[PATCH v7 5/9] pwm: rzg2l-gpt: Add calculate_prescale() callback to struct rzg2l_gpt_info

From: Biju

Date: Mon Aug 24 2026 - 09:01:15 EST


From: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>

The RZ/G2L GPT prescaler steps are continuous powers of 4, while RZ/G3E
uses powers of 2 but with a discontinuous sequence. Add a
calculate_prescale function pointer to struct rzg2l_gpt_info to allow
per-SoC prescaler selection logic. Replace the direct call to
rzg2l_gpt_calculate_prescale() in rzg2l_gpt_round_waveform_tohw() with an
indirect call through info->calculate_prescale(). Wire the existing
rzg2l_gpt_calculate_prescale() into rzg2l_data to preserve current RZ/G2L
behaviour.

Reviewed-by: Tommaso Merciai <tommaso.merciai.xr@xxxxxxxxxxxxxx>
Signed-off-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
---
v6->v7:
* No change.
v5->v6:
* No change.
v4->v5:
* Updated commit description.
v3->v4:
* No change.
v2->v3:
* No change.
v1->v2:
* Collected tag.
---
drivers/pwm/pwm-rzg2l-gpt.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/pwm/pwm-rzg2l-gpt.c b/drivers/pwm/pwm-rzg2l-gpt.c
index fc77c27f0a97..2a1c5a22484b 100644
--- a/drivers/pwm/pwm-rzg2l-gpt.c
+++ b/drivers/pwm/pwm-rzg2l-gpt.c
@@ -78,6 +78,7 @@
#define RZG2L_MAX_TICKS ((u64)U32_MAX * RZG2L_MAX_SCALE_FACTOR)

struct rzg2l_gpt_info {
+ u8 (*calculate_prescale)(u64 period);
u32 gtcr_tpcs;
u8 prescale_mult;
};
@@ -291,7 +292,7 @@ static int rzg2l_gpt_round_waveform_tohw(struct pwm_chip *chip,
period_ticks = rzg2l_gpt->period_ticks[ch];
}
} else {
- wfhw->prescale = rzg2l_gpt_calculate_prescale(period_ticks);
+ wfhw->prescale = info->calculate_prescale(period_ticks);
}

wfhw->gtpr = rzg2l_gpt_calculate_pv_or_dc(info, period_ticks, wfhw->prescale);
@@ -498,6 +499,7 @@ static int rzg2l_gpt_probe(struct platform_device *pdev)
}

static const struct rzg2l_gpt_info rzg2l_data = {
+ .calculate_prescale = rzg2l_gpt_calculate_prescale,
.gtcr_tpcs = RZG2L_GTCR_TPCS,
.prescale_mult = 2,
};
--
2.43.0