new file mode 100644
@@ -0,0 +1,65 @@
+Pinctrl-based I2C Bus DeMux
+
+This binding describes an I2C bus demultiplexer that uses pin multiplexing to
+route the I2C signals, and represents the pin multiplexing configuration using
+the pinctrl device tree bindings. This may be used to select one I2C IP core at
+runtime which may have a better feature set for a given task than another I2C
+IP core on the SoC.
+
+ +------------------------------+
+ | SoC |
+ | | +-----+ +-----+
+ | +------------+ | | dev | | dev |
+ | |I2C IP Core1|--\ | +-----+ +-----+
+ | +------------+ \------+ | | |
+ | |Pinmux|--|------+--------+
+ | +------------+ +------+ |
+ | |I2C IP Core2|--/ |
+ | +------------+ |
+ | |
+ +------------------------------+
+
+Required properties:
+- compatible: i2c-demux-pinctrl
+- i2c-parent: List of phandles of I2C cores to be selected
+
+Also required are:
+
+* Standard pinctrl properties that specify the pin mux state for each child
+ bus. See ../pinctrl/pinctrl-bindings.txt.
+
+* Standard I2C mux properties. See mux.txt in this directory.
+
+* I2C child bus nodes. See mux.txt in this directory.
+
+Note: The child bus nodes must be connected to sub-bus number 0 as shown in the
+example below.
+
+Example:
+
+ i2c-demux {
+
+ compatible = "i2c-demux-pinctrl";
+ i2c-parent = <&iic2>, <&i2c2>;
+ #address-cells = <1>;
+ #size-cells = <0>;
+
+ i2c@0 {
+ reg = <0>;
+ #address-cells = <1>;
+ #size-cells = <0>;
+
+ composite-in@20 {
+ compatible = "adi,adv7180";
+ reg = <0x20>;
+ remote = <&vin1>;
+
+ port {
+ adv7180: endpoint {
+ bus-width = <8>;
+ remote-endpoint = <&vin1ep0>;
+ };
+ };
+ };
+ };
+ };
@@ -60,4 +60,10 @@ config I2C_MUX_PINCTRL
This driver can also be built as a module. If so, the module will be
called pinctrl-i2cmux.
+config I2C_DEMUX_PINCTRL
+ tristate "pinctrl-based I2C demultiplexer"
+ depends on PINCTRL
+ help
+ PROTOYPE! Understand the docs!
+
endmenu
@@ -3,6 +3,8 @@
obj-$(CONFIG_I2C_ARB_GPIO_CHALLENGE) += i2c-arb-gpio-challenge.o
+obj-$(CONFIG_I2C_DEMUX_PINCTRL) += i2c-demux-pinctrl.o
+
obj-$(CONFIG_I2C_MUX_GPIO) += i2c-mux-gpio.o
obj-$(CONFIG_I2C_MUX_PCA9541) += i2c-mux-pca9541.o
obj-$(CONFIG_I2C_MUX_PCA954x) += i2c-mux-pca954x.o
new file mode 100644
@@ -0,0 +1,183 @@
+/*
+ * Pinctrl based I2C DeMultiplexer PROTOTYPE!
+ *
+ * Copyright (C) 2014 by Wolfram Sang, Sang Engineering <wsa@sang-engineering.com>
+ * Copyright (C) 2014 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.
+ *
+ * For n parents, n+1 new busses are created:
+ * 1st new bus is the demuxed bus with the first parent as the master
+ * Nth new bus is the demuxed bus with the N-th parent as the master
+ * N+1st new bus is the demuxed bus using the last active master
+ * (needed because kernel client drivers need a static bus number for the client)
+ *
+ * Example:
+ * i2c-0 is native I2C IP core A and first parent of the demuxed bus
+ * i2c-1 is native I2C IP core B and second parent of the demuxed bus
+ * i2c-2 accesses the demuxed bus with IP core A
+ * i2c-3 accesses the demuxed bus with IP core B
+ * i2c-4 accesses the demuxed bus with the last used IP core
+ *
+ * i2c-0 and i2c-1 should not be used directly. Their pins might not be muxed.
+ * All kernel I2C clients should be attached to i2c-4, so they have static bus number.
+ *
+ * Switching a master currently needs some access to either i2c-2 or i2c-3.
+ * Switching could also be done via sysfs or any other config mechanism.
+ * For this proof-of-concept, extra busses have been used since it simplifies
+ * locking a little.
+ */
+
+#include <linux/i2c.h>
+#include <linux/i2c-mux.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/slab.h>
+
+struct i2c_demux_pinctrl_chan {
+ struct i2c_adapter *parent;
+ struct i2c_adapter *child;
+ struct pinctrl *p;
+ struct pinctrl_state *p_state;
+};
+
+struct i2c_demux_pinctrl_priv {
+ u32 last_chan;
+ int num_chan;
+ struct i2c_demux_pinctrl_chan chan[];
+};
+
+//FIXME: Lock also inacticve adapters
+static int i2c_demux_pinctrl_dummy(struct i2c_adapter *adap, void *data, u32 new_chan)
+{
+ return 0;
+}
+
+static int i2c_demux_pinctrl_select(struct i2c_adapter *adap, void *data, u32 new_chan)
+{
+ struct i2c_demux_pinctrl_priv *priv = data;
+ int err;
+
+ if (new_chan == priv->last_chan)
+ return 0;
+
+ pinctrl_deselect_state(priv->chan[priv->last_chan].p);
+ err = pinctrl_select_state(priv->chan[new_chan].p,
+ priv->chan[new_chan].p_state);
+ if (!err) {
+ priv->last_chan = new_chan;
+ i2c_mux_reparent(priv->chan[0].child, priv->chan[new_chan].parent);
+ }
+
+ return err;
+}
+
+//FIXME: Proper error paths and correct rollback
+static int i2c_demux_pinctrl_probe(struct platform_device *pdev)
+{
+ struct i2c_demux_pinctrl_priv *priv;
+ struct device_node *np = pdev->dev.of_node;
+ int num_chan, i;
+
+ num_chan = 1 + of_count_phandle_with_args(np, "i2c-parent", NULL);
+
+ priv = devm_kzalloc(&pdev->dev, sizeof(*priv)
+ + num_chan * sizeof(struct i2c_demux_pinctrl_chan), GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+
+ priv->num_chan = num_chan;
+
+ for (i = 1; i < num_chan; i++) {
+ struct device_node *adap_np;
+ struct i2c_adapter *adap;
+
+ adap_np = of_parse_phandle(np, "i2c-parent", i - 1);
+ if (!adap_np) {
+ dev_err(&pdev->dev, "Can't get phandle for bus %d\n", i);
+ return -ENODEV;
+ }
+
+ adap = of_find_i2c_adapter_by_node(adap_np);
+ if (!adap) {
+ dev_err(&pdev->dev, "Cannot find parent bus %d\n", i);
+ return -EPROBE_DEFER;
+ }
+
+ priv->chan[i].p = devm_pinctrl_get(adap->dev.parent);
+ if (IS_ERR(priv->chan[i].p)) {
+ dev_err(&pdev->dev, "no pinctrl handle\n");
+ return -ENODEV;
+ }
+
+ priv->chan[i].p_state = pinctrl_lookup_state(priv->chan[i].p, "active");
+ if (IS_ERR(priv->chan[i].p_state)) {
+ dev_err(&pdev->dev, "no demux pinctrl state\n");
+ return -ENODEV;
+ }
+
+ priv->chan[i].child = i2c_add_mux_adapter(adap, &pdev->dev, priv,
+ 0, i, 0, i2c_demux_pinctrl_select, NULL);
+ if (!priv->chan[i].child) {
+ dev_err(&pdev->dev, "Cannot create mux bus %d\n", i);
+ return -ENODEV;
+ }
+
+ priv->chan[i].parent = adap;
+ }
+
+ if (i == 1)
+ return -ENODEV;
+
+ platform_set_drvdata(pdev, priv);
+
+ pinctrl_select_state(priv->chan[1].p, priv->chan[1].p_state);
+ priv->last_chan = 1;
+
+ priv->chan[0].child = i2c_add_mux_adapter(priv->chan[1].child, &pdev->dev, priv,
+ 0, 0, 0, i2c_demux_pinctrl_dummy, NULL);
+
+ return 0;
+}
+
+static int i2c_demux_pinctrl_remove(struct platform_device *pdev)
+{
+ struct i2c_demux_pinctrl_priv *priv = platform_get_drvdata(pdev);
+ int i;
+
+ for (i = 0; i < priv->num_chan; i++) {
+ i2c_del_mux_adapter(priv->chan[i].child);
+ if (i)
+ i2c_put_adapter(priv->chan[i].parent);
+ }
+
+ 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");