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pwm: fsl-ftm: Use write protection for prescaler & polarity 

Modifying the prescaler or polarity value must be done with the
write protection disabled. Currently this is working by chance as
the write protection is in a disabled state by default.
This patch makes sure that we enable/disable the write protection
when needed.

Signed-off-by: Patrick Havelange <patrick.havelange@essensium.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
This commit is contained in:
Patrick Havelange 2019-06-12 16:12:46 +02:00 committed by Thierry Reding
parent 3479bbd1e1
commit a2a28229cd
1 changed files with 21 additions and 0 deletions
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21
drivers/pwm/pwm-fsl-ftm.c
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@ -63,6 +63,21 @@ static inline struct fsl_pwm_chip *to_fsl_chip(struct pwm_chip *chip)
return container_of(chip, struct fsl_pwm_chip, chip);
}
static void ftm_clear_write_protection(struct fsl_pwm_chip *fpc)
{
u32 val;
regmap_read(fpc->regmap, FTM_FMS, &val);
if (val & FTM_FMS_WPEN)
regmap_update_bits(fpc->regmap, FTM_MODE, FTM_MODE_WPDIS,
FTM_MODE_WPDIS);
}
static void ftm_set_write_protection(struct fsl_pwm_chip *fpc)
{
regmap_update_bits(fpc->regmap, FTM_FMS, FTM_FMS_WPEN, FTM_FMS_WPEN);
}
static bool fsl_pwm_periodcfg_are_equal(const struct fsl_pwm_periodcfg *a,
const struct fsl_pwm_periodcfg *b)
{
@ -257,6 +272,8 @@ static int fsl_pwm_apply_config(struct fsl_pwm_chip *fpc,
do_write_period = true;
}
ftm_clear_write_protection(fpc);
if (do_write_period) {
regmap_update_bits(fpc->regmap, FTM_SC, FTM_SC_CLK_MASK,
FTM_SC_CLK(periodcfg.clk_select));
@ -283,6 +300,8 @@ static int fsl_pwm_apply_config(struct fsl_pwm_chip *fpc,
fpc->period.mod_period + 1);
newstate->duty_cycle = fsl_pwm_ticks_to_ns(fpc, duty);
ftm_set_write_protection(fpc);
return 0;
}
@ -367,6 +386,8 @@ static int fsl_pwm_init(struct fsl_pwm_chip *fpc)
static bool fsl_pwm_volatile_reg(struct device *dev, unsigned int reg)
{
switch (reg) {
case FTM_FMS:
case FTM_MODE:
case FTM_CNT:
return true;
}