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Subject[PATCH 2/2] pwm: pwm-fsl-ftm: Use write protection for prescaler & polarity
Date
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>
---
drivers/pwm/pwm-fsl-ftm.c | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)

diff --git a/drivers/pwm/pwm-fsl-ftm.c b/drivers/pwm/pwm-fsl-ftm.c
index cd5fe39ab95d..e955b1cdfd2f 100644
--- a/drivers/pwm/pwm-fsl-ftm.c
+++ b/drivers/pwm/pwm-fsl-ftm.c
@@ -59,6 +59,21 @@ 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)
{
@@ -253,6 +268,8 @@ 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));
@@ -279,6 +296,8 @@ 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;
}

@@ -359,6 +378,8 @@ 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;
}
--
2.19.1
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