Merge branch 'net-ipa-add-a-driver-shutdown-callback'

Alex Elder says:

====================
net: ipa: add a driver shutdown callback

The final patch in this series adds a driver shutdown callback for
the IPA driver.  The patches leading up to that address some issues
encountered while ensuring that callback worked as expected:
  - The first just reports a little more information when channels
    or event rings are in unexpected states
  - The second patch recognizes a condition where an as-yet-unused
    channel does not require a reset during teardown
  - The third patch explicitly ignores a certain error condition,
    because it can't be avoided, and is harmless if it occurs
  - The fourth properly handles requests to retry a channel HALT
    request
  - The fifth makes a second attempt to stop modem activity during
    shutdown if it's busy

The shutdown callback is implemented by calling the existing remove
callback function (reporting if that returns an error).
====================

Link: https://lore.kernel.org/r/20201119224929.23819-1-elder@linaro.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

3 files changed, 94 insertions, 27 deletions

diff --git a/drivers/net/ipa/gsi.c b/drivers/net/ipa/gsi.c
index 55151960a698..eb4c5d408a83 100644
--- a/drivers/net/ipa/gsi.c
+++ b/drivers/net/ipa/gsi.c
@@ -92,6 +92,7 @@
 #define GSI_CMD_TIMEOUT			5	/* seconds */
 
 #define GSI_CHANNEL_STOP_RX_RETRIES	10
+#define GSI_CHANNEL_MODEM_HALT_RETRIES	10
 
 #define GSI_MHI_EVENT_ID_START		10	/* 1st reserved event id */
 #define GSI_MHI_EVENT_ID_END		16	/* Last reserved event id */
@@ -365,15 +366,15 @@ static int gsi_evt_ring_alloc_command(struct gsi *gsi, u32 evt_ring_id)
 	/* Get initial event ring state */
 	evt_ring->state = gsi_evt_ring_state(gsi, evt_ring_id);
 	if (evt_ring->state != GSI_EVT_RING_STATE_NOT_ALLOCATED) {
-		dev_err(gsi->dev, "bad event ring state %u before alloc\n",
-			evt_ring->state);
+		dev_err(gsi->dev, "event ring %u bad state %u before alloc\n",
+			evt_ring_id, evt_ring->state);
 		return -EINVAL;
 	}
 
 	ret = evt_ring_command(gsi, evt_ring_id, GSI_EVT_ALLOCATE);
 	if (!ret && evt_ring->state != GSI_EVT_RING_STATE_ALLOCATED) {
-		dev_err(gsi->dev, "bad event ring state %u after alloc\n",
-			evt_ring->state);
+		dev_err(gsi->dev, "event ring %u bad state %u after alloc\n",
+			evt_ring_id, evt_ring->state);
 		ret = -EIO;
 	}
 
@@ -389,15 +390,15 @@ static void gsi_evt_ring_reset_command(struct gsi *gsi, u32 evt_ring_id)
 
 	if (state != GSI_EVT_RING_STATE_ALLOCATED &&
 	    state != GSI_EVT_RING_STATE_ERROR) {
-		dev_err(gsi->dev, "bad event ring state %u before reset\n",
-			evt_ring->state);
+		dev_err(gsi->dev, "event ring %u bad state %u before reset\n",
+			evt_ring_id, evt_ring->state);
 		return;
 	}
 
 	ret = evt_ring_command(gsi, evt_ring_id, GSI_EVT_RESET);
 	if (!ret && evt_ring->state != GSI_EVT_RING_STATE_ALLOCATED)
-		dev_err(gsi->dev, "bad event ring state %u after reset\n",
-			evt_ring->state);
+		dev_err(gsi->dev, "event ring %u bad state %u after reset\n",
+			evt_ring_id, evt_ring->state);
 }
 
 /* Issue a hardware de-allocation request for an allocated event ring */
@@ -407,15 +408,15 @@ static void gsi_evt_ring_de_alloc_command(struct gsi *gsi, u32 evt_ring_id)
 	int ret;
 
 	if (evt_ring->state != GSI_EVT_RING_STATE_ALLOCATED) {
-		dev_err(gsi->dev, "bad event ring state %u before dealloc\n",
-			evt_ring->state);
+		dev_err(gsi->dev, "event ring %u state %u before dealloc\n",
+			evt_ring_id, evt_ring->state);
 		return;
 	}
 
 	ret = evt_ring_command(gsi, evt_ring_id, GSI_EVT_DE_ALLOC);
 	if (!ret && evt_ring->state != GSI_EVT_RING_STATE_NOT_ALLOCATED)
-		dev_err(gsi->dev, "bad event ring state %u after dealloc\n",
-			evt_ring->state);
+		dev_err(gsi->dev, "event ring %u bad state %u after dealloc\n",
+			evt_ring_id, evt_ring->state);
 }
 
 /* Fetch the current state of a channel from hardware */
@@ -479,7 +480,8 @@ static int gsi_channel_alloc_command(struct gsi *gsi, u32 channel_id)
 	/* Get initial channel state */
 	state = gsi_channel_state(channel);
 	if (state != GSI_CHANNEL_STATE_NOT_ALLOCATED) {
-		dev_err(dev, "bad channel state %u before alloc\n", state);
+		dev_err(dev, "channel %u bad state %u before alloc\n",
+			channel_id, state);
 		return -EINVAL;
 	}
 
@@ -488,7 +490,8 @@ static int gsi_channel_alloc_command(struct gsi *gsi, u32 channel_id)
 	/* Channel state will normally have been updated */
 	state = gsi_channel_state(channel);
 	if (!ret && state != GSI_CHANNEL_STATE_ALLOCATED) {
-		dev_err(dev, "bad channel state %u after alloc\n", state);
+		dev_err(dev, "channel %u bad state %u after alloc\n",
+			channel_id, state);
 		ret = -EIO;
 	}
 
@@ -505,7 +508,8 @@ static int gsi_channel_start_command(struct gsi_channel *channel)
 	state = gsi_channel_state(channel);
 	if (state != GSI_CHANNEL_STATE_ALLOCATED &&
 	    state != GSI_CHANNEL_STATE_STOPPED) {
-		dev_err(dev, "bad channel state %u before start\n", state);
+		dev_err(dev, "channel %u bad state %u before start\n",
+			gsi_channel_id(channel), state);
 		return -EINVAL;
 	}
 
@@ -514,7 +518,8 @@ static int gsi_channel_start_command(struct gsi_channel *channel)
 	/* Channel state will normally have been updated */
 	state = gsi_channel_state(channel);
 	if (!ret && state != GSI_CHANNEL_STATE_STARTED) {
-		dev_err(dev, "bad channel state %u after start\n", state);
+		dev_err(dev, "channel %u bad state %u after start\n",
+			gsi_channel_id(channel), state);
 		ret = -EIO;
 	}
 
@@ -538,7 +543,8 @@ static int gsi_channel_stop_command(struct gsi_channel *channel)
 
 	if (state != GSI_CHANNEL_STATE_STARTED &&
 	    state != GSI_CHANNEL_STATE_STOP_IN_PROC) {
-		dev_err(dev, "bad channel state %u before stop\n", state);
+		dev_err(dev, "channel %u bad state %u before stop\n",
+			gsi_channel_id(channel), state);
 		return -EINVAL;
 	}
 
@@ -553,7 +559,8 @@ static int gsi_channel_stop_command(struct gsi_channel *channel)
 	if (state == GSI_CHANNEL_STATE_STOP_IN_PROC)
 		return -EAGAIN;
 
-	dev_err(dev, "bad channel state %u after stop\n", state);
+	dev_err(dev, "channel %u bad state %u after stop\n",
+		gsi_channel_id(channel), state);
 
 	return -EIO;
 }
@@ -570,7 +577,10 @@ static void gsi_channel_reset_command(struct gsi_channel *channel)
 	state = gsi_channel_state(channel);
 	if (state != GSI_CHANNEL_STATE_STOPPED &&
 	    state != GSI_CHANNEL_STATE_ERROR) {
-		dev_err(dev, "bad channel state %u before reset\n", state);
+		/* No need to reset a channel already in ALLOCATED state */
+		if (state != GSI_CHANNEL_STATE_ALLOCATED)
+			dev_err(dev, "channel %u bad state %u before reset\n",
+				gsi_channel_id(channel), state);
 		return;
 	}
 
@@ -579,7 +589,8 @@ static void gsi_channel_reset_command(struct gsi_channel *channel)
 	/* Channel state will normally have been updated */
 	state = gsi_channel_state(channel);
 	if (!ret && state != GSI_CHANNEL_STATE_ALLOCATED)
-		dev_err(dev, "bad channel state %u after reset\n", state);
+		dev_err(dev, "channel %u bad state %u after reset\n",
+			gsi_channel_id(channel), state);
 }
 
 /* Deallocate an ALLOCATED GSI channel */
@@ -592,7 +603,8 @@ static void gsi_channel_de_alloc_command(struct gsi *gsi, u32 channel_id)
 
 	state = gsi_channel_state(channel);
 	if (state != GSI_CHANNEL_STATE_ALLOCATED) {
-		dev_err(dev, "bad channel state %u before dealloc\n", state);
+		dev_err(dev, "channel %u bad state %u before dealloc\n",
+			channel_id, state);
 		return;
 	}
 
@@ -601,7 +613,8 @@ static void gsi_channel_de_alloc_command(struct gsi *gsi, u32 channel_id)
 	/* Channel state will normally have been updated */
 	state = gsi_channel_state(channel);
 	if (!ret && state != GSI_CHANNEL_STATE_NOT_ALLOCATED)
-		dev_err(dev, "bad channel state %u after dealloc\n", state);
+		dev_err(dev, "channel %u bad state %u after dealloc\n",
+			channel_id, state);
 }
 
 /* Ring an event ring doorbell, reporting the last entry processed by the AP.
@@ -1075,10 +1088,38 @@ static void gsi_isr_gp_int1(struct gsi *gsi)
 	u32 result;
 	u32 val;
 
+	/* This interrupt is used to handle completions of the two GENERIC
+	 * GSI commands.  We use these to allocate and halt channels on
+	 * the modem's behalf due to a hardware quirk on IPA v4.2.  Once
+	 * allocated, the modem "owns" these channels, and as a result we
+	 * have no way of knowing the channel's state at any given time.
+	 *
+	 * It is recommended that we halt the modem channels we allocated
+	 * when shutting down, but it's possible the channel isn't running
+	 * at the time we issue the HALT command.  We'll get an error in
+	 * that case, but it's harmless (the channel is already halted).
+	 *
+	 * For this reason, we silently ignore a CHANNEL_NOT_RUNNING error
+	 * if we receive it.
+	 */
 	val = ioread32(gsi->virt + GSI_CNTXT_SCRATCH_0_OFFSET);
 	result = u32_get_bits(val, GENERIC_EE_RESULT_FMASK);
-	if (result != GENERIC_EE_SUCCESS)
+
+	switch (result) {
+	case GENERIC_EE_SUCCESS:
+	case GENERIC_EE_CHANNEL_NOT_RUNNING:
+		gsi->result = 0;
+		break;
+
+	case GENERIC_EE_RETRY:
+		gsi->result = -EAGAIN;
+		break;
+
+	default:
 		dev_err(gsi->dev, "global INT1 generic result %u\n", result);
+		gsi->result = -EIO;
+		break;
+	}
 
 	complete(&gsi->completion);
 }
@@ -1590,7 +1631,7 @@ static int gsi_generic_command(struct gsi *gsi, u32 channel_id,
 	iowrite32(BIT(ERROR_INT), gsi->virt + GSI_CNTXT_GLOB_IRQ_EN_OFFSET);
 
 	if (success)
-		return 0;
+		return gsi->result;
 
 	dev_err(gsi->dev, "GSI generic command %u to channel %u timed out\n",
 		opcode, channel_id);
@@ -1606,7 +1647,17 @@ static int gsi_modem_channel_alloc(struct gsi *gsi, u32 channel_id)
 
 static void gsi_modem_channel_halt(struct gsi *gsi, u32 channel_id)
 {
-	(void)gsi_generic_command(gsi, channel_id, GSI_GENERIC_HALT_CHANNEL);
+	u32 retries = GSI_CHANNEL_MODEM_HALT_RETRIES;
+	int ret;
+
+	do
+		ret = gsi_generic_command(gsi, channel_id,
+					  GSI_GENERIC_HALT_CHANNEL);
+	while (ret == -EAGAIN && retries--);
+
+	if (ret)
+		dev_err(gsi->dev, "error %d halting modem channel %u\n",
+			ret, channel_id);
 }
 
 /* Setup function for channels */
diff --git a/drivers/net/ipa/gsi.h b/drivers/net/ipa/gsi.h
index ecc784e3a812..96c9aed397aa 100644
--- a/drivers/net/ipa/gsi.h
+++ b/drivers/net/ipa/gsi.h
@@ -161,6 +161,7 @@ struct gsi {
 	u32 type_enabled_bitmap;	/* GSI IRQ types enabled */
 	u32 ieob_enabled_bitmap;	/* IEOB IRQ enabled (event rings) */
 	struct completion completion;	/* for global EE commands */
+	int result;			/* Negative errno (generic commands) */
 	struct mutex mutex;		/* protects commands, programming */
 };
 
diff --git a/drivers/net/ipa/ipa_main.c b/drivers/net/ipa/ipa_main.c
index 468ab1acc20e..e9bd0d72f2db 100644
--- a/drivers/net/ipa/ipa_main.c
+++ b/drivers/net/ipa/ipa_main.c
@@ -863,6 +863,11 @@ static int ipa_remove(struct platform_device *pdev)
 
 	if (ipa->setup_complete) {
 		ret = ipa_modem_stop(ipa);
+		/* If starting or stopping is in progress, try once more */
+		if (ret == -EBUSY) {
+			usleep_range(USEC_PER_MSEC, 2 * USEC_PER_MSEC);
+			ret = ipa_modem_stop(ipa);
+		}
 		if (ret)
 			return ret;
 
@@ -883,6 +888,15 @@ static int ipa_remove(struct platform_device *pdev)
 	return 0;
 }
 
+static void ipa_shutdown(struct platform_device *pdev)
+{
+	int ret;
+
+	ret = ipa_remove(pdev);
+	if (ret)
+		dev_err(&pdev->dev, "shutdown: remove returned %d\n", ret);
+}
+
 /**
  * ipa_suspend() - Power management system suspend callback
  * @dev:	IPA device structure
@@ -940,8 +954,9 @@ static const struct dev_pm_ops ipa_pm_ops = {
 };
 
 static struct platform_driver ipa_driver = {
-	.probe	= ipa_probe,
-	.remove	= ipa_remove,
+	.probe		= ipa_probe,
+	.remove		= ipa_remove,
+	.shutdown	= ipa_shutdown,
 	.driver	= {
 		.name		= "ipa",
 		.pm		= &ipa_pm_ops,