Hi Alexander,
Thank you for the patch.
On Monday 15 December 2014 02:25:18 Alexander Sverdlin wrote:
> of: i2c: Add DT bindings for idle states to PCA954x mux driver
>
> Introduce two new device tree bindings to specify idle state of PCA954x
> family of I2C multiplexors:
> - idle-state: specifies particular child bus to be selected in idle;
> - idle-disconnect: signals that mux should disconnect all child buses in
> idle;
Could you please briefly explain your use case(s) for those two properties ?
> Signed-off-by: Alexander Sverdlin <alexander.sverdlin@xxxxxxx>
> ---
> .../devicetree/bindings/i2c/i2c-mux-pca954x.txt | 3 +
> drivers/i2c/muxes/i2c-mux-pca954x.c | 51 +++++++++++++++--
> 2 files changed, 48 insertions(+), 6 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/i2c/i2c-mux-pca954x.txt
> b/Documentation/devicetree/bindings/i2c/i2c-mux-pca954x.txt index
> 34a3fb6..1fbe287 100644
> --- a/Documentation/devicetree/bindings/i2c/i2c-mux-pca954x.txt
> +++ b/Documentation/devicetree/bindings/i2c/i2c-mux-pca954x.txt
> @@ -16,6 +16,9 @@ Required Properties:
> Optional Properties:
>
> - reset-gpios: Reference to the GPIO connected to the reset input.
> + - idle-state: Child bus connected in idle state (specified by its "reg"
> value) + - idle-disconnect: Boolean; if defined, forces mux to disconnect
> all children + in idle state
>
>
> Example:
> diff --git a/drivers/i2c/muxes/i2c-mux-pca954x.c
> b/drivers/i2c/muxes/i2c-mux-pca954x.c index ec11b40..69cf603 100644
> --- a/drivers/i2c/muxes/i2c-mux-pca954x.c
> +++ b/drivers/i2c/muxes/i2c-mux-pca954x.c
> @@ -43,6 +43,7 @@
> #include <linux/module.h>
> #include <linux/pm.h>
> #include <linux/slab.h>
> +#include <linux/of.h>
Could you please keep headers sorted alphabetically ?
> #define PCA954X_MAX_NCHANS 8
>
> @@ -62,6 +63,8 @@ struct pca954x {
> struct i2c_adapter *virt_adaps[PCA954X_MAX_NCHANS];
>
> u8 last_chan; /* last register value */
> + bool idle_disconnect;
> + s8 idle_chan; /* valid if not negative */
> };
>
> struct chip_desc {
> @@ -172,10 +175,20 @@ static int pca954x_deselect_mux(struct i2c_adapter
> *adap, void *client, u32 chan)
> {
> struct pca954x *data = i2c_get_clientdata(client);
> + struct pca954x_platform_data *pdata =
> + dev_get_platdata(&((struct i2c_client *)client)->dev);
> +
> + if ((pdata && pdata->modes[chan].deselect_on_exit) ||
> + data->idle_disconnect) {
I would copy pdata->modes[chan].deselect_on_exit to data->idle_disconnect in
the probe function, so you could avoiding accessing pdata here.
> + /* Deselect active channel */
> + data->last_chan = 0;
> + return pca954x_reg_write(adap, client, data->last_chan);
> + }
>
> - /* Deselect active channel */
> - data->last_chan = 0;
> - return pca954x_reg_write(adap, client, data->last_chan);
> + if (data->idle_chan >= 0)
> + return pca954x_select_chan(adap, client, data->idle_chan);
> +
> + return 0;
> }
>
> /*
> @@ -186,6 +199,7 @@ 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;
> struct gpio_desc *gpio;
> int num, force, class;
> struct pca954x *data;
> @@ -216,6 +230,27 @@ static int pca954x_probe(struct i2c_client *client,
>
> data->type = id->driver_data;
> data->last_chan = 0; /* force the first selection */
> + data->idle_chan = -1; /* no forced idle state */
> +
> + if (of_node) {
> + u32 ch;
> +
> + if (of_property_read_bool(of_node, "idle-disconnect"))
> + data->idle_disconnect = true;
> +
> + if (!of_property_read_u32_index(of_node, "idle-state", 0, &ch)) {
> + if (ch < PCA954X_MAX_NCHANS) {
> + data->idle_chan = ch;
> + /* Force idle state from the beginning */
> + ret = pca954x_select_chan(adap, client, ch);
> + if (ret)
> + return ret;
> + } else {
> + dev_warn(&client->dev,
> + "Invalid idle-state property\n");
> + }
> + }
> + }
>
> /* Now create an adapter for each channel */
> for (num = 0; num < chips[data->type].nchans; num++) {
> @@ -234,8 +269,7 @@ static int pca954x_probe(struct i2c_client *client,
> 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)
> - ? pca954x_deselect_mux : NULL);
> + pca954x_deselect_mux);
>
> if (data->virt_adaps[num] == NULL) {
> ret = -ENODEV;
> @@ -281,7 +315,12 @@ static int pca954x_resume(struct device *dev)
> struct pca954x *data = i2c_get_clientdata(client);
>
> data->last_chan = 0;
> - return i2c_smbus_write_byte(client, 0);
> + /* Restore idle state on resume */
> + if (data->idle_chan >= 0)
> + return pca954x_select_chan(to_i2c_adapter(client->dev.parent),
> + client, data->idle_chan);
> + else
> + return i2c_smbus_write_byte(client, 0);
> }
> #endif
--
Regards,
Laurent Pinchart
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