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Subject[PATCH v6 7/9] i2c: i2c-mux-simple: new driver
Date
This is a generic simple i2c mux that uses the generic multiplexer
subsystem to do the muxing.

The user can select if the mux is to be mux-locked and parent-locked
as described in Documentation/i2c/i2c-topology.

Signed-off-by: Peter Rosin <peda@axentia.se>
---
drivers/i2c/muxes/Kconfig | 13 +++
drivers/i2c/muxes/Makefile | 1 +
drivers/i2c/muxes/i2c-mux-simple.c | 179 +++++++++++++++++++++++++++++++++++++
3 files changed, 193 insertions(+)
create mode 100644 drivers/i2c/muxes/i2c-mux-simple.c

diff --git a/drivers/i2c/muxes/Kconfig b/drivers/i2c/muxes/Kconfig
index 10b3d17ae3ea..565921e09a96 100644
--- a/drivers/i2c/muxes/Kconfig
+++ b/drivers/i2c/muxes/Kconfig
@@ -73,6 +73,19 @@ config I2C_MUX_REG
This driver can also be built as a module. If so, the module
will be called i2c-mux-reg.

+config I2C_MUX_SIMPLE
+ tristate "Simple I2C multiplexer"
+ select MULTIPLEXER
+ depends on OF
+ help
+ If you say yes to this option, support will be included for a
+ simple generic I2C multiplexer. This driver provides access to
+ I2C busses connected through a MUX, which is controlled
+ by a generic MUX controller.
+
+ This driver can also be built as a module. If so, the module
+ will be called i2c-mux-simple.
+
config I2C_DEMUX_PINCTRL
tristate "pinctrl-based I2C demultiplexer"
depends on PINCTRL && OF
diff --git a/drivers/i2c/muxes/Makefile b/drivers/i2c/muxes/Makefile
index 9948fa45037f..6821d95c92a3 100644
--- a/drivers/i2c/muxes/Makefile
+++ b/drivers/i2c/muxes/Makefile
@@ -11,5 +11,6 @@ obj-$(CONFIG_I2C_MUX_PCA9541) += i2c-mux-pca9541.o
obj-$(CONFIG_I2C_MUX_PCA954x) += i2c-mux-pca954x.o
obj-$(CONFIG_I2C_MUX_PINCTRL) += i2c-mux-pinctrl.o
obj-$(CONFIG_I2C_MUX_REG) += i2c-mux-reg.o
+obj-$(CONFIG_I2C_MUX_SIMPLE) += i2c-mux-simple.o

ccflags-$(CONFIG_I2C_DEBUG_BUS) := -DDEBUG
diff --git a/drivers/i2c/muxes/i2c-mux-simple.c b/drivers/i2c/muxes/i2c-mux-simple.c
new file mode 100644
index 000000000000..4a03493e1ad7
--- /dev/null
+++ b/drivers/i2c/muxes/i2c-mux-simple.c
@@ -0,0 +1,179 @@
+/*
+ * Generic simple I2C multiplexer
+ *
+ * Copyright (C) 2016 Axentia Technologies AB
+ *
+ * Author: Peter Rosin <peda@axentia.se>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/i2c.h>
+#include <linux/i2c-mux.h>
+#include <linux/module.h>
+#include <linux/mux.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+
+struct mux {
+ struct mux_control *control;
+
+ bool do_not_deselect;
+};
+
+static int i2c_mux_select(struct i2c_mux_core *muxc, u32 chan)
+{
+ struct mux *mux = i2c_mux_priv(muxc);
+ int ret;
+
+ ret = mux_control_select(mux->control, chan);
+ mux->do_not_deselect = ret < 0;
+
+ return ret;
+}
+
+static int i2c_mux_deselect(struct i2c_mux_core *muxc, u32 chan)
+{
+ struct mux *mux = i2c_mux_priv(muxc);
+
+ if (mux->do_not_deselect)
+ return 0;
+
+ return mux_control_deselect(mux->control);
+}
+
+static struct i2c_adapter *mux_parent_adapter(struct device *dev)
+{
+ struct device_node *np = dev->of_node;
+ struct device_node *parent_np;
+ struct i2c_adapter *parent;
+
+ parent_np = of_parse_phandle(np, "i2c-parent", 0);
+ if (!parent_np) {
+ dev_err(dev, "Cannot parse i2c-parent\n");
+ return ERR_PTR(-ENODEV);
+ }
+ parent = of_find_i2c_adapter_by_node(parent_np);
+ of_node_put(parent_np);
+ if (!parent)
+ return ERR_PTR(-EPROBE_DEFER);
+
+ return parent;
+}
+
+static const struct of_device_id i2c_mux_of_match[] = {
+ { .compatible = "i2c-mux-simple,parent-locked",
+ .data = (void *)0, },
+ { .compatible = "i2c-mux-simple,mux-locked",
+ .data = (void *)1, },
+ {},
+};
+MODULE_DEVICE_TABLE(of, i2c_mux_of_match);
+
+static int i2c_mux_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct device_node *np = dev->of_node;
+ struct device_node *child;
+ const struct of_device_id *match;
+ struct i2c_mux_core *muxc;
+ struct mux *mux;
+ struct i2c_adapter *parent;
+ int children;
+ int ret;
+
+ if (!np)
+ return -ENODEV;
+
+ mux = devm_kzalloc(dev, sizeof(*mux), GFP_KERNEL);
+ if (!mux)
+ return -ENOMEM;
+
+ mux->control = devm_mux_control_get(dev, NULL);
+ if (IS_ERR(mux->control)) {
+ if (PTR_ERR(mux->control) != -EPROBE_DEFER)
+ dev_err(dev, "failed to get control-mux\n");
+ return PTR_ERR(mux->control);
+ }
+
+ parent = mux_parent_adapter(dev);
+ if (IS_ERR(parent)) {
+ if (PTR_ERR(parent) != -EPROBE_DEFER)
+ dev_err(dev, "failed to get i2c-parent adapter\n");
+ return PTR_ERR(parent);
+ }
+
+ children = of_get_child_count(np);
+
+ muxc = i2c_mux_alloc(parent, dev, children, 0, 0,
+ i2c_mux_select, i2c_mux_deselect);
+ if (!muxc) {
+ ret = -ENOMEM;
+ goto err_parent;
+ }
+ muxc->priv = mux;
+
+ platform_set_drvdata(pdev, muxc);
+
+ match = of_match_device(of_match_ptr(i2c_mux_of_match), dev);
+ if (match)
+ muxc->mux_locked = !!of_device_get_match_data(dev);
+
+ for_each_child_of_node(np, child) {
+ u32 chan;
+
+ ret = of_property_read_u32(child, "reg", &chan);
+ if (ret < 0) {
+ dev_err(dev, "no reg property for node '%s'\n",
+ child->name);
+ goto err_children;
+ }
+
+ if (chan >= mux->control->states) {
+ dev_err(dev, "invalid reg %u\n", chan);
+ ret = -EINVAL;
+ goto err_children;
+ }
+
+ ret = i2c_mux_add_adapter(muxc, 0, chan, 0);
+ if (ret)
+ goto err_children;
+ }
+
+ dev_info(dev, "%d-port mux on %s adapter\n", children, parent->name);
+
+ return 0;
+
+err_children:
+ i2c_mux_del_adapters(muxc);
+err_parent:
+ i2c_put_adapter(parent);
+
+ return ret;
+}
+
+static int i2c_mux_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 struct platform_driver i2c_mux_driver = {
+ .probe = i2c_mux_probe,
+ .remove = i2c_mux_remove,
+ .driver = {
+ .name = "i2c-mux-simple",
+ .of_match_table = i2c_mux_of_match,
+ },
+};
+module_platform_driver(i2c_mux_driver);
+
+MODULE_DESCRIPTION("Simple I2C multiplexer driver");
+MODULE_AUTHOR("Peter Rosin <peda@axentia.se>");
+MODULE_LICENSE("GPL v2");
--
2.1.4
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