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 return dev_err_probe(dev, rc, "Cannot get address\n"); 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 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 device *gpio_dev; 180 struct gpio_desc *gpiod; 181 enum gpiod_flags flag; 182 183 if (initial_state & BIT(i)) 184 flag = GPIOD_OUT_HIGH; 185 else 186 flag = GPIOD_OUT_LOW; 187 gpiod = devm_gpiod_get_index(&pdev->dev, "mux", i, flag); 188 if (IS_ERR(gpiod)) { 189 ret = PTR_ERR(gpiod); 190 goto alloc_failed; 191 } 192 193 mux->gpios[i] = gpiod; 194 195 if (!muxc->mux_locked) 196 continue; 197 198 /* FIXME: find a proper way to access the GPIO device */ 199 gpio_dev = &gpiod->gdev->dev; 200 muxc->mux_locked = i2c_root_adapter(gpio_dev) == root; 201 } 202 203 if (muxc->mux_locked) 204 dev_info(&pdev->dev, "mux-locked i2c mux\n"); 205 206 for (i = 0; i < mux->data.n_values; i++) { 207 u32 nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0; 208 unsigned int class = mux->data.classes ? mux->data.classes[i] : 0; 209 210 ret = i2c_mux_add_adapter(muxc, nr, mux->data.values[i], class); 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