- our-claim-gpio: The GPIO that we use to claim the bus.
- their-claim-gpios: The GPIOs that the other sides use to claim the bus.
Note that some implementations may only support a single other master.
-- Standard I2C mux properties. See i2c-mux.txt in this directory.
-- Single I2C child bus node at reg 0. See i2c-mux.txt in this directory.
+- I2C arbitration bus node. See i2c-arb.txt in this directory.
Optional properties:
- slew-delay-us: microseconds to wait for a GPIO to go high. Default is 10 us.
i2c-arbitrator {
compatible = "i2c-arb-gpio-challenge";
- #address-cells = <1>;
- #size-cells = <0>;
i2c-parent = <&{/i2c@12CA0000}>;
wait-retry-us = <3000>;
wait-free-us = <50000>;
- i2c@0 {
- reg = <0>;
+ i2c-arb {
#address-cells = <1>;
#size-cells = <0>;
--- /dev/null
+Common i2c arbitration bus properties.
+
+- i2c-arb child node
+
+Required properties for the i2c-arb child node:
+- #address-cells = <1>;
+- #size-cells = <0>;
+
+Optional properties for i2c-arb child node:
+- Child nodes conforming to i2c bus binding
+
+
+Example :
+
+ /*
+ An NXP pca9541 I2C bus master selector at address 0x74
+ with a NXP pca8574 GPIO expander attached.
+ */
+
+ arb@74 {
+ compatible = "nxp,pca9541";
+ reg = <0x74>;
+
+ i2c-arb {
+ #address-cells = <1>;
+ #size-cells = <0>;
+
+ gpio@38 {
+ compatible = "nxp,pca8574";
+ reg = <0x38>;
+ #gpio-cells = <2>;
+ gpio-controller;
+ };
+ };
+ };
--- /dev/null
+An i2c gate is useful to e.g. reduce the digital noise for RF tuners connected
+to the i2c bus. Gates are similar to arbitrators in that you need to perform
+some kind of operation to access the i2c bus past the arbitrator/gate, but
+there are no competing masters to consider for gates and therefore there is
+no arbitration happening for gates.
+
+Common i2c gate properties.
+
+- i2c-gate child node
+
+Required properties for the i2c-gate child node:
+- #address-cells = <1>;
+- #size-cells = <0>;
+
+Optional properties for i2c-gate child node:
+- Child nodes conforming to i2c bus binding
+
+
+Example :
+
+ /*
+ An Invensense mpu9150 at address 0x68 featuring an on-chip Asahi
+ Kasei ak8975 compass behind a gate.
+ */
+
+ mpu9150@68 {
+ compatible = "invensense,mpu9150";
+ reg = <0x68>;
+ interrupt-parent = <&gpio1>;
+ interrupts = <18 1>;
+
+ i2c-gate {
+ #address-cells = <1>;
+ #size-cells = <0>;
+
+ ax8975@c {
+ compatible = "ak,ak8975";
+ reg = <0x0c>;
+ };
+ };
+ };
An i2c bus multiplexer/switch will have several child busses that are
numbered uniquely in a device dependent manner. The nodes for an i2c bus
-multiplexer/switch will have one child node for each child
-bus.
+multiplexer/switch will have one child node for each child bus.
-Required properties:
+Optional properties:
+- #address-cells = <1>;
+ This property is required is the i2c-mux child node does not exist.
+
+- #size-cells = <0>;
+ This property is required is the i2c-mux child node does not exist.
+
+- i2c-mux
+ For i2c multiplexers/switches that have child nodes that are a mixture
+ of both i2c child busses and other child nodes, the 'i2c-mux' subnode
+ can be used for populating the i2c child busses. If an 'i2c-mux'
+ subnode is present, only subnodes of this will be considered as i2c
+ child busses.
+
+Required properties for the i2c-mux child node:
- #address-cells = <1>;
- #size-cells = <0>;
-Required properties for child nodes:
+Required properties for i2c child bus nodes:
- #address-cells = <1>;
- #size-cells = <0>;
- reg : The sub-bus number.
-Optional properties for child nodes:
+Optional properties for i2c child bus nodes:
- Other properties specific to the multiplexer/switch hardware.
- Child nodes conforming to i2c bus binding
--- /dev/null
+* NXP PCA9541 I2C bus master selector
+
+Required Properties:
+
+ - compatible: Must be "nxp,pca9541"
+
+ - reg: The I2C address of the device.
+
+ The following required properties are defined externally:
+
+ - I2C arbitration bus node. See i2c-arb.txt in this directory.
+
+
+Example:
+
+ i2c-arbitrator@74 {
+ compatible = "nxp,pca9541";
+ reg = <0x74>;
+
+ i2c-arb {
+ #address-cells = <1>;
+ #size-cells = <0>;
+
+ eeprom@54 {
+ compatible = "at,24c08";
+ reg = <0x54>;
+ };
+ };
+ };
F: Documentation/i2c/i2c-topology
F: Documentation/i2c/muxes/
F: Documentation/devicetree/bindings/i2c/i2c-mux*
+F: Documentation/devicetree/bindings/i2c/i2c-arb*
+F: Documentation/devicetree/bindings/i2c/i2c-gate*
F: drivers/i2c/i2c-mux.c
F: drivers/i2c/muxes/
F: include/linux/i2c-mux.h
muxc->dev = dev;
if (flags & I2C_MUX_LOCKED)
muxc->mux_locked = true;
+ if (flags & I2C_MUX_ARBITRATOR)
+ muxc->arbitrator = true;
+ if (flags & I2C_MUX_GATE)
+ muxc->gate = true;
muxc->select = select;
muxc->deselect = deselect;
muxc->max_adapters = max_adapters;
* nothing if !CONFIG_OF.
*/
if (muxc->dev->of_node) {
- struct device_node *child;
+ struct device_node *dev_node = muxc->dev->of_node;
+ struct device_node *mux_node, *child = NULL;
u32 reg;
- for_each_child_of_node(muxc->dev->of_node, child) {
- ret = of_property_read_u32(child, "reg", ®);
- if (ret)
- continue;
- if (chan_id == reg) {
- priv->adap.dev.of_node = child;
- break;
+ if (muxc->arbitrator)
+ mux_node = of_get_child_by_name(dev_node, "i2c-arb");
+ else if (muxc->gate)
+ mux_node = of_get_child_by_name(dev_node, "i2c-gate");
+ else
+ mux_node = of_get_child_by_name(dev_node, "i2c-mux");
+
+ if (mux_node) {
+ /* A "reg" property indicates an old-style DT entry */
+ if (!of_property_read_u32(mux_node, "reg", ®)) {
+ of_node_put(mux_node);
+ mux_node = NULL;
+ }
+ }
+
+ if (!mux_node)
+ mux_node = of_node_get(dev_node);
+ else if (muxc->arbitrator || muxc->gate)
+ child = of_node_get(mux_node);
+
+ if (!child) {
+ for_each_child_of_node(mux_node, child) {
+ ret = of_property_read_u32(child, "reg", ®);
+ if (ret)
+ continue;
+ if (chan_id == reg)
+ break;
}
}
+
+ priv->adap.dev.of_node = child;
+ of_node_put(mux_node);
}
/*
return -EINVAL;
}
- muxc = i2c_mux_alloc(NULL, dev, 1, sizeof(*arb), 0,
+ muxc = i2c_mux_alloc(NULL, dev, 1, sizeof(*arb), I2C_MUX_ARBITRATOR,
i2c_arbitrator_select, i2c_arbitrator_deselect);
if (!muxc)
return -ENOMEM;
MODULE_DEVICE_TABLE(i2c, pca9541_id);
+#ifdef CONFIG_OF
+static const struct of_device_id pca9541_of_match[] = {
+ { .compatible = "nxp,pca9541" },
+ {}
+};
+#endif
+
/*
* Write to chip register. Don't use i2c_transfer()/i2c_smbus_xfer()
* as they will try to lock the adapter a second time.
force = 0;
if (pdata)
force = pdata->modes[0].adap_id;
- muxc = i2c_mux_alloc(adap, &client->dev, 1, sizeof(*data), 0,
+ muxc = i2c_mux_alloc(adap, &client->dev, 1, sizeof(*data),
+ I2C_MUX_ARBITRATOR,
pca9541_select_chan, pca9541_release_chan);
if (!muxc)
return -ENOMEM;
static struct i2c_driver pca9541_driver = {
.driver = {
.name = "pca9541",
+ .of_match_table = of_match_ptr(pca9541_of_match),
},
.probe = pca9541_probe,
.remove = pca9541_remove,
#include <linux/i2c/pca954x.h>
#include <linux/module.h>
#include <linux/of.h>
+#include <linux/of_device.h>
#include <linux/pm.h>
#include <linux/slab.h>
pca_9548,
};
-struct pca954x {
- enum pca_type type;
-
- u8 last_chan; /* last register value */
- u8 deselect;
- struct i2c_client *client;
-};
-
struct chip_desc {
u8 nchans;
u8 enable; /* used for muxes only */
} muxtype;
};
+struct pca954x {
+ const struct chip_desc *chip;
+
+ u8 last_chan; /* last register value */
+ u8 deselect;
+ struct i2c_client *client;
+};
+
/* Provide specs for the PCA954x types we know about */
static const struct chip_desc chips[] = {
[pca_9540] = {
};
MODULE_DEVICE_TABLE(i2c, pca954x_id);
+#ifdef CONFIG_OF
+static const struct of_device_id pca954x_of_match[] = {
+ { .compatible = "nxp,pca9540", .data = &chips[pca_9540] },
+ { .compatible = "nxp,pca9542", .data = &chips[pca_9542] },
+ { .compatible = "nxp,pca9543", .data = &chips[pca_9543] },
+ { .compatible = "nxp,pca9544", .data = &chips[pca_9544] },
+ { .compatible = "nxp,pca9545", .data = &chips[pca_9545] },
+ { .compatible = "nxp,pca9546", .data = &chips[pca_9546] },
+ { .compatible = "nxp,pca9547", .data = &chips[pca_9547] },
+ { .compatible = "nxp,pca9548", .data = &chips[pca_9548] },
+ {}
+};
+#endif
+
/* Write to mux register. Don't use i2c_transfer()/i2c_smbus_xfer()
for this as they will try to lock adapter a second time */
static int pca954x_reg_write(struct i2c_adapter *adap,
{
struct pca954x *data = i2c_mux_priv(muxc);
struct i2c_client *client = data->client;
- const struct chip_desc *chip = &chips[data->type];
+ const struct chip_desc *chip = data->chip;
u8 regval;
int ret = 0;
int num, force, class;
struct i2c_mux_core *muxc;
struct pca954x *data;
+ const struct of_device_id *match;
int ret;
if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE))
return -ENODEV;
}
- data->type = id->driver_data;
+ match = of_match_device(of_match_ptr(pca954x_of_match), &client->dev);
+ if (match)
+ data->chip = of_device_get_match_data(&client->dev);
+ else
+ data->chip = &chips[id->driver_data];
+
data->last_chan = 0; /* force the first selection */
idle_disconnect_dt = of_node &&
of_property_read_bool(of_node, "i2c-mux-idle-disconnect");
/* Now create an adapter for each channel */
- for (num = 0; num < chips[data->type].nchans; num++) {
+ for (num = 0; num < data->chip->nchans; num++) {
bool idle_disconnect_pd = false;
force = 0; /* dynamic adap number */
dev_info(&client->dev,
"registered %d multiplexed busses for I2C %s %s\n",
- num, chips[data->type].muxtype == pca954x_ismux
+ num, data->chip->muxtype == pca954x_ismux
? "mux" : "switch", client->name);
return 0;
.driver = {
.name = "pca954x",
.pm = &pca954x_pm,
+ .of_match_table = of_match_ptr(pca954x_of_match),
},
.probe = pca954x_probe,
.remove = pca954x_remove,
struct i2c_mux_core {
struct i2c_adapter *parent;
struct device *dev;
- bool mux_locked;
+ unsigned int mux_locked:1;
+ unsigned int arbitrator:1;
+ unsigned int gate:1;
void *priv;
int (*deselect)(struct i2c_mux_core *, u32));
/* flags for i2c_mux_alloc */
-#define I2C_MUX_LOCKED BIT(0)
+#define I2C_MUX_LOCKED BIT(0)
+#define I2C_MUX_ARBITRATOR BIT(1)
+#define I2C_MUX_GATE BIT(2)
static inline void *i2c_mux_priv(struct i2c_mux_core *muxc)
{
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