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From:   <min.li.xe@renesas.com>
To:     <richardcochran@gmail.com>
CC:     <netdev@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        Min Li <min.li.xe@renesas.com>
Subject: [PATCH v4 net-next 2/3] ptp: idt82p33: use i2c_master_send for bus write
Date:   Thu, 5 Nov 2020 22:52:08 -0500
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From: Min Li <min.li.xe@renesas.com>

Refactor idt82p33_xfer and use i2c_master_send for write operation.
Because some I2C controllers are only working with single-burst write
transaction.

Changes since v1:
- Fix broken build.

Signed-off-by: Min Li <min.li.xe@renesas.com>

Acked-by: Richard Cochran <richardcochran@gmail.com>
---
 drivers/ptp/ptp_idt82p33.c | 47 +++++++++++++++++++++++++++++++++++-----------
 drivers/ptp/ptp_idt82p33.h |  1 +
 2 files changed, 37 insertions(+), 11 deletions(-)

diff --git a/drivers/ptp/ptp_idt82p33.c b/drivers/ptp/ptp_idt82p33.c
index 50af339..223bc11 100644
--- a/drivers/ptp/ptp_idt82p33.c
+++ b/drivers/ptp/ptp_idt82p33.c
@@ -78,11 +78,10 @@ static void idt82p33_timespec_to_byte_array(struct timespec64 const *ts,
 	}
 }
 
-static int idt82p33_xfer(struct idt82p33 *idt82p33,
-			 unsigned char regaddr,
-			 unsigned char *buf,
-			 unsigned int count,
-			 int write)
+static int idt82p33_xfer_read(struct idt82p33 *idt82p33,
+			      unsigned char regaddr,
+			      unsigned char *buf,
+			      unsigned int count)
 {
 	struct i2c_client *client = idt82p33->client;
 	struct i2c_msg msg[2];
@@ -94,7 +93,7 @@ static int idt82p33_xfer(struct idt82p33 *idt82p33,
 	msg[0].buf = &regaddr;
 
 	msg[1].addr = client->addr;
-	msg[1].flags = write ? 0 : I2C_M_RD;
+	msg[1].flags = I2C_M_RD;
 	msg[1].len = count;
 	msg[1].buf = buf;
 
@@ -110,6 +109,31 @@ static int idt82p33_xfer(struct idt82p33 *idt82p33,
 	return 0;
 }
 
+static int idt82p33_xfer_write(struct idt82p33 *idt82p33,
+			       u8 regaddr,
+			       u8 *buf,
+			       u16 count)
+{
+	struct i2c_client *client = idt82p33->client;
+	/* we add 1 byte for device register */
+	u8 msg[IDT82P33_MAX_WRITE_COUNT + 1];
+	int err;
+
+	if (count > IDT82P33_MAX_WRITE_COUNT)
+		return -EINVAL;
+
+	msg[0] = regaddr;
+	memcpy(&msg[1], buf, count);
+
+	err = i2c_master_send(client, msg, count + 1);
+	if (err < 0) {
+		dev_err(&client->dev, "i2c_master_send returned %d\n", err);
+		return err;
+	}
+
+	return 0;
+}
+
 static int idt82p33_page_offset(struct idt82p33 *idt82p33, unsigned char val)
 {
 	int err;
@@ -117,7 +141,7 @@ static int idt82p33_page_offset(struct idt82p33 *idt82p33, unsigned char val)
 	if (idt82p33->page_offset == val)
 		return 0;
 
-	err = idt82p33_xfer(idt82p33, PAGE_ADDR, &val, sizeof(val), 1);
+	err = idt82p33_xfer_write(idt82p33, PAGE_ADDR, &val, sizeof(val));
 	if (err)
 		dev_err(&idt82p33->client->dev,
 			"failed to set page offset %d\n", val);
@@ -138,11 +162,12 @@ static int idt82p33_rdwr(struct idt82p33 *idt82p33, unsigned int regaddr,
 
 	err = idt82p33_page_offset(idt82p33, page);
 	if (err)
-		goto out;
+		return err;
 
-	err = idt82p33_xfer(idt82p33, offset, buf, count, write);
-out:
-	return err;
+	if (write)
+		return idt82p33_xfer_write(idt82p33, offset, buf, count);
+
+	return idt82p33_xfer_read(idt82p33, offset, buf, count);
 }
 
 static int idt82p33_read(struct idt82p33 *idt82p33, unsigned int regaddr,
diff --git a/drivers/ptp/ptp_idt82p33.h b/drivers/ptp/ptp_idt82p33.h
index 3a0e001..1c7a0f0 100644
--- a/drivers/ptp/ptp_idt82p33.h
+++ b/drivers/ptp/ptp_idt82p33.h
@@ -95,6 +95,7 @@ enum hw_tod_trig_sel {
 #define MAX_MEASURMENT_COUNT (5)
 #define SNAP_THRESHOLD_NS (150000)
 #define SYNC_TOD_TIMEOUT_SEC (5)
+#define IDT82P33_MAX_WRITE_COUNT (512)
 
 #define PLLMASK_ADDR_HI	0xFF
 #define PLLMASK_ADDR_LO	0xA5
-- 
2.7.4