Re: [PATCH v5 1/4] gpio: idio-16: Migrate to the regmap API

Andy Shevchenko
2023-04-05T09:01:15Z

On Tue, Apr 04, 2023 at 10:32:45AM -0400, 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.
>
> By leveraging the regmap API, the idio-16 library is reduced to simply a
> devm_idio_16_regmap_register() function and a configuration structure
> struct idio_16_regmap_config.
>
> Legacy functions and code will be removed once all consumers have
> migrated to the new idio-16 library interface.
>
> For IDIO-16 devices we have the following IRQ registers:
>
> Base Address +1 (Write): Clear Interrupt
> Base Address +2 (Read): Enable Interrupt
> Base Address +2 (Write): Disable Interrupt
>
> An interrupt is asserted whenever a change-of-state is detected on any
> of the inputs. Any write to 0x2 will disable interrupts, while any read
> will enable interrupts. Interrupts are cleared by a write to 0x1.
>
> For 104-IDIO-16 devices, there is no IRQ status register, so software
> has to assume that if an interrupt is raised then it was for the
> 104-IDIO-16 device.
>
> For PCI-IDIO-16 devices, there is an additional IRQ register:
>
> Base Address +6 (Read): Interrupt Status
>
> Interrupt status can be read from 0x6 where bit 2 set indicates that an
> IRQ has been generated.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

> Signed-off-by: William Breathitt Gray <william.gray@linaro.org>
> ---
> Changes in v5: none
>
> drivers/gpio/Kconfig | 3 +
> drivers/gpio/gpio-idio-16.c | 155 ++++++++++++++++++++++++++++++++++++
> drivers/gpio/gpio-idio-16.h | 26 ++++++
> 3 files changed, 184 insertions(+)
>
> diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
> index 68f58b0ba79f..415b86cfd1a9 100644
> --- a/drivers/gpio/Kconfig
> +++ b/drivers/gpio/Kconfig
> @@ -111,6 +111,9 @@ config GPIO_MAX730X
>
> config GPIO_IDIO_16
> tristate
> + select REGMAP_IRQ
> + select GPIOLIB_IRQCHIP
> + select GPIO_REGMAP
> help
> Enables support for the idio-16 library functions. The idio-16 library
> provides functions to facilitate communication with devices within the
> diff --git a/drivers/gpio/gpio-idio-16.c b/drivers/gpio/gpio-idio-16.c
> index 13315242d220..f9349e8d7fdc 100644
> --- a/drivers/gpio/gpio-idio-16.c
> +++ b/drivers/gpio/gpio-idio-16.c
> @@ -4,9 +4,13 @@
> * Copyright (C) 2022 William Breathitt Gray
> */
> #include <linux/bitmap.h>
> +#include <linux/device.h>
> +#include <linux/err.h>
> #include <linux/export.h>
> +#include <linux/gpio/regmap.h>
> #include <linux/io.h>
> #include <linux/module.h>
> +#include <linux/regmap.h>
> #include <linux/spinlock.h>
> #include <linux/types.h>
>
> @@ -14,6 +18,157 @@
>
> #define DEFAULT_SYMBOL_NAMESPACE GPIO_IDIO_16
>
> +#define IDIO_16_DAT_BASE 0x0
> +#define IDIO_16_OUT_BASE IDIO_16_DAT_BASE
> +#define IDIO_16_IN_BASE (IDIO_16_DAT_BASE + 1)
> +#define IDIO_16_CLEAR_INTERRUPT 0x1
> +#define IDIO_16_ENABLE_IRQ 0x2
> +#define IDIO_16_DEACTIVATE_INPUT_FILTERS 0x3
> +#define IDIO_16_DISABLE_IRQ IDIO_16_ENABLE_IRQ
> +#define IDIO_16_INTERRUPT_STATUS 0x6
> +
> +#define IDIO_16_NGPIO 32
> +#define IDIO_16_NGPIO_PER_REG 8
> +#define IDIO_16_REG_STRIDE 4
> +
> +struct idio_16_data {
> + struct regmap *map;
> + unsigned int irq_mask;
> +};
> +
> +static int idio_16_handle_mask_sync(const int index, const unsigned int mask_buf_def,
> + const unsigned int mask_buf, void *const irq_drv_data)
> +{
> + struct idio_16_data *const data = irq_drv_data;
> + const unsigned int prev_mask = data->irq_mask;
> + int err;
> + unsigned int val;
> +
> + /* exit early if no change since the previous mask */
> + if (mask_buf == prev_mask)
> + return 0;
> +
> + /* remember the current mask for the next mask sync */
> + data->irq_mask = mask_buf;
> +
> + /* if all previously masked, enable interrupts when unmasking */
> + if (prev_mask == mask_buf_def) {
> + err = regmap_write(data->map, IDIO_16_CLEAR_INTERRUPT, 0x00);
> + if (err)
> + return err;
> + return regmap_read(data->map, IDIO_16_ENABLE_IRQ, &val);
> + }
> +
> + /* if all are currently masked, disable interrupts */
> + if (mask_buf == mask_buf_def)
> + return regmap_write(data->map, IDIO_16_DISABLE_IRQ, 0x00);
> +
> + return 0;
> +}
> +
> +static int idio_16_reg_mask_xlate(struct gpio_regmap *const gpio, const unsigned int base,
> + const unsigned int offset, unsigned int *const reg,
> + unsigned int *const mask)
> +{
> + unsigned int stride;
> +
> + /* Input lines start at GPIO 16 */
> + if (offset < 16) {
> + stride = offset / IDIO_16_NGPIO_PER_REG;
> + *reg = IDIO_16_OUT_BASE + stride * IDIO_16_REG_STRIDE;
> + } else {
> + stride = (offset - 16) / IDIO_16_NGPIO_PER_REG;
> + *reg = IDIO_16_IN_BASE + stride * IDIO_16_REG_STRIDE;
> + }
> +
> + *mask = BIT(offset % IDIO_16_NGPIO_PER_REG);
> +
> + return 0;
> +}
> +
> +static const char *idio_16_names[IDIO_16_NGPIO] = {
> + "OUT0", "OUT1", "OUT2", "OUT3", "OUT4", "OUT5", "OUT6", "OUT7",
> + "OUT8", "OUT9", "OUT10", "OUT11", "OUT12", "OUT13", "OUT14", "OUT15",
> + "IIN0", "IIN1", "IIN2", "IIN3", "IIN4", "IIN5", "IIN6", "IIN7",
> + "IIN8", "IIN9", "IIN10", "IIN11", "IIN12", "IIN13", "IIN14", "IIN15",
> +};
> +
> +/**
> + * devm_idio_16_regmap_register - Register an IDIO-16 GPIO device
> + * @dev: device that is registering this IDIO-16 GPIO device
> + * @config: configuration for idio_16_regmap_config
> + *
> + * Registers an IDIO-16 GPIO device. Returns 0 on success and negative error number on failure.
> + */
> +int devm_idio_16_regmap_register(struct device *const dev,
> + const struct idio_16_regmap_config *const config)
> +{
> + struct gpio_regmap_config gpio_config = {};
> + int err;
> + struct idio_16_data *data;
> + struct regmap_irq_chip *chip;
> + struct regmap_irq_chip_data *chip_data;
> +
> + if (!config->parent)
> + return -EINVAL;
> +
> + if (!config->map)
> + return -EINVAL;
> +
> + if (!config->regmap_irqs)
> + return -EINVAL;
> +
> + data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
> + if (!data)
> + return -ENOMEM;
> + data->map = config->map;
> +
> + chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
> + if (!chip)
> + return -ENOMEM;
> +
> + chip->name = dev_name(dev);
> + chip->status_base = IDIO_16_INTERRUPT_STATUS;
> + chip->mask_base = IDIO_16_ENABLE_IRQ;
> + chip->ack_base = IDIO_16_CLEAR_INTERRUPT;
> + chip->no_status = config->no_status;
> + chip->num_regs = 1;
> + chip->irqs = config->regmap_irqs;
> + chip->num_irqs = config->num_regmap_irqs;
> + chip->handle_mask_sync = idio_16_handle_mask_sync;
> + chip->irq_drv_data = data;
> +
> + /* Disable IRQ to prevent spurious interrupts before we're ready */
> + err = regmap_write(data->map, IDIO_16_DISABLE_IRQ, 0x00);
> + if (err)
> + return err;
> +
> + err = devm_regmap_add_irq_chip(dev, data->map, config->irq, 0, 0, chip, &chip_data);
> + if (err)
> + return dev_err_probe(dev, err, "IRQ registration failed\n");
> +
> + if (config->filters) {
> + /* Deactivate input filters */
> + err = regmap_write(data->map, IDIO_16_DEACTIVATE_INPUT_FILTERS, 0x00);
> + if (err)
> + return err;
> + }
> +
> + gpio_config.parent = config->parent;
> + gpio_config.regmap = data->map;
> + gpio_config.ngpio = IDIO_16_NGPIO;
> + gpio_config.names = idio_16_names;
> + gpio_config.reg_dat_base = GPIO_REGMAP_ADDR(IDIO_16_DAT_BASE);
> + gpio_config.reg_set_base = GPIO_REGMAP_ADDR(IDIO_16_DAT_BASE);
> + gpio_config.ngpio_per_reg = IDIO_16_NGPIO_PER_REG;
> + gpio_config.reg_stride = IDIO_16_REG_STRIDE;
> + gpio_config.irq_domain = regmap_irq_get_domain(chip_data);
> + gpio_config.reg_mask_xlate = idio_16_reg_mask_xlate;
> +
> + return PTR_ERR_OR_ZERO(devm_gpio_regmap_register(dev, &gpio_config));
> +}
> +EXPORT_SYMBOL_GPL(devm_idio_16_regmap_register);
> +
> /**
> * idio_16_get - get signal value at signal offset
> * @reg: ACCES IDIO-16 device registers
> diff --git a/drivers/gpio/gpio-idio-16.h b/drivers/gpio/gpio-idio-16.h
> index 928f8251a2bd..255bd8504ed7 100644
> --- a/drivers/gpio/gpio-idio-16.h
> +++ b/drivers/gpio/gpio-idio-16.h
> @@ -6,6 +6,30 @@
> #include <linux/spinlock.h>
> #include <linux/types.h>
>
> +struct device;
> +struct regmap;
> +struct regmap_irq;
> +
> +/**
> + * struct idio_16_regmap_config - Configuration for the IDIO-16 register map
> + * @parent: parent device
> + * @map: regmap for the IDIO-16 device
> + * @regmap_irqs: descriptors for individual IRQs
> + * @num_regmap_irqs: number of IRQ descriptors
> + * @irq: IRQ number for the IDIO-16 device
> + * @no_status: device has no status register
> + * @filters: device has input filters
> + */
> +struct idio_16_regmap_config {
> + struct device *parent;
> + struct regmap *map;
> + const struct regmap_irq *regmap_irqs;
> + int num_regmap_irqs;
> + unsigned int irq;
> + bool no_status;
> + bool filters;
> +};
> +
> /**
> * struct idio_16 - IDIO-16 registers structure
> * @out0_7: Read: FET Drive Outputs 0-7
> @@ -68,4 +92,6 @@ void idio_16_set_multiple(struct idio_16 __iomem *reg,
> const unsigned long *mask, const unsigned long *bits);
> void idio_16_state_init(struct idio_16_state *state);
>
> +int devm_idio_16_regmap_register(struct device *dev, const struct idio_16_regmap_config *config);
> +
> #endif /* _IDIO_16_H_ */
> --
> 2.39.2
>

--
With Best Regards,
Andy Shevchenko