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Message-ID: <20240307133306.383045-10-fabrice.gasnier@foss.st.com>
Date: Thu, 7 Mar 2024 14:33:05 +0100
From: Fabrice Gasnier <fabrice.gasnier@...s.st.com>
To: <william.gray@...aro.org>
CC: <lee@...nel.org>, <alexandre.torgue@...s.st.com>,
<fabrice.gasnier@...s.st.com>, <linux-iio@...r.kernel.org>,
<linux-stm32@...md-mailman.stormreply.com>,
<linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH v5 09/10] counter: stm32-timer-cnt: add support for overflow events
Add support overflow events. Also add the related validation and
configuration routine. Register and enable interrupts to push events.
STM32 Timers can have either 1 global interrupt, or 4 dedicated interrupt
lines. Request only the necessary interrupt, e.g. either global interrupt
that can report all event types, or update interrupt only for overflow
event.
Reviewed-by: William Breathitt Gray <william.gray@...aro.org>
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@...s.st.com>
---
Changes in v5:
- Add William's Reviewed-by tag.
Changes in v4:
- drop *irq from stm32_timer_cnt, as only used at probe time.
- Declare nb_ovf as u64 instead of atomic_t, to fit the API, and avoid
unsuitable range check. This also avoid checking for negative value.
Use a spin_lock to protect it, as it is updated in interrupt context.
- use regmap_test_bits() to avoid intermediate variable.
- fix error message in probe (ddata->irq[0] instead of ddata->irq[i])
- move mfd header to subsequent patch, where the defines are actually
used.
Changes in v3:
- patch split from: "counter: stm32-timer-cnt: add support for events", to
focus on the overflow events only here. Move the capture event support
to a separate patch.
- simplify the patch, by removing diversity introduced by the number of
possible channels. All channels are now exposed instead.
Report an error when trying to access a channel that doesn't exist.
Changes in v2:
- fix warnings (kernel test robot)
- fix a typo
- add collected ack from Lee
---
drivers/counter/stm32-timer-cnt.c | 138 +++++++++++++++++++++++++++++-
1 file changed, 137 insertions(+), 1 deletion(-)
diff --git a/drivers/counter/stm32-timer-cnt.c b/drivers/counter/stm32-timer-cnt.c
index e1c0a502b74c..9fcafec682b7 100644
--- a/drivers/counter/stm32-timer-cnt.c
+++ b/drivers/counter/stm32-timer-cnt.c
@@ -8,6 +8,7 @@
*
*/
#include <linux/counter.h>
+#include <linux/interrupt.h>
#include <linux/mfd/stm32-timers.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
@@ -43,6 +44,9 @@ struct stm32_timer_cnt {
struct stm32_timer_regs bak;
bool has_encoder;
unsigned int nchannels;
+ unsigned int nr_irqs;
+ spinlock_t lock; /* protects nb_ovf */
+ u64 nb_ovf;
};
static const enum counter_function stm32_count_functions[] = {
@@ -258,6 +262,32 @@ static int stm32_count_prescaler_write(struct counter_device *counter,
return regmap_write(priv->regmap, TIM_PSC, psc);
}
+static int stm32_count_nb_ovf_read(struct counter_device *counter,
+ struct counter_count *count, u64 *val)
+{
+ struct stm32_timer_cnt *const priv = counter_priv(counter);
+ unsigned long irqflags;
+
+ spin_lock_irqsave(&priv->lock, irqflags);
+ *val = priv->nb_ovf;
+ spin_unlock_irqrestore(&priv->lock, irqflags);
+
+ return 0;
+}
+
+static int stm32_count_nb_ovf_write(struct counter_device *counter,
+ struct counter_count *count, u64 val)
+{
+ struct stm32_timer_cnt *const priv = counter_priv(counter);
+ unsigned long irqflags;
+
+ spin_lock_irqsave(&priv->lock, irqflags);
+ priv->nb_ovf = val;
+ spin_unlock_irqrestore(&priv->lock, irqflags);
+
+ return 0;
+}
+
static struct counter_comp stm32_count_ext[] = {
COUNTER_COMP_DIRECTION(stm32_count_direction_read),
COUNTER_COMP_ENABLE(stm32_count_enable_read, stm32_count_enable_write),
@@ -265,6 +295,7 @@ static struct counter_comp stm32_count_ext[] = {
stm32_count_ceiling_write),
COUNTER_COMP_COUNT_U64("prescaler", stm32_count_prescaler_read,
stm32_count_prescaler_write),
+ COUNTER_COMP_COUNT_U64("num_overflows", stm32_count_nb_ovf_read, stm32_count_nb_ovf_write),
};
static const enum counter_synapse_action stm32_clock_synapse_actions[] = {
@@ -322,12 +353,57 @@ static int stm32_action_read(struct counter_device *counter,
}
}
+static int stm32_count_events_configure(struct counter_device *counter)
+{
+ struct stm32_timer_cnt *const priv = counter_priv(counter);
+ struct counter_event_node *event_node;
+ u32 dier = 0;
+
+ list_for_each_entry(event_node, &counter->events_list, l) {
+ switch (event_node->event) {
+ case COUNTER_EVENT_OVERFLOW_UNDERFLOW:
+ /* first clear possibly latched UIF before enabling */
+ if (!regmap_test_bits(priv->regmap, TIM_DIER, TIM_DIER_UIE))
+ regmap_write(priv->regmap, TIM_SR, (u32)~TIM_SR_UIF);
+ dier |= TIM_DIER_UIE;
+ break;
+ default:
+ /* should never reach this path */
+ return -EINVAL;
+ }
+ }
+
+ /* Enable / disable all events at once, from events_list, so write all DIER bits */
+ regmap_write(priv->regmap, TIM_DIER, dier);
+
+ return 0;
+}
+
+static int stm32_count_watch_validate(struct counter_device *counter,
+ const struct counter_watch *watch)
+{
+ struct stm32_timer_cnt *const priv = counter_priv(counter);
+
+ /* Interrupts are optional */
+ if (!priv->nr_irqs)
+ return -EOPNOTSUPP;
+
+ switch (watch->event) {
+ case COUNTER_EVENT_OVERFLOW_UNDERFLOW:
+ return 0;
+ default:
+ return -EINVAL;
+ }
+}
+
static const struct counter_ops stm32_timer_cnt_ops = {
.count_read = stm32_count_read,
.count_write = stm32_count_write,
.function_read = stm32_count_function_read,
.function_write = stm32_count_function_write,
.action_read = stm32_action_read,
+ .events_configure = stm32_count_events_configure,
+ .watch_validate = stm32_count_watch_validate,
};
static int stm32_count_clk_get_freq(struct counter_device *counter,
@@ -417,6 +493,37 @@ static struct counter_count stm32_counts = {
.num_ext = ARRAY_SIZE(stm32_count_ext)
};
+static irqreturn_t stm32_timer_cnt_isr(int irq, void *ptr)
+{
+ struct counter_device *counter = ptr;
+ struct stm32_timer_cnt *const priv = counter_priv(counter);
+ u32 clr = GENMASK(31, 0); /* SR flags can be cleared by writing 0 (wr 1 has no effect) */
+ u32 sr, dier;
+
+ regmap_read(priv->regmap, TIM_SR, &sr);
+ regmap_read(priv->regmap, TIM_DIER, &dier);
+ /*
+ * Some status bits in SR don't match with the enable bits in DIER. Only take care of
+ * the possibly enabled bits in DIER (that matches in between SR and DIER).
+ */
+ dier &= TIM_DIER_UIE;
+ sr &= dier;
+
+ if (sr & TIM_SR_UIF) {
+ spin_lock(&priv->lock);
+ priv->nb_ovf++;
+ spin_unlock(&priv->lock);
+ counter_push_event(counter, COUNTER_EVENT_OVERFLOW_UNDERFLOW, 0);
+ dev_dbg(counter->parent, "COUNTER_EVENT_OVERFLOW_UNDERFLOW\n");
+ /* SR flags can be cleared by writing 0, only clear relevant flag */
+ clr &= ~TIM_SR_UIF;
+ }
+
+ regmap_write(priv->regmap, TIM_SR, clr);
+
+ return IRQ_HANDLED;
+};
+
static void stm32_timer_cnt_detect_channels(struct device *dev,
struct stm32_timer_cnt *priv)
{
@@ -480,7 +587,7 @@ static int stm32_timer_cnt_probe(struct platform_device *pdev)
struct device *dev = &pdev->dev;
struct stm32_timer_cnt *priv;
struct counter_device *counter;
- int ret;
+ int i, ret;
if (IS_ERR_OR_NULL(ddata))
return -EINVAL;
@@ -494,6 +601,7 @@ static int stm32_timer_cnt_probe(struct platform_device *pdev)
priv->regmap = ddata->regmap;
priv->clk = ddata->clk;
priv->max_arr = ddata->max_arr;
+ priv->nr_irqs = ddata->nr_irqs;
ret = stm32_timer_cnt_probe_encoder(dev, priv);
if (ret)
@@ -509,8 +617,36 @@ static int stm32_timer_cnt_probe(struct platform_device *pdev)
counter->signals = stm32_signals;
counter->num_signals = ARRAY_SIZE(stm32_signals);
+ spin_lock_init(&priv->lock);
+
platform_set_drvdata(pdev, priv);
+ /* STM32 Timers can have either 1 global, or 4 dedicated interrupts (optional) */
+ if (priv->nr_irqs == 1) {
+ /* All events reported through the global interrupt */
+ ret = devm_request_irq(&pdev->dev, ddata->irq[0], stm32_timer_cnt_isr,
+ 0, dev_name(dev), counter);
+ if (ret) {
+ dev_err(dev, "Failed to request irq %d (err %d)\n",
+ ddata->irq[0], ret);
+ return ret;
+ }
+ } else {
+ for (i = 0; i < priv->nr_irqs; i++) {
+ /* Only take care of update IRQ for overflow events */
+ if (i != STM32_TIMERS_IRQ_UP)
+ continue;
+
+ ret = devm_request_irq(&pdev->dev, ddata->irq[i], stm32_timer_cnt_isr,
+ 0, dev_name(dev), counter);
+ if (ret) {
+ dev_err(dev, "Failed to request irq %d (err %d)\n",
+ ddata->irq[i], ret);
+ return ret;
+ }
+ }
+ }
+
/* Reset input selector to its default input */
regmap_write(priv->regmap, TIM_TISEL, 0x0);
--
2.25.1
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