Introduce set_parent_hw and set_parent_done to support setting parent in early kernel booting where we still can't schedule.
Change the input source of this clock hw; This callback is intended to do the hw part setting of @set_parent work. It should cooperate with @set_parent_done callback to do the whole set parent work. The clock core will check @set_parent_done in either sleep or polling way according to system state to decide whether the whole set rate work is done. Suggested-by: Thomas Gleixner <[email protected]> Signed-off-by: Dong Aisheng <[email protected]> --- drivers/clk/clk.c | 26 +++++++++++++++++++++++++- include/linux/clk-provider.h | 14 ++++++++++++++ 2 files changed, 39 insertions(+), 1 deletion(-) diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c index 0d031b280c9a..9369dbb71118 100644 --- a/drivers/clk/clk.c +++ b/drivers/clk/clk.c @@ -1236,14 +1236,38 @@ static int __clk_set_parent(struct clk_core *core, struct clk_core *parent, unsigned long flags; int ret = 0; struct clk_core *old_parent; + unsigned long timeout; old_parent = __clk_set_parent_before(core, parent); trace_clk_set_parent(core, parent); /* change clock input source */ - if (parent && core->ops->set_parent) + if (parent && core->ops->set_parent) { ret = core->ops->set_parent(core->hw, p_index); + } else if (parent && core->ops->set_parent_hw) { + ret = core->ops->set_parent_hw(core->hw, p_index); + if (!ret && core->ops->set_parent_done) { + timeout = jiffies + msecs_to_jiffies(10); + while (!core->ops->set_parent_done(core->hw)) { + if (time_after(jiffies, timeout)) { + pr_err("%s: clock %s set parent timeout\n", + __func__, core->name); + ret = -ETIMEDOUT; + break; + } + if (system_state == SYSTEM_BOOTING) + /* + * Busy loop as we can't + * schedule in early boot + */ + continue; + else + usleep_range(core->delay_min, + core->delay_max); + } + } + } trace_clk_set_parent_complete(core, parent); diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h index 3dcb99ad6bd2..16fa75cdd656 100644 --- a/include/linux/clk-provider.h +++ b/include/linux/clk-provider.h @@ -146,6 +146,18 @@ struct clk_rate_request { * array index into the value programmed into the hardware. * Returns 0 on success, -EERROR otherwise. * + * @set_parent_hw: Change the input source of this clock hw; This callback + * is intended to do the hw part setting of @set_parent work. It + * should cooperate with @set_parent_done callback to do the whole + * set parent work. The clock core will check @set_parent_done + * in either sleep or polling way according to system state to + * decide whether the whole set rate work is done. Optional + * if @set_parent is used. This function must not sleep. + * + * @set_parent_done: Queries the hardware to determine if the set parent is + * done. Optional, if this op is not set then the set parent + * simply return. This function must not sleep. + * * @get_parent: Queries the hardware to determine the parent of a clock. The * return value is a u8 which specifies the index corresponding to * the parent clock. This index can be applied to either the @@ -243,6 +255,8 @@ struct clk_ops { int (*determine_rate)(struct clk_hw *hw, struct clk_rate_request *req); int (*set_parent)(struct clk_hw *hw, u8 index); + int (*set_parent_hw)(struct clk_hw *hw, u8 index); + int (*set_parent_done)(struct clk_hw *hw); u8 (*get_parent)(struct clk_hw *hw); int (*set_rate)(struct clk_hw *hw, unsigned long rate, unsigned long parent_rate); -- 1.9.1
