Message-Id: <be8ddc3befbcce31546d64f70523d08b3e1e0070.1669996867.git.william.gray@linaro.org>
Date:   Fri,  2 Dec 2022 11:27:09 -0500
From:   William Breathitt Gray <william.gray@...aro.org>
To:     linus.walleij@...aro.org, brgl@...ev.pl
Cc:     andriy.shevchenko@...ux.intel.com, linux-gpio@...r.kernel.org,
        linux-kernel@...r.kernel.org, michael@...le.cc, broonie@...nel.org,
        William Breathitt Gray <william.gray@...aro.org>
Subject: [PATCH v4 3/9] gpio: 104-dio-48e: Migrate to the regmap-irq API

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@...aro.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

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