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i2c: rcar: refactor handling of first message 

After moving ICMSR handling to interrupt handlers previously to fix a
race condition, we can now also move ICMSR handling for the first
message out of the function to prepare a message. By introducing a
seperate function to initialize the first message, we can not only
remove some code duplication but the remaining code is also easier to
follow. The function to prepare a message is much simpler without ICMSR
handling.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
This commit is contained in:
Wolfram Sang 2022-05-20 12:33:25 +02:00 committed by Wolfram Sang
parent a0fb48c9bd
commit 238904dd64
1 changed files with 23 additions and 27 deletions
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50
drivers/i2c/busses/i2c-rcar.c
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@ -98,7 +98,6 @@
#define RCAR_IRQ_STOP (MST)
#define ID_LAST_MSG (1 << 0)
#define ID_FIRST_MSG (1 << 1)
#define ID_DONE (1 << 2)
#define ID_ARBLOST (1 << 3)
#define ID_NACK (1 << 4)
@ -333,11 +332,19 @@ scgd_find:
return 0;
}
/*
* We don't have a test case but the HW engineers say that the write order of
* ICMSR and ICMCR depends on whether we issue START or REP_START. So, ICMSR
* handling is outside of this function. First messages clear ICMSR before this
* function, interrupt handlers clear the relevant bits after this function.
*/
static void rcar_i2c_prepare_msg(struct rcar_i2c_priv *priv)
{
int read = !!rcar_i2c_is_recv(priv);
priv->pos = 0;
priv->flags &= ID_P_MASK;
if (priv->msgs_left == 1)
priv->flags |= ID_LAST_MSG;
@ -345,29 +352,27 @@ static void rcar_i2c_prepare_msg(struct rcar_i2c_priv *priv)
if (!priv->atomic_xfer)
rcar_i2c_write(priv, ICMIER, read ? RCAR_IRQ_RECV : RCAR_IRQ_SEND);
/*
* We don't have a test case but the HW engineers say that the write order
* of ICMSR and ICMCR depends on whether we issue START or REP_START. Since
* it didn't cause a drawback for me, let's rather be safe than sorry.
*/
if (priv->flags & ID_FIRST_MSG) {
rcar_i2c_write(priv, ICMSR, 0);
if (priv->flags & ID_P_REP_AFTER_RD)
priv->flags &= ~ID_P_REP_AFTER_RD;
else
rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_START);
} else {
if (priv->flags & ID_P_REP_AFTER_RD)
priv->flags &= ~ID_P_REP_AFTER_RD;
else
rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_START);
/* ICMSR is cleared in interrupt handlers */
}
}
static void rcar_i2c_first_msg(struct rcar_i2c_priv *priv,
struct i2c_msg *msgs, int num)
{
priv->msg = msgs;
priv->msgs_left = num;
rcar_i2c_write(priv, ICMSR, 0); /* must be before preparing msg */
rcar_i2c_prepare_msg(priv);
}
static void rcar_i2c_next_msg(struct rcar_i2c_priv *priv)
{
priv->msg++;
priv->msgs_left--;
priv->flags &= ID_P_MASK;
rcar_i2c_prepare_msg(priv);
/* ICMSR handling must come afterwards in the irq handler */
}
static void rcar_i2c_cleanup_dma(struct rcar_i2c_priv *priv, bool terminate)
@ -852,11 +857,7 @@ static int rcar_i2c_master_xfer(struct i2c_adapter *adap,
for (i = 0; i < num; i++)
rcar_i2c_request_dma(priv, msgs + i);
/* init first message */
priv->msg = msgs;
priv->msgs_left = num;
priv->flags = (priv->flags & ID_P_MASK) | ID_FIRST_MSG;
rcar_i2c_prepare_msg(priv);
rcar_i2c_first_msg(priv, msgs, num);
time_left = wait_event_timeout(priv->wait, priv->flags & ID_DONE,
num * adap->timeout);
@ -906,12 +907,7 @@ static int rcar_i2c_master_xfer_atomic(struct i2c_adapter *adap,
goto out;
rcar_i2c_init(priv);
/* init first message */
priv->msg = msgs;
priv->msgs_left = num;
priv->flags = (priv->flags & ID_P_MASK) | ID_FIRST_MSG;
rcar_i2c_prepare_msg(priv);
rcar_i2c_first_msg(priv, msgs, num);
j = jiffies + num * adap->timeout;
do {