[PATCH 5.11 501/601] i2c: rcar: protect against supurious interrupts on V3U

Greg Kroah-Hartman
2021-05-12T17:56:24Z

From: Wolfram Sang <wsa+renesas@sang-engineering.com>

[ Upstream commit 9c975c432bc0aa53a90438fc80b369cb35134a48 ]

V3U creates spurious interrupts which we need to handle. This costs time
until BUS_PHASE_DATA can be activated which is problematic for Gen2 SoCs
and earlier. Because of this we introduce two interrupt handlers here
which will call a generic main irq function once the timing critical
stuff is done.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/i2c/busses/i2c-rcar.c | 57 ++++++++++++++++++++++++++---------
1 file changed, 43 insertions(+), 14 deletions(-)

diff --git a/drivers/i2c/busses/i2c-rcar.c b/drivers/i2c/busses/i2c-rcar.c
index 3c9c3a6f7ac8..12f6d452c0f7 100644
--- a/drivers/i2c/busses/i2c-rcar.c
+++ b/drivers/i2c/busses/i2c-rcar.c
@@ -625,20 +625,11 @@ static bool rcar_i2c_slave_irq(struct rcar_i2c_priv *priv)
* generated. It turned out that taking a spinlock at the beginning of the ISR
* was already causing repeated messages. Thus, this driver was converted to
* the now lockless behaviour. Please keep this in mind when hacking the driver.
+ * R-Car Gen3 seems to have this fixed but earlier versions than R-Car Gen2 are
+ * likely affected. Therefore, we have different interrupt handler entries.
*/
-static irqreturn_t rcar_i2c_irq(int irq, void *ptr)
+static irqreturn_t rcar_i2c_irq(int irq, struct rcar_i2c_priv *priv, u32 msr)
{
- struct rcar_i2c_priv *priv = ptr;
- u32 msr;
-
- /* Clear START or STOP immediately, except for REPSTART after read */
- if (likely(!(priv->flags & ID_P_REP_AFTER_RD)))
- rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_DATA);
-
- msr = rcar_i2c_read(priv, ICMSR);
-
- /* Only handle interrupts that are currently enabled */
- msr &= rcar_i2c_read(priv, ICMIER);
if (!msr) {
if (rcar_i2c_slave_irq(priv))
return IRQ_HANDLED;
@@ -682,6 +673,41 @@ out:
return IRQ_HANDLED;
}

+static irqreturn_t rcar_i2c_gen2_irq(int irq, void *ptr)
+{
+ struct rcar_i2c_priv *priv = ptr;
+ u32 msr;
+
+ /* Clear START or STOP immediately, except for REPSTART after read */
+ if (likely(!(priv->flags & ID_P_REP_AFTER_RD)))
+ rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_DATA);
+
+ /* Only handle interrupts that are currently enabled */
+ msr = rcar_i2c_read(priv, ICMSR);
+ msr &= rcar_i2c_read(priv, ICMIER);
+
+ return rcar_i2c_irq(irq, priv, msr);
+}
+
+static irqreturn_t rcar_i2c_gen3_irq(int irq, void *ptr)
+{
+ struct rcar_i2c_priv *priv = ptr;
+ u32 msr;
+
+ /* Only handle interrupts that are currently enabled */
+ msr = rcar_i2c_read(priv, ICMSR);
+ msr &= rcar_i2c_read(priv, ICMIER);
+
+ /*
+ * Clear START or STOP immediately, except for REPSTART after read or
+ * if a spurious interrupt was detected.
+ */
+ if (likely(!(priv->flags & ID_P_REP_AFTER_RD) && msr))
+ rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_DATA);
+
+ return rcar_i2c_irq(irq, priv, msr);
+}
+
static struct dma_chan *rcar_i2c_request_dma_chan(struct device *dev,
enum dma_transfer_direction dir,
dma_addr_t port_addr)
@@ -929,6 +955,7 @@ static int rcar_i2c_probe(struct platform_device *pdev)
struct i2c_adapter *adap;
struct device *dev = &pdev->dev;
unsigned long irqflags = 0;
+ irqreturn_t (*irqhandler)(int irq, void *ptr) = rcar_i2c_gen3_irq;
int ret;

/* Otherwise logic will break because some bytes must always use PIO */
@@ -977,8 +1004,10 @@ static int rcar_i2c_probe(struct platform_device *pdev)

rcar_i2c_write(priv, ICSAR, 0); /* Gen2: must be 0 if not using slave */

- if (priv->devtype < I2C_RCAR_GEN3)
+ if (priv->devtype < I2C_RCAR_GEN3) {
irqflags |= IRQF_NO_THREAD;
+ irqhandler = rcar_i2c_gen2_irq;
+ }

if (priv->devtype == I2C_RCAR_GEN3) {
priv->rstc = devm_reset_control_get_exclusive(&pdev->dev, NULL);
@@ -999,7 +1028,7 @@ static int rcar_i2c_probe(struct platform_device *pdev)
priv->flags |= ID_P_HOST_NOTIFY;

priv->irq = platform_get_irq(pdev, 0);
- ret = devm_request_irq(dev, priv->irq, rcar_i2c_irq, irqflags, dev_name(dev), priv);
+ ret = devm_request_irq(dev, priv->irq, irqhandler, irqflags, dev_name(dev), priv);
if (ret < 0) {
dev_err(dev, "cannot get irq %d\n", priv->irq);
goto out_pm_disable;
--
2.30.2