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clk: sunxi-ng: nkm: Support constraints on m/n ratio and parent rate

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The Allwinner A64 manual lists the following constraints for the
PLL-MIPI clock:
 - M/N <= 3
 - (PLL_VIDEO0)/M >= 24MHz

The PLL-MIPI clock is implemented as ccu_nkm. Therefore, add support for
these constraints.

Reviewed-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Signed-off-by: Frank Oltmanns <frank@oltmanns.dev>
Link: https://lore.kernel.org/r/20240310-pinephone-pll-fixes-v4-3-46fc80c83637@oltmanns.dev
Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>
This commit is contained in:
Frank Oltmanns 2024-03-10 14:21:13 +01:00 committed by Jernej Skrabec
parent 4cece76496
commit 5723879c14
2 changed files with 23 additions and 0 deletions
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21
drivers/clk/sunxi-ng/ccu_nkm.c
View file

@ -16,6 +16,20 @@ struct _ccu_nkm {
unsigned long m, min_m, max_m;
};
static bool ccu_nkm_is_valid_rate(struct ccu_common *common, unsigned long parent,
unsigned long n, unsigned long m)
{
struct ccu_nkm *nkm = container_of(common, struct ccu_nkm, common);
if (nkm->max_m_n_ratio && (m > nkm->max_m_n_ratio * n))
return false;
if (nkm->min_parent_m_ratio && (parent < nkm->min_parent_m_ratio * m))
return false;
return true;
}
static unsigned long ccu_nkm_find_best_with_parent_adj(struct ccu_common *common,
struct clk_hw *parent_hw,
unsigned long *parent, unsigned long rate,
@ -31,6 +45,10 @@ static unsigned long ccu_nkm_find_best_with_parent_adj(struct ccu_common *common
unsigned long tmp_rate, tmp_parent;
tmp_parent = clk_hw_round_rate(parent_hw, rate * _m / (_n * _k));
if (!ccu_nkm_is_valid_rate(common, tmp_parent, _n, _m))
continue;
tmp_rate = tmp_parent * _n * _k / _m;
if (ccu_is_better_rate(common, rate, tmp_rate, best_rate) ||
@ -64,6 +82,9 @@ static unsigned long ccu_nkm_find_best(unsigned long parent, unsigned long rate,
for (_k = nkm->min_k; _k <= nkm->max_k; _k++) {
for (_n = nkm->min_n; _n <= nkm->max_n; _n++) {
for (_m = nkm->min_m; _m <= nkm->max_m; _m++) {
if (!ccu_nkm_is_valid_rate(common, parent, _n, _m))
continue;
unsigned long tmp_rate;
tmp_rate = parent * _n * _k / _m;

2
drivers/clk/sunxi-ng/ccu_nkm.h
View file

@ -27,6 +27,8 @@ struct ccu_nkm {
struct ccu_mux_internal mux;
unsigned int fixed_post_div;
unsigned long max_m_n_ratio;
unsigned long min_parent_m_ratio;
struct ccu_common common;
};