The purpose of reg_se_cache has been defeated. It should avoid the
read-back of the register to avoid the latency and the fact that the
bits are reset to 0 after the individual conversation took place.
The reason why this is required like this to work, is that read-back of
the register removes the bits of the ADC so they do not start another
conversation after the register is re-written from the TSC side for the
update.
To avoid the unrequired read-back I introduce a "set adc" variant which
does not update the cache mask. After the conversation completes, the
register bit is removed from the SE reister anyway and we don't plan a
new conversation "any time soon".
This is a small preparation for a larger sync-rework.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
---
drivers/iio/adc/ti_am335x_adc.c | 2 +-
drivers/mfd/ti_am335x_tscadc.c | 12 ++++++++++--
include/linux/mfd/ti_am335x_tscadc.h | 1 +
3 files changed, 12 insertions(+), 3 deletions(-)
diff --git a/drivers/iio/adc/ti_am335x_adc.c b/drivers/iio/adc/ti_am335x_adc.c
index e948454..9ad9bd9 100644
--- a/drivers/iio/adc/ti_am335x_adc.c
+++ b/drivers/iio/adc/ti_am335x_adc.c
@@ -335,7 +335,7 @@ static int tiadc_read_raw(struct iio_dev *indio_dev,
return -EBUSY;
step_en = get_adc_step_mask(adc_dev);
- am335x_tsc_se_set(adc_dev->mfd_tscadc, step_en);
+ am335x_tsc_se_adc_set(adc_dev->mfd_tscadc, step_en);
/* Wait for ADC sequencer to complete sampling */
while (tiadc_readl(adc_dev, REG_ADCFSM) & SEQ_STATUS) {
diff --git a/drivers/mfd/ti_am335x_tscadc.c b/drivers/mfd/ti_am335x_tscadc.c
index 67d0eb4..2948a41 100644
--- a/drivers/mfd/ti_am335x_tscadc.c
+++ b/drivers/mfd/ti_am335x_tscadc.c
@@ -58,19 +58,27 @@ void am335x_tsc_se_set(struct ti_tscadc_dev *tsadc, u32 val)
unsigned long flags;
spin_lock_irqsave(&tsadc->reg_lock, flags);
- tsadc->reg_se_cache = tscadc_readl(tsadc, REG_SE);
tsadc->reg_se_cache |= val;
am335x_tsc_se_update(tsadc);
spin_unlock_irqrestore(&tsadc->reg_lock, flags);
}
EXPORT_SYMBOL_GPL(am335x_tsc_se_set);
+void am335x_tsc_se_adc_set(struct ti_tscadc_dev *tsadc, u32 val)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&tsadc->reg_lock, flags);
+ tscadc_writel(tsadc, REG_SE, tsadc->reg_se_cache | val);
+ spin_unlock_irqrestore(&tsadc->reg_lock, flags);
+}
+EXPORT_SYMBOL_GPL(am335x_tsc_se_adc_set);
+
void am335x_tsc_se_clr(struct ti_tscadc_dev *tsadc, u32 val)
{
unsigned long flags;
spin_lock_irqsave(&tsadc->reg_lock, flags);
- tsadc->reg_se_cache = tscadc_readl(tsadc, REG_SE);
tsadc->reg_se_cache &= ~val;
am335x_tsc_se_update(tsadc);
spin_unlock_irqrestore(&tsadc->reg_lock, flags);
diff --git a/include/linux/mfd/ti_am335x_tscadc.h b/include/linux/mfd/ti_am335x_tscadc.h
index 1fe7219..be44a66 100644
--- a/include/linux/mfd/ti_am335x_tscadc.h
+++ b/include/linux/mfd/ti_am335x_tscadc.h
@@ -177,6 +177,7 @@ static inline struct ti_tscadc_dev *ti_tscadc_dev_get(struct platform_device *p)
}
void am335x_tsc_se_set(struct ti_tscadc_dev *tsadc, u32 val);
+void am335x_tsc_se_adc_set(struct ti_tscadc_dev *tsadc, u32 val);
void am335x_tsc_se_clr(struct ti_tscadc_dev *tsadc, u32 val);
#endif
--
1.8.5.1
--
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