// SPDX-License-Identifier: GPL-2.0-only
/*
* Pinctrl based I2C DeMultiplexer
*
* Copyright (C) 2015-16 by Wolfram Sang, Sang Engineering <[email protected]>
* Copyright (C) 2015-16 by Renesas Electronics Corporation
*
* See the bindings doc for DTS setup and the sysfs doc for usage information.
* (look for filenames containing 'i2c-demux-pinctrl' in Documentation/)
*/
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/pinctrl/consumer.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/slab.h>
#include <linux/sysfs.h>
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[] __counted_by(num_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_get_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;
if (adap->algo->master_xfer_atomic)
priv->algo.master_xfer_atomic = 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 = &adap->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 += sysfs_emit_at(buf, count, "%d:%pOF%c",
i, priv->chan[i].parent_np,
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, struct_size(priv, chan, num_chan),
GFP_KERNEL);
props = devm_kcalloc(&pdev->dev, num_chan, sizeof(*props), GFP_KERNEL);
if (!priv || !props)
return -ENOMEM;
priv->num_chan = num_chan;
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);
if (!props[i].name || !props[i].value) {
err = -ENOMEM;
goto err_rollback;
}
props[i].length = 3;
of_changeset_init(&priv->chan[i].chgset);
of_changeset_update_property(&priv->chan[i].chgset, adap_np, &props[i]);
}
priv->dev = &pdev->dev;
platform_set_drvdata(pdev, priv);
pm_runtime_no_callbacks(&pdev->dev);
/* 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 void 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);
}
}
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_new = i2c_demux_pinctrl_remove,
};
module_platform_driver(i2c_demux_pinctrl_driver);
MODULE_DESCRIPTION("pinctrl-based I2C demux driver");
MODULE_AUTHOR("Wolfram Sang <[email protected]>");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:i2c-demux-pinctrl");
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