Merge branch 'next' (accumulated 3.16 merge window patches) into master

Now that 3.15 is released, this merges the 'next' branch into 'master',
bringing us to the normal situation where my 'master' branch is the
merge window.

* accumulated work in next: (6809 commits)
  ufs: sb mutex merge + mutex_destroy
  powerpc: update comments for generic idle conversion
  cris: update comments for generic idle conversion
  idle: remove cpu_idle() forward declarations
  nbd: zero from and len fields in NBD_CMD_DISCONNECT.
  mm: convert some level-less printks to pr_*
  MAINTAINERS: adi-buildroot-devel is moderated
  MAINTAINERS: add linux-api for review of API/ABI changes
  mm/kmemleak-test.c: use pr_fmt for logging
  fs/dlm/debug_fs.c: replace seq_printf by seq_puts
  fs/dlm/lockspace.c: convert simple_str to kstr
  fs/dlm/config.c: convert simple_str to kstr
  mm: mark remap_file_pages() syscall as deprecated
  mm: memcontrol: remove unnecessary memcg argument from soft limit functions
  mm: memcontrol: clean up memcg zoneinfo lookup
  mm/memblock.c: call kmemleak directly from memblock_(alloc|free)
  mm/mempool.c: update the kmemleak stack trace for mempool allocations
  lib/radix-tree.c: update the kmemleak stack trace for radix tree allocations
  mm: introduce kmemleak_update_trace()
  mm/kmemleak.c: use %u to print ->checksum
  ...

1 files changed, 50 insertions, 17 deletions

diff --git a/drivers/mfd/cros_ec_spi.c b/drivers/mfd/cros_ec_spi.c
index 84af8d7a4295..0b8d32829166 100644
--- a/drivers/mfd/cros_ec_spi.c
+++ b/drivers/mfd/cros_ec_spi.c
@@ -39,14 +39,22 @@
 #define EC_MSG_PREAMBLE_COUNT		32
 
 /*
-  * We must get a response from the EC in 5ms. This is a very long
-  * time, but the flash write command can take 2-3ms. The EC command
-  * processing is currently not very fast (about 500us). We could
-  * look at speeding this up and making the flash write command a
-  * 'slow' command, requiring a GET_STATUS wait loop, like flash
-  * erase.
-  */
-#define EC_MSG_DEADLINE_MS		5
+ * Allow for a long time for the EC to respond.  We support i2c
+ * tunneling and support fairly long messages for the tunnel (249
+ * bytes long at the moment).  If we're talking to a 100 kHz device
+ * on the other end and need to transfer ~256 bytes, then we need:
+ *  10 us/bit * ~10 bits/byte * ~256 bytes = ~25ms
+ *
+ * We'll wait 4 times that to handle clock stretching and other
+ * paranoia.
+ *
+ * It's pretty unlikely that we'll really see a 249 byte tunnel in
+ * anything other than testing.  If this was more common we might
+ * consider having slow commands like this require a GET_STATUS
+ * wait loop.  The 'flash write' command would be another candidate
+ * for this, clocking in at 2-3ms.
+ */
+#define EC_MSG_DEADLINE_MS		100
 
 /*
   * Time between raising the SPI chip select (for the end of a
@@ -65,11 +73,13 @@
  *	if no record
  * @end_of_msg_delay: used to set the delay_usecs on the spi_transfer that
  *      is sent when we want to turn off CS at the end of a transaction.
+ * @lock: mutex to ensure only one user of cros_ec_command_spi_xfer at a time
  */
 struct cros_ec_spi {
 	struct spi_device *spi;
 	s64 last_transfer_ns;
 	unsigned int end_of_msg_delay;
+	struct mutex lock;
 };
 
 static void debug_packet(struct device *dev, const char *name, u8 *ptr,
@@ -111,7 +121,9 @@ static int cros_ec_spi_receive_response(struct cros_ec_device *ec_dev,
 
 	/* Receive data until we see the header byte */
 	deadline = jiffies + msecs_to_jiffies(EC_MSG_DEADLINE_MS);
-	do {
+	while (true) {
+		unsigned long start_jiffies = jiffies;
+
 		memset(&trans, 0, sizeof(trans));
 		trans.cs_change = 1;
 		trans.rx_buf = ptr = ec_dev->din;
@@ -132,12 +144,19 @@ static int cros_ec_spi_receive_response(struct cros_ec_device *ec_dev,
 				break;
 			}
 		}
+		if (ptr != end)
+			break;
 
-		if (time_after(jiffies, deadline)) {
+		/*
+		 * Use the time at the start of the loop as a timeout.  This
+		 * gives us one last shot at getting the transfer and is useful
+		 * in case we got context switched out for a while.
+		 */
+		if (time_after(start_jiffies, deadline)) {
 			dev_warn(ec_dev->dev, "EC failed to respond in time\n");
 			return -ETIMEDOUT;
 		}
-	} while (ptr == end);
+	}
 
 	/*
 	 * ptr now points to the header byte. Copy any valid data to the
@@ -208,6 +227,13 @@ static int cros_ec_command_spi_xfer(struct cros_ec_device *ec_dev,
 	int ret = 0, final_ret;
 	struct timespec ts;
 
+	/*
+	 * We have the shared ec_dev buffer plus we do lots of separate spi_sync
+	 * calls, so we need to make sure only one person is using this at a
+	 * time.
+	 */
+	mutex_lock(&ec_spi->lock);
+
 	len = cros_ec_prepare_tx(ec_dev, ec_msg);
 	dev_dbg(ec_dev->dev, "prepared, len=%d\n", len);
 
@@ -219,7 +245,7 @@ static int cros_ec_command_spi_xfer(struct cros_ec_device *ec_dev,
 		ktime_get_ts(&ts);
 		delay = timespec_to_ns(&ts) - ec_spi->last_transfer_ns;
 		if (delay < EC_SPI_RECOVERY_TIME_NS)
-			ndelay(delay);
+			ndelay(EC_SPI_RECOVERY_TIME_NS - delay);
 	}
 
 	/* Transmit phase - send our message */
@@ -260,7 +286,7 @@ static int cros_ec_command_spi_xfer(struct cros_ec_device *ec_dev,
 		ret = final_ret;
 	if (ret < 0) {
 		dev_err(ec_dev->dev, "spi transfer failed: %d\n", ret);
-		return ret;
+		goto exit;
 	}
 
 	/* check response error code */
@@ -269,14 +295,16 @@ static int cros_ec_command_spi_xfer(struct cros_ec_device *ec_dev,
 		dev_warn(ec_dev->dev, "command 0x%02x returned an error %d\n",
 			 ec_msg->cmd, ptr[0]);
 		debug_packet(ec_dev->dev, "in_err", ptr, len);
-		return -EINVAL;
+		ret = -EINVAL;
+		goto exit;
 	}
 	len = ptr[1];
 	sum = ptr[0] + ptr[1];
 	if (len > ec_msg->in_len) {
 		dev_err(ec_dev->dev, "packet too long (%d bytes, expected %d)",
 			len, ec_msg->in_len);
-		return -ENOSPC;
+		ret = -ENOSPC;
+		goto exit;
 	}
 
 	/* copy response packet payload and compute checksum */
@@ -293,10 +321,14 @@ static int cros_ec_command_spi_xfer(struct cros_ec_device *ec_dev,
 		dev_err(ec_dev->dev,
 			"bad packet checksum, expected %02x, got %02x\n",
 			sum, ptr[len + 2]);
-		return -EBADMSG;
+		ret = -EBADMSG;
+		goto exit;
 	}
 
-	return 0;
+	ret = 0;
+exit:
+	mutex_unlock(&ec_spi->lock);
+	return ret;
 }
 
 static void cros_ec_spi_dt_probe(struct cros_ec_spi *ec_spi, struct device *dev)
@@ -327,6 +359,7 @@ static int cros_ec_spi_probe(struct spi_device *spi)
 	if (ec_spi == NULL)
 		return -ENOMEM;
 	ec_spi->spi = spi;
+	mutex_init(&ec_spi->lock);
 	ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL);
 	if (!ec_dev)
 		return -ENOMEM;