counter: stm32-timer-cnt: add support for capture events
authorFabrice Gasnier <fabrice.gasnier@foss.st.com>
Thu, 7 Mar 2024 13:33:06 +0000 (14:33 +0100)
committerWilliam Breathitt Gray <wbg@kernel.org>
Tue, 2 Apr 2024 17:10:34 +0000 (13:10 -0400)
Add support for capture events. Captured counter value for each channel
can be retrieved through CCRx register.
STM32 timers can have up to 4 capture channels (on input channel 1 to
channel 4), hence need to check the number of channels before reading
the capture data.
The capture configuration is hard-coded to capture signals on both edges
(non-inverted). Interrupts are used to report events independently for
each channel.

Reviewed-by: William Breathitt Gray <william.gray@linaro.org>
Acked-by: Lee Jones <lee@kernel.org>
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Link: https://lore.kernel.org/r/20240307133306.383045-11-fabrice.gasnier@foss.st.com
Signed-off-by: William Breathitt Gray <william.gray@linaro.org>
drivers/counter/stm32-timer-cnt.c
include/linux/mfd/stm32-timers.h

index 9fcafec682b708e716f0203b3c6a3837fd05021a..0664ef969f797cd3bc74c13fe8ecf0972feb020d 100644 (file)
@@ -262,6 +262,40 @@ static int stm32_count_prescaler_write(struct counter_device *counter,
        return regmap_write(priv->regmap, TIM_PSC, psc);
 }
 
+static int stm32_count_cap_read(struct counter_device *counter,
+                               struct counter_count *count,
+                               size_t ch, u64 *cap)
+{
+       struct stm32_timer_cnt *const priv = counter_priv(counter);
+       u32 ccrx;
+
+       if (ch >= priv->nchannels)
+               return -EOPNOTSUPP;
+
+       switch (ch) {
+       case 0:
+               regmap_read(priv->regmap, TIM_CCR1, &ccrx);
+               break;
+       case 1:
+               regmap_read(priv->regmap, TIM_CCR2, &ccrx);
+               break;
+       case 2:
+               regmap_read(priv->regmap, TIM_CCR3, &ccrx);
+               break;
+       case 3:
+               regmap_read(priv->regmap, TIM_CCR4, &ccrx);
+               break;
+       default:
+               return -EINVAL;
+       }
+
+       dev_dbg(counter->parent, "CCR%zu: 0x%08x\n", ch + 1, ccrx);
+
+       *cap = ccrx;
+
+       return 0;
+}
+
 static int stm32_count_nb_ovf_read(struct counter_device *counter,
                                   struct counter_count *count, u64 *val)
 {
@@ -288,6 +322,8 @@ static int stm32_count_nb_ovf_write(struct counter_device *counter,
        return 0;
 }
 
+static DEFINE_COUNTER_ARRAY_CAPTURE(stm32_count_cap_array, 4);
+
 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),
@@ -295,6 +331,7 @@ 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_ARRAY_CAPTURE(stm32_count_cap_read, NULL, stm32_count_cap_array),
        COUNTER_COMP_COUNT_U64("num_overflows", stm32_count_nb_ovf_read, stm32_count_nb_ovf_write),
 };
 
@@ -353,11 +390,68 @@ static int stm32_action_read(struct counter_device *counter,
        }
 }
 
+struct stm32_count_cc_regs {
+       u32 ccmr_reg;
+       u32 ccmr_mask;
+       u32 ccmr_bits;
+       u32 ccer_bits;
+};
+
+static const struct stm32_count_cc_regs stm32_cc[] = {
+       { TIM_CCMR1, TIM_CCMR_CC1S, TIM_CCMR_CC1S_TI1,
+               TIM_CCER_CC1E | TIM_CCER_CC1P | TIM_CCER_CC1NP },
+       { TIM_CCMR1, TIM_CCMR_CC2S, TIM_CCMR_CC2S_TI2,
+               TIM_CCER_CC2E | TIM_CCER_CC2P | TIM_CCER_CC2NP },
+       { TIM_CCMR2, TIM_CCMR_CC3S, TIM_CCMR_CC3S_TI3,
+               TIM_CCER_CC3E | TIM_CCER_CC3P | TIM_CCER_CC3NP },
+       { TIM_CCMR2, TIM_CCMR_CC4S, TIM_CCMR_CC4S_TI4,
+               TIM_CCER_CC4E | TIM_CCER_CC4P | TIM_CCER_CC4NP },
+};
+
+static int stm32_count_capture_configure(struct counter_device *counter, unsigned int ch,
+                                        bool enable)
+{
+       struct stm32_timer_cnt *const priv = counter_priv(counter);
+       const struct stm32_count_cc_regs *cc;
+       u32 ccmr, ccer;
+
+       if (ch >= ARRAY_SIZE(stm32_cc) || ch >= priv->nchannels) {
+               dev_err(counter->parent, "invalid ch: %d\n", ch);
+               return -EINVAL;
+       }
+
+       cc = &stm32_cc[ch];
+
+       /*
+        * configure channel in input capture mode, map channel 1 on TI1, channel2 on TI2...
+        * Select both edges / non-inverted to trigger a capture.
+        */
+       if (enable) {
+               /* first clear possibly latched capture flag upon enabling */
+               if (!regmap_test_bits(priv->regmap, TIM_CCER, cc->ccer_bits))
+                       regmap_write(priv->regmap, TIM_SR, ~TIM_SR_CC_IF(ch));
+               regmap_update_bits(priv->regmap, cc->ccmr_reg, cc->ccmr_mask,
+                                  cc->ccmr_bits);
+               regmap_set_bits(priv->regmap, TIM_CCER, cc->ccer_bits);
+       } else {
+               regmap_clear_bits(priv->regmap, TIM_CCER, cc->ccer_bits);
+               regmap_clear_bits(priv->regmap, cc->ccmr_reg, cc->ccmr_mask);
+       }
+
+       regmap_read(priv->regmap, cc->ccmr_reg, &ccmr);
+       regmap_read(priv->regmap, TIM_CCER, &ccer);
+       dev_dbg(counter->parent, "%s(%s) ch%d 0x%08x 0x%08x\n", __func__, enable ? "ena" : "dis",
+               ch, ccmr, ccer);
+
+       return 0;
+}
+
 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;
+       int i, ret;
 
        list_for_each_entry(event_node, &counter->events_list, l) {
                switch (event_node->event) {
@@ -367,6 +461,12 @@ static int stm32_count_events_configure(struct counter_device *counter)
                                regmap_write(priv->regmap, TIM_SR, (u32)~TIM_SR_UIF);
                        dier |= TIM_DIER_UIE;
                        break;
+               case COUNTER_EVENT_CAPTURE:
+                       ret = stm32_count_capture_configure(counter, event_node->channel, true);
+                       if (ret)
+                               return ret;
+                       dier |= TIM_DIER_CC_IE(event_node->channel);
+                       break;
                default:
                        /* should never reach this path */
                        return -EINVAL;
@@ -376,6 +476,15 @@ static int stm32_count_events_configure(struct counter_device *counter)
        /* Enable / disable all events at once, from events_list, so write all DIER bits */
        regmap_write(priv->regmap, TIM_DIER, dier);
 
+       /* check for disabled capture events */
+       for (i = 0 ; i < priv->nchannels; i++) {
+               if (!(dier & TIM_DIER_CC_IE(i))) {
+                       ret = stm32_count_capture_configure(counter, i, false);
+                       if (ret)
+                               return ret;
+               }
+       }
+
        return 0;
 }
 
@@ -389,6 +498,12 @@ static int stm32_count_watch_validate(struct counter_device *counter,
                return -EOPNOTSUPP;
 
        switch (watch->event) {
+       case COUNTER_EVENT_CAPTURE:
+               if (watch->channel >= priv->nchannels) {
+                       dev_err(counter->parent, "Invalid channel %d\n", watch->channel);
+                       return -EINVAL;
+               }
+               return 0;
        case COUNTER_EVENT_OVERFLOW_UNDERFLOW:
                return 0;
        default:
@@ -499,6 +614,7 @@ static irqreturn_t stm32_timer_cnt_isr(int irq, void *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;
+       int i;
 
        regmap_read(priv->regmap, TIM_SR, &sr);
        regmap_read(priv->regmap, TIM_DIER, &dier);
@@ -506,7 +622,7 @@ static irqreturn_t stm32_timer_cnt_isr(int irq, void *ptr)
         * 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;
+       dier &= (TIM_DIER_UIE | TIM_DIER_CC1IE | TIM_DIER_CC2IE | TIM_DIER_CC3IE | TIM_DIER_CC4IE);
        sr &= dier;
 
        if (sr & TIM_SR_UIF) {
@@ -519,6 +635,15 @@ static irqreturn_t stm32_timer_cnt_isr(int irq, void *ptr)
                clr &= ~TIM_SR_UIF;
        }
 
+       /* Check capture events */
+       for (i = 0 ; i < priv->nchannels; i++) {
+               if (sr & TIM_SR_CC_IF(i)) {
+                       counter_push_event(counter, COUNTER_EVENT_CAPTURE, i);
+                       clr &= ~TIM_SR_CC_IF(i);
+                       dev_dbg(counter->parent, "COUNTER_EVENT_CAPTURE, %d\n", i);
+               }
+       }
+
        regmap_write(priv->regmap, TIM_SR, clr);
 
        return IRQ_HANDLED;
@@ -633,8 +758,11 @@ static int stm32_timer_cnt_probe(struct platform_device *pdev)
                }
        } else {
                for (i = 0; i < priv->nr_irqs; i++) {
-                       /* Only take care of update IRQ for overflow events */
-                       if (i != STM32_TIMERS_IRQ_UP)
+                       /*
+                        * Only take care of update IRQ for overflow events, and cc for
+                        * capture events.
+                        */
+                       if (i != STM32_TIMERS_IRQ_UP && i != STM32_TIMERS_IRQ_CC)
                                continue;
 
                        ret = devm_request_irq(&pdev->dev, ddata->irq[i], stm32_timer_cnt_isr,
index ca35af30745f7fdf86867f50be2e9e87c6b8a778..9eb17481b07facac05ef5a68fb660dacc101592c 100644 (file)
 #define TIM_SMCR_SMS   (BIT(0) | BIT(1) | BIT(2)) /* Slave mode selection */
 #define TIM_SMCR_TS    (BIT(4) | BIT(5) | BIT(6)) /* Trigger selection */
 #define TIM_DIER_UIE   BIT(0)  /* Update interrupt        */
+#define TIM_DIER_CC1IE BIT(1)  /* CC1 Interrupt Enable    */
+#define TIM_DIER_CC2IE BIT(2)  /* CC2 Interrupt Enable    */
+#define TIM_DIER_CC3IE BIT(3)  /* CC3 Interrupt Enable    */
+#define TIM_DIER_CC4IE BIT(4)  /* CC4 Interrupt Enable    */
+#define TIM_DIER_CC_IE(x)      BIT((x) + 1) /* CC1, CC2, CC3, CC4 interrupt enable */
 #define TIM_DIER_UDE   BIT(8)  /* Update DMA request Enable */
 #define TIM_DIER_CC1DE BIT(9)  /* CC1 DMA request Enable  */
 #define TIM_DIER_CC2DE BIT(10) /* CC2 DMA request Enable  */
@@ -49,6 +54,7 @@
 #define TIM_DIER_COMDE BIT(13) /* COM DMA request Enable  */
 #define TIM_DIER_TDE   BIT(14) /* Trigger DMA request Enable */
 #define TIM_SR_UIF     BIT(0)  /* Update interrupt flag   */
+#define TIM_SR_CC_IF(x)        BIT((x) + 1) /* CC1, CC2, CC3, CC4 interrupt flag */
 #define TIM_EGR_UG     BIT(0)  /* Update Generation       */
 #define TIM_CCMR_PE    BIT(3)  /* Channel Preload Enable  */
 #define TIM_CCMR_M1    (BIT(6) | BIT(5))  /* Channel PWM Mode 1 */
 #define TIM_CCMR_CC1S_TI2      BIT(1)  /* IC1/IC3 selects TI2/TI4 */
 #define TIM_CCMR_CC2S_TI2      BIT(8)  /* IC2/IC4 selects TI2/TI4 */
 #define TIM_CCMR_CC2S_TI1      BIT(9)  /* IC2/IC4 selects TI1/TI3 */
+#define TIM_CCMR_CC3S          (BIT(0) | BIT(1)) /* Capture/compare 3 sel */
+#define TIM_CCMR_CC4S          (BIT(8) | BIT(9)) /* Capture/compare 4 sel */
+#define TIM_CCMR_CC3S_TI3      BIT(0)  /* IC3 selects TI3 */
+#define TIM_CCMR_CC4S_TI4      BIT(8)  /* IC4 selects TI4 */
 #define TIM_CCER_CC1E  BIT(0)  /* Capt/Comp 1  out Ena    */
 #define TIM_CCER_CC1P  BIT(1)  /* Capt/Comp 1  Polarity   */
 #define TIM_CCER_CC1NE BIT(2)  /* Capt/Comp 1N out Ena    */
 #define TIM_CCER_CC1NP BIT(3)  /* Capt/Comp 1N Polarity   */
 #define TIM_CCER_CC2E  BIT(4)  /* Capt/Comp 2  out Ena    */
 #define TIM_CCER_CC2P  BIT(5)  /* Capt/Comp 2  Polarity   */
+#define TIM_CCER_CC2NP BIT(7)  /* Capt/Comp 2N Polarity   */
 #define TIM_CCER_CC3E  BIT(8)  /* Capt/Comp 3  out Ena    */
 #define TIM_CCER_CC3P  BIT(9)  /* Capt/Comp 3  Polarity   */
+#define TIM_CCER_CC3NP BIT(11) /* Capt/Comp 3N Polarity   */
 #define TIM_CCER_CC4E  BIT(12) /* Capt/Comp 4  out Ena    */
 #define TIM_CCER_CC4P  BIT(13) /* Capt/Comp 4  Polarity   */
+#define TIM_CCER_CC4NP BIT(15) /* Capt/Comp 4N Polarity   */
 #define TIM_CCER_CCXE  (BIT(0) | BIT(4) | BIT(8) | BIT(12))
 #define TIM_BDTR_BKE(x)        BIT(12 + (x) * 12) /* Break input enable */
 #define TIM_BDTR_BKP(x)        BIT(13 + (x) * 12) /* Break input polarity */