clocksource/drivers/timer-ti-dm : Capture functionality for OMAP DM timer

Add PWM capture function in DM timer driver.

OMAP DM timer hardware supports capture feature.It can be used to
timestamp events (falling/rising edges) detected on input signal.

Signed-off-by: Gokul Praveen <g-praveen@ti.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Reviewed-by: Neha Malcom Francis <n-francis@ti.com>
Link: https://lore.kernel.org/r/20250812105346.203541-1-g-praveen@ti.com

diff --git a/drivers/clocksource/timer-ti-dm.c b/drivers/clocksource/timer-ti-dm.c
index e9e32df6b56664bc0bd94050380314a757d05ebd..793e7cdcb1b16b58db3a81668e3c8144efc7baaf 100644 (file)
--- a/drivers/clocksource/timer-ti-dm.c
+++ b/drivers/clocksource/timer-ti-dm.c
@@ -31,6 +31,7 @@
 #include <linux/platform_data/dmtimer-omap.h>
 
 #include <clocksource/timer-ti-dm.h>
+#include <linux/delay.h>
 
 /*
  * timer errata flags
@@ -836,6 +837,48 @@ static int omap_dm_timer_set_match(struct omap_dm_timer *cookie, int enable,
        return 0;
 }
 
+static int omap_dm_timer_set_cap(struct omap_dm_timer *cookie,
+                                       int autoreload, bool config_period)
+{
+       struct dmtimer *timer;
+       struct device *dev;
+       int rc;
+       u32 l;
+
+       timer = to_dmtimer(cookie);
+       if (unlikely(!timer))
+               return -EINVAL;
+
+       dev = &timer->pdev->dev;
+       rc = pm_runtime_resume_and_get(dev);
+       if (rc)
+               return rc;
+       /*
+        *  1. Select autoreload mode. TIMER_TCLR[1] AR bit.
+        *  2. TIMER_TCLR[14]: Sets the functionality of the TIMER IO pin.
+        *  3. TIMER_TCLR[13] : Capture mode select bit.
+        *  3. TIMER_TCLR[9-8] : Select transition capture mode.
+        */
+
+       l = dmtimer_read(timer, OMAP_TIMER_CTRL_REG);
+
+       if (autoreload)
+               l |= OMAP_TIMER_CTRL_AR;
+
+       l |= OMAP_TIMER_CTRL_CAPTMODE | OMAP_TIMER_CTRL_GPOCFG;
+
+       if (config_period == true)
+               l |= OMAP_TIMER_CTRL_TCM_LOWTOHIGH; /* Time Period config */
+       else
+               l |= OMAP_TIMER_CTRL_TCM_BOTHEDGES; /* Duty Cycle config */
+
+       dmtimer_write(timer, OMAP_TIMER_CTRL_REG, l);
+
+       pm_runtime_put_sync(dev);
+
+       return 0;
+}
+
 static int omap_dm_timer_set_pwm(struct omap_dm_timer *cookie, int def_on,
                                 int toggle, int trigger, int autoreload)
 {
@@ -1023,23 +1066,92 @@ static unsigned int omap_dm_timer_read_counter(struct omap_dm_timer *cookie)
        return __omap_dm_timer_read_counter(timer);
 }
 
+static inline unsigned int __omap_dm_timer_cap(struct dmtimer *timer, int idx)
+{
+       return idx == 0 ? dmtimer_read(timer, OMAP_TIMER_CAPTURE_REG) :
+                         dmtimer_read(timer, OMAP_TIMER_CAPTURE2_REG);
+}
+
 static int omap_dm_timer_write_counter(struct omap_dm_timer *cookie, unsigned int value)
 {
        struct dmtimer *timer;
+       struct device *dev;
 
        timer = to_dmtimer(cookie);
-       if (unlikely(!timer || !atomic_read(&timer->enabled))) {
-               pr_err("%s: timer not available or enabled.\n", __func__);
+       if (unlikely(!timer)) {
+               pr_err("%s: timer not available.\n", __func__);
                return -EINVAL;
        }
 
+       dev = &timer->pdev->dev;
+
+       pm_runtime_resume_and_get(dev);
        dmtimer_write(timer, OMAP_TIMER_COUNTER_REG, value);
+       pm_runtime_put_sync(dev);
 
        /* Save the context */
        timer->context.tcrr = value;
        return 0;
 }
 
+/**
+ * omap_dm_timer_cap_counter() - Calculate the high count or period count depending on the
+ * configuration.
+ * @cookie:Pointer to OMAP DM timer
+ * @is_period:Whether to configure timer in period or duty cycle mode
+ *
+ * Return high count or period count if timer is enabled else appropriate error.
+ */
+static unsigned int omap_dm_timer_cap_counter(struct omap_dm_timer *cookie,    bool is_period)
+{
+       struct dmtimer *timer;
+       unsigned int cap1 = 0;
+       unsigned int cap2 = 0;
+       u32 l, ret;
+
+       timer = to_dmtimer(cookie);
+       if (unlikely(!timer || !atomic_read(&timer->enabled))) {
+               pr_err("%s:timer is not available or enabled.%p\n", __func__, (void *)timer);
+               return -EINVAL;
+       }
+
+       /* Stop the timer */
+       omap_dm_timer_stop(cookie);
+
+       /* Clear the timer counter value to 0 */
+       ret = omap_dm_timer_write_counter(cookie, 0);
+       if (ret)
+               return ret;
+
+       /* Sets the timer capture configuration for period/duty cycle calculation */
+       ret = omap_dm_timer_set_cap(cookie, true, is_period);
+       if (ret) {
+               pr_err("%s: Failed to set timer capture configuration.\n", __func__);
+               return ret;
+       }
+       /* Start the timer */
+       omap_dm_timer_start(cookie);
+
+       /*
+        * 1 sec delay is given so as to provide
+        * enough time to capture low frequency signals.
+        */
+       msleep(1000);
+
+       cap1 = __omap_dm_timer_cap(timer, 0);
+       cap2 = __omap_dm_timer_cap(timer, 1);
+
+       /*
+        *  Clears the TCLR configuration.
+        *  The start bit must be set to 1 as the timer is already in start mode.
+        */
+       l = dmtimer_read(timer, OMAP_TIMER_CTRL_REG);
+       l &= ~(0xffff) | 0x1;
+       dmtimer_write(timer, OMAP_TIMER_CTRL_REG, l);
+
+       return (cap2-cap1);
+}
+
 static int __maybe_unused omap_dm_timer_runtime_suspend(struct device *dev)
 {
        struct dmtimer *timer = dev_get_drvdata(dev);
@@ -1246,6 +1358,9 @@ static const struct omap_dm_timer_ops dmtimer_ops = {
        .write_counter = omap_dm_timer_write_counter,
        .read_status = omap_dm_timer_read_status,
        .write_status = omap_dm_timer_write_status,
+       .set_cap = omap_dm_timer_set_cap,
+       .get_cap_status = omap_dm_timer_get_pwm_status,
+       .read_cap = omap_dm_timer_cap_counter,
 };
 
 static const struct dmtimer_platform_data omap3plus_pdata = {

diff --git a/include/linux/platform_data/dmtimer-omap.h b/include/linux/platform_data/dmtimer-omap.h
index 95d852aef130e3d630d5863cf24957d4f6767b31..726d891438429316392fa72af701825b4e59c20d 100644 (file)
--- a/include/linux/platform_data/dmtimer-omap.h
+++ b/include/linux/platform_data/dmtimer-omap.h
@@ -36,9 +36,13 @@ struct omap_dm_timer_ops {
        int     (*set_pwm)(struct omap_dm_timer *timer, int def_on,
                           int toggle, int trigger, int autoreload);
        int     (*get_pwm_status)(struct omap_dm_timer *timer);
+       int     (*set_cap)(struct omap_dm_timer *timer,
+                          int autoreload, bool config_period);
+       int     (*get_cap_status)(struct omap_dm_timer *timer);
        int     (*set_prescaler)(struct omap_dm_timer *timer, int prescaler);
 
        unsigned int (*read_counter)(struct omap_dm_timer *timer);
+       unsigned int (*read_cap)(struct omap_dm_timer *timer, bool is_period);
        int     (*write_counter)(struct omap_dm_timer *timer,
                                 unsigned int value);
        unsigned int (*read_status)(struct omap_dm_timer *timer);