lkml.org 
[lkml]   [2013]   [Jun]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] i2c-designware: Manually set RESTART bit between messages
Date
From: Chew, Chiau Ee <chiau.ee.chew@intel.com>

If both IC_EMPTYFIFO_HOLD_MASTER_EN and IC_RESTART_EN are set to 1, the
Designware I2C controller doesn't generate RESTART unless user specifically
requests it by setting RESTART bit in IC_DATA_CMD register.

Since IC_EMPTYFIFO_HOLD_MASTER_EN setting can't be detected from hardware
register, we must always manually set the restart bit between messages.

Signed-off-by: Chew, Chiau Ee <chiau.ee.chew@intel.com>
---
drivers/i2c/busses/i2c-designware-core.c | 14 ++++++++++++++
1 files changed, 14 insertions(+), 0 deletions(-)

diff --git a/drivers/i2c/busses/i2c-designware-core.c b/drivers/i2c/busses/i2c-designware-core.c
index 3de5494..9348439 100644
--- a/drivers/i2c/busses/i2c-designware-core.c
+++ b/drivers/i2c/busses/i2c-designware-core.c
@@ -403,6 +403,7 @@ i2c_dw_xfer_msg(struct dw_i2c_dev *dev)
u32 addr = msgs[dev->msg_write_idx].addr;
u32 buf_len = dev->tx_buf_len;
u8 *buf = dev->tx_buf;
+ bool need_restart = false;

intr_mask = DW_IC_INTR_DEFAULT_MASK;

@@ -430,6 +431,14 @@ i2c_dw_xfer_msg(struct dw_i2c_dev *dev)
/* new i2c_msg */
buf = msgs[dev->msg_write_idx].buf;
buf_len = msgs[dev->msg_write_idx].len;
+
+ /* If both IC_EMPTYFIFO_HOLD_MASTER_EN and
+ * IC_RESTART_EN are set, we must manually
+ * set restart bit between messages.
+ */
+ if ((dev->master_cfg & DW_IC_CON_RESTART_EN) &&
+ (dev->msg_write_idx > 0))
+ need_restart = true;
}

tx_limit = dev->tx_fifo_depth - dw_readl(dev, DW_IC_TXFLR);
@@ -448,6 +457,11 @@ i2c_dw_xfer_msg(struct dw_i2c_dev *dev)
buf_len == 1)
cmd |= BIT(9);

+ if (need_restart) {
+ cmd |= BIT(10);
+ need_restart = false;
+ }
+
if (msgs[dev->msg_write_idx].flags & I2C_M_RD) {

/* avoid rx buffer overrun */
--
1.7.4.4


\
 
 \ /
  Last update: 2013-06-21 09:41    [W:0.062 / U:0.840 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site