1 files changed, 253 insertions, 0 deletions
diff --git a/drivers/net/ipa/ipa_interrupt.c b/drivers/net/ipa/ipa_interrupt.c
new file mode 100644
index 000000000000..90353987c45f
--- /dev/null
+++ b/drivers/net/ipa/ipa_interrupt.c
@@ -0,0 +1,253 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/* Copyright (c) 2014-2018, The Linux Foundation. All rights reserved.
+ * Copyright (C) 2018-2020 Linaro Ltd.
+ */
+
+/* DOC: IPA Interrupts
+ *
+ * The IPA has an interrupt line distinct from the interrupt used by the GSI
+ * code.  Whereas GSI interrupts are generally related to channel events (like
+ * transfer completions), IPA interrupts are related to other events related
+ * to the IPA.  Some of the IPA interrupts come from a microcontroller
+ * embedded in the IPA.  Each IPA interrupt type can be both masked and
+ * acknowledged independent of the others.
+ *
+ * Two of the IPA interrupts are initiated by the microcontroller.  A third
+ * can be generated to signal the need for a wakeup/resume when an IPA
+ * endpoint has been suspended.  There are other IPA events, but at this
+ * time only these three are supported.
+ */
+
+#include <linux/types.h>
+#include <linux/interrupt.h>
+
+#include "ipa.h"
+#include "ipa_clock.h"
+#include "ipa_reg.h"
+#include "ipa_endpoint.h"
+#include "ipa_interrupt.h"
+
+/**
+ * struct ipa_interrupt - IPA interrupt information
+ * @ipa:		IPA pointer
+ * @irq:		Linux IRQ number used for IPA interrupts
+ * @enabled:		Mask indicating which interrupts are enabled
+ * @handler:		Array of handlers indexed by IPA interrupt ID
+ */
+struct ipa_interrupt {
+	struct ipa *ipa;
+	u32 irq;
+	u32 enabled;
+	ipa_irq_handler_t handler[IPA_IRQ_COUNT];
+};
+
+/* Returns true if the interrupt type is associated with the microcontroller */
+static bool ipa_interrupt_uc(struct ipa_interrupt *interrupt, u32 irq_id)
+{
+	return irq_id == IPA_IRQ_UC_0 || irq_id == IPA_IRQ_UC_1;
+}
+
+/* Process a particular interrupt type that has been received */
+static void ipa_interrupt_process(struct ipa_interrupt *interrupt, u32 irq_id)
+{
+	bool uc_irq = ipa_interrupt_uc(interrupt, irq_id);
+	struct ipa *ipa = interrupt->ipa;
+	u32 mask = BIT(irq_id);
+
+	/* For microcontroller interrupts, clear the interrupt right away,
+	 * "to avoid clearing unhandled interrupts."
+	 */
+	if (uc_irq)
+		iowrite32(mask, ipa->reg_virt + IPA_REG_IRQ_CLR_OFFSET);
+
+	if (irq_id < IPA_IRQ_COUNT && interrupt->handler[irq_id])
+		interrupt->handler[irq_id](interrupt->ipa, irq_id);
+
+	/* Clearing the SUSPEND_TX interrupt also clears the register
+	 * that tells us which suspended endpoint(s) caused the interrupt,
+	 * so defer clearing until after the handler has been called.
+	 */
+	if (!uc_irq)
+		iowrite32(mask, ipa->reg_virt + IPA_REG_IRQ_CLR_OFFSET);
+}
+
+/* Process all IPA interrupt types that have been signaled */
+static void ipa_interrupt_process_all(struct ipa_interrupt *interrupt)
+{
+	struct ipa *ipa = interrupt->ipa;
+	u32 enabled = interrupt->enabled;
+	u32 mask;
+
+	/* The status register indicates which conditions are present,
+	 * including conditions whose interrupt is not enabled.  Handle
+	 * only the enabled ones.
+	 */
+	mask = ioread32(ipa->reg_virt + IPA_REG_IRQ_STTS_OFFSET);
+	while ((mask &= enabled)) {
+		do {
+			u32 irq_id = __ffs(mask);
+
+			mask ^= BIT(irq_id);
+
+			ipa_interrupt_process(interrupt, irq_id);
+		} while (mask);
+		mask = ioread32(ipa->reg_virt + IPA_REG_IRQ_STTS_OFFSET);
+	}
+}
+
+/* Threaded part of the IPA IRQ handler */
+static irqreturn_t ipa_isr_thread(int irq, void *dev_id)
+{
+	struct ipa_interrupt *interrupt = dev_id;
+
+	ipa_clock_get(interrupt->ipa);
+
+	ipa_interrupt_process_all(interrupt);
+
+	ipa_clock_put(interrupt->ipa);
+
+	return IRQ_HANDLED;
+}
+
+/* Hard part (i.e., "real" IRQ handler) of the IRQ handler */
+static irqreturn_t ipa_isr(int irq, void *dev_id)
+{
+	struct ipa_interrupt *interrupt = dev_id;
+	struct ipa *ipa = interrupt->ipa;
+	u32 mask;
+
+	mask = ioread32(ipa->reg_virt + IPA_REG_IRQ_STTS_OFFSET);
+	if (mask & interrupt->enabled)
+		return IRQ_WAKE_THREAD;
+
+	/* Nothing in the mask was supposed to cause an interrupt */
+	iowrite32(mask, ipa->reg_virt + IPA_REG_IRQ_CLR_OFFSET);
+
+	dev_err(&ipa->pdev->dev, "%s: unexpected interrupt, mask 0x%08x\n",
+		__func__, mask);
+
+	return IRQ_HANDLED;
+}
+
+/* Common function used to enable/disable TX_SUSPEND for an endpoint */
+static void ipa_interrupt_suspend_control(struct ipa_interrupt *interrupt,
+					  u32 endpoint_id, bool enable)
+{
+	struct ipa *ipa = interrupt->ipa;
+	u32 mask = BIT(endpoint_id);
+	u32 val;
+
+	/* assert(mask & ipa->available); */
+	val = ioread32(ipa->reg_virt + IPA_REG_SUSPEND_IRQ_EN_OFFSET);
+	if (enable)
+		val |= mask;
+	else
+		val &= ~mask;
+	iowrite32(val, ipa->reg_virt + IPA_REG_SUSPEND_IRQ_EN_OFFSET);
+}
+
+/* Enable TX_SUSPEND for an endpoint */
+void
+ipa_interrupt_suspend_enable(struct ipa_interrupt *interrupt, u32 endpoint_id)
+{
+	ipa_interrupt_suspend_control(interrupt, endpoint_id, true);
+}
+
+/* Disable TX_SUSPEND for an endpoint */
+void
+ipa_interrupt_suspend_disable(struct ipa_interrupt *interrupt, u32 endpoint_id)
+{
+	ipa_interrupt_suspend_control(interrupt, endpoint_id, false);
+}
+
+/* Clear the suspend interrupt for all endpoints that signaled it */
+void ipa_interrupt_suspend_clear_all(struct ipa_interrupt *interrupt)
+{
+	struct ipa *ipa = interrupt->ipa;
+	u32 val;
+
+	val = ioread32(ipa->reg_virt + IPA_REG_IRQ_SUSPEND_INFO_OFFSET);
+	iowrite32(val, ipa->reg_virt + IPA_REG_SUSPEND_IRQ_CLR_OFFSET);
+}
+
+/* Simulate arrival of an IPA TX_SUSPEND interrupt */
+void ipa_interrupt_simulate_suspend(struct ipa_interrupt *interrupt)
+{
+	ipa_interrupt_process(interrupt, IPA_IRQ_TX_SUSPEND);
+}
+
+/* Add a handler for an IPA interrupt */
+void ipa_interrupt_add(struct ipa_interrupt *interrupt,
+		       enum ipa_irq_id ipa_irq, ipa_irq_handler_t handler)
+{
+	struct ipa *ipa = interrupt->ipa;
+
+	/* assert(ipa_irq < IPA_IRQ_COUNT); */
+	interrupt->handler[ipa_irq] = handler;
+
+	/* Update the IPA interrupt mask to enable it */
+	interrupt->enabled |= BIT(ipa_irq);
+	iowrite32(interrupt->enabled, ipa->reg_virt + IPA_REG_IRQ_EN_OFFSET);
+}
+
+/* Remove the handler for an IPA interrupt type */
+void
+ipa_interrupt_remove(struct ipa_interrupt *interrupt, enum ipa_irq_id ipa_irq)
+{
+	struct ipa *ipa = interrupt->ipa;
+
+	/* assert(ipa_irq < IPA_IRQ_COUNT); */
+	/* Update the IPA interrupt mask to disable it */
+	interrupt->enabled &= ~BIT(ipa_irq);
+	iowrite32(interrupt->enabled, ipa->reg_virt + IPA_REG_IRQ_EN_OFFSET);
+
+	interrupt->handler[ipa_irq] = NULL;
+}
+
+/* Set up the IPA interrupt framework */
+struct ipa_interrupt *ipa_interrupt_setup(struct ipa *ipa)
+{
+	struct device *dev = &ipa->pdev->dev;
+	struct ipa_interrupt *interrupt;
+	unsigned int irq;
+	int ret;
+
+	ret = platform_get_irq_byname(ipa->pdev, "ipa");
+	if (ret <= 0) {
+		dev_err(dev, "DT error %d getting \"ipa\" IRQ property\n",
+			ret);
+		return ERR_PTR(ret ? : -EINVAL);
+	}
+	irq = ret;
+
+	interrupt = kzalloc(sizeof(*interrupt), GFP_KERNEL);
+	if (!interrupt)
+		return ERR_PTR(-ENOMEM);
+	interrupt->ipa = ipa;
+	interrupt->irq = irq;
+
+	/* Start with all IPA interrupts disabled */
+	iowrite32(0, ipa->reg_virt + IPA_REG_IRQ_EN_OFFSET);
+
+	ret = request_threaded_irq(irq, ipa_isr, ipa_isr_thread, IRQF_ONESHOT,
+				   "ipa", interrupt);
+	if (ret) {
+		dev_err(dev, "error %d requesting \"ipa\" IRQ\n", ret);
+		goto err_kfree;
+	}
+
+	return interrupt;
+
+err_kfree:
+	kfree(interrupt);
+
+	return ERR_PTR(ret);
+}
+
+/* Tear down the IPA interrupt framework */
+void ipa_interrupt_teardown(struct ipa_interrupt *interrupt)
+{
+	free_irq(interrupt->irq, interrupt);
+	kfree(interrupt);
+}