[PATCH v3 net-next 2/3] ptp: idt82p33: use i2c_master_send for bus write

[min.li.xe]

From: Min Li <min.li...@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...@renesas.com>

Acked-by: Richard Cochran <richardcoch...@gmail.com>
---
 drivers/ptp/ptp_idt82p33.c | 50 ++++++++++++++++++++++++++++++++++------------
 drivers/ptp/ptp_idt82p33.h |  1 +
 2 files changed, 38 insertions(+), 13 deletions(-)

diff --git a/drivers/ptp/ptp_idt82p33.c b/drivers/ptp/ptp_idt82p33.c
index d52fa67..b1528a0 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);
@@ -130,20 +154,20 @@ static int idt82p33_page_offset(struct idt82p33 
*idt82p33, unsigned char val)
 static int idt82p33_rdwr(struct idt82p33 *idt82p33, unsigned int regaddr,
                         unsigned char *buf, unsigned int count, bool write)
 {
+       u8 offset, page;
        int err;
-       u8 page;
-       u8 offset;
 
        page = _PAGE(regaddr);
        offset = _OFFSET(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