1 files changed, 266 insertions, 0 deletions
diff --git a/drivers/i2c/muxes/i2c-mux-reg.c b/drivers/i2c/muxes/i2c-mux-reg.c
new file mode 100644
index 000000000..30a6de169
--- /dev/null
+++ b/drivers/i2c/muxes/i2c-mux-reg.c
@@ -0,0 +1,266 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * I2C multiplexer using a single register
+ *
+ * Copyright 2015 Freescale Semiconductor
+ * York Sun  <yorksun@freescale.com>
+ */
+
+#include <linux/i2c.h>
+#include <linux/i2c-mux.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/platform_data/i2c-mux-reg.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+struct regmux {
+	struct i2c_mux_reg_platform_data data;
+};
+
+static int i2c_mux_reg_set(const struct regmux *mux, unsigned int chan_id)
+{
+	if (!mux->data.reg)
+		return -EINVAL;
+
+	/*
+	 * Write to the register, followed by a read to ensure the write is
+	 * completed on a "posted" bus, for example PCI or write buffers.
+	 * The endianness of reading doesn't matter and the return data
+	 * is not used.
+	 */
+	switch (mux->data.reg_size) {
+	case 4:
+		if (mux->data.little_endian)
+			iowrite32(chan_id, mux->data.reg);
+		else
+			iowrite32be(chan_id, mux->data.reg);
+		if (!mux->data.write_only)
+			ioread32(mux->data.reg);
+		break;
+	case 2:
+		if (mux->data.little_endian)
+			iowrite16(chan_id, mux->data.reg);
+		else
+			iowrite16be(chan_id, mux->data.reg);
+		if (!mux->data.write_only)
+			ioread16(mux->data.reg);
+		break;
+	case 1:
+		iowrite8(chan_id, mux->data.reg);
+		if (!mux->data.write_only)
+			ioread8(mux->data.reg);
+		break;
+	}
+
+	return 0;
+}
+
+static int i2c_mux_reg_select(struct i2c_mux_core *muxc, u32 chan)
+{
+	struct regmux *mux = i2c_mux_priv(muxc);
+
+	return i2c_mux_reg_set(mux, chan);
+}
+
+static int i2c_mux_reg_deselect(struct i2c_mux_core *muxc, u32 chan)
+{
+	struct regmux *mux = i2c_mux_priv(muxc);
+
+	if (mux->data.idle_in_use)
+		return i2c_mux_reg_set(mux, mux->data.idle);
+
+	return 0;
+}
+
+#ifdef CONFIG_OF
+static int i2c_mux_reg_probe_dt(struct regmux *mux,
+				struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	struct device_node *adapter_np, *child;
+	struct i2c_adapter *adapter;
+	struct resource res;
+	unsigned *values;
+	int i = 0;
+
+	if (!np)
+		return -ENODEV;
+
+	adapter_np = of_parse_phandle(np, "i2c-parent", 0);
+	if (!adapter_np) {
+		dev_err(&pdev->dev, "Cannot parse i2c-parent\n");
+		return -ENODEV;
+	}
+	adapter = of_find_i2c_adapter_by_node(adapter_np);
+	of_node_put(adapter_np);
+	if (!adapter)
+		return -EPROBE_DEFER;
+
+	mux->data.parent = i2c_adapter_id(adapter);
+	put_device(&adapter->dev);
+
+	mux->data.n_values = of_get_child_count(np);
+	if (of_property_read_bool(np, "little-endian")) {
+		mux->data.little_endian = true;
+	} else if (of_property_read_bool(np, "big-endian")) {
+		mux->data.little_endian = false;
+	} else {
+#if defined(__BYTE_ORDER) ? __BYTE_ORDER == __LITTLE_ENDIAN : \
+	defined(__LITTLE_ENDIAN)
+		mux->data.little_endian = true;
+#elif defined(__BYTE_ORDER) ? __BYTE_ORDER == __BIG_ENDIAN : \
+	defined(__BIG_ENDIAN)
+		mux->data.little_endian = false;
+#else
+#error Endianness not defined?
+#endif
+	}
+	mux->data.write_only = of_property_read_bool(np, "write-only");
+
+	values = devm_kcalloc(&pdev->dev,
+			      mux->data.n_values, sizeof(*mux->data.values),
+			      GFP_KERNEL);
+	if (!values)
+		return -ENOMEM;
+
+	for_each_child_of_node(np, child) {
+		of_property_read_u32(child, "reg", values + i);
+		i++;
+	}
+	mux->data.values = values;
+
+	if (!of_property_read_u32(np, "idle-state", &mux->data.idle))
+		mux->data.idle_in_use = true;
+
+	/* map address from "reg" if exists */
+	if (of_address_to_resource(np, 0, &res) == 0) {
+		mux->data.reg_size = resource_size(&res);
+		mux->data.reg = devm_ioremap_resource(&pdev->dev, &res);
+		if (IS_ERR(mux->data.reg))
+			return PTR_ERR(mux->data.reg);
+	}
+
+	return 0;
+}
+#else
+static int i2c_mux_reg_probe_dt(struct regmux *mux,
+				struct platform_device *pdev)
+{
+	return 0;
+}
+#endif
+
+static int i2c_mux_reg_probe(struct platform_device *pdev)
+{
+	struct i2c_mux_core *muxc;
+	struct regmux *mux;
+	struct i2c_adapter *parent;
+	struct resource *res;
+	unsigned int class;
+	int i, ret, nr;
+
+	mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
+	if (!mux)
+		return -ENOMEM;
+
+	if (dev_get_platdata(&pdev->dev)) {
+		memcpy(&mux->data, dev_get_platdata(&pdev->dev),
+			sizeof(mux->data));
+	} else {
+		ret = i2c_mux_reg_probe_dt(mux, pdev);
+		if (ret < 0)
+			return dev_err_probe(&pdev->dev, ret,
+					     "Error parsing device tree");
+	}
+
+	parent = i2c_get_adapter(mux->data.parent);
+	if (!parent)
+		return -EPROBE_DEFER;
+
+	if (!mux->data.reg) {
+		dev_info(&pdev->dev,
+			"Register not set, using platform resource\n");
+		mux->data.reg = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
+		if (IS_ERR(mux->data.reg)) {
+			ret = PTR_ERR(mux->data.reg);
+			goto err_put_parent;
+		}
+		mux->data.reg_size = resource_size(res);
+	}
+
+	if (mux->data.reg_size != 4 && mux->data.reg_size != 2 &&
+	    mux->data.reg_size != 1) {
+		dev_err(&pdev->dev, "Invalid register size\n");
+		ret = -EINVAL;
+		goto err_put_parent;
+	}
+
+	muxc = i2c_mux_alloc(parent, &pdev->dev, mux->data.n_values, 0, 0,
+			     i2c_mux_reg_select, NULL);
+	if (!muxc) {
+		ret = -ENOMEM;
+		goto err_put_parent;
+	}
+	muxc->priv = mux;
+
+	platform_set_drvdata(pdev, muxc);
+
+	if (mux->data.idle_in_use)
+		muxc->deselect = i2c_mux_reg_deselect;
+
+	for (i = 0; i < mux->data.n_values; i++) {
+		nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0;
+		class = mux->data.classes ? mux->data.classes[i] : 0;
+
+		ret = i2c_mux_add_adapter(muxc, nr, mux->data.values[i], class);
+		if (ret)
+			goto err_del_mux_adapters;
+	}
+
+	dev_dbg(&pdev->dev, "%d port mux on %s adapter\n",
+		 mux->data.n_values, muxc->parent->name);
+
+	return 0;
+
+err_del_mux_adapters:
+	i2c_mux_del_adapters(muxc);
+err_put_parent:
+	i2c_put_adapter(parent);
+
+	return ret;
+}
+
+static int i2c_mux_reg_remove(struct platform_device *pdev)
+{
+	struct i2c_mux_core *muxc = platform_get_drvdata(pdev);
+
+	i2c_mux_del_adapters(muxc);
+	i2c_put_adapter(muxc->parent);
+
+	return 0;
+}
+
+static const struct of_device_id i2c_mux_reg_of_match[] = {
+	{ .compatible = "i2c-mux-reg", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, i2c_mux_reg_of_match);
+
+static struct platform_driver i2c_mux_reg_driver = {
+	.probe	= i2c_mux_reg_probe,
+	.remove	= i2c_mux_reg_remove,
+	.driver	= {
+		.name	= "i2c-mux-reg",
+		.of_match_table = of_match_ptr(i2c_mux_reg_of_match),
+	},
+};
+
+module_platform_driver(i2c_mux_reg_driver);
+
+MODULE_DESCRIPTION("Register-based I2C multiplexer driver");
+MODULE_AUTHOR("York Sun <yorksun@freescale.com>");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:i2c-mux-reg");