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