Commit 238904dd authored by Wolfram Sang's avatar Wolfram Sang Committed by Wolfram Sang
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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: default avatarWolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: default avatarWolfram Sang <wsa@kernel.org>
parent a0fb48c9

drivers/i2c/busses/i2c-rcar.c

+23 −27
Original line number Diff line number Diff line
@@ -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 @@ static int rcar_i2c_clock_calculate(struct rcar_i2c_priv *priv) 
	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);

		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 {