diff options
author | Claudiu Beznea <claudiu.beznea@microchip.com> | 2021-10-11 14:27:15 +0300 |
---|---|---|
committer | Stephen Boyd <sboyd@kernel.org> | 2021-10-27 04:27:43 +0300 |
commit | 1e229c21a47241626b345c31ba443490372cf2b5 (patch) | |
tree | 4f77303d5ca1dd2808987319f326876ead60cc33 /drivers/clk/at91/pmc.h | |
parent | 0ef99f8202c5078a72c05af76bfaed2ea4daab19 (diff) | |
download | linux-1e229c21a47241626b345c31ba443490372cf2b5.tar.xz |
clk: at91: clk-sam9x60-pll: add notifier for div part of PLL
SAM9X60's PLL which is also part of SAMA7G5 is composed of 2 parts:
one fractional part and one divider. On SAMA7G5 the CPU PLL could be
changed at run-time to implement DVFS. The hardware clock tree on
SAMA7G5 for CPU PLL is as follows:
+---- div1 ----------------> cpuck
|
FRAC PLL ---> DIV PLL -+-> prescaler ---> div0 ---> mck0
The div1 block is not implemented in Linux; on prescaler block it has
been discovered a bug on some scenarios and will be removed from Linux
in next commits. Thus, the final clock tree that will be used in Linux
will be as follows:
+-----------> cpuck
|
FRAC PLL ---> DIV PLL -+-> div0 ---> mck0
It has been proposed in [1] to not introduce a new CPUFreq driver but
to overload the proper clock drivers with proper operation such that
cpufreq-dt to be used. To accomplish this DIV PLL and div0 implement
clock notifiers which applies safe dividers before FRAC PLL is changed.
The current commit treats only the DIV PLL by adding a notifier that
sets a safe divider on PRE_RATE_CHANGE events. The safe divider is
provided by initialization clock code (sama7g5.c). The div0 is treated
in next commits (to keep the changes as clean as possible).
[1] https://lore.kernel.org/lkml/20210105104426.4tmgc2l3vyicwedd@vireshk-i7/
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Link: https://lore.kernel.org/r/20211011112719.3951784-12-claudiu.beznea@microchip.com
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Diffstat (limited to 'drivers/clk/at91/pmc.h')
-rw-r--r-- | drivers/clk/at91/pmc.h | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/clk/at91/pmc.h b/drivers/clk/at91/pmc.h index 45df094498ce..207ecccef29f 100644 --- a/drivers/clk/at91/pmc.h +++ b/drivers/clk/at91/pmc.h @@ -214,7 +214,8 @@ struct clk_hw * __init sam9x60_clk_register_div_pll(struct regmap *regmap, spinlock_t *lock, const char *name, const char *parent_name, u8 id, const struct clk_pll_characteristics *characteristics, - const struct clk_pll_layout *layout, u32 flags); + const struct clk_pll_layout *layout, u32 flags, + u32 safe_div); struct clk_hw * __init sam9x60_clk_register_frac_pll(struct regmap *regmap, spinlock_t *lock, |