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counter: stm32-timer-cnt: probe number of channels from registers

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Probe the number of capture compare channels, by writing CCER register bits
and read them back. Take care to restore the register original value.

This is a precursor patch to support capture channels.

Reviewed-by: William Breathitt Gray <william.gray@linaro.org>
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Link: https://lore.kernel.org/r/20240307133306.383045-9-fabrice.gasnier@foss.st.com
Signed-off-by: William Breathitt Gray <william.gray@linaro.org>
This commit is contained in:
Fabrice Gasnier 2024-03-07 14:33:04 +01:00 committed by William Breathitt Gray
parent efec660d78
commit f7630270b6
1 changed files with 17 additions and 0 deletions
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17
drivers/counter/stm32-timer-cnt.c
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@ -42,6 +42,7 @@ struct stm32_timer_cnt {
bool enabled;
struct stm32_timer_regs bak;
bool has_encoder;
unsigned int nchannels;
};
static const enum counter_function stm32_count_functions[] = {
@ -416,6 +417,20 @@ static struct counter_count stm32_counts = {
.num_ext = ARRAY_SIZE(stm32_count_ext)
};
static void stm32_timer_cnt_detect_channels(struct device *dev,
struct stm32_timer_cnt *priv)
{
u32 ccer, ccer_backup;
regmap_read(priv->regmap, TIM_CCER, &ccer_backup);
regmap_set_bits(priv->regmap, TIM_CCER, TIM_CCER_CCXE);
regmap_read(priv->regmap, TIM_CCER, &ccer);
regmap_write(priv->regmap, TIM_CCER, ccer_backup);
priv->nchannels = hweight32(ccer & TIM_CCER_CCXE);
dev_dbg(dev, "has %d cc channels\n", priv->nchannels);
}
/* encoder supported on TIM1 TIM2 TIM3 TIM4 TIM5 TIM8 */
#define STM32_TIM_ENCODER_SUPPORTED (BIT(0) | BIT(1) | BIT(2) | BIT(3) | BIT(4) | BIT(7))
@ -484,6 +499,8 @@ static int stm32_timer_cnt_probe(struct platform_device *pdev)
if (ret)
return ret;
stm32_timer_cnt_detect_channels(dev, priv);
counter->name = dev_name(dev);
counter->parent = dev;
counter->ops = &stm32_timer_cnt_ops;