kernel/include/linux/mfd/ti_am335x_tscadc.h, branch linux-5.2.y

iio: adc: ti_am335x_tscadc: Improve accuracy of measurement

2018-12-03T11:33:20Z

When performing single ended measurements with TSCADC, its recommended to set negative input (SEL_INM_SWC_3_0) of ADC step to ADC's VREFN in the corresponding STEP_CONFIGx register. Also, the positive(SEL_RFP_SWC_2_0) and negative(SEL_RFM_SWC_1_0) reference voltage for ADC step needs to be set to VREFP and VREFN respectively in STEP_CONFIGx register. Without these changes, there may be variation of as much as ~2% in the ADC's digital output which is bad for precise measurement. Signed-off-by: Vignesh R Acked-by: Jonathan Cameron Signed-off-by: Lee Jones

drivers: iio: ti_am335x_adc: add dma support

2016-11-05T17:32:05Z

This patch adds the required pieces to ti_am335x_adc driver for DMA support Signed-off-by: Mugunthan V N Reviewed-by: Peter Ujfalusi Signed-off-by: Jonathan Cameron

mfd: ti_am335x_tscadc: store physical address

2016-11-05T17:30:51Z

store the physical address of the device in its priv to use it for DMA addressing in the client drivers. Signed-off-by: Mugunthan V N Acked-for-MFD-by: Lee Jones Signed-off-by: Jonathan Cameron

iio: adc: ti_am335x_adc: Increase timeout value waiting for ADC sample

2016-08-21T18:48:31Z

Now that open delay and sample delay for each channel is configurable via DT, the default IDLE_TIMEOUT value is not enough as this is calculated based on hardcoded macros. This results in driver returning EBUSY sometimes. Fix this by increasing the timeout value based on maximum value possible to open delay and sample delays for each channel. Fixes: 5dc11e810676e ("iio: adc: ti_am335x_adc: make sample delay, open delay, averaging DT parameters") Signed-off-by: Vignesh R Acked-by: Lee Jones Cc: Signed-off-by: Jonathan Cameron

mfd: ti_am335x_tscadc: Rename regmap_tscadc to regmap

2016-06-29T09:14:39Z

The regmap structure pointer is named regmap_tscadc, this is not consistent with other drivers and is redundant, it also contributes to several checkpatch warnings involving long lines. Rename this. Signed-off-by: Andrew F. Davis Signed-off-by: Lee Jones

mfd: ti_am335x_tscadc: Remove unwanted reg_se_cache save

2015-03-03T16:41:15Z

In one shot mode, sequencer automatically disables all enabled steps at the end of each cycle. (both ADC steps and TSC steps) Hence these steps need not be saved in reg_se_cache for clearing these steps at a later stage. Also, when ADC wakes up Sequencer should not be busy executing any of the config steps except for the charge step. Previously charge step was 1 ADC clock cycle and hence it was ignored. TSC steps are always disabled at the end of each conversion cycle, hence there is no need to explicitly disable TSC steps by writing 0 to REG_SE. Signed-off-by: Vignesh R Signed-off-by: Lee Jones

Input: ti_am335x_tsc - remove udelay in interrupt handler

2015-02-03T19:50:38Z

TSC interrupt handler had udelay to avoid reporting of false pen-up interrupt to user space. This patch implements workaround suggesting in Advisory 1.0.31 of silicon errata for am335x, thus eliminating udelay and touchscreen lag. This also improves performance of touchscreen and eliminates sudden jump of cursor at touch release. IDLECONFIG and CHARGECONFIG registers are to be configured with same values in order to eliminate false pen-up events. This workaround may result in false pen-down to be detected, hence considerable charge step delay needs to be added. The charge delay is set to 0xB000 (in terms of ADC clock cycles) by default. TSC steps are disabled at the end of every sampling cycle and EOS bit is set. Once the EOS bit is set, the TSC steps need to be re-enabled to begin next sampling cycle. Signed-off-by: Brad Griffis [vigneshr@ti.com: Ported the patch from v3.12 to v3.19rc1] Signed-off-by: Vignesh R Signed-off-by: Dmitry Torokhov

mfd: ti_am335x_tscadc: Update logic in CTRL register for 5-wire TS

2014-09-26T07:24:03Z

The logic in AFE_Pen_Ctrl bitmask in the CTRL register is different for five wire versus four or eight wire touschscreens. This patch should fix this for five-wire touch screens. There should be no change needed here for four and eight wire tousch screens. Signed-off-by: Jeff Lance [bigeasy: keep the change mfd only] Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Lee Jones

mfd: input: iio: ti_amm335x: Rework TSC/ADC synchronization

2014-01-07T08:45:00Z

The ADC driver always programs all possible ADC values and discards them except for the value IIO asked for. On the am335x-evm the driver programs four values and it takes 500us to gather them. Reducing the number of conversations down to the (required) one also reduces the busy loop down to 125us. This leads to another error, namely the FIFOCOUNT register is sometimes (like one out of 10 attempts) not updated in time leading to EBUSY. The next read has the FIFOCOUNT register updated. Checking for the ADCSTAT register for being idle isn't a good choice either. The problem is that if TSC is used at the same time, the HW completes the conversation for ADC *and* before the driver noticed it, the HW begins to perform a TSC conversation and so the driver never seen the HW idle. The next time we would have two values in the FIFO but since the driver reads everything we always see the current one. So instead of polling for the IDLE bit in ADCStatus register, we should check the FIFOCOUNT register. It should be one instead of zero because we request one value. This change in turn leads to another error. Sometimes if TSC & ADC are used together the TSC starts generating interrupts even if nobody actually touched the touchscreen. The interrupts seem valid because TSC's FIFO is filled with values for each channel of the TSC. This condition stops after a few ADC reads but will occur again. Not good. On top of this (even without the changes I just mentioned) there is a ADC & TSC lockup condition which was reported to me by Jeff Lance including the following test case: A busy loop of "cat /sys/bus/iio/devices/iio\:device0/in_voltage4_raw" and a mug on touch screen. With this setup, the hardware will lockup after something between 20 minutes and it could take up to a couple of hours. During that lockup, the ADCSTAT register says 0x30 (or 0x70) which means STEP_ID = IDLE and FSM_BUSY = yes. That means the hardware says that it is idle and busy at the same time which is an invalid condition. For all this reasons I decided to rework this TSC/ADC part and add a handshake / synchronization here: First the ADC signals that it needs the HW and writes a 0 mask into the SE register. The HW (if active) will complete the current conversation and become idle. The TSC driver will gather the values from the FIFO (woken up by an interrupt) and won't "enable" another conversation. Instead it will wake up the ADC driver which is already waiting. The ADC driver will start "its" conversation and once it is done, it will enable the TSC steps so the TSC will work again. After this rework I haven't observed the lockup so far. Plus the busy loop has been reduced from 500us to 125us. The continues-read mode remains unchanged. Signed-off-by: Sebastian Andrzej Siewior Acked-by: Jonathan Cameron Signed-off-by: Lee Jones

mfd: ti_am335x_tscadc: Don't read back REG_SE

2014-01-07T08:41:15Z

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