diff options
| author | H Hartley Sweeten <hsweeten@visionengravers.com> | 2016-03-23 12:24:29 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-03-28 07:30:36 -0700 |
| commit | 581867bd9151ee77fad4b0fe47af96d923ac9ec2 (patch) | |
| tree | f9bdee8e84827959db6472dc3103232238156158 /drivers/staging/comedi/drivers/dt282x.c | |
| parent | 47470216cc2fe413156aa44d7ae55e65712b0931 (diff) | |
staging: comedi: dt282x: refactor dt282x_ns_to_timer()
Define the pacer clock limits and remove the magic numbers. Refactor
the code to use a common path to return the actual 'ns' timing and
the timer divisor value.
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/staging/comedi/drivers/dt282x.c')
| -rw-r--r-- | drivers/staging/comedi/drivers/dt282x.c | 36 |
1 files changed, 24 insertions, 12 deletions
diff --git a/drivers/staging/comedi/drivers/dt282x.c b/drivers/staging/comedi/drivers/dt282x.c index 06a87a10a2d0..e6958eaf5178 100644 --- a/drivers/staging/comedi/drivers/dt282x.c +++ b/drivers/staging/comedi/drivers/dt282x.c @@ -113,6 +113,17 @@ #define DT2821_SUPCSR_XCLK BIT(1) #define DT2821_SUPCSR_BDINIT BIT(0) #define DT2821_TMRCTR_REG 0x0e +#define DT2821_TMRCTR_PRESCALE(x) (((x) & 0xf) << 8) +#define DT2821_TMRCTR_DIVIDER(x) ((255 - ((x) & 0xff)) << 0) + +/* Pacer Clock */ +#define DT2821_OSC_BASE 250 /* 4 MHz (in nanoseconds) */ +#define DT2821_PRESCALE(x) BIT(x) +#define DT2821_PRESCALE_MAX 15 +#define DT2821_DIVIDER_MAX 255 +#define DT2821_OSC_MAX (DT2821_OSC_BASE * \ + DT2821_PRESCALE(DT2821_PRESCALE_MAX) * \ + DT2821_DIVIDER_MAX) static const struct comedi_lrange range_dt282x_ai_lo_bipolar = { 4, { @@ -365,10 +376,10 @@ static unsigned int dt282x_ns_to_timer(unsigned int *ns, unsigned int flags) { unsigned int prescale, base, divider; - for (prescale = 0; prescale < 16; prescale++) { - if (prescale == 1) + for (prescale = 0; prescale <= DT2821_PRESCALE_MAX; prescale++) { + if (prescale == 1) /* 0 and 1 are both divide by 1 */ continue; - base = 250 * (1 << prescale); + base = DT2821_OSC_BASE * DT2821_PRESCALE(prescale); switch (flags & CMDF_ROUND_MASK) { case CMDF_ROUND_NEAREST: default: @@ -381,15 +392,17 @@ static unsigned int dt282x_ns_to_timer(unsigned int *ns, unsigned int flags) divider = DIV_ROUND_UP(*ns, base); break; } - if (divider < 256) { - *ns = divider * base; - return (prescale << 8) | (255 - divider); - } + if (divider <= DT2821_DIVIDER_MAX) + break; + } + if (divider > DT2821_DIVIDER_MAX) { + prescale = DT2821_PRESCALE_MAX; + divider = DT2821_DIVIDER_MAX; + base = DT2821_OSC_BASE * DT2821_PRESCALE(prescale); } - base = 250 * (1 << 15); - divider = 255; *ns = divider * base; - return (15 << 8) | (255 - divider); + return DT2821_TMRCTR_PRESCALE(prescale) | + DT2821_TMRCTR_DIVIDER(divider); } static void dt282x_munge(struct comedi_device *dev, @@ -689,8 +702,7 @@ static int dt282x_ai_cmdtest(struct comedi_device *dev, err |= comedi_check_trigger_arg_min(&cmd->convert_arg, 4000); -#define SLOWEST_TIMER (250*(1<<15)*255) - err |= comedi_check_trigger_arg_max(&cmd->convert_arg, SLOWEST_TIMER); + err |= comedi_check_trigger_arg_max(&cmd->convert_arg, DT2821_OSC_MAX); err |= comedi_check_trigger_arg_min(&cmd->convert_arg, board->ai_speed); err |= comedi_check_trigger_arg_is(&cmd->scan_end_arg, cmd->chanlist_len); |