Merge branch 'net-ipa-wake-up-system-on-RX-available'

Alex Elder says:

====================
net: ipa: wake up system on RX available

This series arranges for the IPA driver to wake up a suspended
system if the IPA hardware has a packet to deliver to the AP.

Version 2 replaced the first patch from version 1 with three
patches, in response to David Miller's feedback. And based on
Bjorn Andersson's feedback on version 2, this version reworks
the tracking of IPA clock references. As a result, we no
longer need a flag to determine whether a "don't' suspend" clock
reference is held (though an bit in a bitmask is still used for
a different purpose).

In summary:
- A refcount_t is used to track IPA clock references where an
atomic_t was previously used. (This may go away soon as well,
with upcoming work to implement runtime PM.)
- We no longer track whether a special reference has been taken
to avoid suspending IPA.
- A bit in a bitmask is used to ensure we only trigger a system
resume once per system suspend.
And from the original series:
- Suspending endpoints only occurs when suspending the driver,
not when dropping the last clock reference. Resuming
endpoints is also disconnected from starting the clock.
- The IPA SUSPEND interrupt is now a wakeup interrupt. If it
fires, it schedules a system resume operation.
- The GSI interrupt is no longer a wakeup interrupt.
====================

Signed-off-by: David S. Miller <[e-mail]>

drivers/net/ipa/gsi.c

···
 	}
 	gsi->irq = irq;
 
-	ret = enable_irq_wake(gsi->irq);
-	if (ret)
-		dev_warn(dev, "error %d enabling gsi wake irq\n", ret);
-	gsi->irq_wake_enabled = !ret;
-
 	/* Get GSI memory range and map it */
 	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "gsi");
 	if (!res) {
 		dev_err(dev, "DT error getting \"gsi\" memory property\n");
 		ret = -ENODEV;
-		goto err_disable_irq_wake;
+		goto err_free_irq;
 	}
 
 	size = resource_size(res);
 	if (res->start > U32_MAX || size > U32_MAX - res->start) {
 		dev_err(dev, "DT memory resource \"gsi\" out of range\n");
 		ret = -EINVAL;
-		goto err_disable_irq_wake;
+		goto err_free_irq;
 	}
 
 	gsi->virt = ioremap(res->start, size);
 	if (!gsi->virt) {
 		dev_err(dev, "unable to remap \"gsi\" memory\n");
 		ret = -ENOMEM;
-		goto err_disable_irq_wake;
+		goto err_free_irq;
 	}
 
 	ret = gsi_channel_init(gsi, prefetch, count, data, modem_alloc);
···
 
 err_iounmap:
 	iounmap(gsi->virt);
-err_disable_irq_wake:
-	if (gsi->irq_wake_enabled)
-		(void)disable_irq_wake(gsi->irq);
+err_free_irq:
 	free_irq(gsi->irq, gsi);
 
 	return ret;
···
 {
 	mutex_destroy(&gsi->mutex);
 	gsi_channel_exit(gsi);
-	if (gsi->irq_wake_enabled)
-		(void)disable_irq_wake(gsi->irq);
 	free_irq(gsi->irq, gsi);
 	iounmap(gsi->virt);
 }

drivers/net/ipa/gsi.h

···
 	struct net_device dummy_dev;	/* needed for NAPI */
 	void __iomem *virt;
 	u32 irq;
-	bool irq_wake_enabled;
 	u32 channel_count;
 	u32 evt_ring_count;
 	struct gsi_channel channel[GSI_CHANNEL_COUNT_MAX];

drivers/net/ipa/ipa.h

···
 struct ipa_interrupt;
 
 /**
+ * enum ipa_flag - IPA state flags
+ * @IPA_FLAG_RESUMED:	Whether resume from suspend has been signaled
+ * @IPA_FLAG_COUNT:	Number of defined IPA flags
+ */
+enum ipa_flag {
+	IPA_FLAG_RESUMED,
+	IPA_FLAG_COUNT,		/* Last; not a flag */
+};
+
+/**
  * struct ipa - IPA information
  * @gsi:		Embedded GSI structure
+ * @flags:		Boolean state flags
  * @version:		IPA hardware version
  * @pdev:		Platform device
  * @modem_rproc:	Remoteproc handle for modem subsystem
  * @smp2p:		SMP2P information
  * @clock:		IPA clocking information
- * @suspend_ref:	Whether clock reference preventing suspend taken
  * @table_addr:		DMA address of filter/route table content
  * @table_virt:		Virtual address of filter/route table content
  * @interrupt:		IPA Interrupt information
···
  */
 struct ipa {
 	struct gsi gsi;
+	DECLARE_BITMAP(flags, IPA_FLAG_COUNT);
 	enum ipa_version version;
 	struct platform_device *pdev;
 	struct rproc *modem_rproc;
···
 	void *notifier;
 	struct ipa_smp2p *smp2p;
 	struct ipa_clock *clock;
-	atomic_t suspend_ref;
 
 	dma_addr_t table_addr;
 	__le64 *table_virt;
···
 	dma_addr_t zero_addr;
 	void *zero_virt;
 	size_t zero_size;
-
-	struct wakeup_source *wakeup_source;
 
 	/* Bit masks indicating endpoint state */
 	u32 available;		/* supported by hardware */

drivers/net/ipa/ipa_clock.c

···
  * Copyright (C) 2018-2020 Linaro Ltd.
  */
 
-#include <linux/atomic.h>
+#include <linux/refcount.h>
 #include <linux/mutex.h>
 #include <linux/clk.h>
 #include <linux/device.h>
···
  * @config_path:	Configuration space interconnect
  */
 struct ipa_clock {
-	atomic_t count;
+	refcount_t count;
 	struct mutex mutex; /* protects clock enable/disable */
 	struct clk *core;
 	struct icc_path *memory_path;
···
  */
 bool ipa_clock_get_additional(struct ipa *ipa)
 {
-	return !!atomic_inc_not_zero(&ipa->clock->count);
+	return refcount_inc_not_zero(&ipa->clock->count);
 }
 
 /* Get an IPA clock reference.  If the reference count is non-zero, it is
  * incremented and return is immediate.  Otherwise it is checked again
- * under protection of the mutex, and if appropriate the clock (and
- * interconnects) are enabled suspended endpoints (if any) are resumed
- * before returning.
+ * under protection of the mutex, and if appropriate the IPA clock
+ * is enabled.
  *
  * Incrementing the reference count is intentionally deferred until
  * after the clock is running and endpoints are resumed.
···
 		goto out_mutex_unlock;
 	}
 
-	ipa_endpoint_resume(ipa);
-
-	atomic_inc(&clock->count);
+	refcount_set(&clock->count, 1);
 
 out_mutex_unlock:
 	mutex_unlock(&clock->mutex);
 }
 
-/* Attempt to remove an IPA clock reference.  If this represents the last
- * reference, suspend endpoints and disable the clock (and interconnects)
- * under protection of a mutex.
+/* Attempt to remove an IPA clock reference.  If this represents the
+ * last reference, disable the IPA clock under protection of the mutex.
  */
 void ipa_clock_put(struct ipa *ipa)
 {
 	struct ipa_clock *clock = ipa->clock;
 
 	/* If this is not the last reference there's nothing more to do */
-	if (!atomic_dec_and_mutex_lock(&clock->count, &clock->mutex))
+	if (!refcount_dec_and_mutex_lock(&clock->count, &clock->mutex))
 		return;
-
-	ipa_endpoint_suspend(ipa);
 
 	ipa_clock_disable(ipa);
 
···
 		goto err_kfree;
 
 	mutex_init(&clock->mutex);
-	atomic_set(&clock->count, 0);
+	refcount_set(&clock->count, 0);
 
 	return clock;
 
···
 {
 	struct clk *clk = clock->core;
 
-	WARN_ON(atomic_read(&clock->count) != 0);
+	WARN_ON(refcount_read(&clock->count) != 0);
 	mutex_destroy(&clock->mutex);
 	ipa_interconnect_exit(clock);
 	kfree(clock);

drivers/net/ipa/ipa_interrupt.c

···
 		goto err_kfree;
 	}
 
+	ret = enable_irq_wake(irq);
+	if (ret) {
+		dev_err(dev, "error %d enabling wakeup for \"ipa\" IRQ\n", ret);
+		goto err_free_irq;
+	}
+
 	return interrupt;
 
+err_free_irq:
+	free_irq(interrupt->irq, interrupt);
 err_kfree:
 	kfree(interrupt);
 
···
 /* Tear down the IPA interrupt framework */
 void ipa_interrupt_teardown(struct ipa_interrupt *interrupt)
 {
+	struct device *dev = &interrupt->ipa->pdev->dev;
+	int ret;
+
+	ret = disable_irq_wake(interrupt->irq);
+	if (ret)
+		dev_err(dev, "error %d disabling \"ipa\" IRQ wakeup\n", ret);
 	free_irq(interrupt->irq, interrupt);
 	kfree(interrupt);
 }

drivers/net/ipa/ipa_main.c

···
  * @ipa:	IPA pointer
  * @irq_id:	IPA interrupt type (unused)
  *
- * When in suspended state, the IPA can trigger a resume by sending a SUSPEND
- * IPA interrupt.
+ * If an RX endpoint is in suspend state, and the IPA has a packet
+ * destined for that endpoint, the IPA generates a SUSPEND interrupt
+ * to inform the AP that it should resume the endpoint.  If we get
+ * one of these interrupts we just resume everything.
  */
 static void ipa_suspend_handler(struct ipa *ipa, enum ipa_irq_id irq_id)
 {
-	/* Take a a single clock reference to prevent suspend.  All
-	 * endpoints will be resumed as a result.  This reference will
-	 * be dropped when we get a power management suspend request.
+	/* Just report the event, and let system resume handle the rest.
+	 * More than one endpoint could signal this; if so, ignore
+	 * all but the first.
 	 */
-	if (!atomic_xchg(&ipa->suspend_ref, 1))
-		ipa_clock_get(ipa);
+	if (!test_and_set_bit(IPA_FLAG_RESUMED, ipa->flags))
+		pm_wakeup_dev_event(&ipa->pdev->dev, 0, true);
 
 	/* Acknowledge/clear the suspend interrupt on all endpoints */
 	ipa_interrupt_suspend_clear_all(ipa->interrupt);
···
 {
 	struct ipa_endpoint *exception_endpoint;
 	struct ipa_endpoint *command_endpoint;
+	struct device *dev = &ipa->pdev->dev;
 	int ret;
 
 	/* Setup for IPA v3.5.1 has some slight differences */
···
 			  ipa_suspend_handler);
 
 	ipa_uc_setup(ipa);
+
+	ret = device_init_wakeup(dev, true);
+	if (ret)
+		goto err_uc_teardown;
 
 	ipa_endpoint_setup(ipa);
 
···
 
 	ipa->setup_complete = true;
 
-	dev_info(&ipa->pdev->dev, "IPA driver setup completed successfully\n");
+	dev_info(dev, "IPA driver setup completed successfully\n");
 
 	return 0;
 
···
 	ipa_endpoint_disable_one(command_endpoint);
 err_endpoint_teardown:
 	ipa_endpoint_teardown(ipa);
+	(void)device_init_wakeup(dev, false);
+err_uc_teardown:
 	ipa_uc_teardown(ipa);
 	ipa_interrupt_remove(ipa->interrupt, IPA_IRQ_TX_SUSPEND);
 	ipa_interrupt_teardown(ipa->interrupt);
···
 	command_endpoint = ipa->name_map[IPA_ENDPOINT_AP_COMMAND_TX];
 	ipa_endpoint_disable_one(command_endpoint);
 	ipa_endpoint_teardown(ipa);
+	(void)device_init_wakeup(&ipa->pdev->dev, false);
 	ipa_uc_teardown(ipa);
 	ipa_interrupt_remove(ipa->interrupt, IPA_IRQ_TX_SUSPEND);
 	ipa_interrupt_teardown(ipa->interrupt);
···
 	 * is held after initialization completes, and won't get dropped
 	 * unless/until a system suspend request arrives.
 	 */
-	atomic_set(&ipa->suspend_ref, 1);
 	ipa_clock_get(ipa);
 
 	ipa_hardware_config(ipa);
···
 err_hardware_deconfig:
 	ipa_hardware_deconfig(ipa);
 	ipa_clock_put(ipa);
-	atomic_set(&ipa->suspend_ref, 0);
 
 	return ret;
 }
···
 	ipa_endpoint_deconfig(ipa);
 	ipa_hardware_deconfig(ipa);
 	ipa_clock_put(ipa);
-	atomic_set(&ipa->suspend_ref, 0);
 }
 
 static int ipa_firmware_load(struct device *dev)
···
  */
 static int ipa_probe(struct platform_device *pdev)
 {
-	struct wakeup_source *wakeup_source;
 	struct device *dev = &pdev->dev;
 	const struct ipa_data *data;
 	struct ipa_clock *clock;
···
 		goto err_clock_exit;
 	}
 
-	/* Create a wakeup source. */
-	wakeup_source = wakeup_source_register(dev, "ipa");
-	if (!wakeup_source) {
-		/* The most likely reason for failure is memory exhaustion */
-		ret = -ENOMEM;
-		goto err_clock_exit;
-	}
-
 	/* Allocate and initialize the IPA structure */
 	ipa = kzalloc(sizeof(*ipa), GFP_KERNEL);
 	if (!ipa) {
 		ret = -ENOMEM;
-		goto err_wakeup_source_unregister;
+		goto err_clock_exit;
 	}
 
 	ipa->pdev = pdev;
 	dev_set_drvdata(dev, ipa);
 	ipa->modem_rproc = rproc;
 	ipa->clock = clock;
-	atomic_set(&ipa->suspend_ref, 0);
-	ipa->wakeup_source = wakeup_source;
 	ipa->version = data->version;
 
 	ret = ipa_reg_init(ipa);
···
 	ipa_reg_exit(ipa);
 err_kfree_ipa:
 	kfree(ipa);
-err_wakeup_source_unregister:
-	wakeup_source_unregister(wakeup_source);
 err_clock_exit:
 	ipa_clock_exit(clock);
 err_rproc_put:
···
 	struct ipa *ipa = dev_get_drvdata(&pdev->dev);
 	struct rproc *rproc = ipa->modem_rproc;
 	struct ipa_clock *clock = ipa->clock;
-	struct wakeup_source *wakeup_source;
 	int ret;
-
-	wakeup_source = ipa->wakeup_source;
 
 	if (ipa->setup_complete) {
 		ret = ipa_modem_stop(ipa);
···
 	ipa_mem_exit(ipa);
 	ipa_reg_exit(ipa);
 	kfree(ipa);
-	wakeup_source_unregister(wakeup_source);
 	ipa_clock_exit(clock);
 	rproc_put(rproc);
 
···
  * Return:	Always returns zero
  *
  * Called by the PM framework when a system suspend operation is invoked.
+ * Suspends endpoints and releases the clock reference held to keep
+ * the IPA clock running until this point.
  */
 static int ipa_suspend(struct device *dev)
 {
 	struct ipa *ipa = dev_get_drvdata(dev);
 
+	/* When a suspended RX endpoint has a packet ready to receive, we
+	 * get an IPA SUSPEND interrupt.  We trigger a system resume in
+	 * that case, but only on the first such interrupt since suspend.
+	 */
+	__clear_bit(IPA_FLAG_RESUMED, ipa->flags);
+
+	ipa_endpoint_suspend(ipa);
+
 	ipa_clock_put(ipa);
-	atomic_set(&ipa->suspend_ref, 0);
 
 	return 0;
 }
···
  * Return:	Always returns 0
  *
  * Called by the PM framework when a system resume operation is invoked.
+ * Takes an IPA clock reference to keep the clock running until suspend,
+ * and resumes endpoints.
  */
 static int ipa_resume(struct device *dev)
 {
···
 	/* This clock reference will keep the IPA out of suspend
 	 * until we get a power management suspend request.
 	 */
-	atomic_set(&ipa->suspend_ref, 1);
 	ipa_clock_get(ipa);
+
+	ipa_endpoint_resume(ipa);
 
 	return 0;
 }