[PATCH V4] i2c: Add generic I2C multiplexer using pinctrl API
Stephen Warren
swarren at wwwdotorg.org
Sat May 19 01:29:34 EST 2012
From: Stephen Warren <swarren at nvidia.com>
This is useful for SoCs whose I2C module's signals can be routed to
different sets of pins at run-time, using the pinctrl API.
+-----+ +-----+
| dev | | dev |
+------------------------+ +-----+ +-----+
| SoC | | |
| /----|------+--------+
| +---+ +------+ | child bus A, on first set of pins
| |I2C|---|Pinmux| |
| +---+ +------+ | child bus B, on second set of pins
| \----|------+--------+--------+
| | | | |
+------------------------+ +-----+ +-----+ +-----+
| dev | | dev | | dev |
+-----+ +-----+ +-----+
Signed-off-by: Stephen Warren <swarren at nvidia.com>
Acked-by: Linus Walleij <linus.walleij at linaro.org>
Acked-by: Rob Herring <rob.herring at calxeda.com>
---
Wolfram, when you apply this for 3.6, could you please put just this
patch into a stable topic branch - that way, I can merge this into a
Tegra branch too so that I can use the new driver in 3.6.
v4: Added diagram from commit message into binding documentation.
v3: Renamed pinctrl-i2cmux.c to i2c-mux-pinctrl.c to match recent changes
to other I2C mux files.
v2: Rebase onto David Daney's i2c-mux OF support, including slight binding
changes. Add more error messages.
i2c mux binding fixup
---
.../devicetree/bindings/i2c/i2c-mux-pinctrl.txt | 93 +++++++
drivers/i2c/muxes/Kconfig | 12 +
drivers/i2c/muxes/Makefile | 1 +
drivers/i2c/muxes/i2c-mux-pinctrl.c | 279 ++++++++++++++++++++
include/linux/i2c-mux-pinctrl.h | 41 +++
5 files changed, 426 insertions(+), 0 deletions(-)
create mode 100644 Documentation/devicetree/bindings/i2c/i2c-mux-pinctrl.txt
create mode 100644 drivers/i2c/muxes/i2c-mux-pinctrl.c
create mode 100644 include/linux/i2c-mux-pinctrl.h
diff --git a/Documentation/devicetree/bindings/i2c/i2c-mux-pinctrl.txt b/Documentation/devicetree/bindings/i2c/i2c-mux-pinctrl.txt
new file mode 100644
index 0000000..ae8af16
--- /dev/null
+++ b/Documentation/devicetree/bindings/i2c/i2c-mux-pinctrl.txt
@@ -0,0 +1,93 @@
+Pinctrl-based I2C Bus Mux
+
+This binding describes an I2C bus multiplexer that uses pin multiplexing to
+route the I2C signals, and represents the pin multiplexing configuration
+using the pinctrl device tree bindings.
+
+ +-----+ +-----+
+ | dev | | dev |
+ +------------------------+ +-----+ +-----+
+ | SoC | | |
+ | /----|------+--------+
+ | +---+ +------+ | child bus A, on first set of pins
+ | |I2C|---|Pinmux| |
+ | +---+ +------+ | child bus B, on second set of pins
+ | \----|------+--------+--------+
+ | | | | |
+ +------------------------+ +-----+ +-----+ +-----+
+ | dev | | dev | | dev |
+ +-----+ +-----+ +-----+
+
+Required properties:
+- compatible: i2c-mux-pinctrl
+- i2c-parent: The phandle of the I2C bus that this multiplexer's master-side
+ port is connected to.
+
+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.
+
+For each named state defined in the pinctrl-names property, an I2C child bus
+will be created. I2C child bus numbers are assigned based on the index into
+the pinctrl-names property.
+
+The only exception is that no bus will be created for a state named "idle". If
+such a state is defined, it must be the last entry in pinctrl-names. For
+example:
+
+ pinctrl-names = "ddc", "pta", "idle" -> ddc = bus 0, pta = bus 1
+ pinctrl-names = "ddc", "idle", "pta" -> Invalid ("idle" not last)
+ pinctrl-names = "idle", "ddc", "pta" -> Invalid ("idle" not last)
+
+Whenever an access is made to a device on a child bus, the relevant pinctrl
+state will be programmed into hardware.
+
+If an idle state is defined, whenever an access is not being made to a device
+on a child bus, the idle pinctrl state will be programmed into hardware.
+
+If an idle state is not defined, the most recently used pinctrl state will be
+left programmed into hardware whenever no access is being made of a device on
+a child bus.
+
+Example:
+
+ i2cmux {
+ compatible = "i2c-mux-pinctrl";
+ #address-cells = <1>;
+ #size-cells = <0>;
+
+ i2c-parent = <&i2c1>;
+
+ pinctrl-names = "ddc", "pta", "idle";
+ pinctrl-0 = <&state_i2cmux_ddc>;
+ pinctrl-1 = <&state_i2cmux_pta>;
+ pinctrl-2 = <&state_i2cmux_idle>;
+
+ i2c at 0 {
+ reg = <0>;
+ #address-cells = <1>;
+ #size-cells = <0>;
+
+ eeprom {
+ compatible = "eeprom";
+ reg = <0x50>;
+ };
+ };
+
+ i2c at 1 {
+ reg = <1>;
+ #address-cells = <1>;
+ #size-cells = <0>;
+
+ eeprom {
+ compatible = "eeprom";
+ reg = <0x50>;
+ };
+ };
+ };
+
diff --git a/drivers/i2c/muxes/Kconfig b/drivers/i2c/muxes/Kconfig
index beb2491..a0edd98 100644
--- a/drivers/i2c/muxes/Kconfig
+++ b/drivers/i2c/muxes/Kconfig
@@ -37,4 +37,16 @@ config I2C_MUX_PCA954x
This driver can also be built as a module. If so, the module
will be called i2c-mux-pca954x.
+config I2C_MUX_PINCTRL
+ tristate "pinctrl-based I2C multiplexer"
+ depends on PINCTRL
+ help
+ If you say yes to this option, support will be included for an I2C
+ multiplexer that uses the pinctrl subsystem, i.e. pin multiplexing.
+ This is useful for SoCs whose I2C module's signals can be routed to
+ different sets of pins at run-time.
+
+ This driver can also be built as a module. If so, the module will be
+ called pinctrl-i2cmux.
+
endmenu
diff --git a/drivers/i2c/muxes/Makefile b/drivers/i2c/muxes/Makefile
index 5826249..76da869 100644
--- a/drivers/i2c/muxes/Makefile
+++ b/drivers/i2c/muxes/Makefile
@@ -4,5 +4,6 @@
obj-$(CONFIG_I2C_MUX_GPIO) += i2c-mux-gpio.o
obj-$(CONFIG_I2C_MUX_PCA9541) += i2c-mux-pca9541.o
obj-$(CONFIG_I2C_MUX_PCA954x) += i2c-mux-pca954x.o
+obj-$(CONFIG_I2C_MUX_PINCTRL) += i2c-mux-pinctrl.o
ccflags-$(CONFIG_I2C_DEBUG_BUS) := -DDEBUG
diff --git a/drivers/i2c/muxes/i2c-mux-pinctrl.c b/drivers/i2c/muxes/i2c-mux-pinctrl.c
new file mode 100644
index 0000000..46a6697
--- /dev/null
+++ b/drivers/i2c/muxes/i2c-mux-pinctrl.c
@@ -0,0 +1,279 @@
+/*
+ * I2C multiplexer using pinctrl API
+ *
+ * Copyright (c) 2012, NVIDIA CORPORATION. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/i2c.h>
+#include <linux/i2c-mux.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/of_i2c.h>
+#include <linux/pinctrl/consumer.h>
+#include <linux/i2c-mux-pinctrl.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+struct i2c_mux_pinctrl {
+ struct device *dev;
+ struct i2c_mux_pinctrl_platform_data *pdata;
+ struct pinctrl *pinctrl;
+ struct pinctrl_state **states;
+ struct pinctrl_state *state_idle;
+ struct i2c_adapter *parent;
+ struct i2c_adapter **busses;
+};
+
+static int i2c_mux_pinctrl_select(struct i2c_adapter *adap, void *data,
+ u32 chan)
+{
+ struct i2c_mux_pinctrl *mux = data;
+
+ return pinctrl_select_state(mux->pinctrl, mux->states[chan]);
+}
+
+static int i2c_mux_pinctrl_deselect(struct i2c_adapter *adap, void *data,
+ u32 chan)
+{
+ struct i2c_mux_pinctrl *mux = data;
+
+ return pinctrl_select_state(mux->pinctrl, mux->state_idle);
+}
+
+#ifdef CONFIG_OF
+static int i2c_mux_pinctrl_parse_dt(struct i2c_mux_pinctrl *mux,
+ struct platform_device *pdev)
+{
+ struct device_node *np = pdev->dev.of_node;
+ int num_names, i, ret;
+ struct device_node *adapter_np;
+ struct i2c_adapter *adapter;
+
+ if (!np)
+ return 0;
+
+ mux->pdata = devm_kzalloc(&pdev->dev, sizeof(*mux->pdata), GFP_KERNEL);
+ if (!mux->pdata) {
+ dev_err(mux->dev,
+ "Cannot allocate i2c_mux_pinctrl_platform_data\n");
+ return -ENOMEM;
+ }
+
+ num_names = of_property_count_strings(np, "pinctrl-names");
+ if (num_names < 0) {
+ dev_err(mux->dev, "Cannot parse pinctrl-names: %d\n",
+ num_names);
+ return num_names;
+ }
+
+ mux->pdata->pinctrl_states = devm_kzalloc(&pdev->dev,
+ sizeof(*mux->pdata->pinctrl_states) * num_names,
+ GFP_KERNEL);
+ if (!mux->pdata->pinctrl_states) {
+ dev_err(mux->dev, "Cannot allocate pinctrl_states\n");
+ return -ENOMEM;
+ }
+
+ for (i = 0; i < num_names; i++) {
+ ret = of_property_read_string_index(np, "pinctrl-names", i,
+ &mux->pdata->pinctrl_states[mux->pdata->bus_count]);
+ if (ret < 0) {
+ dev_err(mux->dev, "Cannot parse pinctrl-names: %d\n",
+ ret);
+ return ret;
+ }
+ if (!strcmp(mux->pdata->pinctrl_states[mux->pdata->bus_count],
+ "idle")) {
+ if (i != num_names - 1) {
+ dev_err(mux->dev, "idle state must be last\n");
+ return -EINVAL;
+ }
+ mux->pdata->pinctrl_state_idle = "idle";
+ } else {
+ mux->pdata->bus_count++;
+ }
+ }
+
+ adapter_np = of_parse_phandle(np, "i2c-parent", 0);
+ if (!adapter_np) {
+ dev_err(mux->dev, "Cannot parse i2c-parent\n");
+ return -ENODEV;
+ }
+ adapter = of_find_i2c_adapter_by_node(adapter_np);
+ if (!adapter) {
+ dev_err(mux->dev, "Cannot find parent bus\n");
+ return -ENODEV;
+ }
+ mux->pdata->parent_bus_num = i2c_adapter_id(adapter);
+ put_device(&adapter->dev);
+
+ return 0;
+}
+#else
+static inline int i2c_mux_pinctrl_parse_dt(struct i2c_mux_pinctrl *mux,
+ struct platform_device *pdev)
+{
+ return 0;
+}
+#endif
+
+static int __devinit i2c_mux_pinctrl_probe(struct platform_device *pdev)
+{
+ struct i2c_mux_pinctrl *mux;
+ int (*deselect)(struct i2c_adapter *, void *, u32);
+ int i, ret;
+
+ mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
+ if (!mux) {
+ dev_err(&pdev->dev, "Cannot allocate i2c_mux_pinctrl\n");
+ ret = -ENOMEM;
+ goto err;
+ }
+ platform_set_drvdata(pdev, mux);
+
+ mux->dev = &pdev->dev;
+
+ mux->pdata = pdev->dev.platform_data;
+ if (!mux->pdata) {
+ ret = i2c_mux_pinctrl_parse_dt(mux, pdev);
+ if (ret < 0)
+ goto err;
+ }
+ if (!mux->pdata) {
+ dev_err(&pdev->dev, "Missing platform data\n");
+ ret = -ENODEV;
+ goto err;
+ }
+
+ mux->states = devm_kzalloc(&pdev->dev,
+ sizeof(*mux->states) * mux->pdata->bus_count,
+ GFP_KERNEL);
+ if (!mux->states) {
+ dev_err(&pdev->dev, "Cannot allocate states\n");
+ ret = -ENOMEM;
+ goto err;
+ }
+
+ mux->busses = devm_kzalloc(&pdev->dev,
+ sizeof(mux->busses) * mux->pdata->bus_count,
+ GFP_KERNEL);
+ if (!mux->states) {
+ dev_err(&pdev->dev, "Cannot allocate busses\n");
+ ret = -ENOMEM;
+ goto err;
+ }
+
+ mux->pinctrl = devm_pinctrl_get(&pdev->dev);
+ if (IS_ERR(mux->pinctrl)) {
+ ret = PTR_ERR(mux->pinctrl);
+ dev_err(&pdev->dev, "Cannot get pinctrl: %d\n", ret);
+ goto err;
+ }
+ for (i = 0; i < mux->pdata->bus_count; i++) {
+ mux->states[i] = pinctrl_lookup_state(mux->pinctrl,
+ mux->pdata->pinctrl_states[i]);
+ if (IS_ERR(mux->states[i])) {
+ ret = PTR_ERR(mux->states[i]);
+ dev_err(&pdev->dev,
+ "Cannot look up pinctrl state %s: %d\n",
+ mux->pdata->pinctrl_states[i], ret);
+ goto err;
+ }
+ }
+ if (mux->pdata->pinctrl_state_idle) {
+ mux->state_idle = pinctrl_lookup_state(mux->pinctrl,
+ mux->pdata->pinctrl_state_idle);
+ if (IS_ERR(mux->state_idle)) {
+ ret = PTR_ERR(mux->state_idle);
+ dev_err(&pdev->dev,
+ "Cannot look up pinctrl state %s: %d\n",
+ mux->pdata->pinctrl_state_idle, ret);
+ goto err;
+ }
+
+ deselect = i2c_mux_pinctrl_deselect;
+ } else {
+ deselect = NULL;
+ }
+
+ mux->parent = i2c_get_adapter(mux->pdata->parent_bus_num);
+ if (!mux->parent) {
+ dev_err(&pdev->dev, "Parent adapter (%d) not found\n",
+ mux->pdata->parent_bus_num);
+ ret = -ENODEV;
+ goto err;
+ }
+
+ for (i = 0; i < mux->pdata->bus_count; i++) {
+ u32 bus = mux->pdata->base_bus_num ?
+ (mux->pdata->base_bus_num + i) : 0;
+
+ mux->busses[i] = i2c_add_mux_adapter(mux->parent, &pdev->dev,
+ mux, bus, i,
+ i2c_mux_pinctrl_select,
+ deselect);
+ if (!mux->busses[i]) {
+ ret = -ENODEV;
+ dev_err(&pdev->dev, "Failed to add adapter %d\n", i);
+ goto err_del_adapter;
+ }
+ }
+
+ return 0;
+
+err_del_adapter:
+ for (; i > 0; i--)
+ i2c_del_mux_adapter(mux->busses[i - 1]);
+ i2c_put_adapter(mux->parent);
+err:
+ return ret;
+}
+
+static int __devexit i2c_mux_pinctrl_remove(struct platform_device *pdev)
+{
+ struct i2c_mux_pinctrl *mux = platform_get_drvdata(pdev);
+ int i;
+
+ for (i = 0; i < mux->pdata->bus_count; i++)
+ i2c_del_mux_adapter(mux->busses[i]);
+
+ i2c_put_adapter(mux->parent);
+
+ return 0;
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id i2c_mux_pinctrl_of_match[] __devinitconst = {
+ { .compatible = "i2c-mux-pinctrl", },
+ {},
+};
+MODULE_DEVICE_TABLE(of, i2c_mux_pinctrl_of_match);
+#endif
+
+static struct platform_driver i2c_mux_pinctrl_driver = {
+ .driver = {
+ .name = "i2c-mux-pinctrl",
+ .owner = THIS_MODULE,
+ .of_match_table = of_match_ptr(i2c_mux_pinctrl_of_match),
+ },
+ .probe = i2c_mux_pinctrl_probe,
+ .remove = __devexit_p(i2c_mux_pinctrl_remove),
+};
+module_platform_driver(i2c_mux_pinctrl_driver);
+
+MODULE_DESCRIPTION("pinctrl-based I2C multiplexer driver");
+MODULE_AUTHOR("Stephen Warren <swarren at nvidia.com>");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:i2c-mux-pinctrl");
diff --git a/include/linux/i2c-mux-pinctrl.h b/include/linux/i2c-mux-pinctrl.h
new file mode 100644
index 0000000..a65c864
--- /dev/null
+++ b/include/linux/i2c-mux-pinctrl.h
@@ -0,0 +1,41 @@
+/*
+ * i2c-mux-pinctrl platform data
+ *
+ * Copyright (c) 2012, NVIDIA CORPORATION. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef _LINUX_I2C_MUX_PINCTRL_H
+#define _LINUX_I2C_MUX_PINCTRL_H
+
+/**
+ * struct i2c_mux_pinctrl_platform_data - Platform data for i2c-mux-pinctrl
+ * @parent_bus_num: Parent I2C bus number
+ * @base_bus_num: Base I2C bus number for the child busses. 0 for dynamic.
+ * @bus_count: Number of child busses. Also the number of elements in
+ * @pinctrl_states
+ * @pinctrl_states: The names of the pinctrl state to select for each child bus
+ * @pinctrl_state_idle: The pinctrl state to select when no child bus is being
+ * accessed. If NULL, the most recently used pinctrl state will be left
+ * selected.
+ */
+struct i2c_mux_pinctrl_platform_data {
+ int parent_bus_num;
+ int base_bus_num;
+ int bus_count;
+ const char **pinctrl_states;
+ const char *pinctrl_state_idle;
+};
+
+#endif
--
1.7.0.4
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