5.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: Wolfram Sang wsa+renesas@sang-engineering.com
[ Upstream commit 093f70c134f70e4632b295240f07d2b50b74e247 ]
When this controller is a target, the NACK handling had two issues. First, the return value from the backend was not checked on the initial WRITE_REQUESTED. So, the driver missed to send a NACK in this case. Also, the NACK always arrives one byte late on the bus, even in the WRITE_RECEIVED case. This seems to be a HW issue. We should then not rely on the backend to correctly NACK the superfluous byte as well. Fix both issues by introducing a flag which gets set whenever the backend requests a NACK and keep sending it until we get a STOP condition.
Fixes: de20d1857dd6 ("i2c: rcar: add slave support") Signed-off-by: Wolfram Sang wsa+renesas@sang-engineering.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/i2c/busses/i2c-rcar.c | 20 +++++++++++++++----- 1 file changed, 15 insertions(+), 5 deletions(-)
diff --git a/drivers/i2c/busses/i2c-rcar.c b/drivers/i2c/busses/i2c-rcar.c index 316dd378fb8c4..afefe99129001 100644 --- a/drivers/i2c/busses/i2c-rcar.c +++ b/drivers/i2c/busses/i2c-rcar.c @@ -112,6 +112,8 @@ #define ID_P_PM_BLOCKED BIT(31) #define ID_P_MASK GENMASK(31, 28)
+#define ID_SLAVE_NACK BIT(0) + enum rcar_i2c_type { I2C_RCAR_GEN1, I2C_RCAR_GEN2, @@ -146,6 +148,7 @@ struct rcar_i2c_priv { int irq;
struct i2c_client *host_notify_client; + u8 slave_flags; };
#define rcar_i2c_priv_to_dev(p) ((p)->adap.dev.parent) @@ -576,6 +579,7 @@ static bool rcar_i2c_slave_irq(struct rcar_i2c_priv *priv) { u32 ssr_raw, ssr_filtered; u8 value; + int ret;
ssr_raw = rcar_i2c_read(priv, ICSSR) & 0xff; ssr_filtered = ssr_raw & rcar_i2c_read(priv, ICSIER); @@ -591,7 +595,10 @@ static bool rcar_i2c_slave_irq(struct rcar_i2c_priv *priv) rcar_i2c_write(priv, ICRXTX, value); rcar_i2c_write(priv, ICSIER, SDE | SSR | SAR); } else { - i2c_slave_event(priv->slave, I2C_SLAVE_WRITE_REQUESTED, &value); + ret = i2c_slave_event(priv->slave, I2C_SLAVE_WRITE_REQUESTED, &value); + if (ret) + priv->slave_flags |= ID_SLAVE_NACK; + rcar_i2c_read(priv, ICRXTX); /* dummy read */ rcar_i2c_write(priv, ICSIER, SDR | SSR | SAR); } @@ -604,18 +611,21 @@ static bool rcar_i2c_slave_irq(struct rcar_i2c_priv *priv) if (ssr_filtered & SSR) { i2c_slave_event(priv->slave, I2C_SLAVE_STOP, &value); rcar_i2c_write(priv, ICSCR, SIE | SDBS); /* clear our NACK */ + priv->slave_flags &= ~ID_SLAVE_NACK; rcar_i2c_write(priv, ICSIER, SAR); rcar_i2c_write(priv, ICSSR, ~SSR & 0xff); }
/* master wants to write to us */ if (ssr_filtered & SDR) { - int ret; - value = rcar_i2c_read(priv, ICRXTX); ret = i2c_slave_event(priv->slave, I2C_SLAVE_WRITE_RECEIVED, &value); - /* Send NACK in case of error */ - rcar_i2c_write(priv, ICSCR, SIE | SDBS | (ret < 0 ? FNA : 0)); + if (ret) + priv->slave_flags |= ID_SLAVE_NACK; + + /* Send NACK in case of error, but it will come 1 byte late :( */ + rcar_i2c_write(priv, ICSCR, SIE | SDBS | + (priv->slave_flags & ID_SLAVE_NACK ? FNA : 0)); rcar_i2c_write(priv, ICSSR, ~SDR & 0xff); }