designware_i2c: Added s/w generation of stop bit
In the newer versions of designware i2c IP there is the possibility
of configuring it with IC_EMPTYFIFO_HOLD_MASTER_EN=1, which basically
requires the s/w to generate the stop bit condition directly, as
the h/w will not automatically generate it when TX_FIFO is empty.
To avoid generation of an extra 0x0 byte sent as data, the
IC_STOP command must be sent along with the last IC_CMD.
This patch always writes bit[9] of ic_data_cmd even in the
older versions, assuming that it is a noop there.
Signed-off-by: Armando Visconti <armando.visconti@st.com>
diff --git a/drivers/i2c/designware_i2c.c b/drivers/i2c/designware_i2c.c
index 4e4bfd4..eab3131 100644
--- a/drivers/i2c/designware_i2c.c
+++ b/drivers/i2c/designware_i2c.c
@@ -283,7 +283,10 @@
start_time_rx = get_timer(0);
while (len) {
- writel(IC_CMD, &i2c_regs_p->ic_cmd_data);
+ if (len == 1)
+ writel(IC_CMD | IC_STOP, &i2c_regs_p->ic_cmd_data);
+ else
+ writel(IC_CMD, &i2c_regs_p->ic_cmd_data);
if (readl(&i2c_regs_p->ic_status) & IC_STATUS_RFNE) {
*buffer++ = (uchar)readl(&i2c_regs_p->ic_cmd_data);
@@ -322,9 +325,11 @@
start_time_tx = get_timer(0);
while (len) {
if (readl(&i2c_regs_p->ic_status) & IC_STATUS_TFNF) {
- writel(*buffer, &i2c_regs_p->ic_cmd_data);
+ if (--len == 0)
+ writel(*buffer | IC_STOP, &i2c_regs_p->ic_cmd_data);
+ else
+ writel(*buffer, &i2c_regs_p->ic_cmd_data);
buffer++;
- len--;
start_time_tx = get_timer(0);
} else if (get_timer(start_time_tx) > (nb * I2C_BYTE_TO)) {