mediatek/mt8173: Add EINT support

Add basic support to configure GPIOs to poll for external interrupts
(EINT).

BRANCH=none
BUG=b:36786804
TEST=Boot rowan w/ serial enabled, verify coreboot and depthcharge are
 configured to use IRQ flow control when talking to the Cr50 TPM.

Change-Id: I9d52591661a5a74ec1fd9a081f606f0a08a3a6ab
Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>
Reviewed-on: https://review.coreboot.org/19362
Reviewed-by: Julius Werner <jwerner@chromium.org>
Tested-by: build bot (Jenkins)

src/soc/mediatek/mt8173/gpio.c

@@ -25,6 +25,7 @@ enum {
 	MAX_GPIO_REG_BITS = 16,
 	MAX_GPIO_MODE_PER_REG = 5,
 	GPIO_MODE_BITS = 3,
+	MAX_EINT_REG_BITS = 32,
 };
 
 enum {
@@ -48,6 +49,12 @@ static void pos_bit_calc_for_mode(u32 pin, u32 *pos, u32 *bit)
 	*bit = (pin % MAX_GPIO_MODE_PER_REG) * GPIO_MODE_BITS;
 }
 
+static void pos_bit_calc_for_eint(u32 pin, u32 *pos, u32 *bit)
+{
+	*pos = pin / MAX_EINT_REG_BITS;
+	*bit = pin % MAX_EINT_REG_BITS;
+}
+
 static s32 gpio_set_dir(u32 pin, u32 dir)
 {
 	u32 pos;
@@ -175,3 +182,58 @@ void gpio_output(gpio_t gpio, int value)
 	gpio_set_dir(gpio, GPIO_DIRECTION_OUT);
 	gpio_set_mode(gpio, GPIO_MODE);
 }
+
+int gpio_eint_poll(gpio_t gpio)
+{
+	u32 pos;
+	u32 bit;
+	u32 status;
+
+	assert(gpio <= MAX_8173_GPIO);
+
+	pos_bit_calc_for_eint(gpio, &pos, &bit);
+
+	status = (read32(&mt8173_eint->sta.regs[pos]) >> bit) & 0x1;
+
+	if (status)
+		write32(&mt8173_eint->ack.regs[pos], 1 << bit);
+
+	return status;
+}
+
+void gpio_eint_configure(gpio_t gpio, enum gpio_irq_type type)
+{
+	u32 pos;
+	u32 bit, mask;
+
+	assert(gpio <= MAX_8173_GPIO);
+
+	pos_bit_calc_for_eint(gpio, &pos, &bit);
+	mask = 1 << bit;
+
+	/* Make it an input first. */
+	gpio_input_pullup(gpio);
+
+	write32(&mt8173_eint->d0en[pos], mask);
+
+	switch (type) {
+	case IRQ_TYPE_EDGE_FALLING:
+		write32(&mt8173_eint->sens_clr.regs[pos], mask);
+		write32(&mt8173_eint->pol_clr.regs[pos], mask);
+		break;
+	case IRQ_TYPE_EDGE_RISING:
+		write32(&mt8173_eint->sens_clr.regs[pos], mask);
+		write32(&mt8173_eint->pol_set.regs[pos], mask);
+		break;
+	case IRQ_TYPE_LEVEL_LOW:
+		write32(&mt8173_eint->sens_set.regs[pos], mask);
+		write32(&mt8173_eint->pol_clr.regs[pos], mask);
+		break;
+	case IRQ_TYPE_LEVEL_HIGH:
+		write32(&mt8173_eint->sens_set.regs[pos], mask);
+		write32(&mt8173_eint->pol_set.regs[pos], mask);
+		break;
+	}
+
+	write32(&mt8173_eint->mask_clr.regs[pos], mask);
+}

src/soc/mediatek/mt8173/include/soc/addressmap.h

@@ -34,6 +34,7 @@ enum {
 	SPM_BASE		= IO_PHYS + 0x6000,
 	RGU_BASE		= IO_PHYS + 0x7000,
 	GPT_BASE		= IO_PHYS + 0x8000,
+	EINT_BASE		= IO_PHYS + 0xB000,
 	PMIC_WRAP_BASE		= IO_PHYS + 0xD000,
 	CHA_DDRPHY_BASE		= IO_PHYS + 0xF000,
 	CHB_DRAMCAO_BASE	= IO_PHYS + 0x11000,

src/soc/mediatek/mt8173/include/soc/gpio.h

@@ -87,4 +87,55 @@ void gpio_set_pull(gpio_t gpio, enum pull_enable enable,
 void gpio_set_mode(gpio_t gpio, int mode);
 void gpio_init(enum external_power);
 
+enum gpio_irq_type {
+	IRQ_TYPE_EDGE_RISING,
+	IRQ_TYPE_EDGE_FALLING,
+	IRQ_TYPE_LEVEL_HIGH,
+	IRQ_TYPE_LEVEL_LOW,
+};
+
+struct eint_section {
+	uint32_t	regs[7];
+	uint32_t	align1[9];
+};
+
+struct eint_regs {
+	struct eint_section sta;
+	struct eint_section ack;
+	struct eint_section mask;
+	struct eint_section mask_set;
+	struct eint_section mask_clr;
+	struct eint_section sens;
+	struct eint_section sens_set;
+	struct eint_section sens_clr;
+	struct eint_section soft;
+	struct eint_section soft_set;
+	struct eint_section soft_clr;
+	struct eint_section rsv00;
+	struct eint_section pol;
+	struct eint_section pol_set;
+	struct eint_section pol_clr;
+	struct eint_section rsv01;
+	uint32_t	    d0en[7];
+	uint32_t	    rsv02;
+	uint32_t	    d1en[7];
+};
+
+check_member(eint_regs, d1en, 0x420);
+
+static struct eint_regs *const mt8173_eint = (void *)(EINT_BASE);
+
+/*
+ * Firmware never enables interrupts on this platform.  This function
+ * reads current EINT status and clears the pending interrupt.
+ *
+ * Returns 1 if the interrupt was pending, else 0.
+ */
+int gpio_eint_poll(gpio_t gpio);
+
+/*
+ * Configure a GPIO to handle external interrupts (EINT) of given irq type.
+ */
+void gpio_eint_configure(gpio_t gpio, enum gpio_irq_type type);
+
 #endif /* SOC_MEDIATEK_MT8173_GPIO_H */