linux-kernel - [RFC PATCH 3/9] i3c: master: svc return actual transfer data len

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Message-Id: <20230905213842.3035779-4-Frank.Li@nxp.com>
Date:   Tue,  5 Sep 2023 17:38:36 -0400
From:   Frank Li <Frank.Li@....com>
To:     miquel.raynal@...tlin.com
Cc:     Frank.Li@....com, alexandre.belloni@...tlin.com,
        conor.culhane@...vaco.com, imx@...ts.linux.dev,
        linux-i3c@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [RFC PATCH 3/9] i3c: master: svc return actual transfer data len

I3C allow devices early terminate data transfer. So set "actual" to
indicate how much data get by i3c_priv_xfer.

Signed-off-by: Frank Li <Frank.Li@....com>
---
 drivers/i3c/master/svc-i3c-master.c | 26 +++++++++++++++++++-------
 1 file changed, 19 insertions(+), 7 deletions(-)

diff --git a/drivers/i3c/master/svc-i3c-master.c b/drivers/i3c/master/svc-i3c-master.c
index 14185ee7dd19b..74c4ce8789daf 100644
--- a/drivers/i3c/master/svc-i3c-master.c
+++ b/drivers/i3c/master/svc-i3c-master.c
@@ -134,6 +134,7 @@ struct svc_i3c_cmd {
 	const void *out;
 	unsigned int len;
 	unsigned int actual_len;
+	struct i3c_priv_xfer *xfer;
 	bool continued;
 };
 
@@ -972,12 +973,14 @@ static int svc_i3c_master_read(struct svc_i3c_master *master,
 }
 
 static int svc_i3c_master_write(struct svc_i3c_master *master,
-				const u8 *out, unsigned int len)
+				const u8 *out, unsigned int len, unsigned int *actual)
 {
-	int offset = 0, ret;
+	int ret;
 	u32 mdctrl;
 
-	while (offset < len) {
+	*actual = 0;
+
+	while (*actual < len) {
 		ret = readl_poll_timeout(master->regs + SVC_I3C_MDATACTRL,
 					 mdctrl,
 					 !(mdctrl & SVC_I3C_MDATACTRL_TXFULL),
@@ -989,10 +992,10 @@ static int svc_i3c_master_write(struct svc_i3c_master *master,
 		 * The last byte to be sent over the bus must either have the
 		 * "end" bit set or be written in MWDATABE.
 		 */
-		if (likely(offset < (len - 1)))
-			writel(out[offset++], master->regs + SVC_I3C_MWDATAB);
+		if (likely(*actual < (len - 1)))
+			writel(out[(*actual)++], master->regs + SVC_I3C_MWDATAB);
 		else
-			writel(out[offset++], master->regs + SVC_I3C_MWDATABE);
+			writel(out[(*actual)++], master->regs + SVC_I3C_MWDATABE);
 	}
 
 	return 0;
@@ -1027,7 +1030,8 @@ static int svc_i3c_master_xfer(struct svc_i3c_master *master,
 	if (rnw)
 		ret = svc_i3c_master_read(master, in, xfer_len);
 	else
-		ret = svc_i3c_master_write(master, out, xfer_len);
+		ret = svc_i3c_master_write(master, out, xfer_len, actual_len);
+
 	if (ret < 0)
 		goto emit_stop;
 
@@ -1047,6 +1051,10 @@ static int svc_i3c_master_xfer(struct svc_i3c_master *master,
 		/* Wait idle if stop is sent. */
 		readl_poll_timeout(master->regs + SVC_I3C_MSTATUS, reg,
 				   SVC_I3C_MSTATUS_STATE_IDLE(reg), 0, 1000);
+
+		if (!rnw)
+			*actual_len -= SVC_I3C_MDATACTRL_RXCOUNT(
+							readl(master->regs + SVC_I3C_MDATACTRL));
 	}
 
 	return 0;
@@ -1116,6 +1124,9 @@ static void svc_i3c_master_start_xfer_locked(struct svc_i3c_master *master)
 					  cmd->addr, cmd->in, cmd->out,
 					  cmd->len, &cmd->actual_len,
 					  cmd->continued);
+		if (cmd->xfer)
+			cmd->xfer->actual = cmd->actual_len;
+
 		if (ret)
 			break;
 	}
@@ -1299,6 +1310,7 @@ static int svc_i3c_master_priv_xfers(struct i3c_dev_desc *dev,
 	for (i = 0; i < nxfers; i++) {
 		struct svc_i3c_cmd *cmd = &xfer->cmds[i];
 
+		cmd->xfer = xfers + i;
 		cmd->addr = master->addrs[data->index];
 		cmd->rnw = xfers[i].rnw;
 		cmd->in = xfers[i].rnw ? xfers[i].data.in : NULL;
-- 
2.34.1