linux-kernel - [PATCH v16 01/11] fw_cfg: fix sparse warnings in fw_cfg_sel

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Date:   Wed, 28 Feb 2018 16:06:05 +0100
From:   Marc-André Lureau <marcandre.lureau@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     arnd@...db.de, bhe@...hat.com, slp@...hat.com, mst@...hat.com,
        somlo@....edu, xiaolong.ye@...el.com,
        Marc-André Lureau <marcandre.lureau@...hat.com>
Subject: [PATCH v16 01/11] fw_cfg: fix sparse warnings in fw_cfg_sel_endianness()

Dispatch to the appropriate iowrite() instead of casting restricted
type to u16.

- if fw_cfg_is_mmio:
  before: iowrite16(cpu_to_be16(key))
  after: iowrite16be(key)
- if !fw_cfg_is_mmio:
  before: iowrite16(cpu_to_le16(key))
  after: iowrite16(key)
  which is equivalent on little-endian systems, where fw_cfg IO is supported.

Fixes:
$ make C=1 CF=-D__CHECK_ENDIAN__ drivers/firmware/qemu_fw_cfg.o

drivers/firmware/qemu_fw_cfg.c:55:33: warning: restricted __be16 degrades to integer
drivers/firmware/qemu_fw_cfg.c:55:52: warning: restricted __le16 degrades to integer

Signed-off-by: Marc-André Lureau <marcandre.lureau@...hat.com>
---
 drivers/firmware/qemu_fw_cfg.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/firmware/qemu_fw_cfg.c b/drivers/firmware/qemu_fw_cfg.c
index a41b572eeeb1..e7ea2b3b1d11 100644
--- a/drivers/firmware/qemu_fw_cfg.c
+++ b/drivers/firmware/qemu_fw_cfg.c
@@ -68,9 +68,12 @@ static void __iomem *fw_cfg_reg_data;
 static DEFINE_MUTEX(fw_cfg_dev_lock);
 
 /* pick appropriate endianness for selector key */
-static inline u16 fw_cfg_sel_endianness(u16 key)
+static void fw_cfg_sel_endianness(u16 key)
 {
-	return fw_cfg_is_mmio ? cpu_to_be16(key) : cpu_to_le16(key);
+	if (fw_cfg_is_mmio)
+		iowrite16be(key, fw_cfg_reg_ctrl);
+	else
+		iowrite16(key, fw_cfg_reg_ctrl);
 }
 
 /* read chunk of given fw_cfg blob (caller responsible for sanity-check) */
@@ -92,7 +95,7 @@ static inline void fw_cfg_read_blob(u16 key,
 	}
 
 	mutex_lock(&fw_cfg_dev_lock);
-	iowrite16(fw_cfg_sel_endianness(key), fw_cfg_reg_ctrl);
+	fw_cfg_sel_endianness(key);
 	while (pos-- > 0)
 		ioread8(fw_cfg_reg_data);
 	ioread8_rep(fw_cfg_reg_data, buf, count);
-- 
2.16.1.73.g5832b7e9f2