diff options
| author | Michael Hennerich <michael.hennerich@analog.com> | 2012-07-20 09:31:00 +0100 |
|---|---|---|
| committer | Jonathan Cameron <jic23@kernel.org> | 2012-08-16 20:24:33 +0100 |
| commit | 8857df3aceb7a8eb7558059b7da109e41dd1fb95 (patch) | |
| tree | ba45e6d7779aab84f6a7c1ba37697d9914158b97 /drivers/iio | |
| parent | dfffd0d65fdf16d034681716dcbea74776f62e40 (diff) | |
iio: frequency: ADF4350: Fix potential reference div factor overflow.
With small channel spacing values and high reference frequencies it is
possible to exceed the range of the 10-bit counter.
Workaround by checking the range and widening some constrains.
We don't use the REG1_PHASE value in this case the datasheet recommends to set
it to 1 if not used.
Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Diffstat (limited to 'drivers/iio')
| -rw-r--r-- | drivers/iio/frequency/adf4350.c | 24 |
1 files changed, 15 insertions, 9 deletions
diff --git a/drivers/iio/frequency/adf4350.c b/drivers/iio/frequency/adf4350.c index 59fbb3ae40e7..e35bb8f6fe75 100644 --- a/drivers/iio/frequency/adf4350.c +++ b/drivers/iio/frequency/adf4350.c @@ -129,7 +129,7 @@ static int adf4350_set_freq(struct adf4350_state *st, unsigned long long freq) { struct adf4350_platform_data *pdata = st->pdata; u64 tmp; - u32 div_gcd, prescaler; + u32 div_gcd, prescaler, chspc; u16 mdiv, r_cnt = 0; u8 band_sel_div; @@ -158,14 +158,20 @@ static int adf4350_set_freq(struct adf4350_state *st, unsigned long long freq) if (pdata->ref_div_factor) r_cnt = pdata->ref_div_factor - 1; - do { - r_cnt = adf4350_tune_r_cnt(st, r_cnt); + chspc = st->chspc; - st->r1_mod = st->fpfd / st->chspc; - while (st->r1_mod > ADF4350_MAX_MODULUS) { - r_cnt = adf4350_tune_r_cnt(st, r_cnt); - st->r1_mod = st->fpfd / st->chspc; - } + do { + do { + do { + r_cnt = adf4350_tune_r_cnt(st, r_cnt); + st->r1_mod = st->fpfd / chspc; + if (r_cnt > ADF4350_MAX_R_CNT) { + /* try higher spacing values */ + chspc++; + r_cnt = 0; + } + } while ((st->r1_mod > ADF4350_MAX_MODULUS) && r_cnt); + } while (r_cnt == 0); tmp = freq * (u64)st->r1_mod + (st->fpfd > 1); do_div(tmp, st->fpfd); /* Div round closest (n + d/2)/d */ @@ -194,7 +200,7 @@ static int adf4350_set_freq(struct adf4350_state *st, unsigned long long freq) st->regs[ADF4350_REG0] = ADF4350_REG0_INT(st->r0_int) | ADF4350_REG0_FRACT(st->r0_fract); - st->regs[ADF4350_REG1] = ADF4350_REG1_PHASE(0) | + st->regs[ADF4350_REG1] = ADF4350_REG1_PHASE(1) | ADF4350_REG1_MOD(st->r1_mod) | prescaler; |