1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Pinctrl based I2C DeMultiplexer 4 * 5 * Copyright (C) 2015-16 by Wolfram Sang, Sang Engineering <wsa@sang-engineering.com> 6 * Copyright (C) 2015-16 by Renesas Electronics Corporation 7 * 8 * See the bindings doc for DTS setup and the sysfs doc for usage information. 9 * (look for filenames containing 'i2c-demux-pinctrl' in Documentation/) 10 */ 11 12 #include <linux/i2c.h> 13 #include <linux/init.h> 14 #include <linux/module.h> 15 #include <linux/of.h> 16 #include <linux/pinctrl/consumer.h> 17 #include <linux/platform_device.h> 18 #include <linux/pm_runtime.h> 19 #include <linux/slab.h> 20 #include <linux/sysfs.h> 21 22 struct i2c_demux_pinctrl_chan { 23 struct device_node *parent_np; 24 struct i2c_adapter *parent_adap; 25 struct of_changeset chgset; 26 }; 27 28 struct i2c_demux_pinctrl_priv { 29 int cur_chan; 30 int num_chan; 31 struct device *dev; 32 const char *bus_name; 33 struct i2c_adapter cur_adap; 34 struct i2c_algorithm algo; 35 struct i2c_demux_pinctrl_chan chan[]; 36 }; 37 i2c_demux_master_xfer(struct i2c_adapter * adap,struct i2c_msg msgs[],int num)38 static int i2c_demux_master_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num) 39 { 40 struct i2c_demux_pinctrl_priv *priv = adap->algo_data; 41 struct i2c_adapter *parent = priv->chan[priv->cur_chan].parent_adap; 42 43 return __i2c_transfer(parent, msgs, num); 44 } 45 i2c_demux_functionality(struct i2c_adapter * adap)46 static u32 i2c_demux_functionality(struct i2c_adapter *adap) 47 { 48 struct i2c_demux_pinctrl_priv *priv = adap->algo_data; 49 struct i2c_adapter *parent = priv->chan[priv->cur_chan].parent_adap; 50 51 return parent->algo->functionality(parent); 52 } 53 i2c_demux_activate_master(struct i2c_demux_pinctrl_priv * priv,u32 new_chan)54 static int i2c_demux_activate_master(struct i2c_demux_pinctrl_priv *priv, u32 new_chan) 55 { 56 struct i2c_adapter *adap; 57 struct pinctrl *p; 58 int ret; 59 60 ret = of_changeset_apply(&priv->chan[new_chan].chgset); 61 if (ret) 62 goto err; 63 64 adap = of_get_i2c_adapter_by_node(priv->chan[new_chan].parent_np); 65 if (!adap) { 66 ret = -ENODEV; 67 goto err_with_revert; 68 } 69 70 /* 71 * Check if there are pinctrl states at all. Note: we cant' use 72 * devm_pinctrl_get_select() because we need to distinguish between 73 * the -ENODEV from devm_pinctrl_get() and pinctrl_lookup_state(). 74 */ 75 p = devm_pinctrl_get(adap->dev.parent); 76 if (IS_ERR(p)) { 77 ret = PTR_ERR(p); 78 /* continue if just no pinctrl states (e.g. i2c-gpio), otherwise exit */ 79 if (ret != -ENODEV) 80 goto err_with_put; 81 } else { 82 /* there are states. check and use them */ 83 struct pinctrl_state *s = pinctrl_lookup_state(p, priv->bus_name); 84 85 if (IS_ERR(s)) { 86 ret = PTR_ERR(s); 87 goto err_with_put; 88 } 89 ret = pinctrl_select_state(p, s); 90 if (ret < 0) 91 goto err_with_put; 92 } 93 94 priv->chan[new_chan].parent_adap = adap; 95 priv->cur_chan = new_chan; 96 97 /* Now fill out current adapter structure. cur_chan must be up to date */ 98 priv->algo.master_xfer = i2c_demux_master_xfer; 99 if (adap->algo->master_xfer_atomic) 100 priv->algo.master_xfer_atomic = i2c_demux_master_xfer; 101 priv->algo.functionality = i2c_demux_functionality; 102 103 snprintf(priv->cur_adap.name, sizeof(priv->cur_adap.name), 104 "i2c-demux (master i2c-%d)", i2c_adapter_id(adap)); 105 priv->cur_adap.owner = THIS_MODULE; 106 priv->cur_adap.algo = &priv->algo; 107 priv->cur_adap.algo_data = priv; 108 priv->cur_adap.dev.parent = &adap->dev; 109 priv->cur_adap.class = adap->class; 110 priv->cur_adap.retries = adap->retries; 111 priv->cur_adap.timeout = adap->timeout; 112 priv->cur_adap.quirks = adap->quirks; 113 priv->cur_adap.dev.of_node = priv->dev->of_node; 114 ret = i2c_add_adapter(&priv->cur_adap); 115 if (ret < 0) 116 goto err_with_put; 117 118 return 0; 119 120 err_with_put: 121 i2c_put_adapter(adap); 122 err_with_revert: 123 of_changeset_revert(&priv->chan[new_chan].chgset); 124 err: 125 dev_err(priv->dev, "failed to setup demux-adapter %d (%d)\n", new_chan, ret); 126 priv->cur_chan = -EINVAL; 127 return ret; 128 } 129 i2c_demux_deactivate_master(struct i2c_demux_pinctrl_priv * priv)130 static int i2c_demux_deactivate_master(struct i2c_demux_pinctrl_priv *priv) 131 { 132 int ret, cur = priv->cur_chan; 133 134 if (cur < 0) 135 return 0; 136 137 i2c_del_adapter(&priv->cur_adap); 138 i2c_put_adapter(priv->chan[cur].parent_adap); 139 140 ret = of_changeset_revert(&priv->chan[cur].chgset); 141 142 priv->chan[cur].parent_adap = NULL; 143 priv->cur_chan = -EINVAL; 144 145 return ret; 146 } 147 i2c_demux_change_master(struct i2c_demux_pinctrl_priv * priv,u32 new_chan)148 static int i2c_demux_change_master(struct i2c_demux_pinctrl_priv *priv, u32 new_chan) 149 { 150 int ret; 151 152 if (new_chan == priv->cur_chan) 153 return 0; 154 155 ret = i2c_demux_deactivate_master(priv); 156 if (ret) 157 return ret; 158 159 return i2c_demux_activate_master(priv, new_chan); 160 } 161 available_masters_show(struct device * dev,struct device_attribute * attr,char * buf)162 static ssize_t available_masters_show(struct device *dev, 163 struct device_attribute *attr, 164 char *buf) 165 { 166 struct i2c_demux_pinctrl_priv *priv = dev_get_drvdata(dev); 167 int count = 0, i; 168 169 for (i = 0; i < priv->num_chan && count < PAGE_SIZE; i++) 170 count += scnprintf(buf + count, PAGE_SIZE - count, "%d:%pOF%c", 171 i, priv->chan[i].parent_np, 172 i == priv->num_chan - 1 ? '\n' : ' '); 173 174 return count; 175 } 176 static DEVICE_ATTR_RO(available_masters); 177 current_master_show(struct device * dev,struct device_attribute * attr,char * buf)178 static ssize_t current_master_show(struct device *dev, 179 struct device_attribute *attr, 180 char *buf) 181 { 182 struct i2c_demux_pinctrl_priv *priv = dev_get_drvdata(dev); 183 184 return sprintf(buf, "%d\n", priv->cur_chan); 185 } 186 current_master_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)187 static ssize_t current_master_store(struct device *dev, 188 struct device_attribute *attr, 189 const char *buf, size_t count) 190 { 191 struct i2c_demux_pinctrl_priv *priv = dev_get_drvdata(dev); 192 unsigned int val; 193 int ret; 194 195 ret = kstrtouint(buf, 0, &val); 196 if (ret < 0) 197 return ret; 198 199 if (val >= priv->num_chan) 200 return -EINVAL; 201 202 ret = i2c_demux_change_master(priv, val); 203 204 return ret < 0 ? ret : count; 205 } 206 static DEVICE_ATTR_RW(current_master); 207 i2c_demux_pinctrl_probe(struct platform_device * pdev)208 static int i2c_demux_pinctrl_probe(struct platform_device *pdev) 209 { 210 struct device_node *np = pdev->dev.of_node; 211 struct i2c_demux_pinctrl_priv *priv; 212 struct property *props; 213 int num_chan, i, j, err; 214 215 num_chan = of_count_phandle_with_args(np, "i2c-parent", NULL); 216 if (num_chan < 2) { 217 dev_err(&pdev->dev, "Need at least two I2C masters to switch\n"); 218 return -EINVAL; 219 } 220 221 priv = devm_kzalloc(&pdev->dev, struct_size(priv, chan, num_chan), 222 GFP_KERNEL); 223 224 props = devm_kcalloc(&pdev->dev, num_chan, sizeof(*props), GFP_KERNEL); 225 226 if (!priv || !props) 227 return -ENOMEM; 228 229 err = of_property_read_string(np, "i2c-bus-name", &priv->bus_name); 230 if (err) 231 return err; 232 233 for (i = 0; i < num_chan; i++) { 234 struct device_node *adap_np; 235 236 adap_np = of_parse_phandle(np, "i2c-parent", i); 237 if (!adap_np) { 238 dev_err(&pdev->dev, "can't get phandle for parent %d\n", i); 239 err = -ENOENT; 240 goto err_rollback; 241 } 242 priv->chan[i].parent_np = adap_np; 243 244 props[i].name = devm_kstrdup(&pdev->dev, "status", GFP_KERNEL); 245 props[i].value = devm_kstrdup(&pdev->dev, "ok", GFP_KERNEL); 246 if (!props[i].name || !props[i].value) { 247 err = -ENOMEM; 248 goto err_rollback; 249 } 250 props[i].length = 3; 251 252 of_changeset_init(&priv->chan[i].chgset); 253 of_changeset_update_property(&priv->chan[i].chgset, adap_np, &props[i]); 254 } 255 256 priv->num_chan = num_chan; 257 priv->dev = &pdev->dev; 258 259 platform_set_drvdata(pdev, priv); 260 261 pm_runtime_no_callbacks(&pdev->dev); 262 263 /* switch to first parent as active master */ 264 err = i2c_demux_activate_master(priv, 0); 265 if (err) 266 goto err_rollback; 267 268 err = device_create_file(&pdev->dev, &dev_attr_available_masters); 269 if (err) 270 goto err_rollback_activation; 271 272 err = device_create_file(&pdev->dev, &dev_attr_current_master); 273 if (err) 274 goto err_rollback_available; 275 276 return 0; 277 278 err_rollback_available: 279 device_remove_file(&pdev->dev, &dev_attr_available_masters); 280 err_rollback_activation: 281 i2c_demux_deactivate_master(priv); 282 err_rollback: 283 for (j = 0; j < i; j++) { 284 of_node_put(priv->chan[j].parent_np); 285 of_changeset_destroy(&priv->chan[j].chgset); 286 } 287 288 return err; 289 } 290 i2c_demux_pinctrl_remove(struct platform_device * pdev)291 static void i2c_demux_pinctrl_remove(struct platform_device *pdev) 292 { 293 struct i2c_demux_pinctrl_priv *priv = platform_get_drvdata(pdev); 294 int i; 295 296 device_remove_file(&pdev->dev, &dev_attr_current_master); 297 device_remove_file(&pdev->dev, &dev_attr_available_masters); 298 299 i2c_demux_deactivate_master(priv); 300 301 for (i = 0; i < priv->num_chan; i++) { 302 of_node_put(priv->chan[i].parent_np); 303 of_changeset_destroy(&priv->chan[i].chgset); 304 } 305 } 306 307 static const struct of_device_id i2c_demux_pinctrl_of_match[] = { 308 { .compatible = "i2c-demux-pinctrl", }, 309 {}, 310 }; 311 MODULE_DEVICE_TABLE(of, i2c_demux_pinctrl_of_match); 312 313 static struct platform_driver i2c_demux_pinctrl_driver = { 314 .driver = { 315 .name = "i2c-demux-pinctrl", 316 .of_match_table = i2c_demux_pinctrl_of_match, 317 }, 318 .probe = i2c_demux_pinctrl_probe, 319 .remove_new = i2c_demux_pinctrl_remove, 320 }; 321 module_platform_driver(i2c_demux_pinctrl_driver); 322 323 MODULE_DESCRIPTION("pinctrl-based I2C demux driver"); 324 MODULE_AUTHOR("Wolfram Sang <wsa@sang-engineering.com>"); 325 MODULE_LICENSE("GPL v2"); 326 MODULE_ALIAS("platform:i2c-demux-pinctrl"); 327