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Commit 8857df3a authored by Michael Hennerich's avatar Michael Hennerich Committed by Jonathan Cameron
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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: default avatarMichael Hennerich <michael.hennerich@analog.com>
Signed-off-by: default avatarJonathan Cameron <jic23@kernel.org>
parent dfffd0d6

drivers/iio/frequency/adf4350.c

+15 −9
Original line number Original line Diff line number Diff line
@@ -129,7 +129,7 @@ static int adf4350_set_freq(struct adf4350_state *st, unsigned long long freq) 
{

{

	struct adf4350_platform_data *pdata = st->pdata;

	struct adf4350_platform_data *pdata = st->pdata;

	u64 tmp;

	u64 tmp;

	u32 div_gcd, prescaler;

	u32 div_gcd, prescaler, chspc;

	u16 mdiv, r_cnt = 0;

	u16 mdiv, r_cnt = 0;

	u8 band_sel_div;

	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)

	if (pdata->ref_div_factor)

		r_cnt = pdata->ref_div_factor - 1;

		r_cnt = pdata->ref_div_factor - 1;





	do  {

	chspc = st->chspc;

		r_cnt = adf4350_tune_r_cnt(st, r_cnt);





		st->r1_mod = st->fpfd / st->chspc;

	do  {

		while (st->r1_mod > ADF4350_MAX_MODULUS) {

		do {

			do {

				r_cnt = adf4350_tune_r_cnt(st, r_cnt);

				r_cnt = adf4350_tune_r_cnt(st, r_cnt);

			st->r1_mod = st->fpfd / st->chspc;

				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);

		tmp = freq * (u64)st->r1_mod + (st->fpfd > 1);

		do_div(tmp, st->fpfd); /* Div round closest (n + d/2)/d */

		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) |

	st->regs[ADF4350_REG0] = ADF4350_REG0_INT(st->r0_int) |

				 ADF4350_REG0_FRACT(st->r0_fract);

				 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) |

				 ADF4350_REG1_MOD(st->r1_mod) |

				 prescaler;

				 prescaler;

include/linux/iio/frequency/adf4350.h

+2 −0
Original line number Original line Diff line number Diff line
@@ -87,6 +87,8 @@ 
#define ADF4350_MAX_BANDSEL_CLK		125000 /* Hz */

#define ADF4350_MAX_BANDSEL_CLK		125000 /* Hz */

#define ADF4350_MAX_FREQ_REFIN		250000000 /* Hz */

#define ADF4350_MAX_FREQ_REFIN		250000000 /* Hz */

#define ADF4350_MAX_MODULUS		4095

#define ADF4350_MAX_MODULUS		4095

#define ADF4350_MAX_R_CNT		1023







/**

/**

 * struct adf4350_platform_data - platform specific information

 * struct adf4350_platform_data - platform specific information