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

William Breathitt Gray
2023-04-04T14:33:05Z

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.

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