Merge branch 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux

Pull i2c fixes from Wolfram Sang:
 "I2C has an interrupt storm fix for the i801, better timeout handling
  for the new virtio driver, and some documentation fixes this time"

* 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
  docs: i2c: smbus-protocol: mention the repeated start condition
  i2c: virtio: disable timeout handling
  i2c: i801: Fix interrupt storm from SMB_ALERT signal
  i2c: i801: Restore INTREN on unload
  dt-bindings: i2c: imx-lpi2c: Fix i.MX 8QM compatible matching

Documentation/devicetree/bindings/i2c/i2c-imx-lpi2c.yaml

@@ -17,9 +17,10 @@ properties:
     oneOf:
       - enum:
           - fsl,imx7ulp-lpi2c
-          - fsl,imx8qm-lpi2c
       - items:
-          - const: fsl,imx8qxp-lpi2c
+          - enum:
+              - fsl,imx8qxp-lpi2c
+              - fsl,imx8qm-lpi2c
           - const: fsl,imx7ulp-lpi2c
 
   reg:

Documentation/i2c/smbus-protocol.rst

@@ -36,6 +36,8 @@ Key to symbols
 
 =============== =============================================================
 S               Start condition
+Sr              Repeated start condition, used to switch from write to
+                read mode.
 P               Stop condition
 Rd/Wr (1 bit)   Read/Write bit. Rd equals 1, Wr equals 0.
 A, NA (1 bit)   Acknowledge (ACK) and Not Acknowledge (NACK) bit
@@ -100,7 +102,7 @@ Implemented by i2c_smbus_read_byte_data()
 This reads a single byte from a device, from a designated register.
 The register is specified through the Comm byte::
 
-  S Addr Wr [A] Comm [A] S Addr Rd [A] [Data] NA P
+  S Addr Wr [A] Comm [A] Sr Addr Rd [A] [Data] NA P
 
 Functionality flag: I2C_FUNC_SMBUS_READ_BYTE_DATA
 
@@ -114,7 +116,7 @@ This operation is very like Read Byte; again, data is read from a
 device, from a designated register that is specified through the Comm
 byte. But this time, the data is a complete word (16 bits)::
 
-  S Addr Wr [A] Comm [A] S Addr Rd [A] [DataLow] A [DataHigh] NA P
+  S Addr Wr [A] Comm [A] Sr Addr Rd [A] [DataLow] A [DataHigh] NA P
 
 Functionality flag: I2C_FUNC_SMBUS_READ_WORD_DATA
 
@@ -164,7 +166,7 @@ This command selects a device register (through the Comm byte), sends
 16 bits of data to it, and reads 16 bits of data in return::
 
   S Addr Wr [A] Comm [A] DataLow [A] DataHigh [A]
-                               S Addr Rd [A] [DataLow] A [DataHigh] NA P
+                              Sr Addr Rd [A] [DataLow] A [DataHigh] NA P
 
 Functionality flag: I2C_FUNC_SMBUS_PROC_CALL
 
@@ -181,7 +183,7 @@ of data is specified by the device in the Count byte.
 ::
 
   S Addr Wr [A] Comm [A]
-             S Addr Rd [A] [Count] A [Data] A [Data] A ... A [Data] NA P
+            Sr Addr Rd [A] [Count] A [Data] A [Data] A ... A [Data] NA P
 
 Functionality flag: I2C_FUNC_SMBUS_READ_BLOCK_DATA
 
@@ -212,7 +214,7 @@ This command selects a device register (through the Comm byte), sends
 1 to 31 bytes of data to it, and reads 1 to 31 bytes of data in return::
 
   S Addr Wr [A] Comm [A] Count [A] Data [A] ...
-                               S Addr Rd [A] [Count] A [Data] ... A P
+                              Sr Addr Rd [A] [Count] A [Data] ... A P
 
 Functionality flag: I2C_FUNC_SMBUS_BLOCK_PROC_CALL
 
@@ -300,7 +302,7 @@ This command reads a block of bytes from a device, from a
 designated register that is specified through the Comm byte::
 
   S Addr Wr [A] Comm [A]
-             S Addr Rd [A] [Data] A [Data] A ... A [Data] NA P
+            Sr Addr Rd [A] [Data] A [Data] A ... A [Data] NA P
 
 Functionality flag: I2C_FUNC_SMBUS_READ_I2C_BLOCK
 

drivers/i2c/busses/i2c-i801.c

@@ -191,6 +191,7 @@
 #define SMBSLVSTS_HST_NTFY_STS	BIT(0)
 
 /* Host Notify Command register bits */
+#define SMBSLVCMD_SMBALERT_DISABLE	BIT(2)
 #define SMBSLVCMD_HST_NTFY_INTREN	BIT(0)
 
 #define STATUS_ERROR_FLAGS	(SMBHSTSTS_FAILED | SMBHSTSTS_BUS_ERR | \
@@ -259,6 +260,7 @@ struct i801_priv {
 	struct i2c_adapter adapter;
 	unsigned long smba;
 	unsigned char original_hstcfg;
+	unsigned char original_hstcnt;
 	unsigned char original_slvcmd;
 	struct pci_dev *pci_dev;
 	unsigned int features;
@@ -641,12 +643,20 @@ static irqreturn_t i801_isr(int irq, void *dev_id)
 		i801_isr_byte_done(priv);
 
 	/*
-	 * Clear irq sources and report transaction result.
+	 * Clear remaining IRQ sources: Completion of last command, errors
+	 * and the SMB_ALERT signal. SMB_ALERT status is set after signal
+	 * assertion independently of the interrupt generation being blocked
+	 * or not so clear it always when the status is set.
+	 */
+	status &= SMBHSTSTS_INTR | STATUS_ERROR_FLAGS | SMBHSTSTS_SMBALERT_STS;
+	if (status)
+		outb_p(status, SMBHSTSTS(priv));
+	status &= ~SMBHSTSTS_SMBALERT_STS; /* SMB_ALERT not reported */
+	/*
+	 * Report transaction result.
 	 * ->status must be cleared before the next transaction is started.
 	 */
-	status &= SMBHSTSTS_INTR | STATUS_ERROR_FLAGS;
 	if (status) {
-		outb_p(status, SMBHSTSTS(priv));
 		priv->status = status;
 		complete(&priv->done);
 	}
@@ -974,9 +984,13 @@ static void i801_enable_host_notify(struct i2c_adapter *adapter)
 	if (!(priv->features & FEATURE_HOST_NOTIFY))
 		return;
 
-	if (!(SMBSLVCMD_HST_NTFY_INTREN & priv->original_slvcmd))
-		outb_p(SMBSLVCMD_HST_NTFY_INTREN | priv->original_slvcmd,
-		       SMBSLVCMD(priv));
+	/*
+	 * Enable host notify interrupt and block the generation of interrupt
+	 * from the SMB_ALERT signal because the driver does not support
+	 * SMBus Alert.
+	 */
+	outb_p(SMBSLVCMD_HST_NTFY_INTREN | SMBSLVCMD_SMBALERT_DISABLE |
+	       priv->original_slvcmd, SMBSLVCMD(priv));
 
 	/* clear Host Notify bit to allow a new notification */
 	outb_p(SMBSLVSTS_HST_NTFY_STS, SMBSLVSTS(priv));
@@ -1805,7 +1819,8 @@ static int i801_probe(struct pci_dev *dev, const struct pci_device_id *id)
 		outb_p(inb_p(SMBAUXCTL(priv)) &
 		       ~(SMBAUXCTL_CRC | SMBAUXCTL_E32B), SMBAUXCTL(priv));
 
-	/* Remember original Host Notify setting */
+	/* Remember original Interrupt and Host Notify settings */
+	priv->original_hstcnt = inb_p(SMBHSTCNT(priv)) & ~SMBHSTCNT_KILL;
 	if (priv->features & FEATURE_HOST_NOTIFY)
 		priv->original_slvcmd = inb_p(SMBSLVCMD(priv));
 
@@ -1869,6 +1884,7 @@ static void i801_remove(struct pci_dev *dev)
 {
 	struct i801_priv *priv = pci_get_drvdata(dev);
 
+	outb_p(priv->original_hstcnt, SMBHSTCNT(priv));
 	i801_disable_host_notify(priv);
 	i801_del_mux(priv);
 	i2c_del_adapter(&priv->adapter);
@@ -1892,6 +1908,7 @@ static void i801_shutdown(struct pci_dev *dev)
 	struct i801_priv *priv = pci_get_drvdata(dev);
 
 	/* Restore config registers to avoid hard hang on some systems */
+	outb_p(priv->original_hstcnt, SMBHSTCNT(priv));
 	i801_disable_host_notify(priv);
 	pci_write_config_byte(dev, SMBHSTCFG, priv->original_hstcfg);
 }
@@ -1901,6 +1918,7 @@ static int i801_suspend(struct device *dev)
 {
 	struct i801_priv *priv = dev_get_drvdata(dev);
 
+	outb_p(priv->original_hstcnt, SMBHSTCNT(priv));
 	pci_write_config_byte(priv->pci_dev, SMBHSTCFG, priv->original_hstcfg);
 	return 0;
 }

drivers/i2c/busses/i2c-virtio.c

@@ -104,11 +104,10 @@ static int virtio_i2c_prepare_reqs(struct virtqueue *vq,
 
 static int virtio_i2c_complete_reqs(struct virtqueue *vq,
 				    struct virtio_i2c_req *reqs,
-				    struct i2c_msg *msgs, int num,
-				    bool timedout)
+				    struct i2c_msg *msgs, int num)
 {
 	struct virtio_i2c_req *req;
-	bool failed = timedout;
+	bool failed = false;
 	unsigned int len;
 	int i, j = 0;
 
@@ -130,7 +129,7 @@ static int virtio_i2c_complete_reqs(struct virtqueue *vq,
 			j++;
 	}
 
-	return timedout ? -ETIMEDOUT : j;
+	return j;
 }
 
 static int virtio_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
@@ -139,7 +138,6 @@ static int virtio_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 	struct virtio_i2c *vi = i2c_get_adapdata(adap);
 	struct virtqueue *vq = vi->vq;
 	struct virtio_i2c_req *reqs;
-	unsigned long time_left;
 	int count;
 
 	reqs = kcalloc(num, sizeof(*reqs), GFP_KERNEL);
@@ -162,11 +160,9 @@ static int virtio_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 	reinit_completion(&vi->completion);
 	virtqueue_kick(vq);
 
-	time_left = wait_for_completion_timeout(&vi->completion, adap->timeout);
-	if (!time_left)
-		dev_err(&adap->dev, "virtio i2c backend timeout.\n");
+	wait_for_completion(&vi->completion);
 
-	count = virtio_i2c_complete_reqs(vq, reqs, msgs, count, !time_left);
+	count = virtio_i2c_complete_reqs(vq, reqs, msgs, count);
 
 err_free:
 	kfree(reqs);