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/platform_data/i2c-mux-gpio.h> 11 #include <linux/platform_device.h> 12 #include <linux/module.h> 13 #include <linux/slab.h> 14 #include <linux/bits.h> 15 #include <linux/gpio/consumer.h> 16 /* FIXME: stop poking around inside gpiolib */ 17 #include "../../gpio/gpiolib.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 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 #ifdef CONFIG_OF 53 static int i2c_mux_gpio_probe_dt(struct gpiomux *mux, 54 struct platform_device *pdev) 55 { 56 struct device_node *np = pdev->dev.of_node; 57 struct device_node *adapter_np, *child; 58 struct i2c_adapter *adapter; 59 unsigned *values; 60 int i = 0; 61 62 if (!np) 63 return -ENODEV; 64 65 adapter_np = of_parse_phandle(np, "i2c-parent", 0); 66 if (!adapter_np) { 67 dev_err(&pdev->dev, "Cannot parse i2c-parent\n"); 68 return -ENODEV; 69 } 70 adapter = of_find_i2c_adapter_by_node(adapter_np); 71 of_node_put(adapter_np); 72 if (!adapter) 73 return -EPROBE_DEFER; 74 75 mux->data.parent = i2c_adapter_id(adapter); 76 put_device(&adapter->dev); 77 78 mux->data.n_values = of_get_child_count(np); 79 80 values = devm_kcalloc(&pdev->dev, 81 mux->data.n_values, sizeof(*mux->data.values), 82 GFP_KERNEL); 83 if (!values) { 84 dev_err(&pdev->dev, "Cannot allocate values array"); 85 return -ENOMEM; 86 } 87 88 for_each_child_of_node(np, child) { 89 of_property_read_u32(child, "reg", values + i); 90 i++; 91 } 92 mux->data.values = values; 93 94 if (of_property_read_u32(np, "idle-state", &mux->data.idle)) 95 mux->data.idle = I2C_MUX_GPIO_NO_IDLE; 96 97 return 0; 98 } 99 #else 100 static int i2c_mux_gpio_probe_dt(struct gpiomux *mux, 101 struct platform_device *pdev) 102 { 103 return 0; 104 } 105 #endif 106 107 static int i2c_mux_gpio_probe(struct platform_device *pdev) 108 { 109 struct i2c_mux_core *muxc; 110 struct gpiomux *mux; 111 struct i2c_adapter *parent; 112 struct i2c_adapter *root; 113 unsigned initial_state; 114 int i, ngpios, ret; 115 116 mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL); 117 if (!mux) 118 return -ENOMEM; 119 120 if (!dev_get_platdata(&pdev->dev)) { 121 ret = i2c_mux_gpio_probe_dt(mux, pdev); 122 if (ret < 0) 123 return ret; 124 } else { 125 memcpy(&mux->data, dev_get_platdata(&pdev->dev), 126 sizeof(mux->data)); 127 } 128 129 ngpios = gpiod_count(&pdev->dev, "mux"); 130 if (ngpios <= 0) { 131 dev_err(&pdev->dev, "no valid gpios provided\n"); 132 return ngpios ?: -EINVAL; 133 } 134 mux->ngpios = ngpios; 135 136 parent = i2c_get_adapter(mux->data.parent); 137 if (!parent) 138 return -EPROBE_DEFER; 139 140 muxc = i2c_mux_alloc(parent, &pdev->dev, mux->data.n_values, 141 ngpios * sizeof(*mux->gpios), 0, 142 i2c_mux_gpio_select, NULL); 143 if (!muxc) { 144 ret = -ENOMEM; 145 goto alloc_failed; 146 } 147 mux->gpios = muxc->priv; 148 muxc->priv = mux; 149 150 platform_set_drvdata(pdev, muxc); 151 152 root = i2c_root_adapter(&parent->dev); 153 154 muxc->mux_locked = true; 155 156 if (mux->data.idle != I2C_MUX_GPIO_NO_IDLE) { 157 initial_state = mux->data.idle; 158 muxc->deselect = i2c_mux_gpio_deselect; 159 } else { 160 initial_state = mux->data.values[0]; 161 } 162 163 for (i = 0; i < ngpios; i++) { 164 struct device *gpio_dev; 165 struct gpio_desc *gpiod; 166 enum gpiod_flags flag; 167 168 if (initial_state & BIT(i)) 169 flag = GPIOD_OUT_HIGH; 170 else 171 flag = GPIOD_OUT_LOW; 172 gpiod = devm_gpiod_get_index(&pdev->dev, "mux", i, flag); 173 if (IS_ERR(gpiod)) { 174 ret = PTR_ERR(gpiod); 175 goto alloc_failed; 176 } 177 178 mux->gpios[i] = gpiod; 179 180 if (!muxc->mux_locked) 181 continue; 182 183 /* FIXME: find a proper way to access the GPIO device */ 184 gpio_dev = &gpiod->gdev->dev; 185 muxc->mux_locked = i2c_root_adapter(gpio_dev) == root; 186 } 187 188 if (muxc->mux_locked) 189 dev_info(&pdev->dev, "mux-locked i2c mux\n"); 190 191 for (i = 0; i < mux->data.n_values; i++) { 192 u32 nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0; 193 unsigned int class = mux->data.classes ? mux->data.classes[i] : 0; 194 195 ret = i2c_mux_add_adapter(muxc, nr, mux->data.values[i], class); 196 if (ret) 197 goto add_adapter_failed; 198 } 199 200 dev_info(&pdev->dev, "%d port mux on %s adapter\n", 201 mux->data.n_values, parent->name); 202 203 return 0; 204 205 add_adapter_failed: 206 i2c_mux_del_adapters(muxc); 207 alloc_failed: 208 i2c_put_adapter(parent); 209 210 return ret; 211 } 212 213 static int i2c_mux_gpio_remove(struct platform_device *pdev) 214 { 215 struct i2c_mux_core *muxc = platform_get_drvdata(pdev); 216 217 i2c_mux_del_adapters(muxc); 218 i2c_put_adapter(muxc->parent); 219 220 return 0; 221 } 222 223 static const struct of_device_id i2c_mux_gpio_of_match[] = { 224 { .compatible = "i2c-mux-gpio", }, 225 {}, 226 }; 227 MODULE_DEVICE_TABLE(of, i2c_mux_gpio_of_match); 228 229 static struct platform_driver i2c_mux_gpio_driver = { 230 .probe = i2c_mux_gpio_probe, 231 .remove = i2c_mux_gpio_remove, 232 .driver = { 233 .name = "i2c-mux-gpio", 234 .of_match_table = i2c_mux_gpio_of_match, 235 }, 236 }; 237 238 module_platform_driver(i2c_mux_gpio_driver); 239 240 MODULE_DESCRIPTION("GPIO-based I2C multiplexer driver"); 241 MODULE_AUTHOR("Peter Korsgaard <peter.korsgaard@barco.com>"); 242 MODULE_LICENSE("GPL"); 243 MODULE_ALIAS("platform:i2c-mux-gpio"); 244