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From:   William Breathitt Gray <william.gray@linaro.org>
To:     linus.walleij@linaro.org, brgl@bgdev.pl
Cc:     andriy.shevchenko@linux.intel.com, linux-gpio@vger.kernel.org,
        linux-kernel@vger.kernel.org, michael@walle.cc, broonie@kernel.org,
        William Breathitt Gray <william.gray@linaro.org>
Subject: [PATCH v4 3/9] gpio: 104-dio-48e: Migrate to the regmap-irq API
Date:   Fri,  2 Dec 2022 11:27:09 -0500
Message-Id: <be8ddc3befbcce31546d64f70523d08b3e1e0070.1669996867.git.william.gray@linaro.org>
In-Reply-To: <cover.1669996866.git.william.gray@linaro.org>
References: <cover.1669996866.git.william.gray@linaro.org>
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The regmap API supports IO port accessors so we can take advantage of
regmap abstractions rather than handling access to the device registers
directly in the driver.

For the 104-dio-48e we have the following IRQ registers (0xB and 0xF):

    Base Address +B (Write): Enable Interrupt
    Base Address +B (Read): Disable Interrupt
    Base Address +F (Read/Write): Clear Interrupt

Any write to 0xB will enable interrupts, while any read will disable
interrupts. Interrupts are cleared by a read or any write to 0xF.
There's no IRQ status register, so software has to assume that if an
interrupt is raised then it was for the 104-DIO-48E device.

Signed-off-by: William Breathitt Gray <william.gray@linaro.org>
---
 drivers/gpio/Kconfig            |   1 +
 drivers/gpio/gpio-104-dio-48e.c | 268 +++++++++++++++-----------------
 2 files changed, 127 insertions(+), 142 deletions(-)

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index ec7cfd4f52b1..b62bef4e563d 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -845,6 +845,7 @@ config GPIO_104_DIO_48E
 	tristate "ACCES 104-DIO-48E GPIO support"
 	depends on PC104
 	select ISA_BUS_API
+	select REGMAP_IRQ
 	select GPIOLIB_IRQCHIP
 	select GPIO_I8255
 	help
diff --git a/drivers/gpio/gpio-104-dio-48e.c b/drivers/gpio/gpio-104-dio-48e.c
index 7b8829c8e423..4c3660d5dea5 100644
--- a/drivers/gpio/gpio-104-dio-48e.c
+++ b/drivers/gpio/gpio-104-dio-48e.c
@@ -8,17 +8,15 @@
  */
 #include <linux/bits.h>
 #include <linux/device.h>
-#include <linux/errno.h>
+#include <linux/err.h>
 #include <linux/gpio/driver.h>
-#include <linux/io.h>
 #include <linux/ioport.h>
-#include <linux/interrupt.h>
-#include <linux/irqdesc.h>
+#include <linux/irq.h>
 #include <linux/isa.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/moduleparam.h>
-#include <linux/spinlock.h>
+#include <linux/regmap.h>
 #include <linux/types.h>
 
 #include "gpio-i8255.h"
@@ -38,46 +36,30 @@ static unsigned int num_irq;
 module_param_hw_array(irq, uint, irq, &num_irq, 0);
 MODULE_PARM_DESC(irq, "ACCES 104-DIO-48E interrupt line numbers");
 
+#define DIO48E_ENABLE_INTERRUPT 0xB
+#define DIO48E_DISABLE_INTERRUPT DIO48E_ENABLE_INTERRUPT
+#define DIO48E_CLEAR_INTERRUPT 0xF
+
 #define DIO48E_NUM_PPI 2
 
 /**
  * struct dio48e_reg - device register structure
  * @ppi:		Programmable Peripheral Interface groups
- * @enable_buffer:	Enable/Disable Buffer groups
- * @unused1:		Unused
- * @enable_interrupt:	Write: Enable Interrupt
- *			Read: Disable Interrupt
- * @unused2:		Unused
- * @enable_counter:	Write: Enable Counter/Timer Addressing
- *			Read: Disable Counter/Timer Addressing
- * @unused3:		Unused
- * @clear_interrupt:	Clear Interrupt
  */
 struct dio48e_reg {
 	struct i8255 ppi[DIO48E_NUM_PPI];
-	u8 enable_buffer[DIO48E_NUM_PPI];
-	u8 unused1;
-	u8 enable_interrupt;
-	u8 unused2;
-	u8 enable_counter;
-	u8 unused3;
-	u8 clear_interrupt;
 };
 
 /**
  * struct dio48e_gpio - GPIO device private data structure
  * @chip:		instance of the gpio_chip
  * @ppi_state:		PPI device states
- * @lock:		synchronization lock to prevent I/O race conditions
  * @reg:		I/O address offset for the device registers
- * @irq_mask:		I/O bits affected by interrupts
  */
 struct dio48e_gpio {
 	struct gpio_chip chip;
 	struct i8255_state ppi_state[DIO48E_NUM_PPI];
-	raw_spinlock_t lock;
 	struct dio48e_reg __iomem *reg;
-	unsigned char irq_mask;
 };
 
 static int dio48e_gpio_get_direction(struct gpio_chip *chip, unsigned int offset)
@@ -144,106 +126,90 @@ static void dio48e_gpio_set_multiple(struct gpio_chip *chip,
 			   bits, chip->ngpio);
 }
 
-static void dio48e_irq_ack(struct irq_data *data)
-{
-}
-
-static void dio48e_irq_mask(struct irq_data *data)
-{
-	struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
-	struct dio48e_gpio *const dio48egpio = gpiochip_get_data(chip);
-	const unsigned long offset = irqd_to_hwirq(data);
-	unsigned long flags;
-
-	/* only bit 3 on each respective Port C supports interrupts */
-	if (offset != 19 && offset != 43)
-		return;
-
-	raw_spin_lock_irqsave(&dio48egpio->lock, flags);
-
-	if (offset == 19)
-		dio48egpio->irq_mask &= ~BIT(0);
-	else
-		dio48egpio->irq_mask &= ~BIT(1);
-	gpiochip_disable_irq(chip, offset);
-
-	if (!dio48egpio->irq_mask)
-		/* disable interrupts */
-		ioread8(&dio48egpio->reg->enable_interrupt);
-
-	raw_spin_unlock_irqrestore(&dio48egpio->lock, flags);
-}
-
-static void dio48e_irq_unmask(struct irq_data *data)
-{
-	struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
-	struct dio48e_gpio *const dio48egpio = gpiochip_get_data(chip);
-	const unsigned long offset = irqd_to_hwirq(data);
-	unsigned long flags;
-
-	/* only bit 3 on each respective Port C supports interrupts */
-	if (offset != 19 && offset != 43)
-		return;
-
-	raw_spin_lock_irqsave(&dio48egpio->lock, flags);
+static const struct regmap_range dio48e_wr_ranges[] = {
+	regmap_reg_range(0x0, 0x9), regmap_reg_range(0xB, 0xB),
+	regmap_reg_range(0xD, 0xD), regmap_reg_range(0xF, 0xF),
+};
+static const struct regmap_range dio48e_rd_ranges[] = {
+	regmap_reg_range(0x0, 0x2), regmap_reg_range(0x4, 0x6),
+	regmap_reg_range(0xB, 0xB), regmap_reg_range(0xD, 0xD),
+	regmap_reg_range(0xF, 0xF),
+};
+static const struct regmap_range dio48e_volatile_ranges[] = {
+	i8255_volatile_regmap_range(0x0), i8255_volatile_regmap_range(0x4),
+	regmap_reg_range(0xB, 0xB), regmap_reg_range(0xD, 0xD),
+	regmap_reg_range(0xF, 0xF),
+};
+static const struct regmap_range dio48e_precious_ranges[] = {
+	regmap_reg_range(0xB, 0xB), regmap_reg_range(0xD, 0xD),
+	regmap_reg_range(0xF, 0xF),
+};
+static const struct regmap_access_table dio48e_wr_table = {
+	.yes_ranges = dio48e_wr_ranges,
+	.n_yes_ranges = ARRAY_SIZE(dio48e_wr_ranges),
+};
+static const struct regmap_access_table dio48e_rd_table = {
+	.yes_ranges = dio48e_rd_ranges,
+	.n_yes_ranges = ARRAY_SIZE(dio48e_rd_ranges),
+};
+static const struct regmap_access_table dio48e_volatile_table = {
+	.yes_ranges = dio48e_volatile_ranges,
+	.n_yes_ranges = ARRAY_SIZE(dio48e_volatile_ranges),
+};
+static const struct regmap_access_table dio48e_precious_table = {
+	.yes_ranges = dio48e_precious_ranges,
+	.n_yes_ranges = ARRAY_SIZE(dio48e_precious_ranges),
+};
+static const struct regmap_config dio48e_regmap_config = {
+	.reg_bits = 8,
+	.reg_stride = 1,
+	.val_bits = 8,
+	.io_port = true,
+	.max_register = 0xF,
+	.wr_table = &dio48e_wr_table,
+	.rd_table = &dio48e_rd_table,
+	.volatile_table = &dio48e_volatile_table,
+	.precious_table = &dio48e_precious_table,
+	.cache_type = REGCACHE_FLAT,
+};
 
-	if (!dio48egpio->irq_mask) {
-		/* enable interrupts */
-		iowrite8(0x00, &dio48egpio->reg->clear_interrupt);
-		iowrite8(0x00, &dio48egpio->reg->enable_interrupt);
+/* only bit 3 on each respective Port C supports interrupts */
+#define DIO48E_REGMAP_IRQ(_ppi)						\
+	[19 + (_ppi) * 24] = {						\
+		.mask = BIT(_ppi),					\
+		.type = { .types_supported = IRQ_TYPE_EDGE_RISING },	\
 	}
 
-	gpiochip_enable_irq(chip, offset);
-	if (offset == 19)
-		dio48egpio->irq_mask |= BIT(0);
-	else
-		dio48egpio->irq_mask |= BIT(1);
-
-	raw_spin_unlock_irqrestore(&dio48egpio->lock, flags);
-}
-
-static int dio48e_irq_set_type(struct irq_data *data, unsigned int flow_type)
-{
-	const unsigned long offset = irqd_to_hwirq(data);
-
-	/* only bit 3 on each respective Port C supports interrupts */
-	if (offset != 19 && offset != 43)
-		return -EINVAL;
-
-	if (flow_type != IRQ_TYPE_NONE && flow_type != IRQ_TYPE_EDGE_RISING)
-		return -EINVAL;
-
-	return 0;
-}
-
-static const struct irq_chip dio48e_irqchip = {
-	.name = "104-dio-48e",
-	.irq_ack = dio48e_irq_ack,
-	.irq_mask = dio48e_irq_mask,
-	.irq_unmask = dio48e_irq_unmask,
-	.irq_set_type = dio48e_irq_set_type,
-	.flags = IRQCHIP_IMMUTABLE,
-	GPIOCHIP_IRQ_RESOURCE_HELPERS,
+static const struct regmap_irq dio48e_regmap_irqs[] = {
+	DIO48E_REGMAP_IRQ(0), DIO48E_REGMAP_IRQ(1),
 };
 
-static irqreturn_t dio48e_irq_handler(int irq, void *dev_id)
+static int dio48e_handle_mask_sync(struct regmap *const map, const int index,
+				   const unsigned int mask_buf_def,
+				   const unsigned int mask_buf,
+				   void *const irq_drv_data)
 {
-	struct dio48e_gpio *const dio48egpio = dev_id;
-	struct gpio_chip *const chip = &dio48egpio->chip;
-	const unsigned long irq_mask = dio48egpio->irq_mask;
-	unsigned long gpio;
+	unsigned int *const irq_mask = irq_drv_data;
+	const unsigned int prev_mask = *irq_mask;
+	const unsigned int all_masked = 0x3;
+	unsigned int val;
 
-	for_each_set_bit(gpio, &irq_mask, 2)
-		generic_handle_domain_irq(chip->irq.domain,
-					  19 + gpio*24);
+	/* exit early if no change since the previous mask */
+	if (mask_buf == prev_mask)
+		return 0;
 
-	raw_spin_lock(&dio48egpio->lock);
+	/* remember the current mask for the next mask sync */
+	*irq_mask = mask_buf;
 
-	iowrite8(0x00, &dio48egpio->reg->clear_interrupt);
+	/* if all previously masked, enable interrupts when unmasking */
+	if (prev_mask == all_masked)
+		return regmap_write(map, DIO48E_ENABLE_INTERRUPT, 0x00);
 
-	raw_spin_unlock(&dio48egpio->lock);
+	/* if all are currently masked, disable interrupts */
+	if (mask_buf == all_masked)
+		return regmap_read(map, DIO48E_DISABLE_INTERRUPT, &val);
 
-	return IRQ_HANDLED;
+	return 0;
 }
 
 #define DIO48E_NGPIO 48
@@ -266,14 +232,12 @@ static const char *dio48e_names[DIO48E_NGPIO] = {
 	"PPI Group 1 Port C 5", "PPI Group 1 Port C 6", "PPI Group 1 Port C 7"
 };
 
-static int dio48e_irq_init_hw(struct gpio_chip *gc)
+static int dio48e_irq_init_hw(struct regmap *const map)
 {
-	struct dio48e_gpio *const dio48egpio = gpiochip_get_data(gc);
+	unsigned int val;
 
 	/* Disable IRQ by default */
-	ioread8(&dio48egpio->reg->enable_interrupt);
-
-	return 0;
+	return regmap_read(map, DIO48E_DISABLE_INTERRUPT, &val);
 }
 
 static void dio48e_init_ppi(struct i8255 __iomem *const ppi,
@@ -295,8 +259,12 @@ static int dio48e_probe(struct device *dev, unsigned int id)
 {
 	struct dio48e_gpio *dio48egpio;
 	const char *const name = dev_name(dev);
-	struct gpio_irq_chip *girq;
+	void __iomem *regs;
+	struct regmap *map;
 	int err;
+	struct regmap_irq_chip *chip;
+	unsigned int irq_mask;
+	struct regmap_irq_chip_data *chip_data;
 
 	dio48egpio = devm_kzalloc(dev, sizeof(*dio48egpio), GFP_KERNEL);
 	if (!dio48egpio)
@@ -308,9 +276,43 @@ static int dio48e_probe(struct device *dev, unsigned int id)
 		return -EBUSY;
 	}
 
-	dio48egpio->reg = devm_ioport_map(dev, base[id], DIO48E_EXTENT);
-	if (!dio48egpio->reg)
+	regs = devm_ioport_map(dev, base[id], DIO48E_EXTENT);
+	if (!regs)
 		return -ENOMEM;
+	dio48egpio->reg = regs;
+
+	map = devm_regmap_init_mmio(dev, regs, &dio48e_regmap_config);
+	if (IS_ERR(map))
+		return dev_err_probe(dev, PTR_ERR(map),
+				     "Unable to initialize register map\n");
+
+	chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
+	if (!chip)
+		return -ENOMEM;
+
+	chip->irq_drv_data = devm_kzalloc(dev, sizeof(irq_mask), GFP_KERNEL);
+	if (!chip->irq_drv_data)
+		return -ENOMEM;
+
+	chip->name = name;
+	/* No IRQ status register so use CLEAR_INTERRUPT register instead */
+	chip->status_base = DIO48E_CLEAR_INTERRUPT;
+	chip->mask_base = DIO48E_ENABLE_INTERRUPT;
+	chip->clear_on_unmask = true;
+	chip->status_invert = true;
+	chip->num_regs = 1;
+	chip->irqs = dio48e_regmap_irqs;
+	chip->num_irqs = ARRAY_SIZE(dio48e_regmap_irqs);
+	chip->handle_mask_sync = dio48e_handle_mask_sync;
+
+	/* Initialize to prevent spurious interrupts before we're ready */
+	err = dio48e_irq_init_hw(map);
+	if (err)
+		return err;
+
+	err = devm_regmap_add_irq_chip(dev, map, irq[id], 0, 0, chip, &chip_data);
+	if (err)
+		return dev_err_probe(dev, err, "IRQ registration failed\n");
 
 	dio48egpio->chip.label = name;
 	dio48egpio->chip.parent = dev;
@@ -326,18 +328,6 @@ static int dio48e_probe(struct device *dev, unsigned int id)
 	dio48egpio->chip.set = dio48e_gpio_set;
 	dio48egpio->chip.set_multiple = dio48e_gpio_set_multiple;
 
-	girq = &dio48egpio->chip.irq;
-	gpio_irq_chip_set_chip(girq, &dio48e_irqchip);
-	/* This will let us handle the parent IRQ in the driver */
-	girq->parent_handler = NULL;
-	girq->num_parents = 0;
-	girq->parents = NULL;
-	girq->default_type = IRQ_TYPE_NONE;
-	girq->handler = handle_edge_irq;
-	girq->init_hw = dio48e_irq_init_hw;
-
-	raw_spin_lock_init(&dio48egpio->lock);
-
 	i8255_state_init(dio48egpio->ppi_state, DIO48E_NUM_PPI);
 	dio48e_init_ppi(dio48egpio->reg->ppi, dio48egpio->ppi_state);
 
@@ -347,14 +337,8 @@ static int dio48e_probe(struct device *dev, unsigned int id)
 		return err;
 	}
 
-	err = devm_request_irq(dev, irq[id], dio48e_irq_handler, 0, name,
-		dio48egpio);
-	if (err) {
-		dev_err(dev, "IRQ handler registering failed (%d)\n", err);
-		return err;
-	}
-
-	return 0;
+	return gpiochip_irqchip_add_domain(&dio48egpio->chip,
+					   regmap_irq_get_domain(chip_data));
 }
 
 static struct isa_driver dio48e_driver = {
-- 
2.38.1