[PATCH] i2c: core: export i2c_smbus_pec()

[PATCH] i2c: core: export i2c_smbus_pec()

[Matt Johnston]

I2C slave interface drivers have to calculate the PEC themselves
in the i2c slave event handler. This will be used for an in-progress
driver for MCTP I2C transport.

Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
---
 drivers/i2c/i2c-core-smbus.c | 3 ++-
 include/linux/i2c.h          | 2 ++
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/i2c/i2c-core-smbus.c b/drivers/i2c/i2c-core-smbus.c
index d2d32c0fd8c3..27a06b80decb 100644
--- a/drivers/i2c/i2c-core-smbus.c
+++ b/drivers/i2c/i2c-core-smbus.c
@@ -38,7 +38,7 @@ static u8 crc8(u16 data)
 }
 
 /* Incremental CRC8 over count bytes in the array pointed to by p */
-static u8 i2c_smbus_pec(u8 crc, u8 *p, size_t count)
+u8 i2c_smbus_pec(u8 crc, u8 *p, size_t count)
 {
 	int i;
 
@@ -46,6 +46,7 @@ static u8 i2c_smbus_pec(u8 crc, u8 *p, size_t count)
 		crc = crc8((crc ^ p[i]) << 8);
 	return crc;
 }
+EXPORT_SYMBOL_GPL(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..9e5e5e8192c3 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -186,6 +186,8 @@ s32 i2c_smbus_read_i2c_block_data_or_emulated(const struct i2c_client *client,
 					      u8 *values);
 int i2c_get_device_id(const struct i2c_client *client,
 		      struct i2c_device_identity *id);
+
+u8 i2c_smbus_pec(u8 crc, u8 *p, size_t count);
 #endif /* I2C */
 
 /**
-- 
2.30.2

Re: [PATCH] i2c: core: export i2c_smbus_pec()

[Wolfram Sang]

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On Mon, May 17, 2021 at 11:11:38AM +0800, Matt Johnston wrote:
> I2C slave interface drivers have to calculate the PEC themselves
> in the i2c slave event handler. This will be used for an in-progress
> driver for MCTP I2C transport.
> 
> Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>

This is fine per se. Yet, there should be a user if we export it. So,
I suggest to resend it together with the slave driver using it and I
will ack this then.


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Re: [PATCH] i2c: core: export i2c_smbus_pec()

[Wolfram Sang]

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On Fri, May 28, 2021 at 10:42:14AM +0200, Wolfram Sang wrote:
> On Mon, May 17, 2021 at 11:11:38AM +0800, Matt Johnston wrote:
> > I2C slave interface drivers have to calculate the PEC themselves
> > in the i2c slave event handler. This will be used for an in-progress
> > driver for MCTP I2C transport.
> > 
> > Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
> 
> This is fine per se. Yet, there should be a user if we export it. So,
> I suggest to resend it together with the slave driver using it and I
> will ack this then.

Okay, there was another user requesting this feature with a patch. It
also provided kdoc for i2c_smbus_pec. This, together with the simplified
dependencies of two users in flight, made me apply the other patch, so
you can base your work on top of for-next or 5.14 now. I added you with
an acked-by tag to have you credited, too. I hope you are fine with this
approach.

http://patchwork.ozlabs.org/project/linux-i2c/patch/20210519074934.20712-2-quan@os.amperecomputing.com/


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