[PATCH v4 4/7] irqchip/qcom-pdc: Configure PDC to pass through mode

[Maulik Shah <maulik.shah@oss.qualcomm.com>]

All PDC HW versions supports pass-through mode in which both Direct SPIs
and GPIO IRQs (as SPIs) are sent to GIC without latching at PDC.

Newer PDCs (v3.0 onwards) also support additional secondary controller
mode where PDC latches the GPIO interrupts and sends them to GIC as level
type interrupts. Direct SPIs works the same as pass-through mode without
latching at PDC even in secondary controller mode.

All the SoCs use pass-through mode with the exception of x1e. x1e PDC may
be set to secondary controller mode for builds on CRD boards whereas it may
be set to pass through mode for IoT-EVK boards. The mode configuration is
done in firmware and initially shipped windows firmware did not have SCM
interface to read or modify the PDC mode. Later only write access is opened
up for the non-secure world.

Using the write access available add changes to modify the PDC mode to
pass-through mode via SCM write. When the write fails (on older firmware)
assume to work in secondary mode.

In secondary mode set the separate irqchip for the GPIOs to perform
additional operations only for the GPIO irqs.

Co-developed-by: Sneh Mankad <sneh.mankad@oss.qualcomm.com>
Signed-off-by: Sneh Mankad <sneh.mankad@oss.qualcomm.com>
Signed-off-by: Maulik Shah <maulik.shah@oss.qualcomm.com>
---
 drivers/irqchip/qcom-pdc.c | 240 ++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 227 insertions(+), 13 deletions(-)

diff --git a/drivers/irqchip/qcom-pdc.c b/drivers/irqchip/qcom-pdc.c
index 53a477aa9765..d122e8e7dc9d 100644
--- a/drivers/irqchip/qcom-pdc.c
+++ b/drivers/irqchip/qcom-pdc.c
@@ -20,12 +20,18 @@
 #include <linux/spinlock.h>
 #include <linux/slab.h>
 #include <linux/types.h>
+#include <linux/firmware/qcom/qcom_scm.h>
 
 #define PDC_MAX_IRQS			256
 #define IRQ_ENABLE_BANK_MAX		BITS_TO_BYTES(PDC_MAX_IRQS)
 #define IRQ_ENABLE_BANK_INDEX_MASK	GENMASK(31, 5)
 #define IRQ_ENABLE_BANK_BIT_MASK	GENMASK(4, 0)
 
+/* Secure DRV register to configure the PDC mode via qcom_scm_io_writel() */
+#define PDC_GPIO_INT_CTL_ENABLE		0xb2045e8
+#define PDC_PASS_THROUGH_MODE		0x0
+#define PDC_SECONDARY_MODE		0x1
+
 #define PDC_DRV_SIZE			0x10000
 #define PDC_VERSION_REG			0x1000
 #define PDC_VERSION_MAJOR		GENMASK(23, 16)
@@ -85,10 +91,14 @@ struct pdc_regs {
 /**
  * struct pdc_irq_cfg: bit fields for PDC IRQ_CFG register
  *
+ * @gpio_irq_sts:   bit number for GPIO_STATUS field
+ * @gpio_irq_mask:  bit number for GPIO_MASK field
  * @irq_enable:     bit number for IRQ_ENABLE field
  * @irq_type:       GENMASK for IRQ_TYPE field
  */
 struct pdc_irq_cfg {
+	u32 gpio_irq_sts;
+	u32 gpio_irq_mask;
 	u32 irq_enable;
 	u32 irq_type;
 };
@@ -102,11 +112,14 @@ struct pdc_irq_cfg {
  * @num_spis:       Total number of direct SPI interrupts
  * @region:         PDC interrupt continuous range
  * @region_cnt:     Total PDC ranges
+ * @mode:           PDC_PASS_THROUGH_MODE or PDC_SECONDARY_MODE
  * @x1e_quirk:      x1e H/W Bug handling
  * @lock:           lock for IRQ_ENABLE_BANK protection
  * @regs:           PDC regs (IRQ_ENABLE_BANK and IRQ_CFG)
  * @cfg_fields:     Fields of IRQ_CFG reg
  * @enable_intr:    pointer to enable function based on PDC version
+ * @unmask_gpio:    pointer to GPIO irq unmask function
+ * @clear_gpio:     pointer to GPIO irq clear function
  */
 struct pdc_desc {
 	void __iomem			*base;
@@ -119,12 +132,15 @@ struct pdc_desc {
 
 	bool				x1e_quirk;
 
+	u8				mode;
 	raw_spinlock_t			lock;
 
 	const struct pdc_regs		*regs;
 	const struct pdc_irq_cfg	*cfg_fields;
 
 	void (*enable_intr)(int pin_out, bool on);
+	void (*unmask_gpio)(int pin_out, bool on);
+	void (*clear_gpio)(int pin_out);
 };
 
 static const struct pdc_regs pdc_v3_2 = {
@@ -133,6 +149,8 @@ static const struct pdc_regs pdc_v3_2 = {
 };
 
 static const struct pdc_irq_cfg pdc_cfg_v3_2 = {
+	.gpio_irq_sts	= 5,
+	.gpio_irq_mask	= 4,
 	.irq_enable	= 3,
 	.irq_type	= GENMASK(2, 0),
 };
@@ -144,6 +162,8 @@ static const struct pdc_regs pdc_v3_0 = {
 };
 
 static const struct pdc_irq_cfg pdc_cfg_v3_0 = {
+	.gpio_irq_sts	= 4,
+	.gpio_irq_mask	= 3,
 	.irq_type	= GENMASK(2, 0),
 };
 
@@ -182,6 +202,15 @@ static u32 pdc_reg_read(int reg, u32 i)
 	return readl_relaxed(pdc->base + reg + i * sizeof(u32));
 }
 
+static inline bool pdc_pin_is_gpio(int pin_out)
+{
+	/*
+	 * PDC allocates direct SPIs at the beginning and
+	 * all GPIOs as SPIs are allocated after direct SPIs.
+	 */
+	return pin_out >= pdc->num_spis;
+}
+
 static void pdc_x1e_irq_enable_write(u32 bank, u32 enable)
 {
 	void __iomem *base;
@@ -229,6 +258,24 @@ static void pdc_enable_intr_bank(int pin_out, bool on)
 		pdc_reg_write(pdc->regs->irq_en_reg, index, enable);
 }
 
+static void pdc_clear_gpio_cfg(int pin_out)
+{
+	unsigned long gpio_sts;
+
+	gpio_sts = pdc_reg_read(pdc->regs->irq_cfg_reg, pin_out);
+	__clear_bit(pdc->cfg_fields->gpio_irq_sts, &gpio_sts);
+	pdc_reg_write(pdc->regs->irq_cfg_reg, pin_out, gpio_sts);
+}
+
+static void pdc_unmask_gpio_cfg(int pin_out, bool unmask)
+{
+	unsigned long gpio_mask;
+
+	gpio_mask = pdc_reg_read(pdc->regs->irq_cfg_reg, pin_out);
+	__assign_bit(pdc->cfg_fields->gpio_irq_mask, &gpio_mask, !unmask);
+	pdc_reg_write(pdc->regs->irq_cfg_reg, pin_out, gpio_mask);
+}
+
 static void pdc_enable_intr_cfg(int pin_out, bool on)
 {
 	unsigned long enable = pdc_reg_read(pdc->regs->irq_cfg_reg, pin_out);
@@ -237,6 +284,13 @@ static void pdc_enable_intr_cfg(int pin_out, bool on)
 	pdc_reg_write(pdc->regs->irq_cfg_reg, pin_out, enable);
 }
 
+static void qcom_pdc_gic_secondary_disable(struct irq_data *d)
+{
+	pdc->enable_intr(d->hwirq, false);
+	pdc->unmask_gpio(d->hwirq, false);
+	irq_chip_disable_parent(d);
+}
+
 static void qcom_pdc_gic_disable(struct irq_data *d)
 {
 	pdc->enable_intr(d->hwirq, false);
@@ -249,6 +303,41 @@ static void qcom_pdc_gic_enable(struct irq_data *d)
 	irq_chip_enable_parent(d);
 }
 
+static void qcom_pdc_gic_secondary_enable(struct irq_data *d)
+{
+	pdc->enable_intr(d->hwirq, true);
+	pdc->unmask_gpio(d->hwirq, true);
+	irq_chip_enable_parent(d);
+}
+
+static void qcom_pdc_secondary_ack(struct irq_data *d)
+{
+	if (!irqd_is_level_type(d))
+		pdc->clear_gpio(d->hwirq);
+}
+
+static void qcom_pdc_gic_secondary_eoi(struct irq_data *d)
+{
+	if (irqd_is_level_type(d))
+		pdc->clear_gpio(d->hwirq);
+
+	irq_chip_eoi_parent(d);
+}
+
+static void qcom_pdc_secondary_mask(struct irq_data *d)
+{
+	pdc->enable_intr(d->hwirq, false);
+	pdc->unmask_gpio(d->hwirq, false);
+	irq_chip_mask_parent(d);
+}
+
+static void qcom_pdc_secondary_unmask(struct irq_data *d)
+{
+	pdc->enable_intr(d->hwirq, true);
+	pdc->unmask_gpio(d->hwirq, true);
+	irq_chip_unmask_parent(d);
+}
+
 /*
  * GIC does not handle falling edge or active low. To allow falling edge and
  * active low interrupts to be handled at GIC, PDC has an inverter that inverts
@@ -275,18 +364,18 @@ enum pdc_irq_config_bits {
 /**
  * qcom_pdc_gic_set_type: Configure PDC for the interrupt
  *
- * @d: the interrupt data
+ * @d:    the interrupt data
  * @type: the interrupt type
  *
- * If @type is edge triggered, forward that as Rising edge as PDC
- * takes care of converting falling edge to rising edge signal
+ * If @type is edge triggered, forward that as rising edge as PDC
+ * takes care of converting all edge types to rising edge signal
  * If @type is level, then forward that as level high as PDC
- * takes care of converting falling edge to rising edge signal
+ * takes care of converting all level types to level high signal
  */
 static int qcom_pdc_gic_set_type(struct irq_data *d, unsigned int type)
 {
-	enum pdc_irq_config_bits pdc_type;
 	enum pdc_irq_config_bits old_pdc_type;
+	enum pdc_irq_config_bits pdc_type;
 	int ret;
 
 	switch (type) {
@@ -336,6 +425,72 @@ static int qcom_pdc_gic_set_type(struct irq_data *d, unsigned int type)
 	return 0;
 }
 
+/**
+ * qcom_pdc_gic_set_type: Configure PDC for the interrupt
+ *
+ * @d:    the interrupt data
+ * @type: the interrupt type
+ *
+ * All @type are forwarded as level high type to parent GIC
+ */
+static int qcom_pdc_gic_secondary_set_type(struct irq_data *d, unsigned int type)
+{
+	enum pdc_irq_config_bits old_pdc_type;
+	enum pdc_irq_config_bits pdc_type;
+	int ret;
+
+	switch (type) {
+	case IRQ_TYPE_EDGE_RISING:
+		pdc_type = PDC_EDGE_RISING;
+		break;
+	case IRQ_TYPE_EDGE_FALLING:
+		pdc_type = PDC_EDGE_FALLING;
+		break;
+	case IRQ_TYPE_EDGE_BOTH:
+		pdc_type = PDC_EDGE_DUAL;
+		break;
+	case IRQ_TYPE_LEVEL_HIGH:
+		pdc_type = PDC_LEVEL_HIGH;
+		break;
+	case IRQ_TYPE_LEVEL_LOW:
+		pdc_type = PDC_LEVEL_LOW;
+		break;
+	default:
+		WARN_ON(1);
+		return -EINVAL;
+	}
+
+	old_pdc_type = pdc_reg_read(pdc->regs->irq_cfg_reg, d->hwirq);
+	pdc_type |= (old_pdc_type & ~pdc->cfg_fields->irq_type);
+	pdc_reg_write(pdc->regs->irq_cfg_reg, d->hwirq, pdc_type);
+
+	/*
+	 * PDC forwards GPIOs as level high to GIC in secondary
+	 * mode. Update the type and clear any previously latched
+	 * phantom interrupt at PDC.
+	 */
+	type = IRQ_TYPE_LEVEL_HIGH;
+	pdc->clear_gpio(d->hwirq);
+
+	ret = irq_chip_set_type_parent(d, type);
+	if (ret)
+		return ret;
+
+	/*
+	 * When we change types the PDC can give a phantom interrupt.
+	 * Clear it.  Specifically the phantom shows up when reconfiguring
+	 * polarity of interrupt without changing the state of the signal
+	 * but let's be consistent and clear it always.
+	 *
+	 * Doing this works because we have IRQCHIP_SET_TYPE_MASKED so the
+	 * interrupt will be cleared before the rest of the system sees it.
+	 */
+	if (old_pdc_type != pdc_type)
+		irq_chip_set_parent_state(d, IRQCHIP_STATE_PENDING, false);
+
+	return 0;
+}
+
 static struct irq_chip qcom_pdc_gic_chip = {
 	.name			= "PDC",
 	.irq_eoi		= irq_chip_eoi_parent,
@@ -355,6 +510,26 @@ static struct irq_chip qcom_pdc_gic_chip = {
 	.irq_set_affinity	= irq_chip_set_affinity_parent,
 };
 
+static struct irq_chip qcom_pdc_gic_secondary_chip = {
+	.name			= "PDC",
+	.irq_ack		= qcom_pdc_secondary_ack,
+	.irq_eoi		= qcom_pdc_gic_secondary_eoi,
+	.irq_mask		= qcom_pdc_secondary_mask,
+	.irq_unmask		= qcom_pdc_secondary_unmask,
+	.irq_disable		= qcom_pdc_gic_secondary_disable,
+	.irq_enable		= qcom_pdc_gic_secondary_enable,
+	.irq_get_irqchip_state	= irq_chip_get_parent_state,
+	.irq_set_irqchip_state	= irq_chip_set_parent_state,
+	.irq_retrigger		= irq_chip_retrigger_hierarchy,
+	.irq_set_type		= qcom_pdc_gic_secondary_set_type,
+	.flags			= IRQCHIP_MASK_ON_SUSPEND |
+				  IRQCHIP_SET_TYPE_MASKED |
+				  IRQCHIP_SKIP_SET_WAKE |
+				  IRQCHIP_ENABLE_WAKEUP_ON_SUSPEND,
+	.irq_set_vcpu_affinity	= irq_chip_set_vcpu_affinity_parent,
+	.irq_set_affinity	= irq_chip_set_affinity_parent,
+};
+
 static struct pdc_pin_region *get_pin_region(int pin)
 {
 	for (int i = 0; i < pdc->region_cnt; i++) {
@@ -388,16 +563,38 @@ static int qcom_pdc_alloc(struct irq_domain *domain, unsigned int virq,
 	if (ret)
 		return ret;
 
+	/*
+	 * PDC secondary chip is only set for the GPIO interrupts as SPIs.
+	 * Direct SPI interrupts are still in pass through mode (no latching
+	 * at PDC).
+	 */
+	if (pdc->mode == PDC_SECONDARY_MODE && pdc_pin_is_gpio(hwirq)) {
+		ret = irq_domain_set_hwirq_and_chip(domain, virq, hwirq,
+						    &qcom_pdc_gic_secondary_chip,
+						    NULL);
+		if (ret)
+			return ret;
+
+		/* Secondary mode converts all interrupts to LEVEL HIGH type */
+		type = IRQ_TYPE_LEVEL_HIGH;
+	} else {
+		ret = irq_domain_set_hwirq_and_chip(domain, virq, hwirq,
+						    &qcom_pdc_gic_chip,
+						    NULL);
+		if (ret)
+			return ret;
+
+		if (type & IRQ_TYPE_EDGE_BOTH)
+			type = IRQ_TYPE_EDGE_RISING;
+
+		if (type & IRQ_TYPE_LEVEL_MASK)
+			type = IRQ_TYPE_LEVEL_HIGH;
+	}
+
 	region = get_pin_region(hwirq);
 	if (!region)
 		return irq_domain_disconnect_hierarchy(domain->parent, virq);
 
-	if (type & IRQ_TYPE_EDGE_BOTH)
-		type = IRQ_TYPE_EDGE_RISING;
-
-	if (type & IRQ_TYPE_LEVEL_MASK)
-		type = IRQ_TYPE_LEVEL_HIGH;
-
 	parent_fwspec.fwnode      = domain->parent->fwnode;
 	parent_fwspec.param_count = 3;
 	parent_fwspec.param[0]    = 0;
@@ -443,8 +640,13 @@ static int pdc_setup_pin_mapping(struct device *dev)
 		if (ret)
 			return ret;
 
-		for (int i = 0; i < pdc->region[n].cnt; i++)
-			pdc->enable_intr(i + pdc->region[n].pin_base, 0);
+		for (int i = 0; i < pdc->region[n].cnt; i++) {
+			if (pdc_pin_is_gpio(i + pdc->region[n].pin_base) &&
+			    pdc->mode == PDC_SECONDARY_MODE)
+				pdc->clear_gpio(i + pdc->region[n].pin_base);
+
+			pdc->enable_intr(i + pdc->region[n].pin_base, false);
+		}
 	}
 
 	return 0;
@@ -495,6 +697,8 @@ static int qcom_pdc_probe(struct platform_device *pdev, struct device_node *pare
 		pdc->enable_intr = pdc_enable_intr_bank;
 	}
 
+	pdc->mode = PDC_PASS_THROUGH_MODE;
+
 	/*
 	 * PDC has multiple DRV regions, each one provides the same set of
 	 * registers for a particular client in the system. Due to a hardware
@@ -512,6 +716,16 @@ static int qcom_pdc_probe(struct platform_device *pdev, struct device_node *pare
 		}
 
 		pdc->x1e_quirk = true;
+
+		if (!qcom_scm_is_available())
+			return -EPROBE_DEFER;
+
+		ret = qcom_scm_io_writel(PDC_GPIO_INT_CTL_ENABLE, PDC_PASS_THROUGH_MODE);
+		if (ret) {
+			pdc->mode = PDC_SECONDARY_MODE;
+			pdc->unmask_gpio = pdc_unmask_gpio_cfg;
+			pdc->clear_gpio = pdc_clear_gpio_cfg;
+		}
 	}
 
 	irq_param = pdc_reg_read(pdc->regs->irq_param_reg, 0);

-- 
2.43.0