linux-kernel - [PATCH v2 1/6] clk: ingenic: Make PLL clock "od" field optional

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Message-Id: <20221026194345.243007-2-aidanmacdonald.0x0@gmail.com>
Date:   Wed, 26 Oct 2022 20:43:40 +0100
From:   Aidan MacDonald <aidanmacdonald.0x0@...il.com>
To:     paul@...pouillou.net, mturquette@...libre.com, sboyd@...nel.org,
        robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org
Cc:     zhouyu@...yeetech.com, linux-mips@...r.kernel.org,
        linux-clk@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2 1/6] clk: ingenic: Make PLL clock "od" field optional

Add support for defining PLL clocks with od_bits = 0, meaning that
OD is fixed to 1 and there is no OD field in the register. In this
case od_max must also be 0, which is enforced with BUG_ON().

Signed-off-by: Aidan MacDonald <aidanmacdonald.0x0@...il.com>
---
v1 -> v2: Simplify od lookup in ingenic_pll_recalc_rate() and
          enforce od_max == 0 when od_bits is zero.

 drivers/clk/ingenic/cgu.c | 21 +++++++++++++++------
 drivers/clk/ingenic/cgu.h |  3 ++-
 2 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/drivers/clk/ingenic/cgu.c b/drivers/clk/ingenic/cgu.c
index 861c50d6cb24..3481129114b1 100644
--- a/drivers/clk/ingenic/cgu.c
+++ b/drivers/clk/ingenic/cgu.c
@@ -83,7 +83,7 @@ ingenic_pll_recalc_rate(struct clk_hw *hw, unsigned long parent_rate)
 	const struct ingenic_cgu_clk_info *clk_info = to_clk_info(ingenic_clk);
 	struct ingenic_cgu *cgu = ingenic_clk->cgu;
 	const struct ingenic_cgu_pll_info *pll_info;
-	unsigned m, n, od_enc, od;
+	unsigned m, n, od, od_enc = 0;
 	bool bypass;
 	u32 ctl;
 
@@ -96,8 +96,11 @@ ingenic_pll_recalc_rate(struct clk_hw *hw, unsigned long parent_rate)
 	m += pll_info->m_offset;
 	n = (ctl >> pll_info->n_shift) & GENMASK(pll_info->n_bits - 1, 0);
 	n += pll_info->n_offset;
-	od_enc = ctl >> pll_info->od_shift;
-	od_enc &= GENMASK(pll_info->od_bits - 1, 0);
+
+	if (pll_info->od_bits > 0) {
+		od_enc = ctl >> pll_info->od_shift;
+		od_enc &= GENMASK(pll_info->od_bits - 1, 0);
+	}
 
 	if (pll_info->bypass_bit >= 0) {
 		ctl = readl(cgu->base + pll_info->bypass_reg);
@@ -112,7 +115,11 @@ ingenic_pll_recalc_rate(struct clk_hw *hw, unsigned long parent_rate)
 		if (pll_info->od_encoding[od] == od_enc)
 			break;
 	}
-	BUG_ON(od == pll_info->od_max);
+	/* if od_max = 0, od_bits should be 0 and od is fixed to 1. */
+	if (pll_info->od_max == 0)
+		BUG_ON(pll_info->od_bits != 0);
+	else
+		BUG_ON(od == pll_info->od_max);
 	od++;
 
 	return div_u64((u64)parent_rate * m * pll_info->rate_multiplier,
@@ -215,8 +222,10 @@ ingenic_pll_set_rate(struct clk_hw *hw, unsigned long req_rate,
 	ctl &= ~(GENMASK(pll_info->n_bits - 1, 0) << pll_info->n_shift);
 	ctl |= (n - pll_info->n_offset) << pll_info->n_shift;
 
-	ctl &= ~(GENMASK(pll_info->od_bits - 1, 0) << pll_info->od_shift);
-	ctl |= pll_info->od_encoding[od - 1] << pll_info->od_shift;
+	if (pll_info->od_bits > 0) {
+		ctl &= ~(GENMASK(pll_info->od_bits - 1, 0) << pll_info->od_shift);
+		ctl |= pll_info->od_encoding[od - 1] << pll_info->od_shift;
+	}
 
 	writel(ctl, cgu->base + pll_info->reg);
 
diff --git a/drivers/clk/ingenic/cgu.h b/drivers/clk/ingenic/cgu.h
index 147b7df0d657..567142b584bb 100644
--- a/drivers/clk/ingenic/cgu.h
+++ b/drivers/clk/ingenic/cgu.h
@@ -33,7 +33,8 @@
  * @od_shift: the number of bits to shift the post-VCO divider value by (ie.
  *            the index of the lowest bit of the post-VCO divider value in
  *            the PLL's control register)
- * @od_bits: the size of the post-VCO divider field in bits
+ * @od_bits: the size of the post-VCO divider field in bits, or 0 if no
+ *	     OD field exists (then the OD is fixed to 1)
  * @od_max: the maximum post-VCO divider value
  * @od_encoding: a pointer to an array mapping post-VCO divider values to
  *               their encoded values in the PLL control register, or -1 for
-- 
2.38.1