regmap: Add a reusable irq_chip for regmap based interrupt controllers

There seem to be lots of regmap-using devices with very similar interrupt
controllers with a small bank of interrupt registers and mask registers
with an interrupt per bit. This won't cover everything but it's a good
start.

Each chip supplies a base for the status registers, a base for the mask
registers, an optional base for writing acknowledgements (which may be the
same as the status registers) and an array of bits within each of these
register banks which indicate the interrupt.

There is an assumption that the bit for each interrupt will be the same
in each of the register bank.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

drivers/base/regmap/Kconfig

@@ -13,3 +13,6 @@ config REGMAP_I2C
 
 config REGMAP_SPI
 	tristate
+
+config REGMAP_IRQ
+	bool

drivers/base/regmap/Makefile

@@ -2,3 +2,4 @@ obj-$(CONFIG_REGMAP) += regmap.o regcache.o regcache-indexed.o regcache-rbtree.o
 obj-$(CONFIG_DEBUG_FS) += regmap-debugfs.o
 obj-$(CONFIG_REGMAP_I2C) += regmap-i2c.o
 obj-$(CONFIG_REGMAP_SPI) += regmap-spi.o
+obj-$(CONFIG_REGMAP_IRQ) += regmap-irq.o

drivers/base/regmap/regmap-irq.c

+/*
+ * regmap based irq_chip
+ *
+ * Copyright 2011 Wolfson Microelectronics plc
+ *
+ * Author: Mark Brown <broonie@opensource.wolfsonmicro.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/export.h>
+#include <linux/regmap.h>
+#include <linux/irq.h>
+#include <linux/interrupt.h>
+#include <linux/slab.h>
+
+#include "internal.h"
+
+struct regmap_irq_chip_data {
+	struct mutex lock;
+
+	struct regmap *map;
+	struct regmap_irq_chip *chip;
+
+	int irq_base;
+
+	void *status_reg_buf;
+	unsigned int *status_buf;
+	unsigned int *mask_buf;
+	unsigned int *mask_buf_def;
+};
+
+static inline const
+struct regmap_irq *irq_to_regmap_irq(struct regmap_irq_chip_data *data,
+				     int irq)
+{
+	return &data->chip->irqs[irq - data->irq_base];
+}
+
+static void regmap_irq_lock(struct irq_data *data)
+{
+	struct regmap_irq_chip_data *d = irq_data_get_irq_chip_data(data);
+
+	mutex_lock(&d->lock);
+}
+
+static void regmap_irq_sync_unlock(struct irq_data *data)
+{
+	struct regmap_irq_chip_data *d = irq_data_get_irq_chip_data(data);
+	int i, ret;
+
+	/*
+	 * If there's been a change in the mask write it back to the
+	 * hardware.  We rely on the use of the regmap core cache to
+	 * suppress pointless writes.
+	 */
+	for (i = 0; i < d->chip->num_regs; i++) {
+		ret = regmap_update_bits(d->map, d->chip->mask_base + i,
+					 d->mask_buf_def[i], d->mask_buf[i]);
+		if (ret != 0)
+			dev_err(d->map->dev, "Failed to sync masks in %x\n",
+				d->chip->mask_base + i);
+	}
+
+	mutex_unlock(&d->lock);
+}
+
+static void regmap_irq_enable(struct irq_data *data)
+{
+	struct regmap_irq_chip_data *d = irq_data_get_irq_chip_data(data);
+	const struct regmap_irq *irq_data = irq_to_regmap_irq(d, data->irq);
+
+	d->mask_buf[irq_data->reg_offset] &= ~irq_data->mask;
+}
+
+static void regmap_irq_disable(struct irq_data *data)
+{
+	struct regmap_irq_chip_data *d = irq_data_get_irq_chip_data(data);
+	const struct regmap_irq *irq_data = irq_to_regmap_irq(d, data->irq);
+
+	d->mask_buf[irq_data->reg_offset] |= irq_data->mask;
+}
+
+static struct irq_chip regmap_irq_chip = {
+	.name			= "regmap",
+	.irq_bus_lock		= regmap_irq_lock,
+	.irq_bus_sync_unlock	= regmap_irq_sync_unlock,
+	.irq_disable		= regmap_irq_disable,
+	.irq_enable		= regmap_irq_enable,
+};
+
+static irqreturn_t regmap_irq_thread(int irq, void *d)
+{
+	struct regmap_irq_chip_data *data = d;
+	struct regmap_irq_chip *chip = data->chip;
+	struct regmap *map = data->map;
+	int ret, i;
+	u8 *buf8 = data->status_reg_buf;
+	u16 *buf16 = data->status_reg_buf;
+	u32 *buf32 = data->status_reg_buf;
+
+	ret = regmap_bulk_read(map, chip->status_base, data->status_reg_buf,
+			       chip->num_regs);
+	if (ret != 0) {
+		dev_err(map->dev, "Failed to read IRQ status: %d\n", ret);
+		return IRQ_NONE;
+	}
+
+	/*
+	 * Ignore masked IRQs and ack if we need to; we ack early so
+	 * there is no race between handling and acknowleding the
+	 * interrupt.  We assume that typically few of the interrupts
+	 * will fire simultaneously so don't worry about overhead from
+	 * doing a write per register.
+	 */
+	for (i = 0; i < data->chip->num_regs; i++) {
+		switch (map->format.val_bytes) {
+		case 1:
+			data->status_buf[i] = buf8[i];
+			break;
+		case 2:
+			data->status_buf[i] = buf16[i];
+			break;
+		case 4:
+			data->status_buf[i] = buf32[i];
+			break;
+		default:
+			BUG();
+			return IRQ_NONE;
+		}
+
+		data->status_buf[i] &= ~data->mask_buf[i];
+
+		if (data->status_buf[i] && chip->ack_base) {
+			ret = regmap_write(map, chip->ack_base + i,
+					   data->status_buf[i]);
+			if (ret != 0)
+				dev_err(map->dev, "Failed to ack 0x%x: %d\n",
+					chip->ack_base + i, ret);
+		}
+	}
+
+	for (i = 0; i < chip->num_irqs; i++) {
+		if (data->status_buf[chip->irqs[i].reg_offset] &
+		    chip->irqs[i].mask) {
+			handle_nested_irq(data->irq_base + i);
+		}
+	}
+
+	return IRQ_HANDLED;
+}
+
+/**
+ * regmap_add_irq_chip(): Use standard regmap IRQ controller handling
+ *
+ * map:       The regmap for the device.
+ * irq:       The IRQ the device uses to signal interrupts
+ * irq_flags: The IRQF_ flags to use for the primary interrupt.
+ * chip:      Configuration for the interrupt controller.
+ * data:      Runtime data structure for the controller, allocated on success
+ *
+ * Returns 0 on success or an errno on failure.
+ *
+ * In order for this to be efficient the chip really should use a
+ * register cache.  The chip driver is responsible for restoring the
+ * register values used by the IRQ controller over suspend and resume.
+ */
+int regmap_add_irq_chip(struct regmap *map, int irq, int irq_flags,
+			int irq_base, struct regmap_irq_chip *chip,
+			struct regmap_irq_chip_data **data)
+{
+	struct regmap_irq_chip_data *d;
+	int cur_irq, i;
+	int ret = -ENOMEM;
+
+	irq_base = irq_alloc_descs(irq_base, 0, chip->num_irqs, 0);
+	if (irq_base < 0) {
+		dev_warn(map->dev, "Failed to allocate IRQs: %d\n",
+			 irq_base);
+		return irq_base;
+	}
+
+	d = kzalloc(sizeof(*d), GFP_KERNEL);
+	if (!d)
+		return -ENOMEM;
+
+	d->status_buf = kzalloc(sizeof(unsigned int) * chip->num_regs,
+				GFP_KERNEL);
+	if (!d->status_buf)
+		goto err_alloc;
+
+	d->status_reg_buf = kzalloc(map->format.val_bytes * chip->num_regs,
+				    GFP_KERNEL);
+	if (!d->status_reg_buf)
+		goto err_alloc;
+
+	d->mask_buf = kzalloc(sizeof(unsigned int) * chip->num_regs,
+			      GFP_KERNEL);
+	if (!d->mask_buf)
+		goto err_alloc;
+
+	d->mask_buf_def = kzalloc(sizeof(unsigned int) * chip->num_regs,
+				  GFP_KERNEL);
+	if (!d->mask_buf_def)
+		goto err_alloc;
+
+	d->map = map;
+	d->chip = chip;
+	d->irq_base = irq_base;
+	mutex_init(&d->lock);
+
+	for (i = 0; i < chip->num_irqs; i++)
+		d->mask_buf_def[chip->irqs[i].reg_offset]
+			|= chip->irqs[i].mask;
+
+	/* Mask all the interrupts by default */
+	for (i = 0; i < chip->num_regs; i++) {
+		d->mask_buf[i] = d->mask_buf_def[i];
+		ret = regmap_write(map, chip->mask_base + i, d->mask_buf[i]);
+		if (ret != 0) {
+			dev_err(map->dev, "Failed to set masks in 0x%x: %d\n",
+				chip->mask_base + i, ret);
+			goto err_alloc;
+		}
+	}
+
+	/* Register them with genirq */
+	for (cur_irq = irq_base;
+	     cur_irq < chip->num_irqs + irq_base;
+	     cur_irq++) {
+		irq_set_chip_data(cur_irq, d);
+		irq_set_chip_and_handler(cur_irq, &regmap_irq_chip,
+					 handle_edge_irq);
+		irq_set_nested_thread(cur_irq, 1);
+
+		/* ARM needs us to explicitly flag the IRQ as valid
+		 * and will set them noprobe when we do so. */
+#ifdef CONFIG_ARM
+		set_irq_flags(cur_irq, IRQF_VALID);
+#else
+		irq_set_noprobe(cur_irq);
+#endif
+	}
+
+	ret = request_threaded_irq(irq, NULL, regmap_irq_thread, irq_flags,
+				   chip->name, d);
+	if (ret != 0) {
+		dev_err(map->dev, "Failed to request IRQ %d: %d\n", irq, ret);
+		goto err_alloc;
+	}
+
+	return 0;
+
+err_alloc:
+	kfree(d->mask_buf_def);
+	kfree(d->mask_buf);
+	kfree(d->status_reg_buf);
+	kfree(d->status_buf);
+	kfree(d);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(regmap_add_irq_chip);
+
+/**
+ * regmap_del_irq_chip(): Stop interrupt handling for a regmap IRQ chip
+ *
+ * @irq: Primary IRQ for the device
+ * @d:   regmap_irq_chip_data allocated by regmap_add_irq_chip()
+ */
+void regmap_del_irq_chip(int irq, struct regmap_irq_chip_data *d)
+{
+	if (!d)
+		return;
+
+	free_irq(irq, d);
+	kfree(d->mask_buf_def);
+	kfree(d->mask_buf);
+	kfree(d->status_reg_buf);
+	kfree(d->status_buf);
+	kfree(d);
+}
+EXPORT_SYMBOL_GPL(regmap_del_irq_chip);

include/linux/regmap.h

@@ -144,4 +144,51 @@ int regcache_sync(struct regmap *map);
 void regcache_cache_only(struct regmap *map, bool enable);
 void regcache_cache_bypass(struct regmap *map, bool enable);
 
+/**
+ * Description of an IRQ for the generic regmap irq_chip.
+ *
+ * @reg_offset: Offset of the status/mask register within the bank
+ * @mask:       Mask used to flag/control the register.
+ */
+struct regmap_irq {
+	unsigned int reg_offset;
+	unsigned int mask;
+};
+
+/**
+ * Description of a generic regmap irq_chip.  This is not intended to
+ * handle every possible interrupt controller, but it should handle a
+ * substantial proportion of those that are found in the wild.
+ *
+ * @name:        Descriptive name for IRQ controller.
+ *
+ * @status_base: Base status register address.
+ * @mask_base:   Base mask register address.
+ * @ack_base:    Base ack address.  If zero then the chip is clear on read.
+ *
+ * @num_regs:    Number of registers in each control bank.
+ * @irqs:        Descriptors for individual IRQs.  Interrupt numbers are
+ *               assigned based on the index in the array of the interrupt.
+ * @num_irqs:    Number of descriptors.
+ */
+struct regmap_irq_chip {
+	const char *name;
+
+	unsigned int status_base;
+	unsigned int mask_base;
+	unsigned int ack_base;
+
+	int num_regs;
+
+	const struct regmap_irq *irqs;
+	int num_irqs;
+};
+
+struct regmap_irq_chip_data;
+
+int regmap_add_irq_chip(struct regmap *map, int irq, int irq_flags,
+			int irq_base, struct regmap_irq_chip *chip,
+			struct regmap_irq_chip_data **data);
+void regmap_del_irq_chip(int irq, struct regmap_irq_chip_data *data);
+
 #endif