1 /* 2 * Pinctrl based I2C DeMultiplexer 3 * 4 * Copyright (C) 2015-16 by Wolfram Sang, Sang Engineering <wsa@sang-engineering.com> 5 * Copyright (C) 2015-16 by Renesas Electronics Corporation 6 * 7 * This program is free software; you can redistribute it and/or modify it 8 * under the terms of the GNU General Public License as published by the 9 * Free Software Foundation; version 2 of the License. 10 * 11 * See the bindings doc for DTS setup and the sysfs doc for usage information. 12 * (look for filenames containing 'i2c-demux-pinctrl' in Documentation/) 13 */ 14 15 #include <linux/i2c.h> 16 #include <linux/init.h> 17 #include <linux/module.h> 18 #include <linux/of.h> 19 #include <linux/pinctrl/consumer.h> 20 #include <linux/platform_device.h> 21 #include <linux/slab.h> 22 #include <linux/sysfs.h> 23 24 struct i2c_demux_pinctrl_chan { 25 struct device_node *parent_np; 26 struct i2c_adapter *parent_adap; 27 struct of_changeset chgset; 28 }; 29 30 struct i2c_demux_pinctrl_priv { 31 int cur_chan; 32 int num_chan; 33 struct device *dev; 34 const char *bus_name; 35 struct i2c_adapter cur_adap; 36 struct i2c_algorithm algo; 37 struct i2c_demux_pinctrl_chan chan[]; 38 }; 39 40 static struct property status_okay = { .name = "status", .length = 3, .value = "ok" }; 41 42 static int i2c_demux_master_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num) 43 { 44 struct i2c_demux_pinctrl_priv *priv = adap->algo_data; 45 struct i2c_adapter *parent = priv->chan[priv->cur_chan].parent_adap; 46 47 return __i2c_transfer(parent, msgs, num); 48 } 49 50 static u32 i2c_demux_functionality(struct i2c_adapter *adap) 51 { 52 struct i2c_demux_pinctrl_priv *priv = adap->algo_data; 53 struct i2c_adapter *parent = priv->chan[priv->cur_chan].parent_adap; 54 55 return parent->algo->functionality(parent); 56 } 57 58 static int i2c_demux_activate_master(struct i2c_demux_pinctrl_priv *priv, u32 new_chan) 59 { 60 struct i2c_adapter *adap; 61 struct pinctrl *p; 62 int ret; 63 64 ret = of_changeset_apply(&priv->chan[new_chan].chgset); 65 if (ret) 66 goto err; 67 68 adap = of_find_i2c_adapter_by_node(priv->chan[new_chan].parent_np); 69 if (!adap) { 70 ret = -ENODEV; 71 goto err; 72 } 73 74 p = devm_pinctrl_get_select(adap->dev.parent, priv->bus_name); 75 if (IS_ERR(p)) { 76 ret = PTR_ERR(p); 77 goto err_with_put; 78 } 79 80 priv->chan[new_chan].parent_adap = adap; 81 priv->cur_chan = new_chan; 82 83 /* Now fill out current adapter structure. cur_chan must be up to date */ 84 priv->algo.master_xfer = i2c_demux_master_xfer; 85 priv->algo.functionality = i2c_demux_functionality; 86 87 snprintf(priv->cur_adap.name, sizeof(priv->cur_adap.name), 88 "i2c-demux (master i2c-%d)", i2c_adapter_id(adap)); 89 priv->cur_adap.owner = THIS_MODULE; 90 priv->cur_adap.algo = &priv->algo; 91 priv->cur_adap.algo_data = priv; 92 priv->cur_adap.dev.parent = priv->dev; 93 priv->cur_adap.class = adap->class; 94 priv->cur_adap.retries = adap->retries; 95 priv->cur_adap.timeout = adap->timeout; 96 priv->cur_adap.quirks = adap->quirks; 97 priv->cur_adap.dev.of_node = priv->dev->of_node; 98 ret = i2c_add_adapter(&priv->cur_adap); 99 if (ret < 0) 100 goto err_with_put; 101 102 return 0; 103 104 err_with_put: 105 i2c_put_adapter(adap); 106 err: 107 dev_err(priv->dev, "failed to setup demux-adapter %d (%d)\n", new_chan, ret); 108 return ret; 109 } 110 111 static int i2c_demux_deactivate_master(struct i2c_demux_pinctrl_priv *priv) 112 { 113 int ret, cur = priv->cur_chan; 114 115 if (cur < 0) 116 return 0; 117 118 i2c_del_adapter(&priv->cur_adap); 119 i2c_put_adapter(priv->chan[cur].parent_adap); 120 121 ret = of_changeset_revert(&priv->chan[cur].chgset); 122 123 priv->chan[cur].parent_adap = NULL; 124 priv->cur_chan = -EINVAL; 125 126 return ret; 127 } 128 129 static int i2c_demux_change_master(struct i2c_demux_pinctrl_priv *priv, u32 new_chan) 130 { 131 int ret; 132 133 if (new_chan == priv->cur_chan) 134 return 0; 135 136 ret = i2c_demux_deactivate_master(priv); 137 if (ret) 138 return ret; 139 140 return i2c_demux_activate_master(priv, new_chan); 141 } 142 143 static ssize_t available_masters_show(struct device *dev, 144 struct device_attribute *attr, 145 char *buf) 146 { 147 struct i2c_demux_pinctrl_priv *priv = dev_get_drvdata(dev); 148 int count = 0, i; 149 150 for (i = 0; i < priv->num_chan && count < PAGE_SIZE; i++) 151 count += scnprintf(buf + count, PAGE_SIZE - count, "%d:%s%c", 152 i, priv->chan[i].parent_np->full_name, 153 i == priv->num_chan - 1 ? '\n' : ' '); 154 155 return count; 156 } 157 static DEVICE_ATTR_RO(available_masters); 158 159 static ssize_t current_master_show(struct device *dev, 160 struct device_attribute *attr, 161 char *buf) 162 { 163 struct i2c_demux_pinctrl_priv *priv = dev_get_drvdata(dev); 164 165 return sprintf(buf, "%d\n", priv->cur_chan); 166 } 167 168 static ssize_t current_master_store(struct device *dev, 169 struct device_attribute *attr, 170 const char *buf, size_t count) 171 { 172 struct i2c_demux_pinctrl_priv *priv = dev_get_drvdata(dev); 173 unsigned int val; 174 int ret; 175 176 ret = kstrtouint(buf, 0, &val); 177 if (ret < 0) 178 return ret; 179 180 if (val >= priv->num_chan) 181 return -EINVAL; 182 183 ret = i2c_demux_change_master(priv, val); 184 185 return ret < 0 ? ret : count; 186 } 187 static DEVICE_ATTR_RW(current_master); 188 189 static int i2c_demux_pinctrl_probe(struct platform_device *pdev) 190 { 191 struct device_node *np = pdev->dev.of_node; 192 struct i2c_demux_pinctrl_priv *priv; 193 int num_chan, i, j, err; 194 195 num_chan = of_count_phandle_with_args(np, "i2c-parent", NULL); 196 if (num_chan < 2) { 197 dev_err(&pdev->dev, "Need at least two I2C masters to switch\n"); 198 return -EINVAL; 199 } 200 201 priv = devm_kzalloc(&pdev->dev, sizeof(*priv) 202 + num_chan * sizeof(struct i2c_demux_pinctrl_chan), GFP_KERNEL); 203 if (!priv) 204 return -ENOMEM; 205 206 err = of_property_read_string(np, "i2c-bus-name", &priv->bus_name); 207 if (err) 208 return err; 209 210 for (i = 0; i < num_chan; i++) { 211 struct device_node *adap_np; 212 213 adap_np = of_parse_phandle(np, "i2c-parent", i); 214 if (!adap_np) { 215 dev_err(&pdev->dev, "can't get phandle for parent %d\n", i); 216 err = -ENOENT; 217 goto err_rollback; 218 } 219 priv->chan[i].parent_np = adap_np; 220 221 of_changeset_init(&priv->chan[i].chgset); 222 of_changeset_update_property(&priv->chan[i].chgset, adap_np, &status_okay); 223 } 224 225 priv->num_chan = num_chan; 226 priv->dev = &pdev->dev; 227 228 platform_set_drvdata(pdev, priv); 229 230 /* switch to first parent as active master */ 231 i2c_demux_activate_master(priv, 0); 232 233 err = device_create_file(&pdev->dev, &dev_attr_available_masters); 234 if (err) 235 goto err_rollback; 236 237 err = device_create_file(&pdev->dev, &dev_attr_current_master); 238 if (err) 239 goto err_rollback_available; 240 241 return 0; 242 243 err_rollback_available: 244 device_remove_file(&pdev->dev, &dev_attr_available_masters); 245 err_rollback: 246 for (j = 0; j < i; j++) { 247 of_node_put(priv->chan[j].parent_np); 248 of_changeset_destroy(&priv->chan[j].chgset); 249 } 250 251 return err; 252 } 253 254 static int i2c_demux_pinctrl_remove(struct platform_device *pdev) 255 { 256 struct i2c_demux_pinctrl_priv *priv = platform_get_drvdata(pdev); 257 int i; 258 259 device_remove_file(&pdev->dev, &dev_attr_current_master); 260 device_remove_file(&pdev->dev, &dev_attr_available_masters); 261 262 i2c_demux_deactivate_master(priv); 263 264 for (i = 0; i < priv->num_chan; i++) { 265 of_node_put(priv->chan[i].parent_np); 266 of_changeset_destroy(&priv->chan[i].chgset); 267 } 268 269 return 0; 270 } 271 272 static const struct of_device_id i2c_demux_pinctrl_of_match[] = { 273 { .compatible = "i2c-demux-pinctrl", }, 274 {}, 275 }; 276 MODULE_DEVICE_TABLE(of, i2c_demux_pinctrl_of_match); 277 278 static struct platform_driver i2c_demux_pinctrl_driver = { 279 .driver = { 280 .name = "i2c-demux-pinctrl", 281 .of_match_table = i2c_demux_pinctrl_of_match, 282 }, 283 .probe = i2c_demux_pinctrl_probe, 284 .remove = i2c_demux_pinctrl_remove, 285 }; 286 module_platform_driver(i2c_demux_pinctrl_driver); 287 288 MODULE_DESCRIPTION("pinctrl-based I2C demux driver"); 289 MODULE_AUTHOR("Wolfram Sang <wsa@sang-engineering.com>"); 290 MODULE_LICENSE("GPL v2"); 291 MODULE_ALIAS("platform:i2c-demux-pinctrl"); 292