Re: [PATCH v4 4/9] gpio: 104-idi-48: Migrate to the regmap-irq API

[Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>]

On Fri, Dec 02, 2022 at 11:27:10AM -0500, William Breathitt Gray wrote:
> 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-idi-48, we get an IRQ register with some status information
> and basic masking, but it's broken down by banks rather than individual
> GPIO. There are six banks (8 GPIO lines each) that correspond to the
> lower six bits of the IRQ register (bits 0-5):
> 
>     Base Address + 7 (Read): IRQ Status Register/IRQ Clear
>         Bit 0-5: Respective Bank IRQ Statuses
>         Bit 6: IRQ Status (Active Low)
>         Bit 7: IRQ Enable Status
>     Base Address + 7 (Write): IRQ Enable/Disable
>         Bit 0-5: Respective Bank IRQ Enable/Disable

Assuming the regmap IRQ changes are accepted,
Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>

> Signed-off-by: William Breathitt Gray <william.gray@xxxxxxxxxx>
> ---
>  drivers/gpio/Kconfig           |   1 +
>  drivers/gpio/gpio-104-idi-48.c | 249 ++++++++++++---------------------
>  2 files changed, 92 insertions(+), 158 deletions(-)
> 
> diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
> index b62bef4e563d..6892979e511a 100644
> --- a/drivers/gpio/Kconfig
> +++ b/drivers/gpio/Kconfig
> @@ -871,6 +871,7 @@ config GPIO_104_IDI_48
>  	tristate "ACCES 104-IDI-48 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-idi-48.c b/drivers/gpio/gpio-104-idi-48.c
> index c5e231fde1af..f936e3e0ff12 100644
> --- a/drivers/gpio/gpio-104-idi-48.c
> +++ b/drivers/gpio/gpio-104-idi-48.c
> @@ -8,17 +8,16 @@
>   */
>  #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/ioport.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"
> @@ -38,6 +37,9 @@ static unsigned int num_irq;
>  module_param_hw_array(irq, uint, irq, &num_irq, 0);
>  MODULE_PARM_DESC(irq, "ACCES 104-IDI-48 interrupt line numbers");
>  
> +#define IDI48_IRQ_STATUS 0x7
> +#define IDI48_IRQ_ENABLE IDI48_IRQ_STATUS
> +
>  /**
>   * struct idi_48_reg - device register structure
>   * @port0:	Port 0 Inputs
> @@ -56,17 +58,11 @@ struct idi_48_reg {
>  /**
>   * struct idi_48_gpio - GPIO device private data structure
>   * @chip:	instance of the gpio_chip
> - * @lock:	synchronization lock to prevent I/O race conditions
> - * @irq_mask:	input bits affected by interrupts
>   * @reg:	I/O address offset for the device registers
> - * @cos_enb:	Change-Of-State IRQ enable boundaries mask
>   */
>  struct idi_48_gpio {
>  	struct gpio_chip chip;
> -	spinlock_t lock;
> -	unsigned char irq_mask[6];
>  	struct idi_48_reg __iomem *reg;
> -	unsigned char cos_enb;
>  };
>  
>  static int idi_48_gpio_get_direction(struct gpio_chip *chip, unsigned int offset)
> @@ -98,125 +94,65 @@ static int idi_48_gpio_get_multiple(struct gpio_chip *chip, unsigned long *mask,
>  	return 0;
>  }
>  
> -static void idi_48_irq_ack(struct irq_data *data)
> -{
> -}
> -
> -static void idi_48_irq_mask(struct irq_data *data)
> -{
> -	struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
> -	struct idi_48_gpio *const idi48gpio = gpiochip_get_data(chip);
> -	const unsigned int offset = irqd_to_hwirq(data);
> -	const unsigned long boundary = offset / 8;
> -	const unsigned long mask = BIT(offset % 8);
> -	unsigned long flags;
> -
> -	spin_lock_irqsave(&idi48gpio->lock, flags);
> -
> -	idi48gpio->irq_mask[boundary] &= ~mask;
> -	gpiochip_disable_irq(chip, offset);
> -
> -	/* Exit early if there are still input lines with IRQ unmasked */
> -	if (idi48gpio->irq_mask[boundary])
> -		goto exit;
> -
> -	idi48gpio->cos_enb &= ~BIT(boundary);
> -
> -	iowrite8(idi48gpio->cos_enb, &idi48gpio->reg->irq);
> -
> -exit:
> -	spin_unlock_irqrestore(&idi48gpio->lock, flags);
> -}
> -
> -static void idi_48_irq_unmask(struct irq_data *data)
> -{
> -	struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
> -	struct idi_48_gpio *const idi48gpio = gpiochip_get_data(chip);
> -	const unsigned int offset = irqd_to_hwirq(data);
> -	const unsigned long boundary = offset / 8;
> -	const unsigned long mask = BIT(offset % 8);
> -	unsigned int prev_irq_mask;
> -	unsigned long flags;
> -
> -	spin_lock_irqsave(&idi48gpio->lock, flags);
> -
> -	prev_irq_mask = idi48gpio->irq_mask[boundary];
> -
> -	gpiochip_enable_irq(chip, offset);
> -	idi48gpio->irq_mask[boundary] |= mask;
> -
> -	/* Exit early if IRQ was already unmasked for this boundary */
> -	if (prev_irq_mask)
> -		goto exit;
> -
> -	idi48gpio->cos_enb |= BIT(boundary);
> -
> -	iowrite8(idi48gpio->cos_enb, &idi48gpio->reg->irq);
> -
> -exit:
> -	spin_unlock_irqrestore(&idi48gpio->lock, flags);
> -}
> -
> -static int idi_48_irq_set_type(struct irq_data *data, unsigned int flow_type)
> -{
> -	/* The only valid irq types are none and both-edges */
> -	if (flow_type != IRQ_TYPE_NONE &&
> -		(flow_type & IRQ_TYPE_EDGE_BOTH) != IRQ_TYPE_EDGE_BOTH)
> -		return -EINVAL;
> -
> -	return 0;
> -}
> -
> -static const struct irq_chip idi_48_irqchip = {
> -	.name = "104-idi-48",
> -	.irq_ack = idi_48_irq_ack,
> -	.irq_mask = idi_48_irq_mask,
> -	.irq_unmask = idi_48_irq_unmask,
> -	.irq_set_type = idi_48_irq_set_type,
> -	.flags = IRQCHIP_IMMUTABLE,
> -	GPIOCHIP_IRQ_RESOURCE_HELPERS,
> +static const struct regmap_range idi_48_wr_ranges[] = {
> +	regmap_reg_range(0x0, 0x6),
> +};
> +static const struct regmap_range idi_48_rd_ranges[] = {
> +	regmap_reg_range(0x0, 0x2), regmap_reg_range(0x4, 0x7),
> +};
> +static const struct regmap_range idi_48_precious_ranges[] = {
> +	regmap_reg_range(0x7, 0x7),
> +};
> +static const struct regmap_access_table idi_48_wr_table = {
> +	.no_ranges = idi_48_wr_ranges,
> +	.n_no_ranges = ARRAY_SIZE(idi_48_wr_ranges),
> +};
> +static const struct regmap_access_table idi_48_rd_table = {
> +	.yes_ranges = idi_48_rd_ranges,
> +	.n_yes_ranges = ARRAY_SIZE(idi_48_rd_ranges),
> +};
> +static const struct regmap_access_table idi_48_precious_table = {
> +	.yes_ranges = idi_48_precious_ranges,
> +	.n_yes_ranges = ARRAY_SIZE(idi_48_precious_ranges),
> +};
> +static const struct regmap_config idi48_regmap_config = {
> +	.reg_bits = 8,
> +	.reg_stride = 1,
> +	.val_bits = 8,
> +	.io_port = true,
> +	.max_register = 0x6,
> +	.wr_table = &idi_48_wr_table,
> +	.rd_table = &idi_48_rd_table,
> +	.precious_table = &idi_48_precious_table,
>  };
>  
> -static irqreturn_t idi_48_irq_handler(int irq, void *dev_id)
> -{
> -	struct idi_48_gpio *const idi48gpio = dev_id;
> -	unsigned long cos_status;
> -	unsigned long boundary;
> -	unsigned long irq_mask;
> -	unsigned long bit_num;
> -	unsigned long gpio;
> -	struct gpio_chip *const chip = &idi48gpio->chip;
> -
> -	spin_lock(&idi48gpio->lock);
> -
> -	cos_status = ioread8(&idi48gpio->reg->irq);
> -
> -	/* IRQ Status (bit 6) is active low (0 = IRQ generated by device) */
> -	if (cos_status & BIT(6)) {
> -		spin_unlock(&idi48gpio->lock);
> -		return IRQ_NONE;
> -	}
> -
> -	/* Bit 0-5 indicate which Change-Of-State boundary triggered the IRQ */
> -	cos_status &= 0x3F;
> -
> -	for_each_set_bit(boundary, &cos_status, 6) {
> -		irq_mask = idi48gpio->irq_mask[boundary];
> -
> -		for_each_set_bit(bit_num, &irq_mask, 8) {
> -			gpio = bit_num + boundary * 8;
> +#define IDI48_NGPIO 48
>  
> -			generic_handle_domain_irq(chip->irq.domain,
> -						  gpio);
> -		}
> +#define IDI48_REGMAP_IRQ(_id)						\
> +	[_id] = {							\
> +		.mask = BIT((_id) / 8),					\
> +		.type = { .types_supported = IRQ_TYPE_EDGE_BOTH },	\
>  	}
>  
> -	spin_unlock(&idi48gpio->lock);
> -
> -	return IRQ_HANDLED;
> -}
> +static const struct regmap_irq idi48_regmap_irqs[IDI48_NGPIO] = {
> +	IDI48_REGMAP_IRQ(0), IDI48_REGMAP_IRQ(1), IDI48_REGMAP_IRQ(2), /* 0-2 */
> +	IDI48_REGMAP_IRQ(3), IDI48_REGMAP_IRQ(4), IDI48_REGMAP_IRQ(5), /* 3-5 */
> +	IDI48_REGMAP_IRQ(6), IDI48_REGMAP_IRQ(7), IDI48_REGMAP_IRQ(8), /* 6-8 */
> +	IDI48_REGMAP_IRQ(9), IDI48_REGMAP_IRQ(10), IDI48_REGMAP_IRQ(11), /* 9-11 */
> +	IDI48_REGMAP_IRQ(12), IDI48_REGMAP_IRQ(13), IDI48_REGMAP_IRQ(14), /* 12-14 */
> +	IDI48_REGMAP_IRQ(15), IDI48_REGMAP_IRQ(16), IDI48_REGMAP_IRQ(17), /* 15-17 */
> +	IDI48_REGMAP_IRQ(18), IDI48_REGMAP_IRQ(19), IDI48_REGMAP_IRQ(20), /* 18-20 */
> +	IDI48_REGMAP_IRQ(21), IDI48_REGMAP_IRQ(22), IDI48_REGMAP_IRQ(23), /* 21-23 */
> +	IDI48_REGMAP_IRQ(24), IDI48_REGMAP_IRQ(25), IDI48_REGMAP_IRQ(26), /* 24-26 */
> +	IDI48_REGMAP_IRQ(27), IDI48_REGMAP_IRQ(28), IDI48_REGMAP_IRQ(29), /* 27-29 */
> +	IDI48_REGMAP_IRQ(30), IDI48_REGMAP_IRQ(31), IDI48_REGMAP_IRQ(32), /* 30-32 */
> +	IDI48_REGMAP_IRQ(33), IDI48_REGMAP_IRQ(34), IDI48_REGMAP_IRQ(35), /* 33-35 */
> +	IDI48_REGMAP_IRQ(36), IDI48_REGMAP_IRQ(37), IDI48_REGMAP_IRQ(38), /* 36-38 */
> +	IDI48_REGMAP_IRQ(39), IDI48_REGMAP_IRQ(40), IDI48_REGMAP_IRQ(41), /* 39-41 */
> +	IDI48_REGMAP_IRQ(42), IDI48_REGMAP_IRQ(43), IDI48_REGMAP_IRQ(44), /* 42-44 */
> +	IDI48_REGMAP_IRQ(45), IDI48_REGMAP_IRQ(46), IDI48_REGMAP_IRQ(47), /* 45-47 */
> +};
>  
> -#define IDI48_NGPIO 48
>  static const char *idi48_names[IDI48_NGPIO] = {
>  	"Bit 0 A", "Bit 1 A", "Bit 2 A", "Bit 3 A", "Bit 4 A", "Bit 5 A",
>  	"Bit 6 A", "Bit 7 A", "Bit 8 A", "Bit 9 A", "Bit 10 A", "Bit 11 A",
> @@ -228,22 +164,14 @@ static const char *idi48_names[IDI48_NGPIO] = {
>  	"Bit 18 B", "Bit 19 B", "Bit 20 B", "Bit 21 B", "Bit 22 B", "Bit 23 B"
>  };
>  
> -static int idi_48_irq_init_hw(struct gpio_chip *gc)
> -{
> -	struct idi_48_gpio *const idi48gpio = gpiochip_get_data(gc);
> -
> -	/* Disable IRQ by default */
> -	iowrite8(0, &idi48gpio->reg->irq);
> -	ioread8(&idi48gpio->reg->irq);
> -
> -	return 0;
> -}
> -
>  static int idi_48_probe(struct device *dev, unsigned int id)
>  {
>  	struct idi_48_gpio *idi48gpio;
>  	const char *const name = dev_name(dev);
> -	struct gpio_irq_chip *girq;
> +	void __iomem *regs;
> +	struct regmap *map;
> +	struct regmap_irq_chip *chip;
> +	struct regmap_irq_chip_data *chip_data;
>  	int err;
>  
>  	idi48gpio = devm_kzalloc(dev, sizeof(*idi48gpio), GFP_KERNEL);
> @@ -256,9 +184,32 @@ static int idi_48_probe(struct device *dev, unsigned int id)
>  		return -EBUSY;
>  	}
>  
> -	idi48gpio->reg = devm_ioport_map(dev, base[id], IDI_48_EXTENT);
> -	if (!idi48gpio->reg)
> +	regs = devm_ioport_map(dev, base[id], IDI_48_EXTENT);
> +	if (!regs)
>  		return -ENOMEM;
> +	idi48gpio->reg = regs;
> +
> +	map = devm_regmap_init_mmio(dev, regs, &idi48_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->name = name;
> +	chip->status_base = IDI48_IRQ_STATUS;
> +	chip->unmask_base = IDI48_IRQ_ENABLE;
> +	chip->clear_on_unmask = true;
> +	chip->num_regs = 1;
> +	chip->irqs = idi48_regmap_irqs;
> +	chip->num_irqs = ARRAY_SIZE(idi48_regmap_irqs);
> +
> +	err = devm_regmap_add_irq_chip(dev, map, irq[id], IRQF_SHARED, 0, chip,
> +				       &chip_data);
> +	if (err)
> +		return dev_err_probe(dev, err, "IRQ registration failed\n");
>  
>  	idi48gpio->chip.label = name;
>  	idi48gpio->chip.parent = dev;
> @@ -271,32 +222,14 @@ static int idi_48_probe(struct device *dev, unsigned int id)
>  	idi48gpio->chip.get = idi_48_gpio_get;
>  	idi48gpio->chip.get_multiple = idi_48_gpio_get_multiple;
>  
> -	girq = &idi48gpio->chip.irq;
> -	gpio_irq_chip_set_chip(girq, &idi_48_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 = idi_48_irq_init_hw;
> -
> -	spin_lock_init(&idi48gpio->lock);
> -
>  	err = devm_gpiochip_add_data(dev, &idi48gpio->chip, idi48gpio);
>  	if (err) {
>  		dev_err(dev, "GPIO registering failed (%d)\n", err);
>  		return err;
>  	}
>  
> -	err = devm_request_irq(dev, irq[id], idi_48_irq_handler, IRQF_SHARED,
> -		name, idi48gpio);
> -	if (err) {
> -		dev_err(dev, "IRQ handler registering failed (%d)\n", err);
> -		return err;
> -	}
> -
> -	return 0;
> +	return gpiochip_irqchip_add_domain(&idi48gpio->chip,
> +					   regmap_irq_get_domain(chip_data));
>  }
>  
>  static struct isa_driver idi_48_driver = {
> -- 
> 2.38.1
> 

-- 
With Best Regards,
Andy Shevchenko