i2c: mux: Add dt support to i2c-mux-gpio driver
Allow the i2c-mux-gpio to be used by a device tree enabled device. The bindings are inspired by the one found in the i2c-mux-pinctrl driver. Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com> Reviewed-by: Stephen Warren <swarren@nvidia.com> Acked-by: Peter Korsgaard <peter.korsgaard@barco.com> [wsa: fixed some whitespace] Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
This commit is contained in:
Maxime Ripard
Wolfram Sang
Родитель
29fb08c300
Коммит
9b7a0c40de
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@ -0,0 +1,81 @@
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GPIO-based I2C Bus Mux
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This binding describes an I2C bus multiplexer that uses GPIOs to
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route the I2C signals.
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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 GPIO value set to 0
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| | I2C |-|--| Mux |
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| +------+ | +--+---+ child bus B, on GPIO value set to 1
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| | | \----------+--------+--------+
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| +------+ | | | | |
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| | GPIO |-|-----+ +-----+ +-----+ +-----+
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| +------+ | | dev | | dev | | dev |
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+------------+ +-----+ +-----+ +-----+
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Required properties:
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- compatible: i2c-mux-gpio
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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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- mux-gpios: list of gpios used to control the muxer
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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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Optional properties:
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- idle-state: value to set the muxer to when idle. When no value is
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given, it defaults to the last value used.
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For each i2c child node, an I2C child bus will be created. They will
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be numbered based on their order in the device tree.
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Whenever an access is made to a device on a child bus, the value set
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in the revelant node's reg property will be output using the list of
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GPIOs, the first in the list holding the least-significant value.
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If an idle state is defined, using the idle-state (optional) property,
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whenever an access is not being made to a device on a child bus, the
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GPIOs will be set according to the idle value.
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If an idle state is not defined, the most recently used value will be
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left programmed into hardware whenever no access is being made to a
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device on a child bus.
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Example:
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i2cmux {
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compatible = "i2c-mux-gpio";
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#address-cells = <1>;
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#size-cells = <0>;
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mux-gpios = <&gpio1 22 0 &gpio1 23 0>;
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i2c-parent = <&i2c1>;
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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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ssd1307: oled@3c {
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compatible = "solomon,ssd1307fb-i2c";
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reg = <0x3c>;
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pwms = <&pwm 4 3000>;
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reset-gpios = <&gpio2 7 1>;
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reset-active-low;
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};
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};
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i2c@3 {
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reg = <3>;
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#address-cells = <1>;
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#size-cells = <0>;
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pca9555: pca9555@20 {
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compatible = "nxp,pca9555";
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gpio-controller;
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#gpio-cells = <2>;
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reg = <0x20>;
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};
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};
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};
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@ -16,6 +16,8 @@
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/gpio.h>
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#include <linux/of_i2c.h>
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#include <linux/of_gpio.h>
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struct gpiomux {
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struct i2c_adapter *parent;
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@ -57,29 +59,110 @@ static int __devinit match_gpio_chip_by_label(struct gpio_chip *chip,
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return !strcmp(chip->label, data);
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}
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#ifdef CONFIG_OF
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static int __devinit i2c_mux_gpio_probe_dt(struct gpiomux *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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struct device_node *adapter_np, *child;
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struct i2c_adapter *adapter;
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unsigned *values, *gpios;
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int i = 0;
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if (!np)
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return -ENODEV;
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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(&pdev->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(&pdev->dev, "Cannot find parent bus\n");
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return -ENODEV;
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}
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mux->data.parent = i2c_adapter_id(adapter);
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put_device(&adapter->dev);
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mux->data.n_values = of_get_child_count(np);
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values = devm_kzalloc(&pdev->dev,
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sizeof(*mux->data.values) * mux->data.n_values,
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GFP_KERNEL);
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if (!values) {
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dev_err(&pdev->dev, "Cannot allocate values array");
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return -ENOMEM;
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}
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for_each_child_of_node(np, child) {
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of_property_read_u32(child, "reg", values + i);
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i++;
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}
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mux->data.values = values;
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if (of_property_read_u32(np, "idle-state", &mux->data.idle))
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mux->data.idle = I2C_MUX_GPIO_NO_IDLE;
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mux->data.n_gpios = of_gpio_named_count(np, "mux-gpios");
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if (mux->data.n_gpios < 0) {
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dev_err(&pdev->dev, "Missing mux-gpios property in the DT.\n");
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return -EINVAL;
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}
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gpios = devm_kzalloc(&pdev->dev,
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sizeof(*mux->data.gpios) * mux->data.n_gpios, GFP_KERNEL);
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if (!gpios) {
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dev_err(&pdev->dev, "Cannot allocate gpios array");
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return -ENOMEM;
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}
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for (i = 0; i < mux->data.n_gpios; i++)
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gpios[i] = of_get_named_gpio(np, "mux-gpios", i);
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mux->data.gpios = gpios;
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return 0;
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}
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#else
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static int __devinit i2c_mux_gpio_probe_dt(struct gpiomux *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_gpio_probe(struct platform_device *pdev)
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{
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struct gpiomux *mux;
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struct i2c_mux_gpio_platform_data *pdata;
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struct i2c_adapter *parent;
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int (*deselect) (struct i2c_adapter *, void *, u32);
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unsigned initial_state, gpio_base;
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int i, ret;
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pdata = pdev->dev.platform_data;
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if (!pdata) {
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dev_err(&pdev->dev, "Missing platform data\n");
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return -ENODEV;
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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 gpiomux structure");
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return -ENOMEM;
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}
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platform_set_drvdata(pdev, mux);
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if (!pdev->dev.platform_data) {
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ret = i2c_mux_gpio_probe_dt(mux, pdev);
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if (ret < 0)
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return ret;
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} else
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memcpy(&mux->data, pdev->dev.platform_data, sizeof(mux->data));
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/*
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* If a GPIO chip name is provided, the GPIO pin numbers provided are
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* relative to its base GPIO number. Otherwise they are absolute.
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*/
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if (pdata->gpio_chip) {
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if (mux->data.gpio_chip) {
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struct gpio_chip *gpio;
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gpio = gpiochip_find(pdata->gpio_chip,
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gpio = gpiochip_find(mux->data.gpio_chip,
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match_gpio_chip_by_label);
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if (!gpio)
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return -EPROBE_DEFER;
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@ -89,49 +172,44 @@ static int __devinit i2c_mux_gpio_probe(struct platform_device *pdev)
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gpio_base = 0;
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}
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parent = i2c_get_adapter(pdata->parent);
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parent = i2c_get_adapter(mux->data.parent);
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if (!parent) {
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dev_err(&pdev->dev, "Parent adapter (%d) not found\n",
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pdata->parent);
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mux->data.parent);
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return -ENODEV;
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}
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mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
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if (!mux) {
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ret = -ENOMEM;
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goto alloc_failed;
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}
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mux->parent = parent;
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mux->data = *pdata;
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mux->gpio_base = gpio_base;
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mux->adap = devm_kzalloc(&pdev->dev,
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sizeof(*mux->adap) * pdata->n_values,
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sizeof(*mux->adap) * mux->data.n_values,
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GFP_KERNEL);
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if (!mux->adap) {
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dev_err(&pdev->dev, "Cannot allocate i2c_adapter structure");
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ret = -ENOMEM;
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goto alloc_failed;
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}
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if (pdata->idle != I2C_MUX_GPIO_NO_IDLE) {
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initial_state = pdata->idle;
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if (mux->data.idle != I2C_MUX_GPIO_NO_IDLE) {
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initial_state = mux->data.idle;
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deselect = i2c_mux_gpio_deselect;
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} else {
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initial_state = pdata->values[0];
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initial_state = mux->data.values[0];
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deselect = NULL;
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}
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for (i = 0; i < pdata->n_gpios; i++) {
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ret = gpio_request(gpio_base + pdata->gpios[i], "i2c-mux-gpio");
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for (i = 0; i < mux->data.n_gpios; i++) {
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ret = gpio_request(gpio_base + mux->data.gpios[i], "i2c-mux-gpio");
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if (ret)
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goto err_request_gpio;
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gpio_direction_output(gpio_base + pdata->gpios[i],
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gpio_direction_output(gpio_base + mux->data.gpios[i],
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initial_state & (1 << i));
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}
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for (i = 0; i < pdata->n_values; i++) {
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u32 nr = pdata->base_nr ? (pdata->base_nr + i) : 0;
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unsigned int class = pdata->classes ? pdata->classes[i] : 0;
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for (i = 0; i < mux->data.n_values; i++) {
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u32 nr = mux->data.base_nr ? (mux->data.base_nr + i) : 0;
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unsigned int class = mux->data.classes ? mux->data.classes[i] : 0;
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mux->adap[i] = i2c_add_mux_adapter(parent, &pdev->dev, mux, nr,
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i, class,
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@ -144,19 +222,17 @@ static int __devinit i2c_mux_gpio_probe(struct platform_device *pdev)
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}
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dev_info(&pdev->dev, "%d port mux on %s adapter\n",
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pdata->n_values, parent->name);
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platform_set_drvdata(pdev, mux);
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mux->data.n_values, parent->name);
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return 0;
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add_adapter_failed:
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for (; i > 0; i--)
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i2c_del_mux_adapter(mux->adap[i - 1]);
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i = pdata->n_gpios;
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i = mux->data.n_gpios;
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err_request_gpio:
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for (; i > 0; i--)
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gpio_free(gpio_base + pdata->gpios[i - 1]);
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gpio_free(gpio_base + mux->data.gpios[i - 1]);
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alloc_failed:
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i2c_put_adapter(parent);
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@ -180,12 +256,19 @@ static int __devexit i2c_mux_gpio_remove(struct platform_device *pdev)
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return 0;
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}
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static const struct of_device_id i2c_mux_gpio_of_match[] __devinitconst = {
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{ .compatible = "i2c-mux-gpio", },
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{},
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};
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MODULE_DEVICE_TABLE(of, i2c_mux_gpio_of_match);
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static struct platform_driver i2c_mux_gpio_driver = {
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.probe = i2c_mux_gpio_probe,
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.remove = __devexit_p(i2c_mux_gpio_remove),
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.driver = {
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.owner = THIS_MODULE,
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.name = "i2c-mux-gpio",
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.of_match_table = of_match_ptr(i2c_mux_gpio_of_match),
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},
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};
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