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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>
hifive-unleashed-5.1
Michael Hennerich 2012-07-20 09:31:00 +01:00 committed by Jonathan Cameron
parent dfffd0d65f
commit 8857df3ace
2 changed files with 17 additions and 9 deletions
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24
drivers/iio/frequency/adf4350.c
View File

@ -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;

2
include/linux/iio/frequency/adf4350.h
View File

@ -87,6 +87,8 @@
#define ADF4350_MAX_BANDSEL_CLK 125000 /* Hz */
#define ADF4350_MAX_FREQ_REFIN 250000000 /* Hz */
#define ADF4350_MAX_MODULUS 4095
#define ADF4350_MAX_R_CNT 1023
/**
* struct adf4350_platform_data - platform specific information