linux-kernel - [PATCH RFC v1 3/3] clk: meson: pll: switch to determine

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Message-Id: <20210517203724.1006254-4-martin.blumenstingl@googlemail.com>
Date:   Mon, 17 May 2021 22:37:24 +0200
From:   Martin Blumenstingl <martin.blumenstingl@...glemail.com>
To:     mturquette@...libre.com, sboyd@...nel.org, narmstrong@...libre.com,
        jbrunet@...libre.com, linux-clk@...r.kernel.org
Cc:     khilman@...libre.com, linux-kernel@...r.kernel.org,
        linux-amlogic@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>
Subject: [PATCH RFC v1 3/3] clk: meson: pll: switch to determine_rate for the PLL ops

This increases the maxmium supported frequency on 32-bit systems from
2^31 (signed long as used by clk_ops.round_rate, maximum value:
approx. 2.14GHz) to 2^32 (unsigned long as used by
clk_ops.determine_rate, maximum value: approx. 4.29GHz).
On Meson8/8b/8m2 the HDMI PLL and it's OD (post-dividers) are
capable of running at up to 2.97GHz. So switch the divider
implementation in clk-regmap to clk_ops.determine_rate to support these
higher frequencies on 32-bit systems.

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@...glemail.com>
---
 drivers/clk/meson/clk-pll.c | 26 +++++++++++++++-----------
 1 file changed, 15 insertions(+), 11 deletions(-)

diff --git a/drivers/clk/meson/clk-pll.c b/drivers/clk/meson/clk-pll.c
index 49f27fe53213..9e55617bc3b4 100644
--- a/drivers/clk/meson/clk-pll.c
+++ b/drivers/clk/meson/clk-pll.c
@@ -242,8 +242,8 @@ static int meson_clk_get_pll_settings(unsigned long rate,
 	return best ? 0 : -EINVAL;
 }
 
-static long meson_clk_pll_round_rate(struct clk_hw *hw, unsigned long rate,
-				     unsigned long *parent_rate)
+static int meson_clk_pll_determine_rate(struct clk_hw *hw,
+					struct clk_rate_request *req)
 {
 	struct clk_regmap *clk = to_clk_regmap(hw);
 	struct meson_clk_pll_data *pll = meson_clk_pll_data(clk);
@@ -251,22 +251,26 @@ static long meson_clk_pll_round_rate(struct clk_hw *hw, unsigned long rate,
 	unsigned long round;
 	int ret;
 
-	ret = meson_clk_get_pll_settings(rate, *parent_rate, &m, &n, pll);
+	ret = meson_clk_get_pll_settings(req->rate, req->best_parent_rate,
+					 &m, &n, pll);
 	if (ret)
-		return meson_clk_pll_recalc_rate(hw, *parent_rate);
+		return ret;
 
-	round = __pll_params_to_rate(*parent_rate, m, n, 0, pll);
+	round = __pll_params_to_rate(req->best_parent_rate, m, n, 0, pll);
 
-	if (!MESON_PARM_APPLICABLE(&pll->frac) || rate == round)
-		return round;
+	if (!MESON_PARM_APPLICABLE(&pll->frac) || req->rate == round) {
+		req->rate = round;
+		return 0;
+	}
 
 	/*
 	 * The rate provided by the setting is not an exact match, let's
 	 * try to improve the result using the fractional parameter
 	 */
-	frac = __pll_params_with_frac(rate, *parent_rate, m, n, pll);
+	frac = __pll_params_with_frac(req->rate, req->best_parent_rate, m, n, pll);
+	req->rate = __pll_params_to_rate(req->best_parent_rate, m, n, frac, pll);
 
-	return __pll_params_to_rate(*parent_rate, m, n, frac, pll);
+	return 0;
 }
 
 static int meson_clk_pll_wait_lock(struct clk_hw *hw)
@@ -419,7 +423,7 @@ static int meson_clk_pll_set_rate(struct clk_hw *hw, unsigned long rate,
  */
 const struct clk_ops meson_clk_pcie_pll_ops = {
 	.recalc_rate	= meson_clk_pll_recalc_rate,
-	.round_rate	= meson_clk_pll_round_rate,
+	.determine_rate	= meson_clk_pll_determine_rate,
 	.is_enabled	= meson_clk_pll_is_enabled,
 	.enable		= meson_clk_pcie_pll_enable,
 	.disable	= meson_clk_pll_disable
@@ -429,7 +433,7 @@ EXPORT_SYMBOL_GPL(meson_clk_pcie_pll_ops);
 const struct clk_ops meson_clk_pll_ops = {
 	.init		= meson_clk_pll_init,
 	.recalc_rate	= meson_clk_pll_recalc_rate,
-	.round_rate	= meson_clk_pll_round_rate,
+	.determine_rate	= meson_clk_pll_determine_rate,
 	.set_rate	= meson_clk_pll_set_rate,
 	.is_enabled	= meson_clk_pll_is_enabled,
 	.enable		= meson_clk_pll_enable,
-- 
2.31.1