Re: [PATCH RFC v1 1/3] clk: divider: Add re-usable determine_rate implementations
From: Jerome Brunet <jbrunet@baylibre.com>
Date: 2021-05-18 07:45:39
Also in:
linux-amlogic, linux-clk, lkml
On Mon 17 May 2021 at 22:37, Martin Blumenstingl [off-list ref] wrote:
quoted hunk ↗ jump to hunk
These are useful when running on 32-bit systems to increase the upper supported frequency limit. clk_ops.round_rate returns a signed long which limits the maximum rate on 32-bit systems to 2^31 (or approx. 2.14GHz). clk_ops.determine_rate internally uses an unsigned long so the maximum rate on 32-bit systems is 2^32 or approx. 4.29GHz. Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com> --- drivers/clk/clk-divider.c | 39 +++++++++++++++++++++++++++++++++++- include/linux/clk-provider.h | 6 ++++++ 2 files changed, 44 insertions(+), 1 deletion(-)diff --git a/drivers/clk/clk-divider.c b/drivers/clk/clk-divider.c index 344997203f0e..24c94d2a3643 100644 --- a/drivers/clk/clk-divider.c +++ b/drivers/clk/clk-divider.c@@ -377,7 +377,6 @@ long divider_ro_round_rate_parent(struct clk_hw *hw, struct clk_hw *parent, } EXPORT_SYMBOL_GPL(divider_ro_round_rate_parent); - static long clk_divider_round_rate(struct clk_hw *hw, unsigned long rate, unsigned long *prate) {@@ -399,6 +398,44 @@ static long clk_divider_round_rate(struct clk_hw *hw, unsigned long rate, divider->width, divider->flags); } +int divider_determine_rate(struct clk_hw *hw, struct clk_rate_request *req, + const struct clk_div_table *table, u8 width, + unsigned long flags) +{ + int div; + + div = clk_divider_bestdiv(hw, req->best_parent_hw, req->rate, + &req->best_parent_rate, table, width, flags); + + req->rate = DIV_ROUND_UP_ULL((u64)req->best_parent_rate, div); + + return 0; +} +EXPORT_SYMBOL_GPL(divider_determine_rate); + +int divider_ro_determine_rate(struct clk_hw *hw, struct clk_rate_request *req, + const struct clk_div_table *table, u8 width, + unsigned long flags, unsigned int val) +{ + int div; + + div = _get_div(table, val, flags, width); + + /* Even a read-only clock can propagate a rate change */ + if (clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT) { + if (!req->best_parent_hw) + return -EINVAL; + + req->best_parent_rate = clk_hw_round_rate(req->best_parent_hw, + req->rate * div); + } + + req->rate = DIV_ROUND_UP_ULL((u64)req->best_parent_rate, div); + + return 0; +} +EXPORT_SYMBOL_GPL(divider_ro_determine_rate);
For a final version, could you factorize the code with the .round_rate() variant ? It would remove a bit of duplication. Maybe determine_rate() can also replace round_rate() in the generic divider ops ?
quoted hunk ↗ jump to hunk
+ int divider_get_val(unsigned long rate, unsigned long parent_rate, const struct clk_div_table *table, u8 width, unsigned long flags)diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h index 162a2e5546a3..d83b829305c0 100644 --- a/include/linux/clk-provider.h +++ b/include/linux/clk-provider.h@@ -629,6 +629,12 @@ long divider_ro_round_rate_parent(struct clk_hw *hw, struct clk_hw *parent, unsigned long rate, unsigned long *prate, const struct clk_div_table *table, u8 width, unsigned long flags, unsigned int val); +int divider_determine_rate(struct clk_hw *hw, struct clk_rate_request *req, + const struct clk_div_table *table, u8 width, + unsigned long flags); +int divider_ro_determine_rate(struct clk_hw *hw, struct clk_rate_request *req, + const struct clk_div_table *table, u8 width, + unsigned long flags, unsigned int val); int divider_get_val(unsigned long rate, unsigned long parent_rate, const struct clk_div_table *table, u8 width, unsigned long flags);
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