From 238904dd646c60017d75144760510454062bcc8a Mon Sep 17 00:00:00 2001 From: Wolfram Sang Date: Fri, 20 May 2022 12:33:25 +0200 Subject: 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 Signed-off-by: Wolfram Sang --- drivers/i2c/busses/i2c-rcar.c | 50 ++++++++++++++++++++----------------------- 1 file changed, 23 insertions(+), 27 deletions(-) (limited to 'drivers/i2c') diff --git a/drivers/i2c/busses/i2c-rcar.c b/drivers/i2c/busses/i2c-rcar.c index cfc49c3ffd3e..6e932f948293 100644 --- a/drivers/i2c/busses/i2c-rcar.c +++ b/drivers/i2c/busses/i2c-rcar.c @@ -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 { -- cgit v1.2.3