linux/drivers/iio/adc/ti_am335x_adc.c

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/*
* TI ADC MFD driver
*
* Copyright (C) 2012 Texas Instruments Incorporated - http://www.ti.com/
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation version 2.
*
* This program is distributed "as is" WITHOUT ANY WARRANTY of any
* kind, whether express or implied; without even the implied warranty
* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/err.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>
#include <linux/io.h>
#include <linux/iio/iio.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/iio/machine.h>
#include <linux/iio/driver.h>
#include <linux/mfd/ti_am335x_tscadc.h>
#include <linux/iio/buffer.h>
#include <linux/iio/kfifo_buf.h>
struct tiadc_device {
struct ti_tscadc_dev *mfd_tscadc;
int channels;
u8 channel_line[8];
u8 channel_step[8];
int buffer_en_ch_steps;
u16 data[8];
};
static unsigned int tiadc_readl(struct tiadc_device *adc, unsigned int reg)
{
return readl(adc->mfd_tscadc->tscadc_base + reg);
}
static void tiadc_writel(struct tiadc_device *adc, unsigned int reg,
unsigned int val)
{
writel(val, adc->mfd_tscadc->tscadc_base + reg);
}
static u32 get_adc_step_mask(struct tiadc_device *adc_dev)
{
u32 step_en;
step_en = ((1 << adc_dev->channels) - 1);
step_en <<= TOTAL_STEPS - adc_dev->channels + 1;
return step_en;
}
mfd: input: iio: ti_amm335x: Rework TSC/ADC synchronization 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 <bigeasy@linutronix.de> Acked-by: Jonathan Cameron <jic23@kernel.org> Signed-off-by: Lee Jones <lee.jones@linaro.org>
2013-12-19 23:28:31 +08:00
static u32 get_adc_chan_step_mask(struct tiadc_device *adc_dev,
struct iio_chan_spec const *chan)
{
int i;
for (i = 0; i < ARRAY_SIZE(adc_dev->channel_step); i++) {
if (chan->channel == adc_dev->channel_line[i]) {
u32 step;
step = adc_dev->channel_step[i];
/* +1 for the charger */
return 1 << (step + 1);
}
}
WARN_ON(1);
return 0;
}
static u32 get_adc_step_bit(struct tiadc_device *adc_dev, int chan)
{
return 1 << adc_dev->channel_step[chan];
}
static void tiadc_step_config(struct iio_dev *indio_dev)
{
struct tiadc_device *adc_dev = iio_priv(indio_dev);
unsigned int stepconfig;
int i, steps;
/*
* There are 16 configurable steps and 8 analog input
* lines available which are shared between Touchscreen and ADC.
*
* Steps backwards i.e. from 16 towards 0 are used by ADC
* depending on number of input lines needed.
* Channel would represent which analog input
* needs to be given to ADC to digitalize data.
*/
steps = TOTAL_STEPS - adc_dev->channels;
if (iio_buffer_enabled(indio_dev))
stepconfig = STEPCONFIG_AVG_16 | STEPCONFIG_FIFO1
| STEPCONFIG_MODE_SWCNT;
else
stepconfig = STEPCONFIG_AVG_16 | STEPCONFIG_FIFO1;
for (i = 0; i < adc_dev->channels; i++) {
int chan;
chan = adc_dev->channel_line[i];
tiadc_writel(adc_dev, REG_STEPCONFIG(steps),
stepconfig | STEPCONFIG_INP(chan));
tiadc_writel(adc_dev, REG_STEPDELAY(steps),
STEPCONFIG_OPENDLY);
adc_dev->channel_step[i] = steps;
steps++;
}
}
static irqreturn_t tiadc_irq_h(int irq, void *private)
{
struct iio_dev *indio_dev = private;
struct tiadc_device *adc_dev = iio_priv(indio_dev);
unsigned int status, config;
status = tiadc_readl(adc_dev, REG_IRQSTATUS);
/*
* ADC and touchscreen share the IRQ line.
* FIFO0 interrupts are used by TSC. Handle FIFO1 IRQs here only
*/
if (status & IRQENB_FIFO1OVRRUN) {
/* FIFO Overrun. Clear flag. Disable/Enable ADC to recover */
config = tiadc_readl(adc_dev, REG_CTRL);
config &= ~(CNTRLREG_TSCSSENB);
tiadc_writel(adc_dev, REG_CTRL, config);
tiadc_writel(adc_dev, REG_IRQSTATUS, IRQENB_FIFO1OVRRUN
| IRQENB_FIFO1UNDRFLW | IRQENB_FIFO1THRES);
tiadc_writel(adc_dev, REG_CTRL, (config | CNTRLREG_TSCSSENB));
return IRQ_HANDLED;
} else if (status & IRQENB_FIFO1THRES) {
/* Disable irq and wake worker thread */
tiadc_writel(adc_dev, REG_IRQCLR, IRQENB_FIFO1THRES);
return IRQ_WAKE_THREAD;
}
return IRQ_NONE;
}
static irqreturn_t tiadc_worker_h(int irq, void *private)
{
struct iio_dev *indio_dev = private;
struct tiadc_device *adc_dev = iio_priv(indio_dev);
int i, k, fifo1count, read;
u16 *data = adc_dev->data;
fifo1count = tiadc_readl(adc_dev, REG_FIFO1CNT);
for (k = 0; k < fifo1count; k = k + i) {
for (i = 0; i < (indio_dev->scan_bytes)/2; i++) {
read = tiadc_readl(adc_dev, REG_FIFO1);
data[i] = read & FIFOREAD_DATA_MASK;
}
iio_push_to_buffers(indio_dev, (u8 *) data);
}
tiadc_writel(adc_dev, REG_IRQSTATUS, IRQENB_FIFO1THRES);
tiadc_writel(adc_dev, REG_IRQENABLE, IRQENB_FIFO1THRES);
return IRQ_HANDLED;
}
static int tiadc_buffer_preenable(struct iio_dev *indio_dev)
{
struct tiadc_device *adc_dev = iio_priv(indio_dev);
int i, fifo1count, read;
tiadc_writel(adc_dev, REG_IRQCLR, (IRQENB_FIFO1THRES |
IRQENB_FIFO1OVRRUN |
IRQENB_FIFO1UNDRFLW));
/* Flush FIFO. Needed in corner cases in simultaneous tsc/adc use */
fifo1count = tiadc_readl(adc_dev, REG_FIFO1CNT);
for (i = 0; i < fifo1count; i++)
read = tiadc_readl(adc_dev, REG_FIFO1);
return 0;
}
static int tiadc_buffer_postenable(struct iio_dev *indio_dev)
{
struct tiadc_device *adc_dev = iio_priv(indio_dev);
struct iio_buffer *buffer = indio_dev->buffer;
unsigned int enb = 0;
u8 bit;
tiadc_step_config(indio_dev);
for_each_set_bit(bit, buffer->scan_mask, adc_dev->channels)
enb |= (get_adc_step_bit(adc_dev, bit) << 1);
adc_dev->buffer_en_ch_steps = enb;
am335x_tsc_se_set_cache(adc_dev->mfd_tscadc, enb);
tiadc_writel(adc_dev, REG_IRQSTATUS, IRQENB_FIFO1THRES
| IRQENB_FIFO1OVRRUN | IRQENB_FIFO1UNDRFLW);
tiadc_writel(adc_dev, REG_IRQENABLE, IRQENB_FIFO1THRES
| IRQENB_FIFO1OVRRUN);
return 0;
}
static int tiadc_buffer_predisable(struct iio_dev *indio_dev)
{
struct tiadc_device *adc_dev = iio_priv(indio_dev);
int fifo1count, i, read;
tiadc_writel(adc_dev, REG_IRQCLR, (IRQENB_FIFO1THRES |
IRQENB_FIFO1OVRRUN | IRQENB_FIFO1UNDRFLW));
am335x_tsc_se_clr(adc_dev->mfd_tscadc, adc_dev->buffer_en_ch_steps);
adc_dev->buffer_en_ch_steps = 0;
/* Flush FIFO of leftover data in the time it takes to disable adc */
fifo1count = tiadc_readl(adc_dev, REG_FIFO1CNT);
for (i = 0; i < fifo1count; i++)
read = tiadc_readl(adc_dev, REG_FIFO1);
return 0;
}
static int tiadc_buffer_postdisable(struct iio_dev *indio_dev)
{
tiadc_step_config(indio_dev);
return 0;
}
static const struct iio_buffer_setup_ops tiadc_buffer_setup_ops = {
.preenable = &tiadc_buffer_preenable,
.postenable = &tiadc_buffer_postenable,
.predisable = &tiadc_buffer_predisable,
.postdisable = &tiadc_buffer_postdisable,
};
static int tiadc_iio_buffered_hardware_setup(struct iio_dev *indio_dev,
irqreturn_t (*pollfunc_bh)(int irq, void *p),
irqreturn_t (*pollfunc_th)(int irq, void *p),
int irq,
unsigned long flags,
const struct iio_buffer_setup_ops *setup_ops)
{
struct iio_buffer *buffer;
int ret;
buffer = iio_kfifo_allocate(indio_dev);
if (!buffer)
return -ENOMEM;
iio_device_attach_buffer(indio_dev, buffer);
ret = request_threaded_irq(irq, pollfunc_th, pollfunc_bh,
flags, indio_dev->name, indio_dev);
if (ret)
goto error_kfifo_free;
indio_dev->setup_ops = setup_ops;
indio_dev->modes |= INDIO_BUFFER_HARDWARE;
ret = iio_buffer_register(indio_dev,
indio_dev->channels,
indio_dev->num_channels);
if (ret)
goto error_free_irq;
return 0;
error_free_irq:
free_irq(irq, indio_dev);
error_kfifo_free:
iio_kfifo_free(indio_dev->buffer);
return ret;
}
static void tiadc_iio_buffered_hardware_remove(struct iio_dev *indio_dev)
{
struct tiadc_device *adc_dev = iio_priv(indio_dev);
free_irq(adc_dev->mfd_tscadc->irq, indio_dev);
iio_kfifo_free(indio_dev->buffer);
iio_buffer_unregister(indio_dev);
}
static const char * const chan_name_ain[] = {
"AIN0",
"AIN1",
"AIN2",
"AIN3",
"AIN4",
"AIN5",
"AIN6",
"AIN7",
};
static int tiadc_channel_init(struct iio_dev *indio_dev, int channels)
{
struct tiadc_device *adc_dev = iio_priv(indio_dev);
struct iio_chan_spec *chan_array;
struct iio_chan_spec *chan;
int i;
indio_dev->num_channels = channels;
chan_array = kcalloc(channels,
sizeof(struct iio_chan_spec), GFP_KERNEL);
if (chan_array == NULL)
return -ENOMEM;
chan = chan_array;
for (i = 0; i < channels; i++, chan++) {
chan->type = IIO_VOLTAGE;
chan->indexed = 1;
chan->channel = adc_dev->channel_line[i];
chan->info_mask_separate = BIT(IIO_CHAN_INFO_RAW);
chan->datasheet_name = chan_name_ain[chan->channel];
chan->scan_index = i;
chan->scan_type.sign = 'u';
chan->scan_type.realbits = 12;
chan->scan_type.storagebits = 16;
}
indio_dev->channels = chan_array;
return 0;
}
static void tiadc_channels_remove(struct iio_dev *indio_dev)
{
kfree(indio_dev->channels);
}
static int tiadc_read_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int *val, int *val2, long mask)
{
struct tiadc_device *adc_dev = iio_priv(indio_dev);
int i, map_val;
unsigned int fifo1count, read, stepid;
bool found = false;
u32 step_en;
mfd: input: iio: ti_amm335x: Rework TSC/ADC synchronization 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 <bigeasy@linutronix.de> Acked-by: Jonathan Cameron <jic23@kernel.org> Signed-off-by: Lee Jones <lee.jones@linaro.org>
2013-12-19 23:28:31 +08:00
unsigned long timeout;
if (iio_buffer_enabled(indio_dev))
return -EBUSY;
mfd: input: iio: ti_amm335x: Rework TSC/ADC synchronization 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 <bigeasy@linutronix.de> Acked-by: Jonathan Cameron <jic23@kernel.org> Signed-off-by: Lee Jones <lee.jones@linaro.org>
2013-12-19 23:28:31 +08:00
step_en = get_adc_chan_step_mask(adc_dev, chan);
if (!step_en)
return -EINVAL;
fifo1count = tiadc_readl(adc_dev, REG_FIFO1CNT);
while (fifo1count--)
tiadc_readl(adc_dev, REG_FIFO1);
am335x_tsc_se_set_once(adc_dev->mfd_tscadc, step_en);
mfd: input: iio: ti_amm335x: Rework TSC/ADC synchronization 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 <bigeasy@linutronix.de> Acked-by: Jonathan Cameron <jic23@kernel.org> Signed-off-by: Lee Jones <lee.jones@linaro.org>
2013-12-19 23:28:31 +08:00
timeout = jiffies + usecs_to_jiffies
(IDLE_TIMEOUT * adc_dev->channels);
/* Wait for Fifo threshold interrupt */
while (1) {
fifo1count = tiadc_readl(adc_dev, REG_FIFO1CNT);
if (fifo1count)
break;
if (time_after(jiffies, timeout)) {
am335x_tsc_se_adc_done(adc_dev->mfd_tscadc);
return -EAGAIN;
}
}
map_val = chan->channel + TOTAL_CHANNELS;
/*
mfd: input: iio: ti_amm335x: Rework TSC/ADC synchronization 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 <bigeasy@linutronix.de> Acked-by: Jonathan Cameron <jic23@kernel.org> Signed-off-by: Lee Jones <lee.jones@linaro.org>
2013-12-19 23:28:31 +08:00
* We check the complete FIFO. We programmed just one entry but in case
* something went wrong we left empty handed (-EAGAIN previously) and
* then the value apeared somehow in the FIFO we would have two entries.
* Therefore we read every item and keep only the latest version of the
* requested channel.
*/
for (i = 0; i < fifo1count; i++) {
read = tiadc_readl(adc_dev, REG_FIFO1);
stepid = read & FIFOREAD_CHNLID_MASK;
stepid = stepid >> 0x10;
if (stepid == map_val) {
read = read & FIFOREAD_DATA_MASK;
found = true;
*val = (u16) read;
}
}
mfd: input: iio: ti_amm335x: Rework TSC/ADC synchronization 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 <bigeasy@linutronix.de> Acked-by: Jonathan Cameron <jic23@kernel.org> Signed-off-by: Lee Jones <lee.jones@linaro.org>
2013-12-19 23:28:31 +08:00
am335x_tsc_se_adc_done(adc_dev->mfd_tscadc);
if (found == false)
return -EBUSY;
return IIO_VAL_INT;
}
static const struct iio_info tiadc_info = {
.read_raw = &tiadc_read_raw,
.driver_module = THIS_MODULE,
};
static int tiadc_probe(struct platform_device *pdev)
{
struct iio_dev *indio_dev;
struct tiadc_device *adc_dev;
struct device_node *node = pdev->dev.of_node;
struct property *prop;
const __be32 *cur;
int err;
u32 val;
int channels = 0;
if (!node) {
dev_err(&pdev->dev, "Could not find valid DT data.\n");
return -EINVAL;
}
indio_dev = devm_iio_device_alloc(&pdev->dev,
sizeof(struct tiadc_device));
if (indio_dev == NULL) {
dev_err(&pdev->dev, "failed to allocate iio device\n");
return -ENOMEM;
}
adc_dev = iio_priv(indio_dev);
adc_dev->mfd_tscadc = ti_tscadc_dev_get(pdev);
of_property_for_each_u32(node, "ti,adc-channels", prop, cur, val) {
adc_dev->channel_line[channels] = val;
channels++;
}
adc_dev->channels = channels;
indio_dev->dev.parent = &pdev->dev;
indio_dev->name = dev_name(&pdev->dev);
indio_dev->modes = INDIO_DIRECT_MODE;
indio_dev->info = &tiadc_info;
tiadc_step_config(indio_dev);
tiadc_writel(adc_dev, REG_FIFO1THR, FIFO1_THRESHOLD);
err = tiadc_channel_init(indio_dev, adc_dev->channels);
if (err < 0)
return err;
err = tiadc_iio_buffered_hardware_setup(indio_dev,
&tiadc_worker_h,
&tiadc_irq_h,
adc_dev->mfd_tscadc->irq,
IRQF_SHARED,
&tiadc_buffer_setup_ops);
if (err)
goto err_free_channels;
err = iio_device_register(indio_dev);
if (err)
goto err_buffer_unregister;
platform_set_drvdata(pdev, indio_dev);
return 0;
err_buffer_unregister:
tiadc_iio_buffered_hardware_remove(indio_dev);
err_free_channels:
tiadc_channels_remove(indio_dev);
return err;
}
static int tiadc_remove(struct platform_device *pdev)
{
struct iio_dev *indio_dev = platform_get_drvdata(pdev);
struct tiadc_device *adc_dev = iio_priv(indio_dev);
u32 step_en;
iio_device_unregister(indio_dev);
tiadc_iio_buffered_hardware_remove(indio_dev);
tiadc_channels_remove(indio_dev);
step_en = get_adc_step_mask(adc_dev);
am335x_tsc_se_clr(adc_dev->mfd_tscadc, step_en);
return 0;
}
#ifdef CONFIG_PM
static int tiadc_suspend(struct device *dev)
{
struct iio_dev *indio_dev = dev_get_drvdata(dev);
struct tiadc_device *adc_dev = iio_priv(indio_dev);
struct ti_tscadc_dev *tscadc_dev;
unsigned int idle;
tscadc_dev = ti_tscadc_dev_get(to_platform_device(dev));
if (!device_may_wakeup(tscadc_dev->dev)) {
idle = tiadc_readl(adc_dev, REG_CTRL);
idle &= ~(CNTRLREG_TSCSSENB);
tiadc_writel(adc_dev, REG_CTRL, (idle |
CNTRLREG_POWERDOWN));
}
return 0;
}
static int tiadc_resume(struct device *dev)
{
struct iio_dev *indio_dev = dev_get_drvdata(dev);
struct tiadc_device *adc_dev = iio_priv(indio_dev);
unsigned int restore;
/* Make sure ADC is powered up */
restore = tiadc_readl(adc_dev, REG_CTRL);
restore &= ~(CNTRLREG_POWERDOWN);
tiadc_writel(adc_dev, REG_CTRL, restore);
tiadc_step_config(indio_dev);
mfd: input: iio: ti_amm335x: Rework TSC/ADC synchronization 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 <bigeasy@linutronix.de> Acked-by: Jonathan Cameron <jic23@kernel.org> Signed-off-by: Lee Jones <lee.jones@linaro.org>
2013-12-19 23:28:31 +08:00
am335x_tsc_se_set_cache(adc_dev->mfd_tscadc,
adc_dev->buffer_en_ch_steps);
return 0;
}
static const struct dev_pm_ops tiadc_pm_ops = {
.suspend = tiadc_suspend,
.resume = tiadc_resume,
};
#define TIADC_PM_OPS (&tiadc_pm_ops)
#else
#define TIADC_PM_OPS NULL
#endif
static const struct of_device_id ti_adc_dt_ids[] = {
{ .compatible = "ti,am3359-adc", },
{ }
};
MODULE_DEVICE_TABLE(of, ti_adc_dt_ids);
static struct platform_driver tiadc_driver = {
.driver = {
.name = "TI-am335x-adc",
.owner = THIS_MODULE,
.pm = TIADC_PM_OPS,
.of_match_table = ti_adc_dt_ids,
},
.probe = tiadc_probe,
.remove = tiadc_remove,
};
module_platform_driver(tiadc_driver);
MODULE_DESCRIPTION("TI ADC controller driver");
MODULE_AUTHOR("Rachna Patil <rachna@ti.com>");
MODULE_LICENSE("GPL");