gpio: adp5588.c: Switch to events system

Interupts were generated using GPIN interrupts of
ADP5588. These interrupts have two important limitations:
1. Interrupts can only be generated for either rising or
falling edges but not both.
2. Interrupts are reasserted as long as the interrupt condition
persists (i.e. high or low level on that GPIN). This generates
lots of interrupts unless the event is very short.

To overcome this, ADP5588 provides an event system which queues
up to 10 events in a buffer. GPIN events are queued whenever the
GPIN is asserted or deasserted. This makes it possible to support
generating GPIN interrupts for both edges and to generate only one
interrupt per state change.
Thus it is possible to chain the gpio-keys driver for some GPIOs.

Signed-off-by: Nikolaus Voss <[e-mail]>
Acked-by: Michael Hennerich <[e-mail]>
Signed-off-by: Linus Walleij <[e-mail]>

drivers/gpio/gpio-adp5588.c

···
 	struct mutex irq_lock;
 	uint8_t dat_out[3];
 	uint8_t dir[3];
-	uint8_t int_lvl[3];
+	uint8_t int_lvl_low[3];
+	uint8_t int_lvl_high[3];
 	uint8_t int_en[3];
 	uint8_t irq_mask[3];
-	uint8_t irq_stat[3];
 	uint8_t int_input_en[3];
-	uint8_t int_lvl_cached[3];
 };
 
 static int adp5588_gpio_read(struct i2c_client *client, u8 reg)
···
 			mutex_unlock(&dev->lock);
 		}
 
-		if (dev->int_lvl_cached[i] != dev->int_lvl[i]) {
-			dev->int_lvl_cached[i] = dev->int_lvl[i];
-			adp5588_gpio_write(dev->client, GPIO_INT_LVL1 + i,
-					   dev->int_lvl[i]);
-		}
-
 		if (dev->int_en[i] ^ dev->irq_mask[i]) {
 			dev->int_en[i] = dev->irq_mask[i];
-			adp5588_gpio_write(dev->client, GPIO_INT_EN1 + i,
+			adp5588_gpio_write(dev->client, GPI_EM1 + i,
 					   dev->int_en[i]);
 		}
 	}
···
 	uint16_t gpio = d->hwirq;
 	unsigned bank, bit;
 
-	if ((type & IRQ_TYPE_EDGE_BOTH)) {
-		dev_err(&dev->client->dev, "irq %d: unsupported type %d\n",
-			d->irq, type);
-		return -EINVAL;
-	}
-
 	bank = ADP5588_BANK(gpio);
 	bit = ADP5588_BIT(gpio);
 
-	if (type & IRQ_TYPE_LEVEL_HIGH)
-		dev->int_lvl[bank] |= bit;
-	else if (type & IRQ_TYPE_LEVEL_LOW)
-		dev->int_lvl[bank] &= ~bit;
-	else
-		return -EINVAL;
+	dev->int_lvl_low[bank] &= ~bit;
+	dev->int_lvl_high[bank] &= ~bit;
+
+	if (type & IRQ_TYPE_EDGE_BOTH || type & IRQ_TYPE_LEVEL_HIGH)
+		dev->int_lvl_high[bank] |= bit;
+
+	if (type & IRQ_TYPE_EDGE_BOTH || type & IRQ_TYPE_LEVEL_LOW)
+		dev->int_lvl_low[bank] |= bit;
 
 	dev->int_input_en[bank] |= bit;
 
···
 	.irq_set_type		= adp5588_irq_set_type,
 };
 
-static int adp5588_gpio_read_intstat(struct i2c_client *client, u8 *buf)
-{
-	int ret = i2c_smbus_read_i2c_block_data(client, GPIO_INT_STAT1, 3, buf);
-
-	if (ret < 0)
-		dev_err(&client->dev, "Read INT_STAT Error\n");
-
-	return ret;
-}
-
 static irqreturn_t adp5588_irq_handler(int irq, void *devid)
 {
 	struct adp5588_gpio *dev = devid;
-	unsigned status, bank, bit, pending;
-	int ret;
-	status = adp5588_gpio_read(dev->client, INT_STAT);
+	int status = adp5588_gpio_read(dev->client, INT_STAT);
 
-	if (status & ADP5588_GPI_INT) {
-		ret = adp5588_gpio_read_intstat(dev->client, dev->irq_stat);
-		if (ret < 0)
-			memset(dev->irq_stat, 0, ARRAY_SIZE(dev->irq_stat));
+	if (status & ADP5588_KE_INT) {
+		int ev_cnt = adp5588_gpio_read(dev->client, KEY_LCK_EC_STAT);
 
-		for (bank = 0, bit = 0; bank <= ADP5588_BANK(ADP5588_MAXGPIO);
-			bank++, bit = 0) {
-			pending = dev->irq_stat[bank] & dev->irq_mask[bank];
+		if (ev_cnt > 0) {
+			int i;
 
-			while (pending) {
-				if (pending & (1 << bit)) {
-					handle_nested_irq(
-						irq_find_mapping(
-						   dev->gpio_chip.irq.domain,
-						   (bank << 3) + bit));
-					pending &= ~(1 << bit);
-				}
-				bit++;
+			for (i = 0; i < (ev_cnt & ADP5588_KEC); i++) {
+				int key = adp5588_gpio_read(dev->client,
+							    Key_EVENTA + i);
+				/* GPIN events begin at 97,
+				 * bit 7 indicates logic level
+				 */
+				int gpio = (key & 0x7f) - 97;
+				int lvl = key & (1 << 7);
+				int bank = ADP5588_BANK(gpio);
+				int bit = ADP5588_BIT(gpio);
+
+				if ((lvl && dev->int_lvl_high[bank] & bit) ||
+				    (!lvl && dev->int_lvl_low[bank] & bit))
+					handle_nested_irq(irq_find_mapping(
+					      dev->gpio_chip.irq.domain, gpio));
 			}
 		}
 	}
···
 
 	adp5588_gpio_write(client, CFG, ADP5588_AUTO_INC);
 	adp5588_gpio_write(client, INT_STAT, -1); /* status is W1C */
-	adp5588_gpio_read_intstat(client, dev->irq_stat); /* read to clear */
 
 	mutex_init(&dev->irq_lock);
 
···
 				    client->irq);
 
 	adp5588_gpio_write(client, CFG,
-		ADP5588_AUTO_INC | ADP5588_INT_CFG | ADP5588_GPI_INT);
+		ADP5588_AUTO_INC | ADP5588_INT_CFG | ADP5588_KE_IEN);
 
 	return 0;
 }