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Date: Sat, 16 Oct 2021 20:33:38 -0500
From: David Lechner <david@...hnology.com>
To: linux-iio@...r.kernel.org
Cc: David Lechner <david@...hnology.com>,
William Breathitt Gray <vilhelm.gray@...il.com>,
Robert Nelson <robertcnelson@...il.com>,
linux-kernel@...r.kernel.org
Subject: [PATCH 3/8] counter/ti-eqep: add support for unit timer
This adds support to the TI eQEP counter driver for the Unit Timer.
The Unit Timer is a device-level extension that provides a timer to be
used for speed calculations. The sysfs interface for the Unit Timer is
new and will be documented in a later commit. It contains a R/W time
attribute for the current time, a R/W period attribute for the timeout
period and a R/W enable attribute to start/stop the timer. It also
implements a timeout event on the chrdev interface that is triggered
each time the period timeout is reached.
Signed-off-by: David Lechner <david@...hnology.com>
---
drivers/counter/ti-eqep.c | 132 ++++++++++++++++++++++++++++++++++-
include/uapi/linux/counter.h | 2 +
2 files changed, 133 insertions(+), 1 deletion(-)
diff --git a/drivers/counter/ti-eqep.c b/drivers/counter/ti-eqep.c
index 9881e5115da6..a4a5a4486329 100644
--- a/drivers/counter/ti-eqep.c
+++ b/drivers/counter/ti-eqep.c
@@ -6,6 +6,7 @@
*/
#include <linux/bitops.h>
+#include <linux/clk.h>
#include <linux/counter.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
@@ -131,6 +132,7 @@ enum ti_eqep_count_func {
struct ti_eqep_cnt {
struct counter_device counter;
+ unsigned long sysclkout_rate;
struct regmap *regmap32;
struct regmap *regmap16;
};
@@ -298,6 +300,9 @@ static int ti_eqep_events_configure(struct counter_device *counter)
case COUNTER_EVENT_DIRECTION_CHANGE:
qeint |= QEINT_QDC;
break;
+ case COUNTER_EVENT_TIMEOUT:
+ qeint |= QEINT_UTO;
+ break;
}
}
@@ -311,6 +316,7 @@ static int ti_eqep_watch_validate(struct counter_device *counter,
case COUNTER_EVENT_OVERFLOW:
case COUNTER_EVENT_UNDERFLOW:
case COUNTER_EVENT_DIRECTION_CHANGE:
+ case COUNTER_EVENT_TIMEOUT:
return 0;
default:
return -EINVAL;
@@ -457,6 +463,106 @@ static struct counter_count ti_eqep_counts[] = {
},
};
+static int ti_eqep_unit_timer_time_read(struct counter_device *counter,
+ u64 *value)
+{
+ struct ti_eqep_cnt *priv = counter->priv;
+ u32 qutmr;
+
+ regmap_read(priv->regmap32, QUTMR, &qutmr);
+
+ /* convert timer ticks to nanoseconds */
+ *value = mul_u64_u32_div(qutmr, NSEC_PER_SEC, priv->sysclkout_rate);
+
+ return 0;
+}
+
+static int ti_eqep_unit_timer_time_write(struct counter_device *counter,
+ u64 value)
+{
+ struct ti_eqep_cnt *priv = counter->priv;
+ u32 qutmr;
+
+ /* convert nanoseconds to timer ticks */
+ qutmr = value = mul_u64_u32_div(value, priv->sysclkout_rate, NSEC_PER_SEC);
+ if (qutmr != value)
+ return -ERANGE;
+
+ regmap_write(priv->regmap32, QUTMR, qutmr);
+
+ return 0;
+}
+
+static int ti_eqep_unit_timer_period_read(struct counter_device *counter,
+ u64 *value)
+{
+ struct ti_eqep_cnt *priv = counter->priv;
+ u32 quprd;
+
+ regmap_read(priv->regmap32, QUPRD, &quprd);
+
+ /* convert timer ticks to nanoseconds */
+ *value = mul_u64_u32_div(quprd, NSEC_PER_SEC, priv->sysclkout_rate);
+
+ return 0;
+}
+
+static int ti_eqep_unit_timer_period_write(struct counter_device *counter,
+ u64 value)
+{
+ struct ti_eqep_cnt *priv = counter->priv;
+ u32 quprd;
+
+ /* convert nanoseconds to timer ticks */
+ quprd = value = mul_u64_u32_div(value, priv->sysclkout_rate, NSEC_PER_SEC);
+ if (quprd != value)
+ return -ERANGE;
+
+ /* protect against infinite unit timeout interrupts */
+ if (quprd == 0)
+ return -EINVAL;
+
+ regmap_write(priv->regmap32, QUPRD, quprd);
+
+ return 0;
+}
+
+static int ti_eqep_unit_timer_enable_read(struct counter_device *counter,
+ u8 *value)
+{
+ struct ti_eqep_cnt *priv = counter->priv;
+ u32 qepctl;
+
+ regmap_read(priv->regmap16, QEPCTL, &qepctl);
+ *value = !!(qepctl & QEPCTL_UTE);
+
+ return 0;
+}
+
+static int ti_eqep_unit_timer_enable_write(struct counter_device *counter,
+ u8 value)
+{
+ struct ti_eqep_cnt *priv = counter->priv;
+
+ if (value)
+ regmap_set_bits(priv->regmap16, QEPCTL, QEPCTL_UTE);
+ else
+ regmap_clear_bits(priv->regmap16, QEPCTL, QEPCTL_UTE);
+
+ return 0;
+}
+
+static struct counter_comp ti_eqep_device_ext[] = {
+ COUNTER_COMP_DEVICE_U64("unit_timer_time", ti_eqep_unit_timer_time_read,
+ ti_eqep_unit_timer_time_write),
+ COUNTER_COMP_DEVICE_U64("unit_timer_period",
+ ti_eqep_unit_timer_period_read,
+ ti_eqep_unit_timer_period_write),
+ COUNTER_COMP_DEVICE_BOOL("unit_timer_enable",
+ ti_eqep_unit_timer_enable_read,
+ ti_eqep_unit_timer_enable_write),
+};
+
static irqreturn_t ti_eqep_irq_handler(int irq, void *dev_id)
{
struct ti_eqep_cnt *priv = dev_id;
@@ -474,6 +580,8 @@ static irqreturn_t ti_eqep_irq_handler(int irq, void *dev_id)
if (qflg & QFLG_QDC)
counter_push_event(counter, COUNTER_EVENT_DIRECTION_CHANGE, 0);
+ if (qflg & QFLG_UTO)
+ counter_push_event(counter, COUNTER_EVENT_TIMEOUT, 0);
regmap_set_bits(priv->regmap16, QCLR, ~0);
@@ -500,6 +608,7 @@ static int ti_eqep_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct ti_eqep_cnt *priv;
+ struct clk *clk;
void __iomem *base;
int err;
int irq;
@@ -508,6 +617,24 @@ static int ti_eqep_probe(struct platform_device *pdev)
if (!priv)
return -ENOMEM;
+ clk = devm_clk_get(dev, "sysclkout");
+ if (IS_ERR(clk)) {
+ if (PTR_ERR(clk) != -EPROBE_DEFER)
+ dev_err(dev, "failed to get sysclkout");
+ return PTR_ERR(clk);
+ }
+
+ priv->sysclkout_rate = clk_get_rate(clk);
+ if (priv->sysclkout_rate == 0) {
+ dev_err(dev, "failed to get sysclkout rate");
+ /* prevent divide by zero */
+ priv->sysclkout_rate = 1;
+ /*
+ * This error is not expected and the driver is mostly usable
+ * without clock rate anyway, so don't exit here.
+ */
+ }
+
base = devm_platform_ioremap_resource(pdev, 0);
if (IS_ERR(base))
return PTR_ERR(base);
@@ -536,6 +663,8 @@ static int ti_eqep_probe(struct platform_device *pdev)
priv->counter.ops = &ti_eqep_counter_ops;
priv->counter.counts = ti_eqep_counts;
priv->counter.num_counts = ARRAY_SIZE(ti_eqep_counts);
+ priv->counter.ext = ti_eqep_device_ext;
+ priv->counter.num_ext = ARRAY_SIZE(ti_eqep_device_ext);
priv->counter.signals = ti_eqep_signals;
priv->counter.num_signals = ARRAY_SIZE(ti_eqep_signals);
priv->counter.priv = priv;
@@ -552,10 +681,11 @@ static int ti_eqep_probe(struct platform_device *pdev)
/*
* We can end up with an interupt infinite loop (interrupts triggered
- * as soon as they are cleared) if we leave this at the default value
+ * as soon as they are cleared) if we leave these at the default value
* of 0 and events are enabled.
*/
regmap_write(priv->regmap32, QPOSMAX, UINT_MAX);
+ regmap_write(priv->regmap32, QUPRD, UINT_MAX);
err = counter_register(&priv->counter);
if (err < 0) {
diff --git a/include/uapi/linux/counter.h b/include/uapi/linux/counter.h
index 36dd3b474d09..640d9719b88c 100644
--- a/include/uapi/linux/counter.h
+++ b/include/uapi/linux/counter.h
@@ -63,6 +63,8 @@ enum counter_event_type {
COUNTER_EVENT_INDEX,
/* Direction change detected */
COUNTER_EVENT_DIRECTION_CHANGE,
+ /* Timer exceeded timeout */
+ COUNTER_EVENT_TIMEOUT,
};
/**
--
2.25.1
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