path: root/drivers/i2c/busses
diff options
authorJaemin Yoo <jmin.yoo@samsung.com>2013-03-26 04:29:56 +0000
committerWolfram Sang <wsa@the-dreams.de>2013-04-09 11:23:05 +0200
commit85747311ecb6167c989093c64a13807366fdd3a9 (patch)
treef0fdf82d8c9173441bfce04a5b7dfcf491ce908d /drivers/i2c/busses
parent51d95709dddf7fdf6769a547de37a9c98edf8df9 (diff)
i2c: s3c2410: Add SMBus emulation for block read
SMBus read and write are supported by the emulation layer of i2c framework if the controller doesn't have SMBus features. I2C_M_RECV_LEN flag is used to let i2c drivers know rx length is not yet determined but will be read to the first byte in rx buffer. s3c2410 doesn't handle this flag. So only one byte is read from slave. There fore following two features are added to the driver code. 1. skip rx length check if I2C_M_RECV_LEN is set and the length is 1. 2. add actual bytes to the rx length after reading first bytes if I2C_M_RECV_LEN. I2C_M_RECV_LEN is only set for SMBus command. So this code does not affect legacy codes which only use i2c command for s3c2410. Signed-off-by: Jaemin Yoo <jmin.yoo@samsung.com> Tested-by: Prasanna Kumar <prasanna.ps@samsung.com> Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Diffstat (limited to 'drivers/i2c/busses')
1 files changed, 9 insertions, 0 deletions
diff --git a/drivers/i2c/busses/i2c-s3c2410.c b/drivers/i2c/busses/i2c-s3c2410.c
index 0a81f1f4aee..6e8ee92ab55 100644
--- a/drivers/i2c/busses/i2c-s3c2410.c
+++ b/drivers/i2c/busses/i2c-s3c2410.c
@@ -346,6 +346,12 @@ static inline int is_lastmsg(struct s3c24xx_i2c *i2c)
static inline int is_msglast(struct s3c24xx_i2c *i2c)
+ /* msg->len is always 1 for the first byte of smbus block read.
+ * Actual length will be read from slave. More bytes will be
+ * read according to the length then. */
+ if (i2c->msg->flags & I2C_M_RECV_LEN && i2c->msg->len == 1)
+ return 0;
return i2c->msg_ptr == i2c->msg->len-1;
@@ -485,6 +491,9 @@ static int i2c_s3c_irq_nextbyte(struct s3c24xx_i2c *i2c, unsigned long iicstat)
byte = readb(i2c->regs + S3C2410_IICDS);
i2c->msg->buf[i2c->msg_ptr++] = byte;
+ /* Add actual length to read for smbus block read */
+ if (i2c->msg->flags & I2C_M_RECV_LEN && i2c->msg->len == 1)
+ i2c->msg->len += byte;
if (is_msglast(i2c)) {
/* last byte of buffer */