diff options
| author | Ian Abbott <abbotti@mev.co.uk> | 2015-10-27 16:59:17 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-10-29 08:58:36 +0900 |
| commit | 66d4da800d1a70e7c6b27ba7a61e4bc39b1f3304 (patch) | |
| tree | 6353bd16d773801bccb84790209b8bee2067b3f2 /drivers/staging/comedi | |
| parent | 21ec1bf73483f1cceb252ecf9323160fc9473f7b (diff) | |
| download | linux-66d4da800d1a70e7c6b27ba7a61e4bc39b1f3304.tar.bz2 | |
staging: comedi: comedi_test: simplify time since last AI scan
The private data structure `struct waveform_private` currently uses
member `last` to remember the time of the last timer interrupt, and the
member `usec_remainder` to keep track of how far into a simulated scan
the interrupt occurred. Replace these with a single new member
`ai_last_scan_time` that records the time of the last scan. This
simplifies the calculation of the number of scans to simulate in the
timer routine, `waveform_ai_interrupt()`.
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/staging/comedi')
| -rw-r--r-- | drivers/staging/comedi/drivers/comedi_test.c | 27 |
1 files changed, 10 insertions, 17 deletions
diff --git a/drivers/staging/comedi/drivers/comedi_test.c b/drivers/staging/comedi/drivers/comedi_test.c index 158e090e81ad..78fde3afc379 100644 --- a/drivers/staging/comedi/drivers/comedi_test.c +++ b/drivers/staging/comedi/drivers/comedi_test.c @@ -62,11 +62,10 @@ enum waveform_state_bits { /* Data unique to this driver */ struct waveform_private { struct timer_list timer; - ktime_t last; /* time last timer interrupt occurred */ + u64 ai_last_scan_time; /* time of last AI scan in usec */ unsigned int uvolt_amplitude; /* waveform amplitude in microvolts */ unsigned int usec_period; /* waveform period in microseconds */ unsigned int usec_current; /* current time (mod waveform period) */ - unsigned long usec_remainder; /* usec since last scan */ unsigned long state_bits; unsigned int scan_period; /* scan period in usec */ unsigned int convert_period; /* conversion period in usec */ @@ -184,27 +183,19 @@ static void waveform_ai_interrupt(unsigned long arg) struct comedi_async *async = s->async; struct comedi_cmd *cmd = &async->cmd; unsigned int i, j; - /* all times in microsec */ unsigned long elapsed_time; unsigned int num_scans; - ktime_t now; /* check command is still active */ if (!test_bit(WAVEFORM_AI_RUNNING, &devpriv->state_bits)) return; - now = ktime_get(); - - elapsed_time = ktime_to_us(ktime_sub(now, devpriv->last)); - devpriv->last = now; - num_scans = - (devpriv->usec_remainder + elapsed_time) / devpriv->scan_period; - devpriv->usec_remainder = - (devpriv->usec_remainder + elapsed_time) % devpriv->scan_period; + elapsed_time = ktime_to_us(ktime_get()) - devpriv->ai_last_scan_time; + num_scans = elapsed_time / devpriv->scan_period; num_scans = comedi_nscans_left(s, num_scans); for (i = 0; i < num_scans; i++) { - unsigned long scan_remain_period = devpriv->scan_period; + unsigned int scan_remain_period = devpriv->scan_period; for (j = 0; j < cmd->chanlist_len; j++) { unsigned short sample; @@ -219,6 +210,7 @@ static void waveform_ai_interrupt(unsigned long arg) scan_remain_period -= devpriv->convert_period; } devpriv->usec_current += scan_remain_period; + devpriv->ai_last_scan_time += devpriv->scan_period; } if (devpriv->usec_current >= devpriv->usec_period) devpriv->usec_current %= devpriv->usec_period; @@ -337,6 +329,7 @@ static int waveform_ai_cmd(struct comedi_device *dev, { struct waveform_private *devpriv = dev->private; struct comedi_cmd *cmd = &s->async->cmd; + u64 usec_current; if (cmd->flags & CMDF_PRIORITY) { dev_err(dev->class_dev, @@ -356,10 +349,10 @@ static int waveform_ai_cmd(struct comedi_device *dev, devpriv->scan_period = cmd->scan_begin_arg / NSEC_PER_USEC; } - devpriv->last = ktime_get(); - devpriv->usec_current = - ((u32)ktime_to_us(devpriv->last)) % devpriv->usec_period; - devpriv->usec_remainder = 0; + devpriv->ai_last_scan_time = ktime_to_us(ktime_get()); + /* Determine time within waveform period. */ + usec_current = devpriv->ai_last_scan_time; + devpriv->usec_current = do_div(usec_current, devpriv->usec_period); devpriv->timer.expires = jiffies + 1; /* mark command as active */ |