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From:   Quan Nguyen <quan@os.amperecomputing.com>
To:     Corey Minyard <minyard@acm.org>, Rob Herring <robh+dt@kernel.org>,
        Joel Stanley <joel@jms.id.au>,
        Andrew Jeffery <andrew@aj.id.au>,
        Brendan Higgins <brendanhiggins@google.com>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
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        Philipp Zabel <p.zabel@pengutronix.de>,
        openipmi-developer@lists.sourceforge.net,
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        linux-aspeed@lists.ozlabs.org, linux-kernel@vger.kernel.org,
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Cc:     Open Source Submission <patches@amperecomputing.com>,
        Phong Vo <phong@os.amperecomputing.com>,
        "Thang Q . Nguyen" <thang@os.amperecomputing.com>,
        openbmc@lists.ozlabs.org
Subject: [PATCH v3 1/7] i2c: i2c-core-smbus: Expose PEC calculate function for generic use
Date:   Wed, 19 May 2021 14:49:28 +0700
Message-Id: <20210519074934.20712-2-quan@os.amperecomputing.com>
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Expose the PEC calculation i2c_smbus_pec() for generic use.

Signed-off-by: Quan Nguyen <quan@os.amperecomputing.com>
---
 drivers/i2c/i2c-core-smbus.c | 12 ++++++++++--
 include/linux/i2c.h          |  1 +
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/i2c-core-smbus.c b/drivers/i2c/i2c-core-smbus.c
index d2d32c0fd8c3..e5b2d1465e7e 100644
--- a/drivers/i2c/i2c-core-smbus.c
+++ b/drivers/i2c/i2c-core-smbus.c
@@ -37,8 +37,15 @@ static u8 crc8(u16 data)
 	return (u8)(data >> 8);
 }
 
-/* Incremental CRC8 over count bytes in the array pointed to by p */
-static u8 i2c_smbus_pec(u8 crc, u8 *p, size_t count)
+/**
+ * i2c_smbus_pec - Incremental CRC8 over the given input data array
+ * @crc: previous return crc8 value
+ * @p: pointer to data buffer.
+ * @count: number of bytes in data buffer.
+ *
+ * Incremental CRC8 over count bytes in the array pointed to by p
+ */
+u8 i2c_smbus_pec(u8 crc, u8 *p, size_t count)
 {
 	int i;
 
@@ -46,6 +53,7 @@ static u8 i2c_smbus_pec(u8 crc, u8 *p, size_t count)
 		crc = crc8((crc ^ p[i]) << 8);
 	return crc;
 }
+EXPORT_SYMBOL(i2c_smbus_pec);
 
 /* Assume a 7-bit address, which is reasonable for SMBus */
 static u8 i2c_smbus_msg_pec(u8 pec, struct i2c_msg *msg)
diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index e8f2ac8c9c3d..2494a007dfda 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -147,6 +147,7 @@ s32 __i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr,
 /* Now follow the 'nice' access routines. These also document the calling
    conventions of i2c_smbus_xfer. */
 
+u8 i2c_smbus_pec(u8 crc, u8 *p, size_t count);
 s32 i2c_smbus_read_byte(const struct i2c_client *client);
 s32 i2c_smbus_write_byte(const struct i2c_client *client, u8 value);
 s32 i2c_smbus_read_byte_data(const struct i2c_client *client, u8 command);
-- 
2.28.0