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Message-Id: <3a54a6703879d10f08cf0275a2a69297ebd2b1d4.1637592133.git.geert+renesas@glider.be>
Date: Mon, 22 Nov 2021 16:53:54 +0100
From: Geert Uytterhoeven <geert+renesas@...der.be>
To: Tony Lindgren <tony@...mide.com>,
Russell King <linux@...linux.org.uk>,
Rajendra Nayak <rnayak@...eaurora.org>,
Paul Walmsley <paul@...an.com>,
Michael Turquette <mturquette@...libre.com>,
Stephen Boyd <sboyd@...nel.org>,
Nicolas Ferre <nicolas.ferre@...rochip.com>,
Alexandre Belloni <alexandre.belloni@...tlin.com>,
Ludovic Desroches <ludovic.desroches@...rochip.com>,
Tero Kristo <kristo@...nel.org>,
Jonathan Cameron <jic23@...nel.org>,
Lars-Peter Clausen <lars@...afoo.de>,
Lorenzo Bianconi <lorenzo.bianconi83@...il.com>,
Benoit Parrot <bparrot@...com>,
Mauro Carvalho Chehab <mchehab@...nel.org>,
Adrian Hunter <adrian.hunter@...el.com>,
Andrew Jeffery <andrew@...id.au>,
Ulf Hansson <ulf.hansson@...aro.org>,
Joel Stanley <joel@....id.au>,
Ping-Ke Shih <pkshih@...ltek.com>,
Kalle Valo <kvalo@...eaurora.org>,
"David S . Miller" <davem@...emloft.net>,
Jakub Kicinski <kuba@...nel.org>,
Linus Walleij <linus.walleij@...aro.org>,
Liam Girdwood <lgirdwood@...il.com>,
Mark Brown <broonie@...nel.org>,
Magnus Damm <magnus.damm@...il.com>,
Eduardo Valentin <edubezval@...il.com>,
Keerthy <j-keerthy@...com>,
"Rafael J . Wysocki" <rafael@...nel.org>,
Daniel Lezcano <daniel.lezcano@...aro.org>,
Amit Kucheria <amitk@...nel.org>,
Zhang Rui <rui.zhang@...el.com>,
Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.com>
Cc: linux-arm-kernel@...ts.infradead.org, linux-omap@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-clk@...r.kernel.org,
linux-renesas-soc@...r.kernel.org, linux-iio@...r.kernel.org,
linux-media@...r.kernel.org, linux-mmc@...r.kernel.org,
linux-aspeed@...ts.ozlabs.org, openbmc@...ts.ozlabs.org,
linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
linux-gpio@...r.kernel.org, linux-pm@...r.kernel.org,
alsa-devel@...a-project.org,
Geert Uytterhoeven <geert+renesas@...der.be>
Subject: [PATCH 01/17] bitfield: Add non-constant field_{prep,get}() helpers
The existing FIELD_{GET,PREP}() macros are limited to compile-time
constants. However, it is very common to prepare or extract bitfield
elements where the bitfield mask is not a compile-time constant.
To avoid this limitation, the AT91 clock driver already has its own
field_{prep,get}() macros. Make them available for general use by
moving them to <linux/bitfield.h>, and improve them slightly:
1. Avoid evaluating macro parameters more than once,
2. Replace "ffs() - 1" by "__ffs()", as the latter operates on
"unsigned long", just like BIT() and GENMASK().
Signed-off-by: Geert Uytterhoeven <geert+renesas@...der.be>
---
Using __ffs() actually reduces code size (16 bytes for each of
drivers/clk/at91/clk-{generated,peripheral}.o), as __ffs() doesn't
need to verify that the value passed is non-zero.
---
drivers/clk/at91/clk-peripheral.c | 1 +
drivers/clk/at91/pmc.h | 3 ---
include/linux/bitfield.h | 30 ++++++++++++++++++++++++++++++
3 files changed, 31 insertions(+), 3 deletions(-)
diff --git a/drivers/clk/at91/clk-peripheral.c b/drivers/clk/at91/clk-peripheral.c
index e14fa5ac734cead7..e2f33498139a1b8c 100644
--- a/drivers/clk/at91/clk-peripheral.c
+++ b/drivers/clk/at91/clk-peripheral.c
@@ -3,6 +3,7 @@
* Copyright (C) 2013 Boris BREZILLON <b.brezillon@...rkiz.com>
*/
+#include <linux/bitfield.h>
#include <linux/bitops.h>
#include <linux/clk-provider.h>
#include <linux/clkdev.h>
diff --git a/drivers/clk/at91/pmc.h b/drivers/clk/at91/pmc.h
index 3a1bf6194c287d09..1256e1ab91526a25 100644
--- a/drivers/clk/at91/pmc.h
+++ b/drivers/clk/at91/pmc.h
@@ -114,9 +114,6 @@ struct at91_clk_pms {
unsigned int parent;
};
-#define field_get(_mask, _reg) (((_reg) & (_mask)) >> (ffs(_mask) - 1))
-#define field_prep(_mask, _val) (((_val) << (ffs(_mask) - 1)) & (_mask))
-
#define ndck(a, s) (a[s - 1].id + 1)
#define nck(a) (a[ARRAY_SIZE(a) - 1].id + 1)
struct pmc_data *pmc_data_allocate(unsigned int ncore, unsigned int nsystem,
diff --git a/include/linux/bitfield.h b/include/linux/bitfield.h
index 4e035aca6f7e6000..f03b0712e4babec1 100644
--- a/include/linux/bitfield.h
+++ b/include/linux/bitfield.h
@@ -156,4 +156,34 @@ __MAKE_OP(64)
#undef __MAKE_OP
#undef ____MAKE_OP
+/**
+ * field_prep() - prepare a bitfield element
+ * @_mask: shifted mask defining the field's length and position
+ * @_val: value to put in the field
+ *
+ * field_prep() masks and shifts up the value. The result should be
+ * combined with other fields of the bitfield using logical OR.
+ * Unlike FIELD_PREP(), @_mask is not limited to a compile-time constant.
+ */
+#define field_prep(_mask, _val) \
+ ({ \
+ typeof(_mask) ___mask = (_mask); \
+ (((_val) << __ffs(___mask)) & (___mask)); \
+ })
+
+/**
+ * field_get() - extract a bitfield element
+ * @_mask: shifted mask defining the field's length and position
+ * @_reg: value of entire bitfield
+ *
+ * field_get() extracts the field specified by @_mask from the
+ * bitfield passed in as @_reg by masking and shifting it down.
+ * Unlike FIELD_GET(), @_mask is not limited to a compile-time constant.
+ */
+#define field_get(_mask, _reg) \
+ ({ \
+ typeof(_mask) ___mask = _mask; \
+ (((_reg) & (___mask)) >> __ffs(___mask)); \
+ })
+
#endif
--
2.25.1
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