[PATCH 2/3] i2c: mux: Add dt support to i2c-mux-gpio driver

Maxime Ripard
2012-09-21T15:32:13Z

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-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
---
.../devicetree/bindings/i2c/i2c-mux-gpio.txt | 86 +++++++++++
drivers/i2c/muxes/i2c-mux-gpio.c | 158 +++++++++++++++-----
2 files changed, 208 insertions(+), 36 deletions(-)
create mode 100644 Documentation/devicetree/bindings/i2c/i2c-mux-gpio.txt

diff --git a/Documentation/devicetree/bindings/i2c/i2c-mux-gpio.txt b/Documentation/devicetree/bindings/i2c/i2c-mux-gpio.txt
new file mode 100644
index 0000000..f2bd120
--- /dev/null
+++ b/Documentation/devicetree/bindings/i2c/i2c-mux-gpio.txt
@@ -0,0 +1,86 @@
+GPIO-based I2C Bus Mux
+
+This binding describes an I2C bus multiplexer that uses GPIOs to
+route the I2C signals.
+
+ +-----+ +-----+
+ | dev | | dev |
+ +------------------------+ +-----+ +-----+
+ | SoC | | |
+ | /----|------+--------+
+ | +---+ +------+ | child bus A, on GPIO value set to 0
+ | |I2C|---| Mux | |
+ | +---+ +--+---+ | child bus B, on GPIO value set to 1
+ | | \----|------+--------+--------+
+ | +------+ | | | | |
+ | | GPIO |---+ | +-----+ +-----+ +-----+
+ | +------+ | | dev | | dev | | dev |
+ +------------------------+ +-----+ +-----+ +-----+
+
+Required properties:
+- compatible: i2c-mux-gpio
+- i2c-parent: The phandle of the I2C bus that this multiplexer's master-side
+ port is connected to.
+
+Also required are:
+
+- muxer-gpios: list of gpios to use to control the muxer
+
+* Standard I2C mux properties. See mux.txt in this directory.
+
+* I2C child bus nodes. See mux.txt in this directory.
+
+For each i2c child nodes, an I2C child bus will be created. They will
+be numbered based on the reg property of each nodes.
+
+Whenever an access is made to a device on a child bus, the value set
+in the revelant node's reg property will be outputed using the list of
+GPIOs, the first in the list holding the most-significant value.
+
+If an idle state is defined, using the idle-state (optional) property,
+whenever an access is not being made to a device on a child bus, the
+idle value will be programmed into the GPIOs.
+
+If an idle state is not defined, the most recently used value will be
+left programmed into hardware whenever no access is being made of a
+device on a child bus.
+
+Example:
+ i2cmux {
+ compatible = "i2c-mux-gpio";
+ #address-cells = <1>;
+ #size-cells = <0>;
+ muxer-gpios = <&gpio1 22 0 &gpio1 23 0>;
+ i2c-parent = <&i2c1>;
+
+ i2c@0 {
+ reg = <0>;
+ #address-cells = <1>;
+ #size-cells = <0>;
+ };
+
+ i2c@1 {
+ reg = <1>;
+ #address-cells = <1>;
+ #size-cells = <0>;
+ };
+
+ i2c@2 {
+ reg = <2>;
+ #address-cells = <1>;
+ #size-cells = <0>;
+ };
+
+ i2c@3 {
+ reg = <3>;
+ #address-cells = <1>;
+ #size-cells = <0>;
+
+ pca9555: pca9555@20 {
+ compatible = "nxp,pca9555";
+ gpio-controller;
+ #gpio-cells = <2>;
+ reg = <0x20>;
+ };
+ };
+ };
diff --git a/drivers/i2c/muxes/i2c-mux-gpio.c b/drivers/i2c/muxes/i2c-mux-gpio.c
index fbc400b..108caaa 100644
--- a/drivers/i2c/muxes/i2c-mux-gpio.c
+++ b/drivers/i2c/muxes/i2c-mux-gpio.c
@@ -16,26 +16,28 @@
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/gpio.h>
+#include <linux/of_i2c.h>
+#include <linux/of_gpio.h>

struct gpiomux {
struct i2c_adapter *parent;
struct i2c_adapter **adap; /* child busses */
- struct i2c_mux_gpio_platform_data data;
+ struct i2c_mux_gpio_platform_data *data;
};

static void i2c_mux_gpio_set(const struct gpiomux *mux, unsigned val)
{
int i;

- for (i = 0; i < mux->data.n_gpios; i++)
- gpio_set_value(mux->data.gpios[i], val & (1 << i));
+ for (i = 0; i < mux->data->n_gpios; i++)
+ gpio_set_value(mux->data->gpios[i], val & (1 << i));
}

static int i2c_mux_gpio_select(struct i2c_adapter *adap, void *data, u32 chan)
{
struct gpiomux *mux = data;

- i2c_mux_gpio_set(mux, mux->data.values[chan]);
+ i2c_mux_gpio_set(mux, mux->data->values[chan]);

return 0;
}
@@ -44,67 +46,146 @@ static int i2c_mux_gpio_deselect(struct i2c_adapter *adap, void *data, u32 chan)
{
struct gpiomux *mux = data;

- i2c_mux_gpio_set(mux, mux->data.idle);
+ i2c_mux_gpio_set(mux, mux->data->idle);

return 0;
}

+#ifdef CONFIG_OF
+static int __devinit i2c_mux_gpio_probe_dt(struct gpiomux *mux,
+ struct platform_device *pdev)
+{
+ struct device_node *np = pdev->dev.of_node;
+ struct device_node *adapter_np, *child;
+ struct i2c_adapter *adapter;
+ unsigned *values, *gpios;
+ int i = 0;
+
+ if (!np)
+ return 0;
+
+ mux->data = devm_kzalloc(&pdev->dev, sizeof(*mux->data),
+ GFP_KERNEL);
+ if (!mux->data) {
+ dev_err(&pdev->dev, "Cannot allocate platform_data");
+ return -ENOMEM;
+ }
+
+ adapter_np = of_parse_phandle(np, "i2c-parent", 0);
+ if (!adapter_np) {
+ dev_err(&pdev->dev, "Cannot parse i2c-parent\n");
+ return -ENODEV;
+ }
+ adapter = of_find_i2c_adapter_by_node(adapter_np);
+ if (!adapter) {
+ dev_err(&pdev->dev, "Cannot find parent bus\n");
+ return -ENODEV;
+ }
+ mux->data->parent = i2c_adapter_id(adapter);
+ put_device(&adapter->dev);
+
+ mux->data->n_values = of_get_child_count(np);
+
+ values = devm_kzalloc(&pdev->dev, sizeof(*mux->data->values), GFP_KERNEL);
+ if (!values) {
+ dev_err(&pdev->dev, "Cannot allocate values array");
+ return -ENOMEM;
+ }
+
+ for_each_child_of_node(np, child) {
+ of_property_read_u32(child, "reg", values + i);
+ i++;
+ }
+ mux->data->values = values;
+
+ if (of_property_read_u32(np, "idle-state", &mux->data->idle))
+ mux->data->idle = I2C_MUX_GPIO_NO_IDLE;
+
+ mux->data->n_gpios = of_gpio_named_count(np, "muxer-gpios");
+ if (mux->data->n_gpios < 0) {
+ dev_err(&pdev->dev, "Missing muxer-gpios property in the DT.\n");
+ return -EINVAL;
+ }
+
+ gpios = devm_kzalloc(&pdev->dev, mux->data->n_gpios, GFP_KERNEL);
+ if (!gpios) {
+ dev_err(&pdev->dev, "Cannot allocate gpios array");
+ return -ENOMEM;
+ }
+
+ for (i = 0; i < mux->data->n_gpios; i++)
+ gpios[i] = of_get_named_gpio(np, "muxer-gpios", i);
+
+ mux->data->gpios = gpios;
+
+ return 0;
+}
+#else
+static int __devinit i2c_mux_gpio_probe_dt(struct gpiomux *mux,
+ struct platform_device *pdev)
+{
+ return 0;
+}
+#endif
+
static int __devinit i2c_mux_gpio_probe(struct platform_device *pdev)
{
struct gpiomux *mux;
- struct i2c_mux_gpio_platform_data *pdata;
struct i2c_adapter *parent;
int (*deselect) (struct i2c_adapter *, void *, u32);
unsigned initial_state;
int i, ret;

- pdata = pdev->dev.platform_data;
- if (!pdata) {
- dev_err(&pdev->dev, "Missing platform data\n");
- return -ENODEV;
+ mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
+ if (!mux) {
+ dev_err(&pdev->dev, "Cannot allocate gpiomux structure");
+ return -ENOMEM;
}

- parent = i2c_get_adapter(pdata->parent);
+ platform_set_drvdata(pdev, mux);
+
+ mux->data = pdev->dev.platform_data;
+ if (!mux->data) {
+ ret = i2c_mux_gpio_probe_dt(mux, pdev);
+ if (ret < 0)
+ return ret;
+ }
+
+ parent = i2c_get_adapter(mux->data->parent);
if (!parent) {
dev_err(&pdev->dev, "Parent adapter (%d) not found\n",
- pdata->parent);
+ mux->data->parent);
return -ENODEV;
}

- mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
- if (!mux) {
- ret = -ENOMEM;
- goto alloc_failed;
- }
-
mux->parent = parent;
- mux->data = *pdata;
mux->adap = devm_kzalloc(&pdev->dev,
- sizeof(struct i2c_adapter *) * pdata->n_values,
+ sizeof(struct i2c_adapter *) * mux->data->n_values,
GFP_KERNEL);
if (!mux->adap) {
+ dev_err(&pdev->dev, "Cannot allocate i2c_adapter structure");
ret = -ENOMEM;
goto alloc_failed;
}

- if (pdata->idle != I2C_MUX_GPIO_NO_IDLE) {
- initial_state = pdata->idle;
+ if (mux->data->idle != I2C_MUX_GPIO_NO_IDLE) {
+ initial_state = mux->data->idle;
deselect = i2c_mux_gpio_deselect;
} else {
- initial_state = pdata->values[0];
+ initial_state = mux->data->values[0];
deselect = NULL;
}

- for (i = 0; i < pdata->n_gpios; i++) {
- ret = gpio_request(pdata->gpios[i], "i2c-mux-gpio");
+ for (i = 0; i < mux->data->n_gpios; i++) {
+ ret = gpio_request(mux->data->gpios[i], "i2c-mux-gpio");
if (ret)
goto err_request_gpio;
- gpio_direction_output(pdata->gpios[i],
+ gpio_direction_output(mux->data->gpios[i],
initial_state & (1 << i));
}

- for (i = 0; i < pdata->n_values; i++) {
- u32 nr = pdata->base_nr ? (pdata->base_nr + i) : 0;
+ for (i = 0; i < mux->data->n_values; i++) {
+ u32 nr = mux->data->base_nr ? (mux->data->base_nr + i) : 0;

mux->adap[i] = i2c_add_mux_adapter(parent, &pdev->dev, mux, nr, i,
i2c_mux_gpio_select, deselect);
@@ -116,19 +197,17 @@ static int __devinit i2c_mux_gpio_probe(struct platform_device *pdev)
}

dev_info(&pdev->dev, "%d port mux on %s adapter\n",
- pdata->n_values, parent->name);
-
- platform_set_drvdata(pdev, mux);
+ mux->data->n_values, parent->name);

return 0;

add_adapter_failed:
for (; i > 0; i--)
i2c_del_mux_adapter(mux->adap[i - 1]);
- i = pdata->n_gpios;
+ i = mux->data->n_gpios;
err_request_gpio:
for (; i > 0; i--)
- gpio_free(pdata->gpios[i - 1]);
+ gpio_free(mux->data->gpios[i - 1]);
alloc_failed:
i2c_put_adapter(parent);

@@ -140,11 +219,11 @@ static int __devexit i2c_mux_gpio_remove(struct platform_device *pdev)
struct gpiomux *mux = platform_get_drvdata(pdev);
int i;

- for (i = 0; i < mux->data.n_values; i++)
+ for (i = 0; i < mux->data->n_values; i++)
i2c_del_mux_adapter(mux->adap[i]);

- for (i = 0; i < mux->data.n_gpios; i++)
- gpio_free(mux->data.gpios[i]);
+ for (i = 0; i < mux->data->n_gpios; i++)
+ gpio_free(mux->data->gpios[i]);

platform_set_drvdata(pdev, NULL);
i2c_put_adapter(mux->parent);
@@ -152,12 +231,19 @@ static int __devexit i2c_mux_gpio_remove(struct platform_device *pdev)
return 0;
}

+static const struct of_device_id i2c_mux_gpio_of_match[] __devinitconst = {
+ { .compatible = "i2c-mux-gpio", },
+ {},
+};
+MODULE_DEVICE_TABLE(of, i2c_mux_gpio_of_match);
+
static struct platform_driver i2c_mux_gpio_driver = {
.probe = i2c_mux_gpio_probe,
.remove = __devexit_p(i2c_mux_gpio_remove),
.driver = {
.owner = THIS_MODULE,
.name = "i2c-mux-gpio",
+ .of_match_table = of_match_ptr(i2c_mux_gpio_of_match),
},
};

--
1.7.9.5