HSI: cmt_speech: fix timestamp interface

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.

- It is using ktime_get_ts under it's deprecated alias
(do_posix_clock_monotonic_gettime).

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 <[e-mail]>
Signed-off-by: Sebastian Reichel <[e-mail]>

drivers/hsi/clients/cmt_speech.c

···
 	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);
+
+		ktime_get_ts(&tspec);
+
+		tstamp->tv_sec = (__u32) tspec.tv_sec;
+		tstamp->tv_nsec = (__u32) tspec.tv_nsec;
 	}
 	spin_unlock(&hi->lock);
 

include/uapi/linux/hsi/cs-protocol.h

···
 };
 
 /*
+ * 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.
  */
···
 	__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'