LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
* [PATCH v4 1/4] clk: fractional-divider: Export approximation algorithm to the CCF users
@ 2021-08-12 17:00 Andy Shevchenko
  2021-08-12 17:00 ` [PATCH v4 2/4] clk: fractional-divider: Hide clk_fractional_divider_ops from wide audience Andy Shevchenko
                   ` (4 more replies)
  0 siblings, 5 replies; 10+ messages in thread
From: Andy Shevchenko @ 2021-08-12 17:00 UTC (permalink / raw)
  To: Rafael J. Wysocki, Andy Shevchenko, Heiko Stuebner, Elaine Zhang,
	Stephen Boyd, linux-kernel, linux-acpi, linux-clk, linux-imx,
	linux-arm-kernel, linux-rockchip
  Cc: Rafael J. Wysocki, Len Brown, Michael Turquette, Abel Vesa,
	Shawn Guo, Sascha Hauer, Pengutronix Kernel Team, Fabio Estevam,
	Lee Jones

At least one user currently duplicates some functions that are provided
by fractional divider module. Let's export approximation algorithm and
replace the open-coded variant.

As a bonus the exported function will get better documentation in place.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Acked-by: Heiko Stuebner <heiko@sntech.de>
---
v4: rebased on top of latest CLK codebase
 drivers/clk/clk-fractional-divider.c | 11 +++++++----
 drivers/clk/clk-fractional-divider.h |  9 +++++++++
 drivers/clk/rockchip/clk.c           | 17 +++--------------
 3 files changed, 19 insertions(+), 18 deletions(-)
 create mode 100644 drivers/clk/clk-fractional-divider.h

diff --git a/drivers/clk/clk-fractional-divider.c b/drivers/clk/clk-fractional-divider.c
index b1e556f20911..535d299af646 100644
--- a/drivers/clk/clk-fractional-divider.c
+++ b/drivers/clk/clk-fractional-divider.c
@@ -14,6 +14,8 @@
 #include <linux/slab.h>
 #include <linux/rational.h>
 
+#include "clk-fractional-divider.h"
+
 static inline u32 clk_fd_readl(struct clk_fractional_divider *fd)
 {
 	if (fd->flags & CLK_FRAC_DIVIDER_BIG_ENDIAN)
@@ -68,9 +70,10 @@ static unsigned long clk_fd_recalc_rate(struct clk_hw *hw,
 	return ret;
 }
 
-static void clk_fd_general_approximation(struct clk_hw *hw, unsigned long rate,
-					 unsigned long *parent_rate,
-					 unsigned long *m, unsigned long *n)
+void clk_fractional_divider_general_approximation(struct clk_hw *hw,
+						  unsigned long rate,
+						  unsigned long *parent_rate,
+						  unsigned long *m, unsigned long *n)
 {
 	struct clk_fractional_divider *fd = to_clk_fd(hw);
 	unsigned long scale;
@@ -102,7 +105,7 @@ static long clk_fd_round_rate(struct clk_hw *hw, unsigned long rate,
 	if (fd->approximation)
 		fd->approximation(hw, rate, parent_rate, &m, &n);
 	else
-		clk_fd_general_approximation(hw, rate, parent_rate, &m, &n);
+		clk_fractional_divider_general_approximation(hw, rate, parent_rate, &m, &n);
 
 	ret = (u64)*parent_rate * m;
 	do_div(ret, n);
diff --git a/drivers/clk/clk-fractional-divider.h b/drivers/clk/clk-fractional-divider.h
new file mode 100644
index 000000000000..4fa359a12ef4
--- /dev/null
+++ b/drivers/clk/clk-fractional-divider.h
@@ -0,0 +1,9 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+struct clk_hw;
+
+void clk_fractional_divider_general_approximation(struct clk_hw *hw,
+						  unsigned long rate,
+						  unsigned long *parent_rate,
+						  unsigned long *m,
+						  unsigned long *n);
diff --git a/drivers/clk/rockchip/clk.c b/drivers/clk/rockchip/clk.c
index 049e5e0b64f6..b7be7e11b0df 100644
--- a/drivers/clk/rockchip/clk.c
+++ b/drivers/clk/rockchip/clk.c
@@ -22,6 +22,8 @@
 #include <linux/regmap.h>
 #include <linux/reboot.h>
 #include <linux/rational.h>
+
+#include "../clk-fractional-divider.h"
 #include "clk.h"
 
 /*
@@ -178,10 +180,8 @@ static void rockchip_fractional_approximation(struct clk_hw *hw,
 		unsigned long rate, unsigned long *parent_rate,
 		unsigned long *m, unsigned long *n)
 {
-	struct clk_fractional_divider *fd = to_clk_fd(hw);
 	unsigned long p_rate, p_parent_rate;
 	struct clk_hw *p_parent;
-	unsigned long scale;
 
 	p_rate = clk_hw_get_rate(clk_hw_get_parent(hw));
 	if ((rate * 20 > p_rate) && (p_rate % rate != 0)) {
@@ -190,18 +190,7 @@ static void rockchip_fractional_approximation(struct clk_hw *hw,
 		*parent_rate = p_parent_rate;
 	}
 
-	/*
-	 * Get rate closer to *parent_rate to guarantee there is no overflow
-	 * for m and n. In the result it will be the nearest rate left shifted
-	 * by (scale - fd->nwidth) bits.
-	 */
-	scale = fls_long(*parent_rate / rate - 1);
-	if (scale > fd->nwidth)
-		rate <<= scale - fd->nwidth;
-
-	rational_best_approximation(rate, *parent_rate,
-			GENMASK(fd->mwidth - 1, 0), GENMASK(fd->nwidth - 1, 0),
-			m, n);
+	clk_fractional_divider_general_approximation(hw, rate, parent_rate, m, n);
 }
 
 static struct clk *rockchip_clk_register_frac_branch(
-- 
2.30.2


^ permalink raw reply	[flat|nested] 10+ messages in thread

end of thread, other threads:[~2021-09-08 10:53 UTC | newest]

Thread overview: 10+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-08-12 17:00 [PATCH v4 1/4] clk: fractional-divider: Export approximation algorithm to the CCF users Andy Shevchenko
2021-08-12 17:00 ` [PATCH v4 2/4] clk: fractional-divider: Hide clk_fractional_divider_ops from wide audience Andy Shevchenko
2021-08-12 17:00 ` [PATCH v4 3/4] clk: fractional-divider: Introduce POWER_OF_TWO_PS flag Andy Shevchenko
2021-08-12 17:00 ` [PATCH v4 4/4] clk: fractional-divider: Document the arithmetics used behind the code Andy Shevchenko
     [not found] ` <162879819529.19113.6409882476721828944@swboyd.mtv.corp.google.com>
2021-08-13  9:43   ` [PATCH v4 1/4] clk: fractional-divider: Export approximation algorithm to the CCF users Andy Shevchenko
2021-08-17 12:45     ` Andy Shevchenko
2021-09-07 15:44 ` Chris Morgan
2021-09-07 17:54   ` Andy Shevchenko
2021-09-07 18:06     ` Andy Shevchenko
     [not found]       ` <SN6PR06MB534203466EA3D4E22858479FA5D49@SN6PR06MB5342.namprd06.prod.outlook.com>
2021-09-08 10:52         ` Andy Shevchenko

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).