/* * Pinctrl based I2C DeMultiplexer * * Copyright (C) 2015-16 by Wolfram Sang, Sang Engineering * Copyright (C) 2015-16 by Renesas Electronics Corporation * * This program is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License as published by the * Free Software Foundation; version 2 of the License. * * See the bindings doc for DTS setup and the sysfs doc for usage information. * (look for filenames containing 'i2c-demux-pinctrl' in Documentation/) */ #include #include #include #include #include #include #include #include struct i2c_demux_pinctrl_chan { struct device_node *parent_np; struct i2c_adapter *parent_adap; struct of_changeset chgset; }; struct i2c_demux_pinctrl_priv { int cur_chan; int num_chan; struct device *dev; const char *bus_name; struct i2c_adapter cur_adap; struct i2c_algorithm algo; struct i2c_demux_pinctrl_chan chan[]; }; static int i2c_demux_master_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num) { struct i2c_demux_pinctrl_priv *priv = adap->algo_data; struct i2c_adapter *parent = priv->chan[priv->cur_chan].parent_adap; return __i2c_transfer(parent, msgs, num); } static u32 i2c_demux_functionality(struct i2c_adapter *adap) { struct i2c_demux_pinctrl_priv *priv = adap->algo_data; struct i2c_adapter *parent = priv->chan[priv->cur_chan].parent_adap; return parent->algo->functionality(parent); } static int i2c_demux_activate_master(struct i2c_demux_pinctrl_priv *priv, u32 new_chan) { struct i2c_adapter *adap; struct pinctrl *p; int ret; ret = of_changeset_apply(&priv->chan[new_chan].chgset); if (ret) goto err; adap = of_find_i2c_adapter_by_node(priv->chan[new_chan].parent_np); if (!adap) { ret = -ENODEV; goto err_with_revert; } /* * Check if there are pinctrl states at all. Note: we cant' use * devm_pinctrl_get_select() because we need to distinguish between * the -ENODEV from devm_pinctrl_get() and pinctrl_lookup_state(). */ p = devm_pinctrl_get(adap->dev.parent); if (IS_ERR(p)) { ret = PTR_ERR(p); /* continue if just no pinctrl states (e.g. i2c-gpio), otherwise exit */ if (ret != -ENODEV) goto err_with_put; } else { /* there are states. check and use them */ struct pinctrl_state *s = pinctrl_lookup_state(p, priv->bus_name); if (IS_ERR(s)) { ret = PTR_ERR(s); goto err_with_put; } ret = pinctrl_select_state(p, s); if (ret < 0) goto err_with_put; } priv->chan[new_chan].parent_adap = adap; priv->cur_chan = new_chan; /* Now fill out current adapter structure. cur_chan must be up to date */ priv->algo.master_xfer = i2c_demux_master_xfer; priv->algo.functionality = i2c_demux_functionality; snprintf(priv->cur_adap.name, sizeof(priv->cur_adap.name), "i2c-demux (master i2c-%d)", i2c_adapter_id(adap)); priv->cur_adap.owner = THIS_MODULE; priv->cur_adap.algo = &priv->algo; priv->cur_adap.algo_data = priv; priv->cur_adap.dev.parent = priv->dev; priv->cur_adap.class = adap->class; priv->cur_adap.retries = adap->retries; priv->cur_adap.timeout = adap->timeout; priv->cur_adap.quirks = adap->quirks; priv->cur_adap.dev.of_node = priv->dev->of_node; ret = i2c_add_adapter(&priv->cur_adap); if (ret < 0) goto err_with_put; return 0; err_with_put: i2c_put_adapter(adap); err_with_revert: of_changeset_revert(&priv->chan[new_chan].chgset); err: dev_err(priv->dev, "failed to setup demux-adapter %d (%d)\n", new_chan, ret); priv->cur_chan = -EINVAL; return ret; } static int i2c_demux_deactivate_master(struct i2c_demux_pinctrl_priv *priv) { int ret, cur = priv->cur_chan; if (cur < 0) return 0; i2c_del_adapter(&priv->cur_adap); i2c_put_adapter(priv->chan[cur].parent_adap); ret = of_changeset_revert(&priv->chan[cur].chgset); priv->chan[cur].parent_adap = NULL; priv->cur_chan = -EINVAL; return ret; } static int i2c_demux_change_master(struct i2c_demux_pinctrl_priv *priv, u32 new_chan) { int ret; if (new_chan == priv->cur_chan) return 0; ret = i2c_demux_deactivate_master(priv); if (ret) return ret; return i2c_demux_activate_master(priv, new_chan); } static ssize_t available_masters_show(struct device *dev, struct device_attribute *attr, char *buf) { struct i2c_demux_pinctrl_priv *priv = dev_get_drvdata(dev); int count = 0, i; for (i = 0; i < priv->num_chan && count < PAGE_SIZE; i++) count += scnprintf(buf + count, PAGE_SIZE - count, "%d:%s%c", i, priv->chan[i].parent_np->full_name, i == priv->num_chan - 1 ? '\n' : ' '); return count; } static DEVICE_ATTR_RO(available_masters); static ssize_t current_master_show(struct device *dev, struct device_attribute *attr, char *buf) { struct i2c_demux_pinctrl_priv *priv = dev_get_drvdata(dev); return sprintf(buf, "%d\n", priv->cur_chan); } static ssize_t current_master_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count) { struct i2c_demux_pinctrl_priv *priv = dev_get_drvdata(dev); unsigned int val; int ret; ret = kstrtouint(buf, 0, &val); if (ret < 0) return ret; if (val >= priv->num_chan) return -EINVAL; ret = i2c_demux_change_master(priv, val); return ret < 0 ? ret : count; } static DEVICE_ATTR_RW(current_master); static int i2c_demux_pinctrl_probe(struct platform_device *pdev) { struct device_node *np = pdev->dev.of_node; struct i2c_demux_pinctrl_priv *priv; struct property *props; int num_chan, i, j, err; num_chan = of_count_phandle_with_args(np, "i2c-parent", NULL); if (num_chan < 2) { dev_err(&pdev->dev, "Need at least two I2C masters to switch\n"); return -EINVAL; } priv = devm_kzalloc(&pdev->dev, sizeof(*priv) + num_chan * sizeof(struct i2c_demux_pinctrl_chan), GFP_KERNEL); props = devm_kcalloc(&pdev->dev, num_chan, sizeof(*props), GFP_KERNEL); if (!priv || !props) return -ENOMEM; err = of_property_read_string(np, "i2c-bus-name", &priv->bus_name); if (err) return err; for (i = 0; i < num_chan; i++) { struct device_node *adap_np; adap_np = of_parse_phandle(np, "i2c-parent", i); if (!adap_np) { dev_err(&pdev->dev, "can't get phandle for parent %d\n", i); err = -ENOENT; goto err_rollback; } priv->chan[i].parent_np = adap_np; props[i].name = devm_kstrdup(&pdev->dev, "status", GFP_KERNEL); props[i].value = devm_kstrdup(&pdev->dev, "ok", GFP_KERNEL); props[i].length = 3; of_changeset_init(&priv->chan[i].chgset); of_changeset_update_property(&priv->chan[i].chgset, adap_np, &props[i]); } priv->num_chan = num_chan; priv->dev = &pdev->dev; platform_set_drvdata(pdev, priv); /* switch to first parent as active master */ i2c_demux_activate_master(priv, 0); err = device_create_file(&pdev->dev, &dev_attr_available_masters); if (err) goto err_rollback_activation; err = device_create_file(&pdev->dev, &dev_attr_current_master); if (err) goto err_rollback_available; return 0; err_rollback_available: device_remove_file(&pdev->dev, &dev_attr_available_masters); err_rollback_activation: i2c_demux_deactivate_master(priv); err_rollback: for (j = 0; j < i; j++) { of_node_put(priv->chan[j].parent_np); of_changeset_destroy(&priv->chan[j].chgset); } return err; } static int i2c_demux_pinctrl_remove(struct platform_device *pdev) { struct i2c_demux_pinctrl_priv *priv = platform_get_drvdata(pdev); int i; device_remove_file(&pdev->dev, &dev_attr_current_master); device_remove_file(&pdev->dev, &dev_attr_available_masters); i2c_demux_deactivate_master(priv); for (i = 0; i < priv->num_chan; i++) { of_node_put(priv->chan[i].parent_np); of_changeset_destroy(&priv->chan[i].chgset); } return 0; } static const struct of_device_id i2c_demux_pinctrl_of_match[] = { { .compatible = "i2c-demux-pinctrl", }, {}, }; MODULE_DEVICE_TABLE(of, i2c_demux_pinctrl_of_match); static struct platform_driver i2c_demux_pinctrl_driver = { .driver = { .name = "i2c-demux-pinctrl", .of_match_table = i2c_demux_pinctrl_of_match, }, .probe = i2c_demux_pinctrl_probe, .remove = i2c_demux_pinctrl_remove, }; module_platform_driver(i2c_demux_pinctrl_driver); MODULE_DESCRIPTION("pinctrl-based I2C demux driver"); MODULE_AUTHOR("Wolfram Sang "); MODULE_LICENSE("GPL v2"); MODULE_ALIAS("platform:i2c-demux-pinctrl");