linux-kernel - [PATCH RFC v1 1/3] clk: divider: Add re-usable determine

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Message-Id: <20210517203724.1006254-2-martin.blumenstingl@googlemail.com>
Date:   Mon, 17 May 2021 22:37:22 +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 1/3] clk: divider: Add re-usable determine_rate implementations

These are useful when running on 32-bit systems to increase the upper
supported frequency limit. clk_ops.round_rate returns a signed long
which limits the maximum rate on 32-bit systems to 2^31 (or approx.
2.14GHz). clk_ops.determine_rate internally uses an unsigned long so
the maximum rate on 32-bit systems is 2^32 or approx. 4.29GHz.

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@...glemail.com>
---
 drivers/clk/clk-divider.c    | 39 +++++++++++++++++++++++++++++++++++-
 include/linux/clk-provider.h |  6 ++++++
 2 files changed, 44 insertions(+), 1 deletion(-)

diff --git a/drivers/clk/clk-divider.c b/drivers/clk/clk-divider.c
index 344997203f0e..24c94d2a3643 100644
--- a/drivers/clk/clk-divider.c
+++ b/drivers/clk/clk-divider.c
@@ -377,7 +377,6 @@ long divider_ro_round_rate_parent(struct clk_hw *hw, struct clk_hw *parent,
 }
 EXPORT_SYMBOL_GPL(divider_ro_round_rate_parent);
 
-
 static long clk_divider_round_rate(struct clk_hw *hw, unsigned long rate,
 				unsigned long *prate)
 {
@@ -399,6 +398,44 @@ static long clk_divider_round_rate(struct clk_hw *hw, unsigned long rate,
 				  divider->width, divider->flags);
 }
 
+int divider_determine_rate(struct clk_hw *hw, struct clk_rate_request *req,
+			   const struct clk_div_table *table, u8 width,
+			   unsigned long flags)
+{
+	int div;
+
+	div = clk_divider_bestdiv(hw, req->best_parent_hw, req->rate,
+				  &req->best_parent_rate, table, width, flags);
+
+	req->rate = DIV_ROUND_UP_ULL((u64)req->best_parent_rate, div);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(divider_determine_rate);
+
+int divider_ro_determine_rate(struct clk_hw *hw, struct clk_rate_request *req,
+			      const struct clk_div_table *table, u8 width,
+			      unsigned long flags, unsigned int val)
+{
+	int div;
+
+	div = _get_div(table, val, flags, width);
+
+	/* Even a read-only clock can propagate a rate change */
+	if (clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT) {
+		if (!req->best_parent_hw)
+			return -EINVAL;
+
+		req->best_parent_rate = clk_hw_round_rate(req->best_parent_hw,
+							  req->rate * div);
+	}
+
+	req->rate = DIV_ROUND_UP_ULL((u64)req->best_parent_rate, div);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(divider_ro_determine_rate);
+
 int divider_get_val(unsigned long rate, unsigned long parent_rate,
 		    const struct clk_div_table *table, u8 width,
 		    unsigned long flags)
diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index 162a2e5546a3..d83b829305c0 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -629,6 +629,12 @@ long divider_ro_round_rate_parent(struct clk_hw *hw, struct clk_hw *parent,
 				  unsigned long rate, unsigned long *prate,
 				  const struct clk_div_table *table, u8 width,
 				  unsigned long flags, unsigned int val);
+int divider_determine_rate(struct clk_hw *hw, struct clk_rate_request *req,
+			   const struct clk_div_table *table, u8 width,
+			   unsigned long flags);
+int divider_ro_determine_rate(struct clk_hw *hw, struct clk_rate_request *req,
+			      const struct clk_div_table *table, u8 width,
+			      unsigned long flags, unsigned int val);
 int divider_get_val(unsigned long rate, unsigned long parent_rate,
 		const struct clk_div_table *table, u8 width,
 		unsigned long flags);
-- 
2.31.1