From 7e170c6e4f7501bea900aa66b2b27a6ce5001e25 Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Thu, 19 Dec 2013 16:28:29 +0100 Subject: mfd: ti_am335x_tscadc: Don't read back REG_SE 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 not required read-back I introduce a "set once" variant which does not update the cache mask. After the conversation completes, the bit is removed from the SE register anyway and we don't plan a new conversation "any time soon". The current set function is renamed to set_cache to distinguish the two operations. This is a small preparation for a larger sync-rework. Signed-off-by: Sebastian Andrzej Siewior Acked-by: Dmitry Torokhov Acked-by: Jonathan Cameron Signed-off-by: Lee Jones --- drivers/mfd/ti_am335x_tscadc.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) (limited to 'drivers/mfd') diff --git a/drivers/mfd/ti_am335x_tscadc.c b/drivers/mfd/ti_am335x_tscadc.c index 67d0eb469a45..cb0c211fc7d8 100644 --- a/drivers/mfd/ti_am335x_tscadc.c +++ b/drivers/mfd/ti_am335x_tscadc.c @@ -53,24 +53,32 @@ static void am335x_tsc_se_update(struct ti_tscadc_dev *tsadc) tscadc_writel(tsadc, REG_SE, tsadc->reg_se_cache); } -void am335x_tsc_se_set(struct ti_tscadc_dev *tsadc, u32 val) +void am335x_tsc_se_set_cache(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); +EXPORT_SYMBOL_GPL(am335x_tsc_se_set_cache); + +void am335x_tsc_se_set_once(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_set_once); 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); -- cgit v1.2.3