[PATCH] HSI: cmt_speech: fix timestamp interface

[Sebastian Reichel <sre@kernel.org>]

The user interface for timestamps in the new cmt_speech
driver is broken in multiple ways:

- The layout is incompatible between 32-bit and 64-bit user
  space, because of the size differences in 'struct timespec'.
  This means that the driver can not work when used with 32-bit
  user space on a 64-bit kernel.

- As there are plans to change 32-bit user space to use
  a 64-bit time_t type in the future, it will also be
  incompatible with new 32-bit user space.

To keep support for the user space tools written for this driver (which
have lived many years out-of-tree), the interface has been hardened to
unsigned 32-bit values.

Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Sebastian Reichel <sre@kernel.org>
---
 drivers/hsi/clients/cmt_speech.c     |  9 +++++++--
 include/uapi/linux/hsi/cs-protocol.h | 16 +++++++++++-----
 2 files changed, 18 insertions(+), 7 deletions(-)

diff --git a/drivers/hsi/clients/cmt_speech.c b/drivers/hsi/clients/cmt_speech.c
index 4983529..67aef3f 100644
--- a/drivers/hsi/clients/cmt_speech.c
+++ b/drivers/hsi/clients/cmt_speech.c
@@ -451,9 +451,14 @@ static void cs_hsi_read_on_control_complete(struct hsi_msg *msg)
 	dev_dbg(&hi->cl->device, "Read on control: %08X\n", cmd);
 	cs_release_cmd(msg);
 	if (hi->flags & CS_FEAT_TSTAMP_RX_CTRL) {
-		struct timespec *tstamp =
+		struct timespec tspec;
+		struct cs_timestamp *tstamp =
 			&hi->mmap_cfg->tstamp_rx_ctrl;
-		do_posix_clock_monotonic_gettime(tstamp);
+
+		do_posix_clock_monotonic_gettime(&tspec);
+
+		tstamp->tv_sec = (__u32) tspec.tv_sec;
+		tstamp->tv_nsec = (__u32) tspec.tv_nsec;
 	}
 	spin_unlock(&hi->lock);
 
diff --git a/include/uapi/linux/hsi/cs-protocol.h b/include/uapi/linux/hsi/cs-protocol.h
index 4957bba..f153d6e 100644
--- a/include/uapi/linux/hsi/cs-protocol.h
+++ b/include/uapi/linux/hsi/cs-protocol.h
@@ -76,6 +76,15 @@ struct cs_buffer_config {
 };
 
 /*
+ * struct for monotonic timestamp taken when the
+ * last control command was received
+ */
+struct cs_timestamp {
+	__u32 tv_sec;  /* seconds */
+	__u32 tv_nsec; /* nanoseconds */
+};
+
+/*
  * Struct describing the layout and contents of the driver mmap area.
  * This information is meant as read-only information for the application.
  */
@@ -91,11 +100,8 @@ struct cs_mmap_config_block {
 	__u32 rx_ptr;
 	__u32 rx_ptr_boundary;
 	__u32 reserved3[2];
-	/*
-	 * if enabled with CS_FEAT_TSTAMP_RX_CTRL, monotonic
-	 * timestamp taken when the last control command was received
-	 */
-	struct timespec tstamp_rx_ctrl;
+	/* enabled with CS_FEAT_TSTAMP_RX_CTRL */
+	struct cs_timestamp tstamp_rx_ctrl;
 };
 
 #define CS_IO_MAGIC		'C'
-- 
2.1.4