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authorArmando Visconti <armando.visconti@st.com>2012-12-06 00:04:16 +0000
committerTom Rini <trini@ti.com>2012-12-11 13:17:32 -0700
commit491739bb7456b95bb863421f6cd76af0ff9b797c (patch)
treec2bfb6e77985079fc24794cc1c512d621a268000 /drivers
parentac6e2fe6e4afe54a9c7ef0d93827a86e264814f2 (diff)
downloadu-boot-linaro-stable-491739bb7456b95bb863421f6cd76af0ff9b797c.tar.gz
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>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/i2c/designware_i2c.c11
-rw-r--r--drivers/i2c/designware_i2c.h1
2 files changed, 9 insertions, 3 deletions
diff --git a/drivers/i2c/designware_i2c.c b/drivers/i2c/designware_i2c.c
index 4e4bfd4f5..eab313102 100644
--- a/drivers/i2c/designware_i2c.c
+++ b/drivers/i2c/designware_i2c.c
@@ -283,7 +283,10 @@ int i2c_read(uchar chip, uint addr, int alen, uchar *buffer, int len)
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 @@ int i2c_write(uchar chip, uint addr, int alen, uchar *buffer, int len)
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)) {
diff --git a/drivers/i2c/designware_i2c.h b/drivers/i2c/designware_i2c.h
index 03b520ed4..e004152ac 100644
--- a/drivers/i2c/designware_i2c.h
+++ b/drivers/i2c/designware_i2c.h
@@ -95,6 +95,7 @@ struct i2c_regs {
/* i2c data buffer and command register definitions */
#define IC_CMD 0x0100
+#define IC_STOP 0x0200
/* i2c interrupt status register definitions */
#define IC_GEN_CALL 0x0800