[U-Boot] [PATCH v5 1/8] imx: mxc_i2c: tweak the i2c transfer method

Martyn Welch
2017-11-08T15:35:09Z

From: Nandor Han <nandor.han@ge.com>

Tweak the i2c transfer to work for devices that want to read data
without addressing a register.

Signed-off-by: Nandor Han <nandor.han@ge.com>
Signed-off-by: Martyn Welch <martyn.welch@collabora.co.uk>
Acked-by: Heiko Schocher <hs@denx.de>
Cc: Heiko Schocher <hs@denx.de>
Cc: Stefano Babic <sbabic@denx.de>
---
Changes for v2:
- Replacing '!= -1' with '>= 0'.

drivers/i2c/mxc_i2c.c | 25 +++++++++++++++----------
1 file changed, 15 insertions(+), 10 deletions(-)

diff --git a/drivers/i2c/mxc_i2c.c b/drivers/i2c/mxc_i2c.c
index abf1da2..205274e 100644
--- a/drivers/i2c/mxc_i2c.c
+++ b/drivers/i2c/mxc_i2c.c
@@ -317,16 +317,19 @@ static int i2c_init_transfer_(struct mxc_i2c_bus *i2c_bus, u8 chip,
temp |= I2CR_MTX | I2CR_TX_NO_AK;
writeb(temp, base + (I2CR << reg_shift));

- /* write slave address */
- ret = tx_byte(i2c_bus, chip << 1);
- if (ret < 0)
- return ret;
-
- while (alen--) {
- ret = tx_byte(i2c_bus, (addr >> (alen * 8)) & 0xff);
+ if (alen >= 0) {
+ /* write slave address */
+ ret = tx_byte(i2c_bus, chip << 1);
if (ret < 0)
return ret;
+
+ while (alen--) {
+ ret = tx_byte(i2c_bus, (addr >> (alen * 8)) & 0xff);
+ if (ret < 0)
+ return ret;
+ }
}
+
return 0;
}

@@ -537,9 +540,11 @@ static int bus_i2c_read(struct mxc_i2c_bus *i2c_bus, u8 chip, u32 addr,
if (ret < 0)
return ret;

- temp = readb(base + (I2CR << reg_shift));
- temp |= I2CR_RSTA;
- writeb(temp, base + (I2CR << reg_shift));
+ if (alen >= 0) {
+ temp = readb(base + (I2CR << reg_shift));
+ temp |= I2CR_RSTA;
+ writeb(temp, base + (I2CR << reg_shift));
+ }

ret = tx_byte(i2c_bus, (chip << 1) | 1);
if (ret < 0) {
--
2.1.4