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    SubjectRe: [PATCH] clk: clk-gpio: add support for sleeping GPIOs in gpio-gate-clk
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    Quoting Thomas Petazzoni (2019-02-11 05:58:18)
    > The current implementation of gpio-gate-clk enables/disables the clock
    > using the GPIO in the ->enable() and ->disable() clock callbacks. This
    > requires the GPIO to be configurable in atomic contexts. While it is
    > the case for most memory-mapped GPIO controllers, it is not the case
    > for GPIO expanders on I2C or SPI.
    >
    > This commit extends the gpio-gate-clk to check whether the GPIO calls
    > require sleeping or not. If sleeping is not required, the current
    > implementation based on ->enable()/->disable() is kept. However, if
    > sleeping is needed, we instead implement the logic in the ->prepare()
    > and ->unprepare() hooks. Thanks to this, a gate clock connected to a
    > GPIO on a GPIO expander can be controlled with the existing driver.
    >
    > Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

    Sounds like a good idea!

    > diff --git a/drivers/clk/clk-gpio.c b/drivers/clk/clk-gpio.c
    > index 6a43ce420492..f5d481713c7d 100644
    > --- a/drivers/clk/clk-gpio.c
    > +++ b/drivers/clk/clk-gpio.c
    > @@ -61,6 +61,35 @@ const struct clk_ops clk_gpio_gate_ops = {
    > };
    > EXPORT_SYMBOL_GPL(clk_gpio_gate_ops);
    >
    > +static int clk_sleeping_gpio_gate_prepare(struct clk_hw *hw)
    > +{
    > + struct clk_gpio *clk = to_clk_gpio(hw);
    > +
    > + gpiod_set_value_cansleep(clk->gpiod, 1);
    > +
    > + return 0;
    > +}
    > +
    > +static void clk_sleeping_gpio_gate_unprepare(struct clk_hw *hw)
    > +{
    > + struct clk_gpio *clk = to_clk_gpio(hw);
    > +
    > + gpiod_set_value_cansleep(clk->gpiod, 0);
    > +}
    > +
    > +static int clk_sleeping_gpio_gate_is_prepared(struct clk_hw *hw)
    > +{
    > + struct clk_gpio *clk = to_clk_gpio(hw);
    > +
    > + return gpiod_get_value_cansleep(clk->gpiod);
    > +}
    > +
    > +const struct clk_ops clk_sleeping_gpio_gate_ops = {

    static?

    > + .prepare = clk_sleeping_gpio_gate_prepare,
    > + .unprepare = clk_sleeping_gpio_gate_unprepare,
    > + .is_prepared = clk_sleeping_gpio_gate_is_prepared,
    > +};
    > +
    > /**
    > * DOC: basic clock multiplexer which can be controlled with a gpio output
    > * Traits of this clock:

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