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pwm: sti: Fix PWM prescaler handling
This patch fixes the pwm driver to write the complete 8 bits of the prescaler value to the PWM Control register. Signed-off-by: Ajit Pal Singh <ajitpal.singh@st.com> Signed-off-by: Lee Jones <lee.jones@linaro.org> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
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@ -25,10 +25,13 @@
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#define STI_DS_REG(ch) (4 * (ch)) /* Channel's Duty Cycle register */
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#define STI_PWMCR 0x50 /* Control/Config register */
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#define STI_INTEN 0x54 /* Interrupt Enable/Disable register */
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#define PWM_PRESCALE_LOW_MASK 0x0f
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#define PWM_PRESCALE_HIGH_MASK 0xf0
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/* Regfield IDs */
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enum {
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PWMCLK_PRESCALE,
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PWMCLK_PRESCALE_LOW,
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PWMCLK_PRESCALE_HIGH,
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PWM_EN,
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PWM_INT_EN,
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@ -49,7 +52,8 @@ struct sti_pwm_chip {
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unsigned long clk_rate;
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struct regmap *regmap;
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struct sti_pwm_compat_data *cdata;
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struct regmap_field *prescale;
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struct regmap_field *prescale_low;
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struct regmap_field *prescale_high;
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struct regmap_field *pwm_en;
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struct regmap_field *pwm_int_en;
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unsigned long *pwm_periods;
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@ -58,7 +62,8 @@ struct sti_pwm_chip {
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};
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static const struct reg_field sti_pwm_regfields[MAX_REGFIELDS] = {
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[PWMCLK_PRESCALE] = REG_FIELD(STI_PWMCR, 0, 3),
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[PWMCLK_PRESCALE_LOW] = REG_FIELD(STI_PWMCR, 0, 3),
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[PWMCLK_PRESCALE_HIGH] = REG_FIELD(STI_PWMCR, 11, 14),
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[PWM_EN] = REG_FIELD(STI_PWMCR, 9, 9),
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[PWM_INT_EN] = REG_FIELD(STI_INTEN, 0, 0),
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};
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@ -109,10 +114,10 @@ static int sti_pwm_cmp_periods(const void *key, const void *elt)
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* For STiH4xx PWM IP, the PWM period is fixed to 256 local clock cycles.
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* The only way to change the period (apart from changing the PWM input clock)
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* is to change the PWM clock prescaler.
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* The prescaler is of 4 bits, so only 16 prescaler values and hence only
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* 16 possible period values are supported (for a particular clock rate).
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* The prescaler is of 8 bits, so 256 prescaler values and hence
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* 256 possible period values are supported (for a particular clock rate).
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* The requested period will be applied only if it matches one of these
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* 16 values.
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* 256 values.
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*/
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static int sti_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
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int duty_ns, int period_ns)
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@ -154,7 +159,13 @@ static int sti_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
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if (ret)
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return ret;
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ret = regmap_field_write(pc->prescale, prescale);
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ret = regmap_field_write(pc->prescale_low,
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prescale & PWM_PRESCALE_LOW_MASK);
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if (ret)
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goto clk_dis;
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ret = regmap_field_write(pc->prescale_high,
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(prescale & PWM_PRESCALE_HIGH_MASK) >> 4);
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if (ret)
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goto clk_dis;
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@ -222,10 +233,15 @@ static int sti_pwm_probe_dt(struct sti_pwm_chip *pc)
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reg_fields = cdata->reg_fields;
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pc->prescale = devm_regmap_field_alloc(dev, pc->regmap,
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reg_fields[PWMCLK_PRESCALE]);
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if (IS_ERR(pc->prescale))
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return PTR_ERR(pc->prescale);
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pc->prescale_low = devm_regmap_field_alloc(dev, pc->regmap,
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reg_fields[PWMCLK_PRESCALE_LOW]);
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if (IS_ERR(pc->prescale_low))
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return PTR_ERR(pc->prescale_low);
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pc->prescale_high = devm_regmap_field_alloc(dev, pc->regmap,
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reg_fields[PWMCLK_PRESCALE_HIGH]);
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if (IS_ERR(pc->prescale_high))
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return PTR_ERR(pc->prescale_high);
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pc->pwm_en = devm_regmap_field_alloc(dev, pc->regmap,
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reg_fields[PWM_EN]);
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