From f24a0b1c22c2e90abb4ee1f7a3b0f0d8fc2ede5f Mon Sep 17 00:00:00 2001 From: Maxime Ripard Date: Tue, 16 Aug 2022 13:25:09 +0200 Subject: clk: Mention that .recalc_rate can return 0 on error Multiple platforms (amlogic, imx8) return 0 when the clock rate cannot be determined properly by the recalc_rate hook. Mention in the documentation that the framework is ok with that. Signed-off-by: Maxime Ripard Link: https://lore.kernel.org/r/20220816112530.1837489-5-maxime@cerno.tech Tested-by: Linux Kernel Functional Testing Tested-by: Naresh Kamboju Signed-off-by: Stephen Boyd --- include/linux/clk-provider.h | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'include/linux') diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h index 1615010aa0ec..9a14cfa0d201 100644 --- a/include/linux/clk-provider.h +++ b/include/linux/clk-provider.h @@ -118,8 +118,9 @@ struct clk_duty { * * @recalc_rate Recalculate the rate of this clock, by querying hardware. The * parent rate is an input parameter. It is up to the caller to - * ensure that the prepare_mutex is held across this call. - * Returns the calculated rate. Optional, but recommended - if + * ensure that the prepare_mutex is held across this call. If the + * driver cannot figure out a rate for this clock, it must return + * 0. Returns the calculated rate. Optional, but recommended - if * this op is not set then clock rate will be initialized to 0. * * @round_rate: Given a target rate as input, returns the closest rate actually -- cgit v1.2.3 From c35e84b0977617f96fb1dbef3fb8d71a861325c0 Mon Sep 17 00:00:00 2001 From: Maxime Ripard Date: Tue, 16 Aug 2022 13:25:21 +0200 Subject: clk: Introduce clk_hw_init_rate_request() clk-divider instantiates clk_rate_request internally for its round_rate implementations to share the code with its determine_rate implementations. However, it's missing a few fields (min_rate, max_rate) that would be initialized properly if it was using clk_core_init_rate_req(). Let's create the clk_hw_init_rate_request() function for clock providers to be able to share the code to instation clk_rate_requests with the framework. This will also be useful for some tests introduced in later patches. Tested-by: Alexander Stein # imx8mp Tested-by: Marek Szyprowski # exynos4210, meson g12b Signed-off-by: Maxime Ripard Link: https://lore.kernel.org/r/20220816112530.1837489-17-maxime@cerno.tech Tested-by: Linux Kernel Functional Testing Tested-by: Naresh Kamboju Signed-off-by: Stephen Boyd --- include/linux/clk-provider.h | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'include/linux') diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h index 9a14cfa0d201..d857717aa386 100644 --- a/include/linux/clk-provider.h +++ b/include/linux/clk-provider.h @@ -42,6 +42,8 @@ struct dentry; * struct clk_rate_request - Structure encoding the clk constraints that * a clock user might require. * + * Should be initialized by calling clk_hw_init_rate_request(). + * * @rate: Requested clock rate. This field will be adjusted by * clock drivers according to hardware capabilities. * @min_rate: Minimum rate imposed by clk users. @@ -60,6 +62,10 @@ struct clk_rate_request { struct clk_hw *best_parent_hw; }; +void clk_hw_init_rate_request(const struct clk_hw *hw, + struct clk_rate_request *req, + unsigned long rate); + /** * struct clk_duty - Struture encoding the duty cycle ratio of a clock * -- cgit v1.2.3 From 22fb0e284fbc3c1b85d24c5a1df8ea3ac82ab1d1 Mon Sep 17 00:00:00 2001 From: Maxime Ripard Date: Tue, 16 Aug 2022 13:25:25 +0200 Subject: clk: Constify clk_has_parent() clk_has_parent() doesn't modify the clocks being passed, so let's make it const. Suggested-by: Stephen Boyd Signed-off-by: Maxime Ripard Link: https://lore.kernel.org/r/20220816112530.1837489-21-maxime@cerno.tech Tested-by: Linux Kernel Functional Testing Tested-by: Naresh Kamboju Signed-off-by: Stephen Boyd --- include/linux/clk.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/clk.h b/include/linux/clk.h index c13061cabdfc..1ef013324237 100644 --- a/include/linux/clk.h +++ b/include/linux/clk.h @@ -799,7 +799,7 @@ int clk_set_rate_exclusive(struct clk *clk, unsigned long rate); * * Returns true if @parent is a possible parent for @clk, false otherwise. */ -bool clk_has_parent(struct clk *clk, struct clk *parent); +bool clk_has_parent(const struct clk *clk, const struct clk *parent); /** * clk_set_rate_range - set a rate range for a clock source -- cgit v1.2.3 From 262ca38f4b6eb418b20b8e1d6d8495c6a98727c1 Mon Sep 17 00:00:00 2001 From: Maxime Ripard Date: Tue, 16 Aug 2022 13:25:26 +0200 Subject: clk: Stop forwarding clk_rate_requests to the parent If the clock cannot modify its rate and has CLK_SET_RATE_PARENT, clk_mux_determine_rate_flags(), clk_core_round_rate_nolock() and a number of drivers will forward the clk_rate_request to the parent clock. clk_core_round_rate_nolock() will pass the pointer directly, which means that we pass a clk_rate_request to the parent that has the rate, min_rate and max_rate of the child, and the best_parent_rate and best_parent_hw fields will be relative to the child as well, so will point to our current clock and its rate. The most common case for CLK_SET_RATE_PARENT is that the child and parent clock rates will be equal, so the rate field isn't a worry, but the other fields are. Similarly, if the parent clock driver ever modifies the best_parent_rate or best_parent_hw, this will be applied to the child once the call to clk_core_round_rate_nolock() is done. best_parent_hw is probably not going to be a valid parent, and best_parent_rate might lead to a parent rate change different to the one that was initially computed. clk_mux_determine_rate_flags() and the affected drivers will copy the request before forwarding it to the parents, so they won't be affected by the latter issue, but the former is still going to be there and will lead to erroneous data and context being passed to the various clock drivers in the same sub-tree. Let's create two new functions, clk_core_forward_rate_req() and clk_hw_forward_rate_request() for the framework and the clock providers that will copy a request from a child clock and update the context to match the parent's. We also update the relevant call sites in the framework and drivers to use that new function. Let's also add a test to make sure we avoid regressions there. Tested-by: Alexander Stein # imx8mp Tested-by: Marek Szyprowski # exynos4210, meson g12b Signed-off-by: Maxime Ripard Link: https://lore.kernel.org/r/20220816112530.1837489-22-maxime@cerno.tech Tested-by: Linux Kernel Functional Testing Tested-by: Naresh Kamboju Signed-off-by: Stephen Boyd --- include/linux/clk-provider.h | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'include/linux') diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h index d857717aa386..8bce6c524f29 100644 --- a/include/linux/clk-provider.h +++ b/include/linux/clk-provider.h @@ -65,6 +65,11 @@ struct clk_rate_request { void clk_hw_init_rate_request(const struct clk_hw *hw, struct clk_rate_request *req, unsigned long rate); +void clk_hw_forward_rate_request(const struct clk_hw *core, + const struct clk_rate_request *old_req, + const struct clk_hw *parent, + struct clk_rate_request *req, + unsigned long parent_rate); /** * struct clk_duty - Struture encoding the duty cycle ratio of a clock -- cgit v1.2.3 From 253993253466ba7187730b196174146d5247e97b Mon Sep 17 00:00:00 2001 From: Maxime Ripard Date: Tue, 16 Aug 2022 13:25:28 +0200 Subject: clk: Introduce the clk_hw_get_rate_range function Some clock providers are hand-crafting their clk_rate_request, and need to figure out the current boundaries of their clk_hw to fill it properly. Let's create such a function for clock providers. Signed-off-by: Maxime Ripard Link: https://lore.kernel.org/r/20220816112530.1837489-24-maxime@cerno.tech Tested-by: Linux Kernel Functional Testing Tested-by: Naresh Kamboju Signed-off-by: Stephen Boyd --- include/linux/clk-provider.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/linux') diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h index 8bce6c524f29..8724a3547a79 100644 --- a/include/linux/clk-provider.h +++ b/include/linux/clk-provider.h @@ -1267,6 +1267,8 @@ int clk_mux_determine_rate_flags(struct clk_hw *hw, struct clk_rate_request *req, unsigned long flags); void clk_hw_reparent(struct clk_hw *hw, struct clk_hw *new_parent); +void clk_hw_get_rate_range(struct clk_hw *hw, unsigned long *min_rate, + unsigned long *max_rate); void clk_hw_set_rate_range(struct clk_hw *hw, unsigned long min_rate, unsigned long max_rate); -- cgit v1.2.3