From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Heiko Stuebner <heiko@sntech.de>,
Elaine Zhang <zhangqing@rock-chips.com>,
Stephen Boyd <sboyd@kernel.org>,
linux-kernel@vger.kernel.org, linux-clk@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-rockchip@lists.infradead.org
Cc: Michael Turquette <mturquette@baylibre.com>
Subject: [PATCH v2 1/3] clk: fractional-divider: Export approximation algo to the CCF users
Date: Fri, 16 Jul 2021 16:34:46 +0300 [thread overview]
Message-ID: <20210716133448.24890-1-andriy.shevchenko@linux.intel.com> (raw)
At least one user currently duplicates some functions that are provided
by fractional divider module. Let's export approximation algo 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>
---
v2: fixed compilation error (LKP), successfully compile-tested on x86
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
next reply other threads:[~2021-07-16 13:34 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-16 13:34 Andy Shevchenko [this message]
2021-07-16 13:34 ` [PATCH v2 2/3] clk: fractional-divider: Introduce NO_PRESCALER flag Andy Shevchenko
2021-07-22 9:29 ` Liu Ying
2021-07-22 9:38 ` Andy Shevchenko
2021-07-22 9:43 ` Liu Ying
2021-07-22 15:42 ` Andy Shevchenko
2021-07-16 13:34 ` [PATCH v2 3/3] clk: fractional-divider: Document the arithmetics used behind the code Andy Shevchenko
2021-07-17 12:19 ` [PATCH v2 1/3] clk: fractional-divider: Export approximation algo to the CCF users Heiko Stübner
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210716133448.24890-1-andriy.shevchenko@linux.intel.com \
--to=andriy.shevchenko@linux.intel.com \
--cc=heiko@sntech.de \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-clk@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-rockchip@lists.infradead.org \
--cc=mturquette@baylibre.com \
--cc=sboyd@kernel.org \
--cc=zhangqing@rock-chips.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
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).