From patchwork Wed Dec 5 14:16:18 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [U-Boot,2/3] designware_i2c: Added s/w generation of stop bit From: Armando Visconti X-Patchwork-Id: 203876 X-Patchwork-Delegate: hs@denx.de Message-Id: <1354716979-13376-3-git-send-email-armando.visconti@st.com> To: , Cc: u-boot@lists.denx.de, spear-devel@list.st.com Date: Wed, 5 Dec 2012 15:16:18 +0100 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 --- drivers/i2c/designware_i2c.c | 11 ++++++++--- drivers/i2c/designware_i2c.h | 1 + 2 files changed, 9 insertions(+), 3 deletions(-) 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 @@ 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 03b520e..e004152 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