1 files changed, 326 insertions, 0 deletions
diff --git a/drivers/i2c/muxes/i2c-demux-pinctrl.c b/drivers/i2c/muxes/i2c-demux-pinctrl.c
new file mode 100644
index 000000000..45a3f7e7b
--- /dev/null
+++ b/drivers/i2c/muxes/i2c-demux-pinctrl.c
@@ -0,0 +1,326 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Pinctrl based I2C DeMultiplexer
+ *
+ * Copyright (C) 2015-16 by Wolfram Sang, Sang Engineering <wsa@sang-engineering.com>
+ * 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[];
+};
+
+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 += scnprintf(buf + count, PAGE_SIZE - 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;
+
+	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->num_chan = num_chan;
+	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 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 <wsa@sang-engineering.com>");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:i2c-demux-pinctrl");