soc/intel/apollolake: set gpio interrupt polarity in ITSS

For APIC routed gpios, set the corresponding interrupt polarity
for the associated IRQ based on the gpio pad's invert setting.
This allows for the APIC redirection entries to match the hardware
active polarity once the double inversion takes place to meet
apollolake interrupt triggering constraints.

BUG=chrome-os-partner:54955

Change-Id: I69c395b6f861946d4774a4206cf8f5f721c6f5f4
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/15648
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Furquan Shaikh <furquan@google.com>

src/soc/intel/apollolake/gpio.c

@@ -19,6 +19,7 @@
 #include <gpio.h>
 #include <soc/gpio.h>
 #include <soc/iosf.h>
+#include <soc/itss.h>
 #include <soc/pm.h>
 
 /* This list must be in order, from highest pad numbers, to lowest pad numbers*/
@@ -53,12 +54,43 @@ static const struct pad_community *gpio_get_community(uint16_t pad)
 	return map;
 }
 
+static void gpio_configure_itss(const struct pad_config *cfg,
+				uint16_t port, uint16_t pad_cfg_offset)
+{
+	int irq;
+
+	/* Set up ITSS polarity if pad is routed to APIC.
+	 *
+	 * The ITSS takes only active high interrupt signals. Therefore,
+	 * if the pad configuration indicates an inversion assume the
+	 * intent is for the ITSS polarity. Before forwarding on the
+	 * request to the APIC there's an inversion setting for how the
+	 * signal is forwarded to the APIC. Honor the inversion setting
+	 * in the GPIO pad configuration so that a hardware active low
+	 * signal looks that way to the APIC (double inversion).
+	 */
+	if (!(cfg->config0 & PAD_CFG0_ROUTE_IOAPIC))
+		return;
+
+	irq = iosf_read(port, pad_cfg_offset + sizeof(uint32_t));
+	irq &= PAD_CFG1_IRQ_MASK;
+	if (!irq) {
+		printk(BIOS_ERR, "GPIO %u doesn't support APIC routing,\n",
+			cfg->pad);
+		return;
+	}
+
+	itss_set_irq_polarity(irq, !!(cfg->config0 & PAD_CFG0_RX_POL_INVERT));
+}
+
 void gpio_configure_pad(const struct pad_config *cfg)
 {
 	const struct pad_community *comm = gpio_get_community(cfg->pad);
 	uint16_t config_offset = PAD_CFG_OFFSET(cfg->pad - comm->first_pad);
 	iosf_write(comm->port, config_offset, cfg->config0);
 	iosf_write(comm->port, config_offset + sizeof(uint32_t), cfg->config1);
+
+	gpio_configure_itss(cfg, comm->port, config_offset);
 }
 
 void gpio_configure_pads(const struct pad_config *cfg, size_t num_pads)

src/soc/intel/apollolake/include/soc/gpio_defs.h

@@ -75,6 +75,7 @@
 #define  PAD_CFG0_RESET_PLTRST		(2 << 30)
 #define  PAD_CFG0_RESET_RSMRST		(3 << 30)
 
+#define PAD_CFG1_IRQ_MASK		(0xff << 0)
 #define PAD_CFG1_PULL_MASK		(0xf << 10)
 #define  PAD_CFG1_PULL_NONE		(0x0 << 10)
 #define  PAD_CFG1_PULL_DN_5K		(0x2 << 10)