dm: irq: Add support for requesting interrupts

At present driver model supports the IRQ uclass but there is no way to
request a particular interrupt for a driver.

Add a mechanism, similar to clock and reset, to read the interrupts
required by a device from the device tree and to request those interrupts.

U-Boot itself does not have interrupt-driven handlers, so just provide a
means to read and clear an interrupt. This can be useful to handle
peripherals which must use an interrupt to determine when data is
available, for example.

Bring over the basic binding file as well, from Linux v5.4. Note that the
older binding is not supported in U-Boot; the newer 'special form' must be
used.

Add a simple test of the new functionality.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

arch/sandbox/dts/test.dts

@@ -93,6 +93,7 @@
 			<&gpio_b 9 0xc 3 2 1>;
 		int-value = <1234>;
 		uint-value = <(-1234)>;
+		interrupts-extended = <&irq 3 0>;
 	};
 
 	junk {
@@ -357,8 +358,10 @@
 		vss-microvolts = <0>;
 	};
 
-	irq {
+	irq: irq {
 		compatible = "sandbox,irq";
+		interrupt-controller;
+		#interrupt-cells = <2>;
 	};
 
 	lcd {

doc/device-tree-bindings/interrupt-controller/interrupts.txt

@@ -0,0 +1,131 @@
+Specifying interrupt information for devices
+============================================
+
+1) Interrupt client nodes
+-------------------------
+
+Nodes that describe devices which generate interrupts must contain an
+"interrupts" property, an "interrupts-extended" property, or both. If both are
+present, the latter should take precedence; the former may be provided simply
+for compatibility with software that does not recognize the latter. These
+properties contain a list of interrupt specifiers, one per output interrupt. The
+format of the interrupt specifier is determined by the interrupt controller to
+which the interrupts are routed; see section 2 below for details.
+
+  Example:
+	interrupt-parent = <&intc1>;
+	interrupts = <5 0>, <6 0>;
+
+The "interrupt-parent" property is used to specify the controller to which
+interrupts are routed and contains a single phandle referring to the interrupt
+controller node. This property is inherited, so it may be specified in an
+interrupt client node or in any of its parent nodes. Interrupts listed in the
+"interrupts" property are always in reference to the node's interrupt parent.
+
+The "interrupts-extended" property is a special form; useful when a node needs
+to reference multiple interrupt parents or a different interrupt parent than
+the inherited one. Each entry in this property contains both the parent phandle
+and the interrupt specifier.
+
+  Example:
+	interrupts-extended = <&intc1 5 1>, <&intc2 1 0>;
+
+(NOTE: only this 'special form' is supported in U-Boot)
+
+
+2) Interrupt controller nodes
+-----------------------------
+
+A device is marked as an interrupt controller with the "interrupt-controller"
+property. This is a empty, boolean property. An additional "#interrupt-cells"
+property defines the number of cells needed to specify a single interrupt.
+
+It is the responsibility of the interrupt controller's binding to define the
+length and format of the interrupt specifier. The following two variants are
+commonly used:
+
+  a) one cell
+  -----------
+  The #interrupt-cells property is set to 1 and the single cell defines the
+  index of the interrupt within the controller.
+
+  Example:
+
+	vic: intc@10140000 {
+		compatible = "arm,versatile-vic";
+		interrupt-controller;
+		#interrupt-cells = <1>;
+		reg = <0x10140000 0x1000>;
+	};
+
+	sic: intc@10003000 {
+		compatible = "arm,versatile-sic";
+		interrupt-controller;
+		#interrupt-cells = <1>;
+		reg = <0x10003000 0x1000>;
+		interrupt-parent = <&vic>;
+		interrupts = <31>; /* Cascaded to vic */
+	};
+
+  b) two cells
+  ------------
+  The #interrupt-cells property is set to 2 and the first cell defines the
+  index of the interrupt within the controller, while the second cell is used
+  to specify any of the following flags:
+    - bits[3:0] trigger type and level flags
+        1 = low-to-high edge triggered
+        2 = high-to-low edge triggered
+        4 = active high level-sensitive
+        8 = active low level-sensitive
+
+  Example:
+
+	i2c@7000c000 {
+		gpioext: gpio-adnp@41 {
+			compatible = "ad,gpio-adnp";
+			reg = <0x41>;
+
+			interrupt-parent = <&gpio>;
+			interrupts = <160 1>;
+
+			gpio-controller;
+			#gpio-cells = <1>;
+
+			interrupt-controller;
+			#interrupt-cells = <2>;
+
+			nr-gpios = <64>;
+		};
+
+		sx8634@2b {
+			compatible = "smtc,sx8634";
+			reg = <0x2b>;
+
+			interrupt-parent = <&gpioext>;
+			interrupts = <3 0x8>;
+
+			#address-cells = <1>;
+			#size-cells = <0>;
+
+			threshold = <0x40>;
+			sensitivity = <7>;
+		};
+	};
+
+
+Example of special form (supported by U-Boot):
+
+	acpi_gpe: general-purpose-events {
+		reg = <IOMAP_ACPI_BASE IOMAP_ACPI_SIZE>;
+		compatible = "intel,acpi-gpe";
+		interrupt-controller;
+		#interrupt-cells = <2>;
+	};
+
+	tpm@50 {
+		reg = <0x50>;
+		compatible = "google,cr50";
+		u-boot,i2c-offset-len = <0>;
+		ready-gpio = <&gpio_n 28 GPIO_ACTIVE_LOW>;
+		interrupts-extended = <&acpi_gpe 0x3c 0>;
+	};

drivers/misc/irq-uclass.c

@@ -4,8 +4,11 @@
  * Written by Simon Glass <sjg@chromium.org>
  */
 
+#define LOG_CATEGORY UCLASS_IRQ
+
 #include <common.h>
 #include <dm.h>
+#include <dt-structs.h>
 #include <irq.h>
 #include <dm/device-internal.h>
 
@@ -49,6 +52,119 @@ int irq_restore_polarities(struct udevice *dev)
 	return ops->restore_polarities(dev);
 }
 
+int irq_read_and_clear(struct irq *irq)
+{
+	const struct irq_ops *ops = irq_get_ops(irq->dev);
+
+	if (!ops->read_and_clear)
+		return -ENOSYS;
+
+	return ops->read_and_clear(irq);
+}
+
+#if CONFIG_IS_ENABLED(OF_PLATDATA)
+int irq_get_by_index_platdata(struct udevice *dev, int index,
+			      struct phandle_1_arg *cells, struct irq *irq)
+{
+	int ret;
+
+	if (index != 0)
+		return -ENOSYS;
+	ret = uclass_get_device(UCLASS_IRQ, 0, &irq->dev);
+	if (ret)
+		return ret;
+	irq->id = cells[0].arg[0];
+
+	return 0;
+}
+#else
+static int irq_of_xlate_default(struct irq *irq,
+				struct ofnode_phandle_args *args)
+{
+	log_debug("(irq=%p)\n", irq);
+
+	if (args->args_count > 1) {
+		log_debug("Invaild args_count: %d\n", args->args_count);
+		return -EINVAL;
+	}
+
+	if (args->args_count)
+		irq->id = args->args[0];
+	else
+		irq->id = 0;
+
+	return 0;
+}
+
+static int irq_get_by_index_tail(int ret, ofnode node,
+				 struct ofnode_phandle_args *args,
+				 const char *list_name, int index,
+				 struct irq *irq)
+{
+	struct udevice *dev_irq;
+	const struct irq_ops *ops;
+
+	assert(irq);
+	irq->dev = NULL;
+	if (ret)
+		goto err;
+
+	ret = uclass_get_device_by_ofnode(UCLASS_IRQ, args->node, &dev_irq);
+	if (ret) {
+		log_debug("uclass_get_device_by_ofnode failed: err=%d\n", ret);
+		return ret;
+	}
+
+	irq->dev = dev_irq;
+
+	ops = irq_get_ops(dev_irq);
+
+	if (ops->of_xlate)
+		ret = ops->of_xlate(irq, args);
+	else
+		ret = irq_of_xlate_default(irq, args);
+	if (ret) {
+		log_debug("of_xlate() failed: %d\n", ret);
+		return ret;
+	}
+
+	return irq_request(dev_irq, irq);
+err:
+	log_debug("Node '%s', property '%s', failed to request IRQ index %d: %d\n",
+		  ofnode_get_name(node), list_name, index, ret);
+	return ret;
+}
+
+int irq_get_by_index(struct udevice *dev, int index, struct irq *irq)
+{
+	struct ofnode_phandle_args args;
+	int ret;
+
+	ret = dev_read_phandle_with_args(dev, "interrupts-extended",
+					 "#interrupt-cells", 0, index, &args);
+
+	return irq_get_by_index_tail(ret, dev_ofnode(dev), &args,
+				     "interrupts-extended", index > 0, irq);
+}
+#endif /* OF_PLATDATA */
+
+int irq_request(struct udevice *dev, struct irq *irq)
+{
+	const struct irq_ops *ops;
+
+	log_debug("(dev=%p, irq=%p)\n", dev, irq);
+	if (!irq)
+		return 0;
+	ops = irq_get_ops(dev);
+
+	irq->dev = dev;
+
+	if (!ops->request)
+		return 0;
+
+	return ops->request(irq);
+}
+
 int irq_first_device_type(enum irq_dev_t type, struct udevice **devp)
 {
 	int ret;

drivers/misc/irq_sandbox.c

@@ -8,6 +8,18 @@
 #include <common.h>
 #include <dm.h>
 #include <irq.h>
+#include <asm/test.h>
+
+/**
+ * struct sandbox_irq_priv - private data for this driver
+ *
+ * @count: Counts the number calls to the read_and_clear() method
+ * @pending: true if an interrupt is pending, else false
+ */
+struct sandbox_irq_priv {
+	int count;
+	bool pending;
+};
 
 static int sandbox_set_polarity(struct udevice *dev, uint irq, bool active_low)
 {
@@ -35,11 +47,39 @@ static int sandbox_restore_polarities(struct udevice *dev)
 	return 0;
 }
 
+static int sandbox_irq_read_and_clear(struct irq *irq)
+{
+	struct sandbox_irq_priv *priv = dev_get_priv(irq->dev);
+
+	if (irq->id != SANDBOX_IRQN_PEND)
+		return -EINVAL;
+	priv->count++;
+	if (priv->pending) {
+		priv->pending = false;
+		return 1;
+	}
+
+	if (!(priv->count % 3))
+		priv->pending = true;
+
+	return 0;
+}
+
+static int sandbox_irq_of_xlate(struct irq *irq,
+				struct ofnode_phandle_args *args)
+{
+	irq->id = args->args[0];
+
+	return 0;
+}
+
 static const struct irq_ops sandbox_irq_ops = {
 	.route_pmc_gpio_gpe	= sandbox_route_pmc_gpio_gpe,
 	.set_polarity		= sandbox_set_polarity,
 	.snapshot_polarities	= sandbox_snapshot_polarities,
 	.restore_polarities	= sandbox_restore_polarities,
+	.read_and_clear		= sandbox_irq_read_and_clear,
+	.of_xlate		= sandbox_irq_of_xlate,
 };
 
 static const struct udevice_id sandbox_irq_ids[] = {
@@ -52,4 +92,5 @@ U_BOOT_DRIVER(sandbox_irq_drv) = {
 	.id		= UCLASS_IRQ,
 	.of_match	= sandbox_irq_ids,
 	.ops		= &sandbox_irq_ops,
+	.priv_auto_alloc_size	= sizeof(struct sandbox_irq_priv),
 };

include/irq.h

@@ -19,8 +19,21 @@ enum irq_dev_t {
 	SANDBOX_IRQT_BASE,	/* Sandbox testing */
 };
 
+/**
+ * struct irq - A single irq line handled by an interrupt controller
+ *
+ * @dev: IRQ device that handles this irq
+ * @id: ID to identify this irq with the device
+ */
+struct irq {
+	struct udevice *dev;
+	ulong id;
+};
+
 /**
  * struct irq_ops - Operations for the IRQ
+ *
+ * Each IRQ device can handle mulitple IRQ lines
  */
 struct irq_ops {
 	/**
@@ -57,6 +70,55 @@ struct irq_ops {
 	 * @return 0
 	 */
 	int (*restore_polarities)(struct udevice *dev);
+
+	/**
+	 * read_and_clear() - get the value of an interrupt and clear it
+	 *
+	 * Clears the interrupt if pending
+	 *
+	 * @irq: IRQ line
+	 * @return 0 if interrupt is not pending, 1 if it was (and so has been
+	 *	cleared), -ve on error
+	 */
+	int (*read_and_clear)(struct irq *irq);
+	/**
+	 * of_xlate - Translate a client's device-tree (OF) irq specifier.
+	 *
+	 * The irq core calls this function as the first step in implementing
+	 * a client's irq_get_by_*() call.
+	 *
+	 * If this function pointer is set to NULL, the irq core will use a
+	 * default implementation, which assumes #interrupt-cells = <1>, and
+	 * that the DT cell contains a simple integer irq ID.
+	 *
+	 * @irq:	The irq struct to hold the translation result.
+	 * @args:	The irq specifier values from device tree.
+	 * @return 0 if OK, or a negative error code.
+	 */
+	int (*of_xlate)(struct irq *irq, struct ofnode_phandle_args *args);
+	/**
+	 * request - Request a translated irq.
+	 *
+	 * The irq core calls this function as the second step in
+	 * implementing a client's irq_get_by_*() call, following a successful
+	 * xxx_xlate() call, or as the only step in implementing a client's
+	 * irq_request() call.
+	 *
+	 * @irq:	The irq struct to request; this has been fille in by
+	 *		a previoux xxx_xlate() function call, or by the caller
+	 *		of irq_request().
+	 * @return 0 if OK, or a negative error code.
+	 */
+	int (*request)(struct irq *irq);
+	/**
+	 * free - Free a previously requested irq.
+	 *
+	 * This is the implementation of the client irq_free() API.
+	 *
+	 * @irq:	The irq to free.
+	 * @return 0 if OK, or a negative error code.
+	 */
+	int (*free)(struct irq *irq);
 };
 
 #define irq_get_ops(dev)	((struct irq_ops *)(dev)->driver->ops)
@@ -96,6 +158,59 @@ int irq_snapshot_polarities(struct udevice *dev);
  */
 int irq_restore_polarities(struct udevice *dev);
 
+/**
+ * read_and_clear() - get the value of an interrupt and clear it
+ *
+ * Clears the interrupt if pending
+ *
+ * @dev: IRQ device
+ * @return 0 if interrupt is not pending, 1 if it was (and so has been
+ *	cleared), -ve on error
+ */
+int irq_read_and_clear(struct irq *irq);
+
+/**
+ * irq_get_by_index - Get/request an irq by integer index.
+ *
+ * This looks up and requests an irq. The index is relative to the client
+ * device; each device is assumed to have n irqs associated with it somehow,
+ * and this function finds and requests one of them. The mapping of client
+ * device irq indices to provider irqs may be via device-tree
+ * properties, board-provided mapping tables, or some other mechanism.
+ *
+ * @dev:	The client device.
+ * @index:	The index of the irq to request, within the client's list of
+ *		irqs.
+ * @irq:	A pointer to a irq struct to initialise.
+ * @return 0 if OK, or a negative error code.
+ */
+int irq_get_by_index(struct udevice *dev, int index, struct irq *irq);
+
+/**
+ * irq_request - Request a irq by provider-specific ID.
+ *
+ * This requests a irq using a provider-specific ID. Generally, this function
+ * should not be used, since irq_get_by_index/name() provide an interface that
+ * better separates clients from intimate knowledge of irq providers.
+ * However, this function may be useful in core SoC-specific code.
+ *
+ * @dev:	The irq provider device.
+ * @irq:	A pointer to a irq struct to initialise. The caller must
+ *		have already initialised any field in this struct which the
+ *		irq provider uses to identify the irq.
+ * @return 0 if OK, or a negative error code.
+ */
+int irq_request(struct udevice *dev, struct irq *irq);
+
+/**
+ * irq_free - Free a previously requested irq.
+ *
+ * @irq:	A irq struct that was previously successfully requested by
+ *		irq_request/get_by_*().
+ * @return 0 if OK, or a negative error code.
+ */
+int irq_free(struct irq *irq);
+
 /**
  * irq_first_device_type() - Get a particular interrupt controller
  *

test/dm/irq.c

@@ -43,3 +43,35 @@ static int dm_test_irq_type(struct unit_test_state *uts)
 	return 0;
 }
 DM_TEST(dm_test_irq_type, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);
+
+/* Test of irq_read_and_clear() */
+static int dm_test_read_and_clear(struct unit_test_state *uts)
+{
+	struct irq irq;
+
+	ut_assertok(irq_first_device_type(SANDBOX_IRQT_BASE, &irq.dev));
+	irq.id = SANDBOX_IRQN_PEND;
+	ut_asserteq(0, irq_read_and_clear(&irq));
+	ut_asserteq(0, irq_read_and_clear(&irq));
+	ut_asserteq(0, irq_read_and_clear(&irq));
+	ut_asserteq(1, irq_read_and_clear(&irq));
+	ut_asserteq(0, irq_read_and_clear(&irq));
+
+	return 0;
+}
+DM_TEST(dm_test_read_and_clear, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);
+
+/* Test of irq_request() */
+static int dm_test_request(struct unit_test_state *uts)
+{
+	struct udevice *dev;
+	struct irq irq;
+
+	ut_assertok(uclass_first_device_err(UCLASS_TEST_FDT, &dev));
+	ut_asserteq_str("a-test", dev->name);
+	ut_assertok(irq_get_by_index(dev, 0, &irq));
+	ut_asserteq(3, irq.id);
+
+	return 0;
+}
+DM_TEST(dm_test_request, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);