiomux *mux, 54 struct platform_device *pdev) 55 { 56 struct device *dev = &pdev->dev; 57 struct fwnode_handle *fwnode = dev_fwnode(dev); 58 struct device_node *np = dev->of_node; 59 struct device_node *adapter_np; 60 struct i2c_adapter *adapter = NULL; 61 struct fwnode_handle *child; 62 unsigned *values; 63 int rc, i = 0; 64 65 if (is_of_node(fwnode)) { 66 if (!np) 67 return -ENODEV; 68 69 adapter_np = of_parse_phandle(np, "i2c-parent", 0); 70 if (!adapter_np) { 71 dev_err(&pdev->dev, "Cannot parse i2c-parent\n"); 72 return -ENODEV; 73 } 74 adapter = of_find_i2c_adapter_by_node(adapter_np); 75 of_node_put(adapter_np); 76 77 } else if (is_acpi_node(fwnode)) { 78 /* 79 * In ACPI land the mux should be a direct child of the i2c 80 * bus it muxes. 81 */ 82 acpi_handle dev_handle = ACPI_HANDLE(dev->parent); 83 84 adapter = i2c_acpi_find_adapter_by_handle(dev_handle); 85 } 86 87 if (!adapter) 88 return -EPROBE_DEFER; 89 90 mux->data.parent = i2c_adapter_id(adapter); 91 put_device(&adapter->dev); 92 93 mux->data.n_values = device_get_child_node_count(dev); 94 values = devm_kcalloc(dev, 95 mux->data.n_values, sizeof(*mux->data.values), 96 GFP_KERNEL); 97 if (!values) { 98 dev_err(dev, "Cannot allocate values array"); 99 return -ENOMEM; 100 } 101 102 device_for_each_child_node(dev, child) { 103 if (is_of_node(child)) { 104 fwnode_property_read_u32(child, "reg", values + i); 105 106 } else if (is_acpi_node(child)) { 107 rc = acpi_get_local_address(ACPI_HANDLE_FWNODE(child), values + i); 108 if (rc) { 109 fwnode_handle_put(child); 110 return dev_err_probe(dev, rc, "Cannot get address\n"); 111 } 112 } 113 114 i++; 115 } 116 mux->data.values = values; 117 118 if (device_property_read_u32(dev, "idle-state", &mux->data.idle)) 119 mux->data.idle = I2C_MUX_GPIO_NO_IDLE; 120 121 return 0; 122 } 123 124 static int i2c_mux_gpio_probe(struct platform_device *pdev) 125 { 126 struct i2c_mux_core *muxc; 127 struct gpiomux *mux; 128 struct i2c_adapter *parent; 129 struct i2c_adapter *root; 130 unsigned initial_state; 131 int i, ngpios, ret; 132 133 mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL); 134 if (!mux) 135 return -ENOMEM; 136 137 if (!dev_get_platdata(&pdev->dev)) { 138 ret = i2c_mux_gpio_probe_fw(mux, pdev); 139 if (ret < 0) 140 return ret; 141 } else { 142 memcpy(&mux->data, dev_get_platdata(&pdev->dev), 143 sizeof(mux->data)); 144 } 145 146 ngpios = gpiod_count(&pdev->dev, "mux"); 147 if (ngpios <= 0) { 148 dev_err(&pdev->dev, "no valid gpios provided\n"); 149 return ngpios ?: -EINVAL; 150 } 151 mux->ngpios = ngpios; 152 153 parent = i2c_get_adapter(mux->data.parent); 154 if (!parent) 155 return -EPROBE_DEFER; 156 157 muxc = i2c_mux_alloc(parent, &pdev->dev, mux->data.n_values, 158 array_size(ngpios, sizeof(*mux->gpios)), 0, 159 i2c_mux_gpio_select, NULL); 160 if (!muxc) { 161 ret = -ENOMEM; 162 goto alloc_failed; 163 } 164 mux->gpios = muxc->priv; 165 muxc->priv = mux; 166 167 platform_set_drvdata(pdev, muxc); 168 169 root = i2c_root_adapter(&parent->dev); 170 171 muxc->mux_locked = true; 172 173 if (mux->data.idle != I2C_MUX_GPIO_NO_IDLE) { 174 initial_state = mux->data.idle; 175 muxc->deselect = i2c_mux_gpio_deselect; 176 } else { 177 initial_state = mux->data.values[0]; 178 } 179 180 for (i = 0; i < ngpios; i++) { 181 struct device *gpio_dev; 182 struct gpio_desc *gpiod; 183 enum gpiod_flags flag; 184 185 if (initial_state & BIT(i)) 186 flag = GPIOD_OUT_HIGH; 187 else 188 flag = GPIOD_OUT_LOW; 189 gpiod = devm_gpiod_get_index(&pdev->dev, "mux", i, flag); 190 if (IS_ERR(gpiod)) { 191 ret = PTR_ERR(gpiod); 192 goto alloc_failed; 193 } 194 195 mux->gpios[i] = gpiod; 196 197 if (!muxc->mux_locked) 198 continue; 199 200 /* FIXME: find a proper way to access the GPIO device */ 201 gpio_dev = &gpiod->gdev->dev; 202 muxc->mux_locked = i2c_root_adapter(gpio_dev) == root; 203 } 204 205 if (muxc->mux_locked) 206 dev_info(&pdev->dev, "mux-locked i2c mux\n"); 207 208 for (i = 0; i < mux->data.n_values; i++) { 209 u32 nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0; 210 unsigned int class = mux->data.classes ? mux->data.classes[i] : 0; 211 212 ret = i2c_mux_add_adapter(muxc, nr, mux->data.values[i], class); 213 if (ret) 214 goto add_adapter_failed; 215 } 216 217 dev_info(&pdev->dev, "%d port mux on %s adapter\n", 218 mux->data.n_values, parent->name); 219 220 return 0; 221 222 add_adapter_failed: 223 i2c_mux_del_adapters(muxc); 224 alloc_failed: 225 i2c_put_adapter(parent); 226 227 return ret; 228 } 229 230 static void i2c_mux_gpio_remove(struct platform_device *pdev) 231 { 232 struct i2c_mux_core *muxc = platform_get_drvdata(pdev); 233 234 i2c_mux_del_adapters(muxc); 235 i2c_put_adapter(muxc->parent); 236 } 237 238 static const struct of_device_id i2c_mux_gpio_of_match[] = { 239 { .compatible = "i2c-mux-gpio", }, 240 {}, 241 }; 242 MODULE_DEVICE_TABLE(of, i2c_mux_gpio_of_match); 243 244 static struct platform_driver i2c_mux_gpio_driver = { 245 .probe = i2c_mux_gpio_probe, 246 .remove_new = i2c_mux_gpio_remove, 247 .driver = { 248 .name = "i2c-mux-gpio", 249 .of_match_table = i2c_mux_gpio_of_match, 250 }, 251 }; 252 253 module_platform_driver(i2c_mux_gpio_driver); 254 255 MODULE_DESCRIPTION("GPIO-based I2C multiplexer driver"); 256 MODULE_AUTHOR("Peter Korsgaard <peter.korsgaard@barco.com>"); 257 MODULE_LICENSE("GPL"); 258 MODULE_ALIAS("platform:i2c-mux-gpio"); 259