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of: i2c: Add i2c-mux-idle-disconnect DT property to PCA954x mux driver

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Add i2c-mux-idle-disconnect device tree property to PCA954x mux driver. The new
property forces the multiplexer to disconnect child buses in idle state. This is
used, for example, when there are several multiplexers on the same bus and the
devices on the underlying buses might have same I2C addresses.

Signed-off-by: Alexander Sverdlin <alexander.sverdlin@nsn.com>
[wsa: added a newline]
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
This commit is contained in:
Alexander Sverdlin 2015-01-23 16:41:29 +01:00 committed by Wolfram Sang
parent 67105c5a94
commit 72f0271576
2 changed files with 13 additions and 1 deletions
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3
Documentation/devicetree/bindings/i2c/i2c-mux-pca954x.txt
View File

@ -16,6 +16,9 @@ Required Properties:
Optional Properties:
- reset-gpios: Reference to the GPIO connected to the reset input.
- i2c-mux-idle-disconnect: Boolean; if defined, forces mux to disconnect all
children in idle state. This is necessary for example, if there are several
multiplexers on the bus and the devices behind them use same I2C addresses.
Example:

11
drivers/i2c/muxes/i2c-mux-pca954x.c
View File

@ -41,6 +41,7 @@
#include <linux/i2c-mux.h>
#include <linux/i2c/pca954x.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/pm.h>
#include <linux/slab.h>
@ -186,6 +187,8 @@ static int pca954x_probe(struct i2c_client *client,
{
struct i2c_adapter *adap = to_i2c_adapter(client->dev.parent);
struct pca954x_platform_data *pdata = dev_get_platdata(&client->dev);
struct device_node *of_node = client->dev.of_node;
bool idle_disconnect_dt;
struct gpio_desc *gpio;
int num, force, class;
struct pca954x *data;
@ -217,8 +220,13 @@ static int pca954x_probe(struct i2c_client *client,
data->type = 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++) {
bool idle_disconnect_pd = false;
force = 0; /* dynamic adap number */
class = 0; /* no class by default */
if (pdata) {
@ -229,12 +237,13 @@ static int pca954x_probe(struct i2c_client *client,
} else
/* discard unconfigured channels */
break;
idle_disconnect_pd = pdata->modes[num].deselect_on_exit;
}
data->virt_adaps[num] =
i2c_add_mux_adapter(adap, &client->dev, client,
force, num, class, pca954x_select_chan,
(pdata && pdata->modes[num].deselect_on_exit)
(idle_disconnect_pd || idle_disconnect_dt)
? pca954x_deselect_mux : NULL);
if (data->virt_adaps[num] == NULL) {