linux-kernel - [PATCH v4 3/6] i3c: add actual_len in i3c_priv

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Message-Id: <20231129221225.387952-4-Frank.Li@nxp.com>
Date:   Wed, 29 Nov 2023 17:12:22 -0500
From:   Frank Li <Frank.Li@....com>
To:     alexandre.belloni@...tlin.com
Cc:     Frank.li@....com, conor.culhane@...vaco.com, imx@...ts.linux.dev,
        joe@...ches.com, linux-i3c@...ts.infradead.org,
        linux-kernel@...r.kernel.org, miquel.raynal@...tlin.com,
        zbigniew.lukwinski@...ux.intel.com
Subject: [PATCH v4 3/6] i3c: add actual_len in i3c_priv_xfer

In MIPI I3C Specification:

"Ninth Bit of SDR Target Returned (Read) Data as End-of-Data: In I2C, the
ninth Data bit from Target to Controller is an ACK by the Controller. By
contrast, in I3C this bit allows the Target to end a Read, and allows the
Controller to Abort a Read. In SDR terms, the ninth bit of Read data is
referred to as the T-Bit (for ‘Transition’)"

I3C allow devices early terminate data transfer. So need "actual_len" field
to indicate how much get by i3c_priv_xfer.

Signed-off-by: Frank Li <Frank.Li@....com>
---
 include/linux/i3c/device.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/linux/i3c/device.h b/include/linux/i3c/device.h
index 90fa83464f003..ef6217da8253b 100644
--- a/include/linux/i3c/device.h
+++ b/include/linux/i3c/device.h
@@ -54,6 +54,7 @@ enum i3c_hdr_mode {
  * struct i3c_priv_xfer - I3C SDR private transfer
  * @rnw: encodes the transfer direction. true for a read, false for a write
  * @len: transfer length in bytes of the transfer
+ * @actual_len: actual length in bytes are transferred by the controller
  * @data: input/output buffer
  * @data.in: input buffer. Must point to a DMA-able buffer
  * @data.out: output buffer. Must point to a DMA-able buffer
@@ -62,6 +63,7 @@ enum i3c_hdr_mode {
 struct i3c_priv_xfer {
 	u8 rnw;
 	u16 len;
+	u16 actual_len;
 	union {
 		void *in;
 		const void *out;
-- 
2.34.1