> In certain boards the source for the clk32k clock can be gated. In these
> boards the clk32k clock can be provided to the driver and it is going to be
> enabled/disabled when it is needed.
> If the clk32k clock is not provided the driver will assume that it is always
> running.
>
> Signed-off-by: Peter Ujfalusi <peter.ujfalusi@xxxxxx>
> ---
> Documentation/devicetree/bindings/mfd/twl6040.txt | 2 ++
> drivers/mfd/twl6040.c | 10 ++++++++++
> include/linux/mfd/twl6040.h | 2 ++
> 3 files changed, 14 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/mfd/twl6040.txt b/Documentation/devicetree/bindings/mfd/twl6040.txt
> index 0f5dd709d752..a41157b5d930 100644
> --- a/Documentation/devicetree/bindings/mfd/twl6040.txt
> +++ b/Documentation/devicetree/bindings/mfd/twl6040.txt
> @@ -19,6 +19,8 @@ Required properties:
>
> Optional properties, nodes:
> - enable-active-high: To power on the twl6040 during boot.
> +- clocks: phandle to the clk32k clock provider
> +- clock-names: Must be "clk32k"
>
> Vibra functionality
> Required properties:
> diff --git a/drivers/mfd/twl6040.c b/drivers/mfd/twl6040.c
> index 2e6504a8e1e3..12b314ea48dc 100644
> --- a/drivers/mfd/twl6040.c
> +++ b/drivers/mfd/twl6040.c
> @@ -291,6 +291,8 @@ int twl6040_power(struct twl6040 *twl6040, int on)
> if (twl6040->power_count++)
> goto out;
>
> + clk_prepare_enable(twl6040->clk32k);
> +
> /* Allow writes to the chip */
> regcache_cache_only(twl6040->regmap, false);
>
> @@ -346,6 +348,8 @@ int twl6040_power(struct twl6040 *twl6040, int on)
>
> twl6040->sysclk = 0;
> twl6040->mclk = 0;
> +
> + clk_disable_unprepare(twl6040->clk32k);
> }
>
> out:
> @@ -644,6 +648,12 @@ static int twl6040_probe(struct i2c_client *client,
>
> i2c_set_clientdata(client, twl6040);
>
> + twl6040->clk32k = devm_clk_get(&client->dev, "clk32k");
> + if (IS_ERR(twl6040->clk32k)) {
> + dev_info(&client->dev, "clk32k is not handled\n");
> + twl6040->clk32k = NULL;
So what happens if you pass a NULL clk reference to clk_prepare_enable()?
--
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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