linux-kernel - [PATCH v4 5/9] pwm: rzg2l-gpt: Add calculate_prescale() callback to struct rzg2l_gpt

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Message-ID: <20251208152133.269316-6-biju.das.jz@bp.renesas.com>
Date: Mon,  8 Dec 2025 15:21:22 +0000
From: Biju <biju.das.au@...il.com>
To: Uwe Kleine-König <ukleinek@...nel.org>,
	Geert Uytterhoeven <geert+renesas@...der.be>,
	Magnus Damm <magnus.damm@...il.com>
Cc: Biju Das <biju.das.jz@...renesas.com>,
	linux-pwm@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-renesas-soc@...r.kernel.org,
	Prabhakar Mahadev Lad <prabhakar.mahadev-lad.rj@...renesas.com>,
	Biju Das <biju.das.au@...il.com>,
	Tommaso Merciai <tommaso.merciai.xr@...renesas.com>
Subject: [PATCH v4 5/9] pwm: rzg2l-gpt: Add calculate_prescale() callback to struct rzg2l_gpt_info

From: Biju Das <biju.das.jz@...renesas.com>

RZ/G2L GPT the prescale factors are continuous power of 4 whereas on RZ/G3E
it is power of 2 but discontinuous. Add calculate_prescale() callback to
struct rzg2l_gpt_info for handling this difference.

Reviewed-by: Tommaso Merciai <tommaso.merciai.xr@...renesas.com>
Signed-off-by: Biju Das <biju.das.jz@...renesas.com>
---
v3->v4:
 * No change.
v2->v3:
 * No change.
v1->v2:
 * Collected tag.
---
 drivers/pwm/pwm-rzg2l-gpt.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/pwm/pwm-rzg2l-gpt.c b/drivers/pwm/pwm-rzg2l-gpt.c
index 47324c9fa6dd..791900f6de3d 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;
 };
@@ -131,8 +132,7 @@ static void rzg2l_gpt_modify(struct rzg2l_gpt_chip *rzg2l_gpt, u32 reg, u32 clr,
 			(rzg2l_gpt_read(rzg2l_gpt, reg) & ~clr) | set);
 }
 
-static u8 rzg2l_gpt_calculate_prescale(struct rzg2l_gpt_chip *rzg2l_gpt,
-				       u64 period_ticks)
+static u8 rzg2l_gpt_calculate_prescale(u64 period_ticks)
 {
 	u32 prescaled_period_ticks;
 	u8 prescale;
@@ -292,7 +292,7 @@ static int rzg2l_gpt_round_waveform_tohw(struct pwm_chip *chip,
 		}
 	}
 
-	wfhw->prescale = rzg2l_gpt_calculate_prescale(rzg2l_gpt, period_ticks);
+	wfhw->prescale = info->calculate_prescale(period_ticks);
 	pv = rzg2l_gpt_calculate_pv_or_dc(info, period_ticks, wfhw->prescale);
 	wfhw->gtpr = pv;
 	if (is_small_second_period)
@@ -494,6 +494,7 @@ 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