i2c: Add generic I2C multiplexer using pinctrl API
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@nvidia.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Rob Herring <rob.herring@calxeda.com>
Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
This commit is contained in:
Stephen Warren
Wolfram Sang
parent
f8f5701bda
commit
ae58d1e406
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@ -0,0 +1,93 @@
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Pinctrl-based I2C Bus Mux
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This binding describes an I2C bus multiplexer that uses pin multiplexing to
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route the I2C signals, and represents the pin multiplexing configuration
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using the pinctrl device tree bindings.
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+-----+ +-----+
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| dev | | dev |
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+------------------------+ +-----+ +-----+
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| SoC | | |
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| /----|------+--------+
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| +---+ +------+ | child bus A, on first set of pins
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| |I2C|---|Pinmux| |
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| +---+ +------+ | child bus B, on second set of pins
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| \----|------+--------+--------+
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| | | | |
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+------------------------+ +-----+ +-----+ +-----+
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| dev | | dev | | dev |
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+-----+ +-----+ +-----+
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Required properties:
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- compatible: i2c-mux-pinctrl
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- i2c-parent: The phandle of the I2C bus that this multiplexer's master-side
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port is connected to.
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Also required are:
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* Standard pinctrl properties that specify the pin mux state for each child
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bus. See ../pinctrl/pinctrl-bindings.txt.
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* Standard I2C mux properties. See mux.txt in this directory.
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* I2C child bus nodes. See mux.txt in this directory.
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For each named state defined in the pinctrl-names property, an I2C child bus
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will be created. I2C child bus numbers are assigned based on the index into
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the pinctrl-names property.
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The only exception is that no bus will be created for a state named "idle". If
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such a state is defined, it must be the last entry in pinctrl-names. For
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example:
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pinctrl-names = "ddc", "pta", "idle" -> ddc = bus 0, pta = bus 1
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pinctrl-names = "ddc", "idle", "pta" -> Invalid ("idle" not last)
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pinctrl-names = "idle", "ddc", "pta" -> Invalid ("idle" not last)
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Whenever an access is made to a device on a child bus, the relevant pinctrl
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state will be programmed into hardware.
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If an idle state is defined, whenever an access is not being made to a device
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on a child bus, the idle pinctrl state will be programmed into hardware.
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If an idle state is not defined, the most recently used pinctrl state will be
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left programmed into hardware whenever no access is being made of a device on
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a child bus.
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Example:
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i2cmux {
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compatible = "i2c-mux-pinctrl";
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#address-cells = <1>;
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#size-cells = <0>;
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i2c-parent = <&i2c1>;
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pinctrl-names = "ddc", "pta", "idle";
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pinctrl-0 = <&state_i2cmux_ddc>;
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pinctrl-1 = <&state_i2cmux_pta>;
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pinctrl-2 = <&state_i2cmux_idle>;
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i2c@0 {
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reg = <0>;
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#address-cells = <1>;
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#size-cells = <0>;
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eeprom {
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compatible = "eeprom";
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reg = <0x50>;
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};
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};
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i2c@1 {
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reg = <1>;
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#address-cells = <1>;
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#size-cells = <0>;
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eeprom {
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compatible = "eeprom";
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reg = <0x50>;
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};
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};
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};
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@ -37,4 +37,16 @@ config I2C_MUX_PCA954x
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This driver can also be built as a module. If so, the module
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will be called i2c-mux-pca954x.
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config I2C_MUX_PINCTRL
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tristate "pinctrl-based I2C multiplexer"
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depends on PINCTRL
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help
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If you say yes to this option, support will be included for an I2C
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multiplexer that uses the pinctrl subsystem, i.e. pin multiplexing.
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This is useful for SoCs whose I2C module's signals can be routed to
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different sets of pins at run-time.
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This driver can also be built as a module. If so, the module will be
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called pinctrl-i2cmux.
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endmenu
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@ -4,5 +4,6 @@
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obj-$(CONFIG_I2C_MUX_GPIO) += i2c-mux-gpio.o
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obj-$(CONFIG_I2C_MUX_PCA9541) += i2c-mux-pca9541.o
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obj-$(CONFIG_I2C_MUX_PCA954x) += i2c-mux-pca954x.o
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obj-$(CONFIG_I2C_MUX_PINCTRL) += i2c-mux-pinctrl.o
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ccflags-$(CONFIG_I2C_DEBUG_BUS) := -DDEBUG
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@ -0,0 +1,279 @@
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/*
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* I2C multiplexer using pinctrl API
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*
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* Copyright (c) 2012, NVIDIA CORPORATION. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <linux/i2c.h>
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#include <linux/i2c-mux.h>
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/of_i2c.h>
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#include <linux/pinctrl/consumer.h>
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#include <linux/i2c-mux-pinctrl.h>
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#include <linux/platform_device.h>
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#include <linux/slab.h>
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struct i2c_mux_pinctrl {
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struct device *dev;
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struct i2c_mux_pinctrl_platform_data *pdata;
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struct pinctrl *pinctrl;
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struct pinctrl_state **states;
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struct pinctrl_state *state_idle;
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struct i2c_adapter *parent;
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struct i2c_adapter **busses;
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};
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static int i2c_mux_pinctrl_select(struct i2c_adapter *adap, void *data,
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u32 chan)
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{
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struct i2c_mux_pinctrl *mux = data;
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return pinctrl_select_state(mux->pinctrl, mux->states[chan]);
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}
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static int i2c_mux_pinctrl_deselect(struct i2c_adapter *adap, void *data,
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u32 chan)
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{
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struct i2c_mux_pinctrl *mux = data;
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return pinctrl_select_state(mux->pinctrl, mux->state_idle);
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}
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#ifdef CONFIG_OF
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static int i2c_mux_pinctrl_parse_dt(struct i2c_mux_pinctrl *mux,
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struct platform_device *pdev)
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{
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struct device_node *np = pdev->dev.of_node;
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int num_names, i, ret;
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struct device_node *adapter_np;
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struct i2c_adapter *adapter;
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if (!np)
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return 0;
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mux->pdata = devm_kzalloc(&pdev->dev, sizeof(*mux->pdata), GFP_KERNEL);
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if (!mux->pdata) {
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dev_err(mux->dev,
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"Cannot allocate i2c_mux_pinctrl_platform_data\n");
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return -ENOMEM;
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}
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num_names = of_property_count_strings(np, "pinctrl-names");
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if (num_names < 0) {
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dev_err(mux->dev, "Cannot parse pinctrl-names: %d\n",
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num_names);
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return num_names;
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}
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mux->pdata->pinctrl_states = devm_kzalloc(&pdev->dev,
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sizeof(*mux->pdata->pinctrl_states) * num_names,
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GFP_KERNEL);
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if (!mux->pdata->pinctrl_states) {
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dev_err(mux->dev, "Cannot allocate pinctrl_states\n");
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return -ENOMEM;
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}
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for (i = 0; i < num_names; i++) {
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ret = of_property_read_string_index(np, "pinctrl-names", i,
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&mux->pdata->pinctrl_states[mux->pdata->bus_count]);
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if (ret < 0) {
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dev_err(mux->dev, "Cannot parse pinctrl-names: %d\n",
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ret);
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return ret;
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}
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if (!strcmp(mux->pdata->pinctrl_states[mux->pdata->bus_count],
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"idle")) {
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if (i != num_names - 1) {
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dev_err(mux->dev, "idle state must be last\n");
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return -EINVAL;
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}
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mux->pdata->pinctrl_state_idle = "idle";
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} else {
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mux->pdata->bus_count++;
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}
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}
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adapter_np = of_parse_phandle(np, "i2c-parent", 0);
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if (!adapter_np) {
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dev_err(mux->dev, "Cannot parse i2c-parent\n");
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return -ENODEV;
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}
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adapter = of_find_i2c_adapter_by_node(adapter_np);
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if (!adapter) {
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dev_err(mux->dev, "Cannot find parent bus\n");
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return -ENODEV;
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}
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mux->pdata->parent_bus_num = i2c_adapter_id(adapter);
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put_device(&adapter->dev);
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return 0;
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}
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#else
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static inline int i2c_mux_pinctrl_parse_dt(struct i2c_mux_pinctrl *mux,
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struct platform_device *pdev)
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{
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return 0;
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}
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#endif
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static int __devinit i2c_mux_pinctrl_probe(struct platform_device *pdev)
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{
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struct i2c_mux_pinctrl *mux;
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int (*deselect)(struct i2c_adapter *, void *, u32);
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int i, ret;
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mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
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if (!mux) {
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dev_err(&pdev->dev, "Cannot allocate i2c_mux_pinctrl\n");
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ret = -ENOMEM;
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goto err;
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}
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platform_set_drvdata(pdev, mux);
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mux->dev = &pdev->dev;
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mux->pdata = pdev->dev.platform_data;
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if (!mux->pdata) {
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ret = i2c_mux_pinctrl_parse_dt(mux, pdev);
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if (ret < 0)
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goto err;
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}
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if (!mux->pdata) {
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dev_err(&pdev->dev, "Missing platform data\n");
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ret = -ENODEV;
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goto err;
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}
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mux->states = devm_kzalloc(&pdev->dev,
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sizeof(*mux->states) * mux->pdata->bus_count,
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GFP_KERNEL);
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if (!mux->states) {
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dev_err(&pdev->dev, "Cannot allocate states\n");
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ret = -ENOMEM;
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goto err;
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}
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mux->busses = devm_kzalloc(&pdev->dev,
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sizeof(mux->busses) * mux->pdata->bus_count,
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GFP_KERNEL);
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if (!mux->states) {
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dev_err(&pdev->dev, "Cannot allocate busses\n");
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ret = -ENOMEM;
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goto err;
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}
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mux->pinctrl = devm_pinctrl_get(&pdev->dev);
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if (IS_ERR(mux->pinctrl)) {
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ret = PTR_ERR(mux->pinctrl);
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dev_err(&pdev->dev, "Cannot get pinctrl: %d\n", ret);
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goto err;
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}
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for (i = 0; i < mux->pdata->bus_count; i++) {
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mux->states[i] = pinctrl_lookup_state(mux->pinctrl,
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mux->pdata->pinctrl_states[i]);
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if (IS_ERR(mux->states[i])) {
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ret = PTR_ERR(mux->states[i]);
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dev_err(&pdev->dev,
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"Cannot look up pinctrl state %s: %d\n",
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mux->pdata->pinctrl_states[i], ret);
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goto err;
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}
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}
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if (mux->pdata->pinctrl_state_idle) {
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mux->state_idle = pinctrl_lookup_state(mux->pinctrl,
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mux->pdata->pinctrl_state_idle);
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if (IS_ERR(mux->state_idle)) {
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ret = PTR_ERR(mux->state_idle);
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dev_err(&pdev->dev,
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"Cannot look up pinctrl state %s: %d\n",
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mux->pdata->pinctrl_state_idle, ret);
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goto err;
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}
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deselect = i2c_mux_pinctrl_deselect;
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} else {
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deselect = NULL;
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}
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mux->parent = i2c_get_adapter(mux->pdata->parent_bus_num);
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if (!mux->parent) {
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dev_err(&pdev->dev, "Parent adapter (%d) not found\n",
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mux->pdata->parent_bus_num);
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ret = -ENODEV;
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goto err;
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}
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for (i = 0; i < mux->pdata->bus_count; i++) {
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u32 bus = mux->pdata->base_bus_num ?
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(mux->pdata->base_bus_num + i) : 0;
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mux->busses[i] = i2c_add_mux_adapter(mux->parent, &pdev->dev,
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mux, bus, i,
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i2c_mux_pinctrl_select,
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deselect);
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if (!mux->busses[i]) {
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ret = -ENODEV;
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dev_err(&pdev->dev, "Failed to add adapter %d\n", i);
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goto err_del_adapter;
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}
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}
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return 0;
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err_del_adapter:
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for (; i > 0; i--)
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i2c_del_mux_adapter(mux->busses[i - 1]);
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i2c_put_adapter(mux->parent);
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err:
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return ret;
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}
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static int __devexit i2c_mux_pinctrl_remove(struct platform_device *pdev)
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{
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struct i2c_mux_pinctrl *mux = platform_get_drvdata(pdev);
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int i;
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for (i = 0; i < mux->pdata->bus_count; i++)
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i2c_del_mux_adapter(mux->busses[i]);
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i2c_put_adapter(mux->parent);
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return 0;
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}
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#ifdef CONFIG_OF
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static const struct of_device_id i2c_mux_pinctrl_of_match[] __devinitconst = {
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{ .compatible = "i2c-mux-pinctrl", },
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{},
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};
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MODULE_DEVICE_TABLE(of, i2c_mux_pinctrl_of_match);
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#endif
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static struct platform_driver i2c_mux_pinctrl_driver = {
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.driver = {
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.name = "i2c-mux-pinctrl",
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.owner = THIS_MODULE,
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.of_match_table = of_match_ptr(i2c_mux_pinctrl_of_match),
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},
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.probe = i2c_mux_pinctrl_probe,
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.remove = __devexit_p(i2c_mux_pinctrl_remove),
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};
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module_platform_driver(i2c_mux_pinctrl_driver);
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MODULE_DESCRIPTION("pinctrl-based I2C multiplexer driver");
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MODULE_AUTHOR("Stephen Warren <swarren@nvidia.com>");
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MODULE_LICENSE("GPL v2");
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MODULE_ALIAS("platform:i2c-mux-pinctrl");
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@ -0,0 +1,41 @@
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/*
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* i2c-mux-pinctrl platform data
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*
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* Copyright (c) 2012, NVIDIA CORPORATION. All rights reserved.
|
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*
|
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* 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/>.
|
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*/
|
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|
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#ifndef _LINUX_I2C_MUX_PINCTRL_H
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#define _LINUX_I2C_MUX_PINCTRL_H
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|
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/**
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* struct i2c_mux_pinctrl_platform_data - Platform data for i2c-mux-pinctrl
|
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* @parent_bus_num: Parent I2C bus number
|
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* @base_bus_num: Base I2C bus number for the child busses. 0 for dynamic.
|
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* @bus_count: Number of child busses. Also the number of elements in
|
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* @pinctrl_states
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* @pinctrl_states: The names of the pinctrl state to select for each child bus
|
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* @pinctrl_state_idle: The pinctrl state to select when no child bus is being
|
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* accessed. If NULL, the most recently used pinctrl state will be left
|
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* selected.
|
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*/
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struct i2c_mux_pinctrl_platform_data {
|
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int parent_bus_num;
|
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int base_bus_num;
|
||||
int bus_count;
|
||||
const char **pinctrl_states;
|
||||
const char *pinctrl_state_idle;
|
||||
};
|
||||
|
||||
#endif
|
||||
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Reference in New Issue