drivers: gpio: pca95xx: add latch for interrupt pins

Basically, once a pin is configured for interrupt, we enable the latch
on it, in order not to miss short pulses.
The bottom half of the interrupt then reads the input port twice, to
read the latch and then read the potentially new state of the pins, to
compute the posedge, negedge, and level callbacks accordingly.

Signed-off-by: Vincent Geneves <[email protected]>

Author: Vincent Geneves

drivers/gpio/gpio_pca95xx.c

@@ -89,6 +89,7 @@ struct gpio_pca95xx_drv_data {
 		uint16_t pud_en;
 		uint16_t pud_sel;
 		uint16_t int_mask;
+		uint16_t input_latch;
 	} reg_cache;
 
 	struct k_sem lock;
@@ -326,6 +327,9 @@ static inline int update_int_mask_reg(const struct device *dev, uint8_t pin,
 	struct gpio_pca95xx_drv_data * const drv_data =
 		(struct gpio_pca95xx_drv_data * const)dev->data;
 
+	/* If the interrupt mask is present, so is the input latch */
+	write_port_reg(dev, REG_INPUT_LATCH_PORT0, pin, &drv_data->reg_cache.input_latch, ~value);
+
 	return write_port_reg(dev, REG_INT_MASK_PORT0, pin,
 			      &drv_data->reg_cache.int_mask, value);
 }
@@ -574,34 +578,45 @@ static int gpio_pca95xx_port_toggle_bits(const struct device *dev,
 }
 
 #ifdef CONFIG_GPIO_PCA95XX_INTERRUPT
-static void gpio_pca95xx_interrupt_worker(struct k_work *work)
+static void get_triggered_it(struct gpio_pca95xx_drv_data *drv_data,
+		uint16_t *trig_edge, uint16_t *trig_level)
 {
-	struct gpio_pca95xx_drv_data * const drv_data = CONTAINER_OF(
-		work, struct gpio_pca95xx_drv_data, interrupt_worker);
-	uint16_t input_new, input_cache, changed_pins, trig_edge;
-	uint16_t trig_level = 0;
-	uint32_t triggered_int = 0;
+	uint16_t input_cache, changed_pins, input_new;
 	int ret;
 
-	k_sem_take(&drv_data->lock, K_FOREVER);
-
 	input_cache = drv_data->reg_cache.input;
-
 	ret = update_input_regs(drv_data->instance, &input_new);
 	if (ret == 0) {
-		/* Note: PCA Interrupt status is cleared by reading inputs */
-
 		changed_pins = (input_cache ^ input_new);
 
-		trig_edge = (changed_pins & input_new &
+		*trig_edge |= (changed_pins & input_new &
 			     drv_data->interrupts.edge_rising);
-		trig_edge |= (changed_pins & input_cache &
+		*trig_edge |= (changed_pins & input_cache &
 			      drv_data->interrupts.edge_falling);
-		trig_level = (input_new & drv_data->interrupts.level_high);
-		trig_level |= (~input_new & drv_data->interrupts.level_low);
+		*trig_level |= (input_new & drv_data->interrupts.level_high);
+		*trig_level |= (~input_new & drv_data->interrupts.level_low);
+	}
+}
 
-		triggered_int = (trig_edge | trig_level);
+static void gpio_pca95xx_interrupt_worker(struct k_work *work)
+{
+	struct gpio_pca95xx_drv_data * const drv_data = CONTAINER_OF(
+		work, struct gpio_pca95xx_drv_data, interrupt_worker);
+	const struct gpio_pca95xx_config * const config = drv_data->instance->config;
+	uint16_t trig_edge = 0, trig_level = 0;
+	uint32_t triggered_int = 0;
+
+	k_sem_take(&drv_data->lock, K_FOREVER);
+
+	/* Note: PCA Interrupt status is cleared by reading inputs */
+	if (config->capabilities & PCA_HAS_INTERRUPT_MASK_REG) {
+		/* gpio latched read values, to be compared to cached ones */
+		get_triggered_it(drv_data, &trig_edge, &trig_level);
 	}
+	/* gpio unlatched read values, in case signal has flipped again */
+	get_triggered_it(drv_data, &trig_edge, &trig_level);
+
+	triggered_int = (trig_edge | trig_level);
 
 	k_sem_give(&drv_data->lock);
 
@@ -847,6 +862,8 @@ static struct gpio_pca95xx_drv_data gpio_pca95xx_##inst##_drvdata = {	\
 	.reg_cache.dir = 0xFFFF,					\
 	.reg_cache.pud_en = 0x0,					\
 	.reg_cache.pud_sel = 0xFFFF,					\
+	.reg_cache.int_mask = 0xFFFF,					\
+	.reg_cache.input_latch = 0x0,				\
 	IF_ENABLED(CONFIG_GPIO_PCA95XX_INTERRUPT, (			\
 	.interrupt_active = false,					\
 	))								\