[PATCH v3 0/6] i2c: designware: Generic polling mode code

[PATCH v3 0/6] i2c: designware: Generic polling mode code

[Jarkko Nikula]

Hi Jiawen, Sanket and Basavaraj

I hope you could give a quick test to this patchset to see it won't cause
regression on your HW. This is mostly the same than the first version what
Jiawen tested earlier but in this 3rd version I decided to drop semphore
touching code patches from v2 due they being out of scope and fix a few
things noted by Andy.

Changes are in the patch 3/6 with two minor fixes to comments while moving
them and the patch 6/6 where i2c_dw_wait_transfer() is slightly modified
by Andy's suggestion plus I decided to remove one comment which became
unclear after this patch.

v2:
https://lore.kernel.org/linux-i2c/20240206145158.227254-1-jarkko.nikula@linux.intel.com/

v1:
https://lore.kernel.org/linux-i2c/20240131141653.2689260-1-jarkko.nikula@linux.intel.com/

Jarkko Nikula (6):
  i2c: designware: Uniform initialization flow for polling mode
  i2c: designware: Do not enable interrupts shortly in polling mode
  i2c: designware: Use accessors to DW_IC_INTR_MASK register
  i2c: designware: Move interrupt handling functions before
    i2c_dw_xfer()
  i2c: designware: Fix RX FIFO depth define on Wangxun 10Gb NIC
  i2c: designware: Implement generic polling mode code for Wangxun 10Gb
    NIC

 drivers/i2c/busses/i2c-designware-common.c  |   2 +-
 drivers/i2c/busses/i2c-designware-core.h    |  23 +-
 drivers/i2c/busses/i2c-designware-master.c  | 419 +++++++++-----------
 drivers/i2c/busses/i2c-designware-pcidrv.c  |   2 +-
 drivers/i2c/busses/i2c-designware-platdrv.c |   2 +-
 5 files changed, 208 insertions(+), 240 deletions(-)

-- 
2.43.0

[PATCH v3 1/6] i2c: designware: Uniform initialization flow for polling mode

[Jarkko Nikula]

Currently initialization flow in i2c_dw_probe_master() skips a few steps
and has code duplication for polling mode implementation.

Simplify this by adding a new ACCESS_POLLING flag that is set for those
two platforms that currently use polling mode and use it to skip
interrupt handler setup.

Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
---
 drivers/i2c/busses/i2c-designware-core.h    |  1 +
 drivers/i2c/busses/i2c-designware-master.c  | 42 ++++-----------------
 drivers/i2c/busses/i2c-designware-pcidrv.c  |  2 +-
 drivers/i2c/busses/i2c-designware-platdrv.c |  2 +-
 4 files changed, 11 insertions(+), 36 deletions(-)

diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h
index a7f6f3eafad7..78c8062a8eb5 100644
--- a/drivers/i2c/busses/i2c-designware-core.h
+++ b/drivers/i2c/busses/i2c-designware-core.h
@@ -303,6 +303,7 @@ struct dw_i2c_dev {
 #define ACCESS_INTR_MASK			BIT(0)
 #define ACCESS_NO_IRQ_SUSPEND			BIT(1)
 #define ARBITRATION_SEMAPHORE			BIT(2)
+#define ACCESS_POLLING				BIT(3)
 
 #define MODEL_MSCC_OCELOT			BIT(8)
 #define MODEL_BAIKAL_BT1			BIT(9)
diff --git a/drivers/i2c/busses/i2c-designware-master.c b/drivers/i2c/busses/i2c-designware-master.c
index 85dbd0eb5392..e879a0f5cc97 100644
--- a/drivers/i2c/busses/i2c-designware-master.c
+++ b/drivers/i2c/busses/i2c-designware-master.c
@@ -953,31 +953,6 @@ static int i2c_dw_init_recovery_info(struct dw_i2c_dev *dev)
 	return 0;
 }
 
-static int i2c_dw_poll_adap_quirk(struct dw_i2c_dev *dev)
-{
-	struct i2c_adapter *adap = &dev->adapter;
-	int ret;
-
-	pm_runtime_get_noresume(dev->dev);
-	ret = i2c_add_numbered_adapter(adap);
-	if (ret)
-		dev_err(dev->dev, "Failed to add adapter: %d\n", ret);
-	pm_runtime_put_noidle(dev->dev);
-
-	return ret;
-}
-
-static bool i2c_dw_is_model_poll(struct dw_i2c_dev *dev)
-{
-	switch (dev->flags & MODEL_MASK) {
-	case MODEL_AMD_NAVI_GPU:
-	case MODEL_WANGXUN_SP:
-		return true;
-	default:
-		return false;
-	}
-}
-
 int i2c_dw_probe_master(struct dw_i2c_dev *dev)
 {
 	struct i2c_adapter *adap = &dev->adapter;
@@ -1033,9 +1008,6 @@ int i2c_dw_probe_master(struct dw_i2c_dev *dev)
 	adap->dev.parent = dev->dev;
 	i2c_set_adapdata(adap, dev);
 
-	if (i2c_dw_is_model_poll(dev))
-		return i2c_dw_poll_adap_quirk(dev);
-
 	if (dev->flags & ACCESS_NO_IRQ_SUSPEND) {
 		irq_flags = IRQF_NO_SUSPEND;
 	} else {
@@ -1049,12 +1021,14 @@ int i2c_dw_probe_master(struct dw_i2c_dev *dev)
 	regmap_write(dev->map, DW_IC_INTR_MASK, 0);
 	i2c_dw_release_lock(dev);
 
-	ret = devm_request_irq(dev->dev, dev->irq, i2c_dw_isr, irq_flags,
-			       dev_name(dev->dev), dev);
-	if (ret) {
-		dev_err(dev->dev, "failure requesting irq %i: %d\n",
-			dev->irq, ret);
-		return ret;
+	if (!(dev->flags & ACCESS_POLLING)) {
+		ret = devm_request_irq(dev->dev, dev->irq, i2c_dw_isr,
+				       irq_flags, dev_name(dev->dev), dev);
+		if (ret) {
+			dev_err(dev->dev, "failure requesting irq %i: %d\n",
+				dev->irq, ret);
+			return ret;
+		}
 	}
 
 	ret = i2c_dw_init_recovery_info(dev);
diff --git a/drivers/i2c/busses/i2c-designware-pcidrv.c b/drivers/i2c/busses/i2c-designware-pcidrv.c
index 61d7a27aa070..9be9a2658e1f 100644
--- a/drivers/i2c/busses/i2c-designware-pcidrv.c
+++ b/drivers/i2c/busses/i2c-designware-pcidrv.c
@@ -154,7 +154,7 @@ static int navi_amd_setup(struct pci_dev *pdev, struct dw_pci_controller *c)
 {
 	struct dw_i2c_dev *dev = dev_get_drvdata(&pdev->dev);
 
-	dev->flags |= MODEL_AMD_NAVI_GPU;
+	dev->flags |= MODEL_AMD_NAVI_GPU | ACCESS_POLLING;
 	dev->timings.bus_freq_hz = I2C_MAX_STANDARD_MODE_FREQ;
 	return 0;
 }
diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
index 855b698e99c0..4ab41ba39d55 100644
--- a/drivers/i2c/busses/i2c-designware-platdrv.c
+++ b/drivers/i2c/busses/i2c-designware-platdrv.c
@@ -290,7 +290,7 @@ static int dw_i2c_plat_probe(struct platform_device *pdev)
 
 	dev->flags = (uintptr_t)device_get_match_data(&pdev->dev);
 	if (device_property_present(&pdev->dev, "wx,i2c-snps-model"))
-		dev->flags = MODEL_WANGXUN_SP;
+		dev->flags = MODEL_WANGXUN_SP | ACCESS_POLLING;
 
 	dev->dev = &pdev->dev;
 	dev->irq = irq;
-- 
2.43.0

[PATCH v3 2/6] i2c: designware: Do not enable interrupts shortly in polling mode

[Jarkko Nikula]

I was testing the polling mode txgbe_i2c_dw_xfer_quirk() on a HW where
the i2c-designware has interrupt connected and shared with other device.
I noticed there is a bogus interrupt for each transfer.

Reason for this that both polling mode functions call the
i2c_dw_xfer_init() which enable interrupts then followed by immediate
disable by the same polling mode functions. This is enough to trigger
TX_EMPTY interrupt.

Fix this by introducing a __i2c_dw_write_intr_mask() helper that unmasks
interrupts conditionally and use it in i2c_dw_xfer_init().

Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
---
 drivers/i2c/busses/i2c-designware-core.h   | 8 ++++++++
 drivers/i2c/busses/i2c-designware-master.c | 4 +---
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h
index 78c8062a8eb5..8ce6111cdda3 100644
--- a/drivers/i2c/busses/i2c-designware-core.h
+++ b/drivers/i2c/busses/i2c-designware-core.h
@@ -352,6 +352,14 @@ static inline void __i2c_dw_disable_nowait(struct dw_i2c_dev *dev)
 	dev->status &= ~STATUS_ACTIVE;
 }
 
+static inline void __i2c_dw_write_intr_mask(struct dw_i2c_dev *dev,
+					    unsigned int intr_mask)
+{
+	unsigned int val = dev->flags & ACCESS_POLLING ? 0 : intr_mask;
+
+	regmap_write(dev->map, DW_IC_INTR_MASK, val);
+}
+
 void __i2c_dw_disable(struct dw_i2c_dev *dev);
 
 extern void i2c_dw_configure_master(struct dw_i2c_dev *dev);
diff --git a/drivers/i2c/busses/i2c-designware-master.c b/drivers/i2c/busses/i2c-designware-master.c
index e879a0f5cc97..835d82e2c5fe 100644
--- a/drivers/i2c/busses/i2c-designware-master.c
+++ b/drivers/i2c/busses/i2c-designware-master.c
@@ -250,7 +250,7 @@ static void i2c_dw_xfer_init(struct dw_i2c_dev *dev)
 
 	/* Clear and enable interrupts */
 	regmap_read(dev->map, DW_IC_CLR_INTR, &dummy);
-	regmap_write(dev->map, DW_IC_INTR_MASK, DW_IC_INTR_MASTER_MASK);
+	__i2c_dw_write_intr_mask(dev, DW_IC_INTR_MASTER_MASK);
 }
 
 static int i2c_dw_check_stopbit(struct dw_i2c_dev *dev)
@@ -300,7 +300,6 @@ static int amd_i2c_dw_xfer_quirk(struct i2c_adapter *adap, struct i2c_msg *msgs,
 	dev->msgs = msgs;
 	dev->msgs_num = num_msgs;
 	i2c_dw_xfer_init(dev);
-	regmap_write(dev->map, DW_IC_INTR_MASK, 0);
 
 	/* Initiate messages read/write transaction */
 	for (msg_wrt_idx = 0; msg_wrt_idx < num_msgs; msg_wrt_idx++) {
@@ -384,7 +383,6 @@ static int txgbe_i2c_dw_xfer_quirk(struct i2c_adapter *adap, struct i2c_msg *msg
 	dev->msgs = msgs;
 	dev->msgs_num = num_msgs;
 	i2c_dw_xfer_init(dev);
-	regmap_write(dev->map, DW_IC_INTR_MASK, 0);
 
 	for (msg_idx = 0; msg_idx < num_msgs; msg_idx++) {
 		buf = msgs[msg_idx].buf;
-- 
2.43.0

[PATCH v3 3/6] i2c: designware: Use accessors to DW_IC_INTR_MASK register

[Jarkko Nikula]

Convert access to DW_IC_INTR_MASK register using the existing
__i2c_dw_write_intr_mask() and a __i2c_dw_read_intr_mask() introduced
here. Motivation to this is to prepare for generic polling mode code
where polling mode will use a SW mask instead of DW_IC_INTR_MASK.

Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
---
 drivers/i2c/busses/i2c-designware-common.c |  2 +-
 drivers/i2c/busses/i2c-designware-core.h   |  7 +++++++
 drivers/i2c/busses/i2c-designware-master.c | 22 ++++++++++++----------
 3 files changed, 20 insertions(+), 11 deletions(-)

diff --git a/drivers/i2c/busses/i2c-designware-common.c b/drivers/i2c/busses/i2c-designware-common.c
index 35f762872b8a..e8a688d04aee 100644
--- a/drivers/i2c/busses/i2c-designware-common.c
+++ b/drivers/i2c/busses/i2c-designware-common.c
@@ -648,7 +648,7 @@ void i2c_dw_disable(struct dw_i2c_dev *dev)
 	__i2c_dw_disable(dev);
 
 	/* Disable all interrupts */
-	regmap_write(dev->map, DW_IC_INTR_MASK, 0);
+	__i2c_dw_write_intr_mask(dev, 0);
 	regmap_read(dev->map, DW_IC_CLR_INTR, &dummy);
 
 	i2c_dw_release_lock(dev);
diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h
index 8ce6111cdda3..4d277ebcca92 100644
--- a/drivers/i2c/busses/i2c-designware-core.h
+++ b/drivers/i2c/busses/i2c-designware-core.h
@@ -360,6 +360,13 @@ static inline void __i2c_dw_write_intr_mask(struct dw_i2c_dev *dev,
 	regmap_write(dev->map, DW_IC_INTR_MASK, val);
 }
 
+static inline void __i2c_dw_read_intr_mask(struct dw_i2c_dev *dev,
+					   unsigned int *intr_mask)
+{
+	if (!(dev->flags & ACCESS_POLLING))
+		regmap_read(dev->map, DW_IC_INTR_MASK, intr_mask);
+}
+
 void __i2c_dw_disable(struct dw_i2c_dev *dev);
 
 extern void i2c_dw_configure_master(struct dw_i2c_dev *dev);
diff --git a/drivers/i2c/busses/i2c-designware-master.c b/drivers/i2c/busses/i2c-designware-master.c
index 835d82e2c5fe..2e8f9733ddd3 100644
--- a/drivers/i2c/busses/i2c-designware-master.c
+++ b/drivers/i2c/busses/i2c-designware-master.c
@@ -240,7 +240,7 @@ static void i2c_dw_xfer_init(struct dw_i2c_dev *dev)
 		     msgs[dev->msg_write_idx].addr | ic_tar);
 
 	/* Enforce disabled interrupts (due to HW issues) */
-	regmap_write(dev->map, DW_IC_INTR_MASK, 0);
+	__i2c_dw_write_intr_mask(dev, 0);
 
 	/* Enable the adapter */
 	__i2c_dw_enable(dev);
@@ -544,7 +544,7 @@ i2c_dw_xfer_msg(struct dw_i2c_dev *dev)
 	if (dev->msg_err)
 		intr_mask = 0;
 
-	regmap_write(dev->map,  DW_IC_INTR_MASK, intr_mask);
+	__i2c_dw_write_intr_mask(dev, intr_mask);
 }
 
 static u8
@@ -552,6 +552,7 @@ i2c_dw_recv_len(struct dw_i2c_dev *dev, u8 len)
 {
 	struct i2c_msg *msgs = dev->msgs;
 	u32 flags = msgs[dev->msg_read_idx].flags;
+	unsigned int intr_mask;
 
 	/*
 	 * Adjust the buffer length and mask the flag
@@ -566,8 +567,9 @@ i2c_dw_recv_len(struct dw_i2c_dev *dev, u8 len)
 	 * Received buffer length, re-enable TX_EMPTY interrupt
 	 * to resume the SMBUS transaction.
 	 */
-	regmap_update_bits(dev->map, DW_IC_INTR_MASK, DW_IC_INTR_TX_EMPTY,
-			   DW_IC_INTR_TX_EMPTY);
+	__i2c_dw_read_intr_mask(dev, &intr_mask);
+	intr_mask |= DW_IC_INTR_TX_EMPTY;
+	__i2c_dw_write_intr_mask(dev, intr_mask);
 
 	return len;
 }
@@ -827,7 +829,7 @@ static irqreturn_t i2c_dw_isr(int this_irq, void *dev_id)
 		 * interrupt really came from this HW (E.g. firmware has left
 		 * the HW active).
 		 */
-		regmap_write(dev->map, DW_IC_INTR_MASK, 0);
+		__i2c_dw_write_intr_mask(dev, 0);
 		return IRQ_HANDLED;
 	}
 
@@ -840,7 +842,7 @@ static irqreturn_t i2c_dw_isr(int this_irq, void *dev_id)
 		 * Anytime TX_ABRT is set, the contents of the tx/rx
 		 * buffers are flushed. Make sure to skip them.
 		 */
-		regmap_write(dev->map, DW_IC_INTR_MASK, 0);
+		__i2c_dw_write_intr_mask(dev, 0);
 		goto tx_aborted;
 	}
 
@@ -862,9 +864,9 @@ static irqreturn_t i2c_dw_isr(int this_irq, void *dev_id)
 		complete(&dev->cmd_complete);
 	else if (unlikely(dev->flags & ACCESS_INTR_MASK)) {
 		/* Workaround to trigger pending interrupt */
-		regmap_read(dev->map, DW_IC_INTR_MASK, &stat);
-		regmap_write(dev->map, DW_IC_INTR_MASK, 0);
-		regmap_write(dev->map, DW_IC_INTR_MASK, stat);
+		__i2c_dw_read_intr_mask(dev, &stat);
+		__i2c_dw_write_intr_mask(dev, 0);
+		__i2c_dw_write_intr_mask(dev, stat);
 	}
 
 	return IRQ_HANDLED;
@@ -1016,7 +1018,7 @@ int i2c_dw_probe_master(struct dw_i2c_dev *dev)
 	if (ret)
 		return ret;
 
-	regmap_write(dev->map, DW_IC_INTR_MASK, 0);
+	__i2c_dw_write_intr_mask(dev, 0);
 	i2c_dw_release_lock(dev);
 
 	if (!(dev->flags & ACCESS_POLLING)) {
-- 
2.43.0

[PATCH v3 4/6] i2c: designware: Move interrupt handling functions before i2c_dw_xfer()

[Jarkko Nikula]

Code is more logically arranged when i2c_dw_read_clear_intrbits() and
i2c_dw_isr() are located before i2c_dw_xfer().

Real reason for this is to prepare for more shared code between
interrupt and polling mode code.

While at it, remove one extra space and refer to the
i2c_dw_init_master() in two comment sections.

Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
---
 drivers/i2c/busses/i2c-designware-master.c | 226 ++++++++++-----------
 1 file changed, 113 insertions(+), 113 deletions(-)

diff --git a/drivers/i2c/busses/i2c-designware-master.c b/drivers/i2c/busses/i2c-designware-master.c
index 2e8f9733ddd3..7c8e95fef9c8 100644
--- a/drivers/i2c/busses/i2c-designware-master.c
+++ b/drivers/i2c/busses/i2c-designware-master.c
@@ -633,119 +633,6 @@ i2c_dw_read(struct dw_i2c_dev *dev)
 	}
 }
 
-/*
- * Prepare controller for a transaction and call i2c_dw_xfer_msg.
- */
-static int
-i2c_dw_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
-{
-	struct dw_i2c_dev *dev = i2c_get_adapdata(adap);
-	int ret;
-
-	dev_dbg(dev->dev, "%s: msgs: %d\n", __func__, num);
-
-	pm_runtime_get_sync(dev->dev);
-
-	/*
-	 * Initiate I2C message transfer when polling mode is enabled,
-	 * As it is polling based transfer mechanism, which does not support
-	 * interrupt based functionalities of existing DesignWare driver.
-	 */
-	switch (dev->flags & MODEL_MASK) {
-	case MODEL_AMD_NAVI_GPU:
-		ret = amd_i2c_dw_xfer_quirk(adap, msgs, num);
-		goto done_nolock;
-	case MODEL_WANGXUN_SP:
-		ret = txgbe_i2c_dw_xfer_quirk(adap, msgs, num);
-		goto done_nolock;
-	default:
-		break;
-	}
-
-	reinit_completion(&dev->cmd_complete);
-	dev->msgs = msgs;
-	dev->msgs_num = num;
-	dev->cmd_err = 0;
-	dev->msg_write_idx = 0;
-	dev->msg_read_idx = 0;
-	dev->msg_err = 0;
-	dev->status = 0;
-	dev->abort_source = 0;
-	dev->rx_outstanding = 0;
-
-	ret = i2c_dw_acquire_lock(dev);
-	if (ret)
-		goto done_nolock;
-
-	ret = i2c_dw_wait_bus_not_busy(dev);
-	if (ret < 0)
-		goto done;
-
-	/* Start the transfers */
-	i2c_dw_xfer_init(dev);
-
-	/* Wait for tx to complete */
-	if (!wait_for_completion_timeout(&dev->cmd_complete, adap->timeout)) {
-		dev_err(dev->dev, "controller timed out\n");
-		/* i2c_dw_init implicitly disables the adapter */
-		i2c_recover_bus(&dev->adapter);
-		i2c_dw_init_master(dev);
-		ret = -ETIMEDOUT;
-		goto done;
-	}
-
-	/*
-	 * We must disable the adapter before returning and signaling the end
-	 * of the current transfer. Otherwise the hardware might continue
-	 * generating interrupts which in turn causes a race condition with
-	 * the following transfer.  Needs some more investigation if the
-	 * additional interrupts are a hardware bug or this driver doesn't
-	 * handle them correctly yet.
-	 */
-	__i2c_dw_disable_nowait(dev);
-
-	if (dev->msg_err) {
-		ret = dev->msg_err;
-		goto done;
-	}
-
-	/* No error */
-	if (likely(!dev->cmd_err && !dev->status)) {
-		ret = num;
-		goto done;
-	}
-
-	/* We have an error */
-	if (dev->cmd_err == DW_IC_ERR_TX_ABRT) {
-		ret = i2c_dw_handle_tx_abort(dev);
-		goto done;
-	}
-
-	if (dev->status)
-		dev_err(dev->dev,
-			"transfer terminated early - interrupt latency too high?\n");
-
-	ret = -EIO;
-
-done:
-	i2c_dw_release_lock(dev);
-
-done_nolock:
-	pm_runtime_mark_last_busy(dev->dev);
-	pm_runtime_put_autosuspend(dev->dev);
-
-	return ret;
-}
-
-static const struct i2c_algorithm i2c_dw_algo = {
-	.master_xfer = i2c_dw_xfer,
-	.functionality = i2c_dw_func,
-};
-
-static const struct i2c_adapter_quirks i2c_dw_quirks = {
-	.flags = I2C_AQ_NO_ZERO_LEN,
-};
-
 static u32 i2c_dw_read_clear_intrbits(struct dw_i2c_dev *dev)
 {
 	unsigned int stat, dummy;
@@ -872,6 +759,119 @@ static irqreturn_t i2c_dw_isr(int this_irq, void *dev_id)
 	return IRQ_HANDLED;
 }
 
+/*
+ * Prepare controller for a transaction and call i2c_dw_xfer_msg.
+ */
+static int
+i2c_dw_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
+{
+	struct dw_i2c_dev *dev = i2c_get_adapdata(adap);
+	int ret;
+
+	dev_dbg(dev->dev, "%s: msgs: %d\n", __func__, num);
+
+	pm_runtime_get_sync(dev->dev);
+
+	/*
+	 * Initiate I2C message transfer when polling mode is enabled,
+	 * As it is polling based transfer mechanism, which does not support
+	 * interrupt based functionalities of existing DesignWare driver.
+	 */
+	switch (dev->flags & MODEL_MASK) {
+	case MODEL_AMD_NAVI_GPU:
+		ret = amd_i2c_dw_xfer_quirk(adap, msgs, num);
+		goto done_nolock;
+	case MODEL_WANGXUN_SP:
+		ret = txgbe_i2c_dw_xfer_quirk(adap, msgs, num);
+		goto done_nolock;
+	default:
+		break;
+	}
+
+	reinit_completion(&dev->cmd_complete);
+	dev->msgs = msgs;
+	dev->msgs_num = num;
+	dev->cmd_err = 0;
+	dev->msg_write_idx = 0;
+	dev->msg_read_idx = 0;
+	dev->msg_err = 0;
+	dev->status = 0;
+	dev->abort_source = 0;
+	dev->rx_outstanding = 0;
+
+	ret = i2c_dw_acquire_lock(dev);
+	if (ret)
+		goto done_nolock;
+
+	ret = i2c_dw_wait_bus_not_busy(dev);
+	if (ret < 0)
+		goto done;
+
+	/* Start the transfers */
+	i2c_dw_xfer_init(dev);
+
+	/* Wait for tx to complete */
+	if (!wait_for_completion_timeout(&dev->cmd_complete, adap->timeout)) {
+		dev_err(dev->dev, "controller timed out\n");
+		/* i2c_dw_init_master() implicitly disables the adapter */
+		i2c_recover_bus(&dev->adapter);
+		i2c_dw_init_master(dev);
+		ret = -ETIMEDOUT;
+		goto done;
+	}
+
+	/*
+	 * We must disable the adapter before returning and signaling the end
+	 * of the current transfer. Otherwise the hardware might continue
+	 * generating interrupts which in turn causes a race condition with
+	 * the following transfer. Needs some more investigation if the
+	 * additional interrupts are a hardware bug or this driver doesn't
+	 * handle them correctly yet.
+	 */
+	__i2c_dw_disable_nowait(dev);
+
+	if (dev->msg_err) {
+		ret = dev->msg_err;
+		goto done;
+	}
+
+	/* No error */
+	if (likely(!dev->cmd_err && !dev->status)) {
+		ret = num;
+		goto done;
+	}
+
+	/* We have an error */
+	if (dev->cmd_err == DW_IC_ERR_TX_ABRT) {
+		ret = i2c_dw_handle_tx_abort(dev);
+		goto done;
+	}
+
+	if (dev->status)
+		dev_err(dev->dev,
+			"transfer terminated early - interrupt latency too high?\n");
+
+	ret = -EIO;
+
+done:
+	i2c_dw_release_lock(dev);
+
+done_nolock:
+	pm_runtime_mark_last_busy(dev->dev);
+	pm_runtime_put_autosuspend(dev->dev);
+
+	return ret;
+}
+
+static const struct i2c_algorithm i2c_dw_algo = {
+	.master_xfer = i2c_dw_xfer,
+	.functionality = i2c_dw_func,
+};
+
+static const struct i2c_adapter_quirks i2c_dw_quirks = {
+	.flags = I2C_AQ_NO_ZERO_LEN,
+};
+
 void i2c_dw_configure_master(struct dw_i2c_dev *dev)
 {
 	struct i2c_timings *t = &dev->timings;
-- 
2.43.0

[PATCH v3 5/6] i2c: designware: Fix RX FIFO depth define on Wangxun 10Gb NIC

[Jarkko Nikula]

I believe RX FIFO depth define 0 is incorrect on Wangxun 10Gb NIC. It
must be at least 1 since code is able to read received data from the
DW_IC_DATA_CMD register.

For now this define is irrelevant since the txgbe_i2c_dw_xfer_quirk()
doesn't use the rx_fifo_depth member variable of struct dw_i2c_dev but
is needed when converting code into generic polling mode implementation.

Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
---
 drivers/i2c/busses/i2c-designware-core.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h
index 4d277ebcca92..bf8f140dc113 100644
--- a/drivers/i2c/busses/i2c-designware-core.h
+++ b/drivers/i2c/busses/i2c-designware-core.h
@@ -319,7 +319,7 @@ struct dw_i2c_dev {
 #define AMD_UCSI_INTR_EN			0xd
 
 #define TXGBE_TX_FIFO_DEPTH			4
-#define TXGBE_RX_FIFO_DEPTH			0
+#define TXGBE_RX_FIFO_DEPTH			1
 
 struct i2c_dw_semaphore_callbacks {
 	int	(*probe)(struct dw_i2c_dev *dev);
-- 
2.43.0

[PATCH v3 6/6] i2c: designware: Implement generic polling mode code for Wangxun 10Gb NIC

[Jarkko Nikula]

I got an idea the i2c-designware should not need duplicated state
machines for the interrupt and polling modes. The IP is practically the
same and state transitions happens in response to the events that can be
observed from the DW_IC_RAW_INTR_STAT register. Either by interrupts or
by polling.

Another reasons are the interrupt mode is the most tested, has handling
for special cases as well as transmit abort handling and those are
missing from two polling mode quirks.

Patch implements a generic polling mode by using existing code for
interrupt mode. This is done by moving event handling from the
i2c_dw_isr() into a new i2c_dw_process_transfer() that will be called
both from the i2c_dw_isr() and a polling loop.

Polling loop is implemented in a new i2c_dw_wait_transfer() that is
shared between both modes. In interrupt mode it waits for the completion
object as before. In polling mode both completion object and
DW_IC_RAW_INTR_STAT are polled to determine completed transfer and state
transitions.

Loop tries to save power by sleeping "stetson guessed" range between
3 and 25 µS which falls between 10 cycles of High-speed mode 3.4 Mb/s
and Fast mode 400 kHz. With it the CPU usage was reduced under heavy
Fast mode I2C transfer without much increase in total transfer time but
otherwise no more effort has been put to optimize this.

I decided to convert the txgbe_i2c_dw_xfer_quirk() straight to generic
polling mode code in this patch. It doesn't have HW dependent quirks
like the amd_i2c_dw_xfer_quirk() does have and without users this patch
is needless.

Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
---
 drivers/i2c/busses/i2c-designware-core.h   |   5 +
 drivers/i2c/busses/i2c-designware-master.c | 172 +++++++++------------
 2 files changed, 75 insertions(+), 102 deletions(-)

diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h
index bf8f140dc113..e9606c00b8d1 100644
--- a/drivers/i2c/busses/i2c-designware-core.h
+++ b/drivers/i2c/busses/i2c-designware-core.h
@@ -212,6 +212,7 @@ struct reset_control;
  * @msg_err: error status of the current transfer
  * @status: i2c master status, one of STATUS_*
  * @abort_source: copy of the TX_ABRT_SOURCE register
+ * @sw_mask: SW mask of DW_IC_INTR_MASK used in polling mode
  * @irq: interrupt number for the i2c master
  * @flags: platform specific flags like type of IO accessors or model
  * @adapter: i2c subsystem adapter node
@@ -270,6 +271,7 @@ struct dw_i2c_dev {
 	int			msg_err;
 	unsigned int		status;
 	unsigned int		abort_source;
+	unsigned int		sw_mask;
 	int			irq;
 	u32			flags;
 	struct i2c_adapter	adapter;
@@ -358,6 +360,7 @@ static inline void __i2c_dw_write_intr_mask(struct dw_i2c_dev *dev,
 	unsigned int val = dev->flags & ACCESS_POLLING ? 0 : intr_mask;
 
 	regmap_write(dev->map, DW_IC_INTR_MASK, val);
+	dev->sw_mask = intr_mask;
 }
 
 static inline void __i2c_dw_read_intr_mask(struct dw_i2c_dev *dev,
@@ -365,6 +368,8 @@ static inline void __i2c_dw_read_intr_mask(struct dw_i2c_dev *dev,
 {
 	if (!(dev->flags & ACCESS_POLLING))
 		regmap_read(dev->map, DW_IC_INTR_MASK, intr_mask);
+	else
+		*intr_mask = dev->sw_mask;
 }
 
 void __i2c_dw_disable(struct dw_i2c_dev *dev);
diff --git a/drivers/i2c/busses/i2c-designware-master.c b/drivers/i2c/busses/i2c-designware-master.c
index 7c8e95fef9c8..c7e56002809a 100644
--- a/drivers/i2c/busses/i2c-designware-master.c
+++ b/drivers/i2c/busses/i2c-designware-master.c
@@ -354,67 +354,6 @@ static int amd_i2c_dw_xfer_quirk(struct i2c_adapter *adap, struct i2c_msg *msgs,
 	return 0;
 }
 
-static int i2c_dw_poll_tx_empty(struct dw_i2c_dev *dev)
-{
-	u32 val;
-
-	return regmap_read_poll_timeout(dev->map, DW_IC_RAW_INTR_STAT, val,
-					val & DW_IC_INTR_TX_EMPTY,
-					100, 1000);
-}
-
-static int i2c_dw_poll_rx_full(struct dw_i2c_dev *dev)
-{
-	u32 val;
-
-	return regmap_read_poll_timeout(dev->map, DW_IC_RAW_INTR_STAT, val,
-					val & DW_IC_INTR_RX_FULL,
-					100, 1000);
-}
-
-static int txgbe_i2c_dw_xfer_quirk(struct i2c_adapter *adap, struct i2c_msg *msgs,
-				   int num_msgs)
-{
-	struct dw_i2c_dev *dev = i2c_get_adapdata(adap);
-	int msg_idx, buf_len, data_idx, ret;
-	unsigned int val, stop = 0;
-	u8 *buf;
-
-	dev->msgs = msgs;
-	dev->msgs_num = num_msgs;
-	i2c_dw_xfer_init(dev);
-
-	for (msg_idx = 0; msg_idx < num_msgs; msg_idx++) {
-		buf = msgs[msg_idx].buf;
-		buf_len = msgs[msg_idx].len;
-
-		for (data_idx = 0; data_idx < buf_len; data_idx++) {
-			if (msg_idx == num_msgs - 1 && data_idx == buf_len - 1)
-				stop |= BIT(9);
-
-			if (msgs[msg_idx].flags & I2C_M_RD) {
-				regmap_write(dev->map, DW_IC_DATA_CMD, 0x100 | stop);
-
-				ret = i2c_dw_poll_rx_full(dev);
-				if (ret)
-					return ret;
-
-				regmap_read(dev->map, DW_IC_DATA_CMD, &val);
-				buf[data_idx] = val;
-			} else {
-				ret = i2c_dw_poll_tx_empty(dev);
-				if (ret)
-					return ret;
-
-				regmap_write(dev->map, DW_IC_DATA_CMD,
-					     buf[data_idx] | stop);
-			}
-		}
-	}
-
-	return num_msgs;
-}
-
 /*
  * Initiate (and continue) low level master read/write transaction.
  * This function is only called from i2c_dw_isr, and pumping i2c_msg
@@ -649,7 +588,12 @@ static u32 i2c_dw_read_clear_intrbits(struct dw_i2c_dev *dev)
 	 *
 	 * The raw version might be useful for debugging purposes.
 	 */
-	regmap_read(dev->map, DW_IC_INTR_STAT, &stat);
+	if (!(dev->flags & ACCESS_POLLING)) {
+		regmap_read(dev->map, DW_IC_INTR_STAT, &stat);
+	} else {
+		regmap_read(dev->map, DW_IC_RAW_INTR_STAT, &stat);
+		stat &= dev->sw_mask;
+	}
 
 	/*
 	 * Do not use the IC_CLR_INTR register to clear interrupts, or
@@ -689,37 +633,8 @@ static u32 i2c_dw_read_clear_intrbits(struct dw_i2c_dev *dev)
 	return stat;
 }
 
-/*
- * Interrupt service routine. This gets called whenever an I2C master interrupt
- * occurs.
- */
-static irqreturn_t i2c_dw_isr(int this_irq, void *dev_id)
+static void i2c_dw_process_transfer(struct dw_i2c_dev *dev, unsigned int stat)
 {
-	struct dw_i2c_dev *dev = dev_id;
-	unsigned int stat, enabled;
-
-	regmap_read(dev->map, DW_IC_ENABLE, &enabled);
-	regmap_read(dev->map, DW_IC_RAW_INTR_STAT, &stat);
-	if (!enabled || !(stat & ~DW_IC_INTR_ACTIVITY))
-		return IRQ_NONE;
-	if (pm_runtime_suspended(dev->dev) || stat == GENMASK(31, 0))
-		return IRQ_NONE;
-	dev_dbg(dev->dev, "enabled=%#x stat=%#x\n", enabled, stat);
-
-	stat = i2c_dw_read_clear_intrbits(dev);
-
-	if (!(dev->status & STATUS_ACTIVE)) {
-		/*
-		 * Unexpected interrupt in driver point of view. State
-		 * variables are either unset or stale so acknowledge and
-		 * disable interrupts for suppressing further interrupts if
-		 * interrupt really came from this HW (E.g. firmware has left
-		 * the HW active).
-		 */
-		__i2c_dw_write_intr_mask(dev, 0);
-		return IRQ_HANDLED;
-	}
-
 	if (stat & DW_IC_INTR_TX_ABRT) {
 		dev->cmd_err |= DW_IC_ERR_TX_ABRT;
 		dev->status &= ~STATUS_MASK;
@@ -755,10 +670,71 @@ static irqreturn_t i2c_dw_isr(int this_irq, void *dev_id)
 		__i2c_dw_write_intr_mask(dev, 0);
 		__i2c_dw_write_intr_mask(dev, stat);
 	}
+}
+
+/*
+ * Interrupt service routine. This gets called whenever an I2C master interrupt
+ * occurs.
+ */
+static irqreturn_t i2c_dw_isr(int this_irq, void *dev_id)
+{
+	struct dw_i2c_dev *dev = dev_id;
+	unsigned int stat, enabled;
+
+	regmap_read(dev->map, DW_IC_ENABLE, &enabled);
+	regmap_read(dev->map, DW_IC_RAW_INTR_STAT, &stat);
+	if (!enabled || !(stat & ~DW_IC_INTR_ACTIVITY))
+		return IRQ_NONE;
+	if (pm_runtime_suspended(dev->dev) || stat == GENMASK(31, 0))
+		return IRQ_NONE;
+	dev_dbg(dev->dev, "enabled=%#x stat=%#x\n", enabled, stat);
+
+	stat = i2c_dw_read_clear_intrbits(dev);
+
+	if (!(dev->status & STATUS_ACTIVE)) {
+		/*
+		 * Unexpected interrupt in driver point of view. State
+		 * variables are either unset or stale so acknowledge and
+		 * disable interrupts for suppressing further interrupts if
+		 * interrupt really came from this HW (E.g. firmware has left
+		 * the HW active).
+		 */
+		__i2c_dw_write_intr_mask(dev, 0);
+		return IRQ_HANDLED;
+	}
+
+	i2c_dw_process_transfer(dev, stat);
 
 	return IRQ_HANDLED;
 }
 
+static int i2c_dw_wait_transfer(struct dw_i2c_dev *dev)
+{
+	unsigned long timeout = dev->adapter.timeout;
+	unsigned int stat;
+	int ret;
+
+	if (!(dev->flags & ACCESS_POLLING)) {
+		ret = wait_for_completion_timeout(&dev->cmd_complete, timeout);
+	} else {
+		timeout += jiffies;
+		do {
+			ret = try_wait_for_completion(&dev->cmd_complete);
+			if (ret)
+				break;
+
+			stat = i2c_dw_read_clear_intrbits(dev);
+			if (stat)
+				i2c_dw_process_transfer(dev, stat);
+			else
+				/* Try save some power */
+				usleep_range(3, 25);
+		} while (time_before(jiffies, timeout));
+	}
+
+	return ret ? 0 : -ETIMEDOUT;
+}
+
 /*
  * Prepare controller for a transaction and call i2c_dw_xfer_msg.
  */
@@ -772,18 +748,10 @@ i2c_dw_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
 
 	pm_runtime_get_sync(dev->dev);
 
-	/*
-	 * Initiate I2C message transfer when polling mode is enabled,
-	 * As it is polling based transfer mechanism, which does not support
-	 * interrupt based functionalities of existing DesignWare driver.
-	 */
 	switch (dev->flags & MODEL_MASK) {
 	case MODEL_AMD_NAVI_GPU:
 		ret = amd_i2c_dw_xfer_quirk(adap, msgs, num);
 		goto done_nolock;
-	case MODEL_WANGXUN_SP:
-		ret = txgbe_i2c_dw_xfer_quirk(adap, msgs, num);
-		goto done_nolock;
 	default:
 		break;
 	}
@@ -811,12 +779,12 @@ i2c_dw_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
 	i2c_dw_xfer_init(dev);
 
 	/* Wait for tx to complete */
-	if (!wait_for_completion_timeout(&dev->cmd_complete, adap->timeout)) {
+	ret = i2c_dw_wait_transfer(dev);
+	if (ret) {
 		dev_err(dev->dev, "controller timed out\n");
 		/* i2c_dw_init_master() implicitly disables the adapter */
 		i2c_recover_bus(&dev->adapter);
 		i2c_dw_init_master(dev);
-		ret = -ETIMEDOUT;
 		goto done;
 	}
 
-- 
2.43.0

RE: [PATCH v3 0/6] i2c: designware: Generic polling mode code

[Jiawen Wu]

On Tue, Feb 13, 2024 8:49 PM, Jarkko Nikula wrote:
> Hi Jiawen, Sanket and Basavaraj
> 
> I hope you could give a quick test to this patchset to see it won't cause
> regression on your HW. This is mostly the same than the first version what
> Jiawen tested earlier but in this 3rd version I decided to drop semphore
> touching code patches from v2 due they being out of scope and fix a few
> things noted by Andy.
> 
> Changes are in the patch 3/6 with two minor fixes to comments while moving
> them and the patch 6/6 where i2c_dw_wait_transfer() is slightly modified
> by Andy's suggestion plus I decided to remove one comment which became
> unclear after this patch.

Hi Jarkko,

I've been testing the v3 patch series on Wangxun 10Gb NIC, it works well, too.
Thanks!

Tested-by: Jiawen Wu <jiawenwu@trustnetic.com>

Re: [PATCH v3 0/6] i2c: designware: Generic polling mode code

[Jarkko Nikula]

Hi

On 2/18/24 11:19, Jiawen Wu wrote:
> On Tue, Feb 13, 2024 8:49 PM, Jarkko Nikula wrote:
>> Hi Jiawen, Sanket and Basavaraj
>>
>> I hope you could give a quick test to this patchset to see it won't cause
>> regression on your HW. This is mostly the same than the first version what
>> Jiawen tested earlier but in this 3rd version I decided to drop semphore
>> touching code patches from v2 due they being out of scope and fix a few
>> things noted by Andy.
>>
>> Changes are in the patch 3/6 with two minor fixes to comments while moving
>> them and the patch 6/6 where i2c_dw_wait_transfer() is slightly modified
>> by Andy's suggestion plus I decided to remove one comment which became
>> unclear after this patch.
> 
> Hi Jarkko,
> 
> I've been testing the v3 patch series on Wangxun 10Gb NIC, it works well, too.
> Thanks!
> 
> Tested-by: Jiawen Wu <jiawenwu@trustnetic.com>
> 
Andy: Was this set ok in your point of view now?

Re: [PATCH v3 0/6] i2c: designware: Generic polling mode code

['Andy Shevchenko']

On Fri, Feb 23, 2024 at 05:09:37PM +0200, Jarkko Nikula wrote:
> On 2/18/24 11:19, Jiawen Wu wrote:
> > On Tue, Feb 13, 2024 8:49 PM, Jarkko Nikula wrote:
> > > Hi Jiawen, Sanket and Basavaraj
> > > 
> > > I hope you could give a quick test to this patchset to see it won't cause
> > > regression on your HW. This is mostly the same than the first version what
> > > Jiawen tested earlier but in this 3rd version I decided to drop semphore
> > > touching code patches from v2 due they being out of scope and fix a few
> > > things noted by Andy.
> > > 
> > > Changes are in the patch 3/6 with two minor fixes to comments while moving
> > > them and the patch 6/6 where i2c_dw_wait_transfer() is slightly modified
> > > by Andy's suggestion plus I decided to remove one comment which became
> > > unclear after this patch.
> > 
> > Hi Jarkko,
> > 
> > I've been testing the v3 patch series on Wangxun 10Gb NIC, it works well, too.
> > Thanks!
> > 
> > Tested-by: Jiawen Wu <jiawenwu@trustnetic.com>
> > 
> Andy: Was this set ok in your point of view now?

Yes, I hoped that Andi applies it earlier last week or so.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v3 0/6] i2c: designware: Generic polling mode code

[Andi Shyti]

Hi

On Tue, 13 Feb 2024 14:48:41 +0200, Jarkko Nikula wrote:
> I hope you could give a quick test to this patchset to see it won't cause
> regression on your HW. This is mostly the same than the first version what
> Jiawen tested earlier but in this 3rd version I decided to drop semphore
> touching code patches from v2 due they being out of scope and fix a few
> things noted by Andy.
> 
> Changes are in the patch 3/6 with two minor fixes to comments while moving
> them and the patch 6/6 where i2c_dw_wait_transfer() is slightly modified
> by Andy's suggestion plus I decided to remove one comment which became
> unclear after this patch.
> 
> [...]

Applied to i2c/i2c-host on

git://git.kernel.org/pub/scm/linux/kernel/git/andi.shyti/linux.git

Thank you,
Andi

Patches applied
===============
[1/6] i2c: designware: Uniform initialization flow for polling mode
      commit: 535677e44d57a31e1363529b5ecddb92653d7136
[2/6] i2c: designware: Do not enable interrupts shortly in polling mode
      commit: 64b6426a6e97a95c044fd2fff3f0adf7c1edb60c
[3/6] i2c: designware: Use accessors to DW_IC_INTR_MASK register
      commit: 04c71da4a9f4eef94bec153ed667d105dacffda3
[4/6] i2c: designware: Move interrupt handling functions before i2c_dw_xfer()
      commit: bd002efaa16e4cfffc25db2d9c4669aaa2b43646
[5/6] i2c: designware: Fix RX FIFO depth define on Wangxun 10Gb NIC
      commit: c94612a72ac87b0337a0d85b9263266776ed4190
[6/6] i2c: designware: Implement generic polling mode code for Wangxun 10Gb NIC
      commit: 197ecadad842855437a36ffc161648418ae02a97