[PATCH 2/2] iio: ti_am335x_adc: Add continuous sampling and trigger support

From: Zubair Lutfullah
Date: Fri Jul 26 2013 - 19:51:47 EST

Previously the driver had only one-shot reading functionality.
This patch adds triggered buffer support to the driver.
A buffer of samples can now be read via /dev/iio.

Patil Rachna (TI) laid the ground work for ADC HW register access.
Russ Dill (TI) fixed bugs in the driver relevant to FIFOs and IRQs.

I fixed channel scanning so multiple ADC channels can be read
simultaneously and pushed to userspace.
Restructured the driver to fit IIO ABI.
And added trigger support.

Signed-off-by: Zubair Lutfullah <zubair.lutfullah@xxxxxxxxx>
Acked-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Russ Dill <Russ.Dill@xxxxxx>
---
drivers/iio/adc/ti_am335x_adc.c | 334 +++++++++++++++++++++++++++-------
include/linux/mfd/ti_am335x_tscadc.h | 13 +-
2 files changed, 285 insertions(+), 62 deletions(-)

diff --git a/drivers/iio/adc/ti_am335x_adc.c b/drivers/iio/adc/ti_am335x_adc.c
index 3ceac3e..630ce85 100644
--- a/drivers/iio/adc/ti_am335x_adc.c
+++ b/drivers/iio/adc/ti_am335x_adc.c
@@ -26,14 +26,25 @@
#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/trigger.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/wait.h>
+#include <linux/sched.h>

struct tiadc_device {
struct ti_tscadc_dev *mfd_tscadc;
int channels;
u8 channel_line[8];
u8 channel_step[8];
+ struct work_struct poll_work;
+ wait_queue_head_t wq_data_avail;
+ bool data_avail;
+ u32 *inputbuffer;
+ int sample_count;
+ int irq;
};

static unsigned int tiadc_readl(struct tiadc_device *adc, unsigned int reg)
@@ -56,27 +67,28 @@ static u32 get_adc_step_mask(struct tiadc_device *adc_dev)
return step_en;
}

-static void tiadc_step_config(struct tiadc_device *adc_dev)
+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;
+ int i, steps, chan;

/*
* 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;
- stepconfig = STEPCONFIG_AVG_16 | STEPCONFIG_FIFO1;
+ 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));
@@ -85,7 +97,190 @@ static void tiadc_step_config(struct tiadc_device *adc_dev)
adc_dev->channel_step[i] = steps;
steps++;
}
+}
+
+static irqreturn_t tiadc_irq(int irq, void *private)
+{
+ struct iio_dev *idev = private;
+ struct tiadc_device *adc_dev = iio_priv(idev);
+ unsigned int status, config;
+ status = tiadc_readl(adc_dev, REG_IRQSTATUS);
+
+ /* FIFO Overrun. Clear flag. Disable/Enable ADC to recover */
+ if (status & IRQENB_FIFO1OVRRUN) {
+ 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) {
+ /* Wake adc_work that pushes FIFO data to iio buffer */
+ tiadc_writel(adc_dev, REG_IRQCLR, IRQENB_FIFO1THRES);
+ adc_dev->data_avail = 1;
+ wake_up_interruptible(&adc_dev->wq_data_avail);
+ return IRQ_HANDLED;
+ } else
+ return IRQ_NONE;
+}
+
+static irqreturn_t tiadc_trigger_h(int irq, void *p)
+{
+ struct iio_poll_func *pf = p;
+ struct iio_dev *indio_dev = pf->indio_dev;
+ struct tiadc_device *adc_dev = iio_priv(indio_dev);
+ unsigned int config;
+
+ schedule_work(&adc_dev->poll_work);
+ config = tiadc_readl(adc_dev, REG_CTRL);
+ tiadc_writel(adc_dev, REG_CTRL, config & ~CNTRLREG_TSCSSENB);
+ tiadc_writel(adc_dev, REG_CTRL, config | CNTRLREG_TSCSSENB);
+
+ tiadc_writel(adc_dev, REG_IRQSTATUS, IRQENB_FIFO1THRES |
+ IRQENB_FIFO1OVRRUN | IRQENB_FIFO1UNDRFLW);
+ tiadc_writel(adc_dev, REG_IRQENABLE, IRQENB_FIFO1THRES
+ | IRQENB_FIFO1OVRRUN);
+
+ iio_trigger_notify_done(indio_dev->trig);
+ return IRQ_HANDLED;
+}
+
+static int tiadc_buffer_preenable(struct iio_dev *indio_dev)
+{
+ return iio_sw_buffer_preenable(indio_dev);
+}
+
+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, stepnum;
+ u8 bit;
+
+ tiadc_step_config(indio_dev);
+ tiadc_writel(adc_dev, REG_SE, 0x00);
+ for_each_set_bit(bit, buffer->scan_mask,
+ adc_dev->channels) {
+ struct iio_chan_spec const *chan = indio_dev->channels + bit;
+ /*
+ * There are a total of 16 steps available
+ * that are shared between ADC and touchscreen.
+ * We start configuring from step 16 to 0 incase of
+ * ADC. Hence the relation between input channel
+ * and step for ADC would be as below.
+ */
+ stepnum = chan->channel + 9;
+ enb = tiadc_readl(adc_dev, REG_SE);
+ enb |= (1 << stepnum);
+ tiadc_writel(adc_dev, REG_SE, enb);
+ }
+
+ return iio_triggered_buffer_postenable(indio_dev);
+}
+
+static int tiadc_buffer_predisable(struct iio_dev *indio_dev)
+{
+ struct tiadc_device *adc_dev = iio_priv(indio_dev);
+ int fifo1count, i, read, config;
+
+ config = tiadc_readl(adc_dev, REG_CTRL);
+ config &= ~(CNTRLREG_TSCSSENB);
+ tiadc_writel(adc_dev, REG_CTRL, config);
+ tiadc_writel(adc_dev, REG_IRQCLR, (IRQENB_FIFO1THRES |
+ IRQENB_FIFO1OVRRUN | IRQENB_FIFO1UNDRFLW));
+ tiadc_writel(adc_dev, REG_SE, STPENB_STEPENB_TC);
+
+ /* Flush FIFO of any leftover data */
+ fifo1count = tiadc_readl(adc_dev, REG_FIFO1CNT);
+ for (i = 0; i < fifo1count; i++)
+ read = tiadc_readl(adc_dev, REG_FIFO1);
+
+ return iio_triggered_buffer_predisable(indio_dev);
+}
+
+static int tiadc_buffer_postdisable(struct iio_dev *indio_dev)
+{
+ struct tiadc_device *adc_dev = iio_priv(indio_dev);
+ int config;
+
+ tiadc_step_config(indio_dev);
+ config = tiadc_readl(adc_dev, REG_CTRL);
+ tiadc_writel(adc_dev, REG_CTRL, (config | CNTRLREG_TSCSSENB));
+
+ 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 void tiadc_adc_work(struct work_struct *work_s)
+{
+ struct tiadc_device *adc_dev =
+ container_of(work_s, struct tiadc_device, poll_work);
+ struct iio_dev *indio_dev = iio_priv_to_dev(adc_dev);
+ struct iio_buffer *buffer = indio_dev->buffer;
+ int i, j, k, fifo1count, read;
+ unsigned int config;
+ int size_to_acquire = buffer->access->get_length(buffer);
+ int sample_count = 0;
+ u32 *data;
+
+ adc_dev->data_avail = 0;
+ data = kmalloc(indio_dev->scan_bytes, GFP_KERNEL);
+ if (data == NULL)
+ goto out;
+
+ while (sample_count < size_to_acquire) {
+ tiadc_writel(adc_dev, REG_IRQSTATUS, IRQENB_FIFO1THRES);
+ tiadc_writel(adc_dev, REG_IRQENABLE, IRQENB_FIFO1THRES);
+
+ wait_event_interruptible(adc_dev->wq_data_avail,
+ (adc_dev->data_avail == 1));
+ adc_dev->data_avail = 0;
+
+ fifo1count = tiadc_readl(adc_dev, REG_FIFO1CNT);
+ if (fifo1count * sizeof(u32) <
+ buffer->access->get_bytes_per_datum(buffer))
+ continue;
+
+ sample_count = sample_count + fifo1count;
+ for (k = 0; k < fifo1count; k = k + i) {
+ for (i = 0, j = 0; i < (indio_dev->scan_bytes)/4; i++) {
+ read = tiadc_readl(adc_dev, REG_FIFO1);
+ data[i] = read & FIFOREAD_DATA_MASK;
+ }
+ iio_push_to_buffers(indio_dev, (u8 *) data);
+ }
+ }
+out:
+ tiadc_writel(adc_dev, REG_IRQCLR, (IRQENB_FIFO1THRES |
+ IRQENB_FIFO1OVRRUN | IRQENB_FIFO1UNDRFLW));
+ config = tiadc_readl(adc_dev, REG_CTRL);
+ tiadc_writel(adc_dev, REG_CTRL, config & ~CNTRLREG_TSCSSENB);
+}

+irqreturn_t tiadc_iio_pollfunc(int irq, void *p)
+{
+ struct iio_poll_func *pf = p;
+ struct iio_dev *indio_dev = pf->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 before trigger */
+ fifo1count = tiadc_readl(adc_dev, REG_FIFO1CNT);
+ for (i = 0; i < fifo1count; i++)
+ read = tiadc_readl(adc_dev, REG_FIFO1);
+
+ return IRQ_WAKE_THREAD;
}

static const char * const chan_name_ain[] = {
@@ -120,13 +315,13 @@ static int tiadc_channel_init(struct iio_dev *indio_dev, int channels)
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 = 32;
}

indio_dev->channels = chan_array;
-
return 0;
}

@@ -141,58 +336,48 @@ static int tiadc_read_raw(struct iio_dev *indio_dev,
{
struct tiadc_device *adc_dev = iio_priv(indio_dev);
int i, map_val;
- unsigned int fifo1count, read, stepid;
- u32 step = UINT_MAX;
- bool found = false;
- u32 step_en;
- unsigned long timeout = jiffies + usecs_to_jiffies
- (IDLE_TIMEOUT * adc_dev->channels);
- step_en = get_adc_step_mask(adc_dev);
- am335x_tsc_se_set(adc_dev->mfd_tscadc, step_en);
-
- /* Wait for ADC sequencer to complete sampling */
- while (tiadc_readl(adc_dev, REG_ADCFSM) & SEQ_STATUS) {
- if (time_after(jiffies, timeout))
- return -EAGAIN;
- }
- map_val = chan->channel + TOTAL_CHANNELS;
-
- /*
- * When the sub-system is first enabled,
- * the sequencer will always start with the
- * lowest step (1) and continue until step (16).
- * For ex: If we have enabled 4 ADC channels and
- * currently use only 1 out of them, the
- * sequencer still configures all the 4 steps,
- * leading to 3 unwanted data.
- * Hence we need to flush out this data.
- */
+ unsigned int fifo1count, read, stepid, step_en;

- for (i = 0; i < ARRAY_SIZE(adc_dev->channel_step); i++) {
- if (chan->channel == adc_dev->channel_line[i]) {
- step = adc_dev->channel_step[i];
- break;
- }
- }
- if (WARN_ON_ONCE(step == UINT_MAX))
- return -EINVAL;
-
- fifo1count = tiadc_readl(adc_dev, REG_FIFO1CNT);
- 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 = read;
+ if (iio_buffer_enabled(indio_dev))
+ return -EBUSY;
+ else {
+ unsigned long timeout = jiffies + usecs_to_jiffies
+ (IDLE_TIMEOUT * adc_dev->channels);
+ step_en = get_adc_step_mask(adc_dev);
+ am335x_tsc_se_set(adc_dev->mfd_tscadc, step_en);
+
+ /* Wait for ADC sequencer to complete sampling */
+ while (tiadc_readl(adc_dev, REG_ADCFSM) & SEQ_STATUS) {
+ if (time_after(jiffies, timeout))
+ return -EAGAIN;
+ }
+ map_val = chan->channel + TOTAL_CHANNELS;
+
+ /*
+ * When the sub-system is first enabled,
+ * the sequencer will always start with the
+ * lowest step (1) and continue until step (16).
+ * For ex: If we have enabled 4 ADC channels and
+ * currently use only 1 out of them, the
+ * sequencer still configures all the 4 steps,
+ * leading to 3 unwanted data.
+ * Hence we need to flush out this data.
+ */
+
+ fifo1count = tiadc_readl(adc_dev, REG_FIFO1CNT);
+ 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;
+ *val = read;
+ return IIO_VAL_INT;
+ }
}
+ return -EAGAIN;
}
-
- if (found == false)
- return -EBUSY;
- return IIO_VAL_INT;
}

static const struct iio_info tiadc_info = {
@@ -231,18 +416,33 @@ static int tiadc_probe(struct platform_device *pdev)
channels++;
}
adc_dev->channels = channels;
+ adc_dev->irq = adc_dev->mfd_tscadc->irq;

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(adc_dev);
+ 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)
goto err_free_device;

+ INIT_WORK(&adc_dev->poll_work, &tiadc_adc_work);
+ init_waitqueue_head(&adc_dev->wq_data_avail);
+
+ err = request_irq(adc_dev->irq, tiadc_irq, IRQF_SHARED,
+ indio_dev->name, indio_dev);
+ if (err)
+ goto err_free_irq;
+
+ err = iio_triggered_buffer_setup(indio_dev, &tiadc_iio_pollfunc,
+ &tiadc_trigger_h, &tiadc_buffer_setup_ops);
+ if (err)
+ goto err_unregister;
+
err = iio_device_register(indio_dev);
if (err)
goto err_free_channels;
@@ -251,6 +451,10 @@ static int tiadc_probe(struct platform_device *pdev)

return 0;

+err_unregister:
+ iio_buffer_unregister(indio_dev);
+err_free_irq:
+ free_irq(adc_dev->irq, indio_dev);
err_free_channels:
tiadc_channels_remove(indio_dev);
err_free_device:
@@ -265,7 +469,9 @@ static int tiadc_remove(struct platform_device *pdev)
struct tiadc_device *adc_dev = iio_priv(indio_dev);
u32 step_en;

+ free_irq(adc_dev->irq, indio_dev);
iio_device_unregister(indio_dev);
+ iio_buffer_unregister(indio_dev);
tiadc_channels_remove(indio_dev);

step_en = get_adc_step_mask(adc_dev);
@@ -303,10 +509,16 @@ static int tiadc_resume(struct device *dev)

/* Make sure ADC is powered up */
restore = tiadc_readl(adc_dev, REG_CTRL);
- restore &= ~(CNTRLREG_POWERDOWN);
+ restore &= ~(CNTRLREG_TSCSSENB);
tiadc_writel(adc_dev, REG_CTRL, restore);

- tiadc_step_config(adc_dev);
+ tiadc_writel(adc_dev, REG_FIFO1THR, FIFO1_THRESHOLD);
+ tiadc_step_config(indio_dev);
+
+ /* Make sure ADC is powered up */
+ restore &= ~(CNTRLREG_POWERDOWN);
+ restore |= CNTRLREG_TSCSSENB;
+ tiadc_writel(adc_dev, REG_CTRL, restore);

return 0;
}
diff --git a/include/linux/mfd/ti_am335x_tscadc.h b/include/linux/mfd/ti_am335x_tscadc.h
index db1791b..cb61027 100644
--- a/include/linux/mfd/ti_am335x_tscadc.h
+++ b/include/linux/mfd/ti_am335x_tscadc.h
@@ -46,17 +46,23 @@
/* Step Enable */
#define STEPENB_MASK (0x1FFFF << 0)
#define STEPENB(val) ((val) << 0)
+#define ENB(val) (1 << (val))
+#define STPENB_STEPENB STEPENB(0x1FFFF)
+#define STPENB_STEPENB_TC STEPENB(0x1FFF)

/* IRQ enable */
#define IRQENB_HW_PEN BIT(0)
#define IRQENB_FIFO0THRES BIT(2)
#define IRQENB_FIFO1THRES BIT(5)
#define IRQENB_PENUP BIT(9)
+#define IRQENB_FIFO1OVRRUN BIT(6)
+#define IRQENB_FIFO1UNDRFLW BIT(7)

/* Step Configuration */
#define STEPCONFIG_MODE_MASK (3 << 0)
#define STEPCONFIG_MODE(val) ((val) << 0)
#define STEPCONFIG_MODE_HWSYNC STEPCONFIG_MODE(2)
+#define STEPCONFIG_MODE_SWCNT STEPCONFIG_MODE(1)
#define STEPCONFIG_AVG_MASK (7 << 2)
#define STEPCONFIG_AVG(val) ((val) << 2)
#define STEPCONFIG_AVG_16 STEPCONFIG_AVG(4)
@@ -124,7 +130,8 @@
#define MAX_CLK_DIV 7
#define TOTAL_STEPS 16
#define TOTAL_CHANNELS 8
-
+#define FIFO1_THRESHOLD 19
+#define FIFO_SIZE 64
/*
* ADC runs at 3MHz, and it takes
* 15 cycles to latch one data output.
@@ -153,6 +160,10 @@ struct ti_tscadc_dev {

/* adc device */
struct adc_device *adc;
+
+ /* Context save */
+ unsigned int irqstat;
+ unsigned int ctrl;
};

static inline struct ti_tscadc_dev *ti_tscadc_dev_get(struct platform_device *p)
--
1.7.9.5

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