[PATCH v5 5/8] gpio: i8255: Migrate to gpio-regmap API

William Breathitt Gray
2022-12-27T14:33:51Z

directly in the driver.

By leveraging the gpio-regmap API, the i8255 library is reduced to
simply a devm_i8255_regmap_register() function, a configuration
structure struct i8255_regmap_config, and a helper macro
i8255_volatile_regmap_range() provided to simplify volatile PPI register
hinting for the regmap.

Legacy functions and code will be removed once all consumers have
migrated to the new i8255 library interface.

Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: William Breathitt Gray <william.gray@linaro.org>
---
drivers/gpio/Kconfig | 1 +
drivers/gpio/gpio-i8255.c | 119 ++++++++++++++++++++++++++++++++++----
drivers/gpio/gpio-i8255.h | 28 +++++++++
3 files changed, 136 insertions(+), 12 deletions(-)

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 84316924574f..63acb9cb4c58 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -831,6 +831,7 @@ menu "Port-mapped I/O GPIO drivers"

config GPIO_I8255
tristate
+ select GPIO_REGMAP
help
Enables support for the i8255 interface library functions. The i8255
interface library provides functions to facilitate communication with
diff --git a/drivers/gpio/gpio-i8255.c b/drivers/gpio/gpio-i8255.c
index 9b97db418df1..9ecb2e9b97f9 100644
--- a/drivers/gpio/gpio-i8255.c
+++ b/drivers/gpio/gpio-i8255.c
@@ -4,23 +4,31 @@
* 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>

#include "gpio-i8255.h"

+#define I8255_NGPIO 24
+#define I8255_NGPIO_PER_REG 8
#define I8255_CONTROL_PORTC_LOWER_DIRECTION BIT(0)
#define I8255_CONTROL_PORTB_DIRECTION BIT(1)
#define I8255_CONTROL_PORTC_UPPER_DIRECTION BIT(3)
#define I8255_CONTROL_PORTA_DIRECTION BIT(4)
#define I8255_CONTROL_MODE_SET BIT(7)
-#define I8255_PORTA 0
-#define I8255_PORTB 1
-#define I8255_PORTC 2
+#define I8255_PORTA 0x0
+#define I8255_PORTB 0x1
+#define I8255_PORTC 0x2
+#define I8255_CONTROL 0x3
+#define I8255_REG_DAT_BASE I8255_PORTA
+#define I8255_REG_DIR_IN_BASE I8255_CONTROL

static int i8255_get_port(struct i8255 __iomem *const ppi,
const unsigned long io_port, const unsigned long mask)
@@ -31,20 +39,19 @@ static int i8255_get_port(struct i8255 __iomem *const ppi,
return ioread8(&ppi[bank].port[ppi_port]) & mask;
}

-static u8 i8255_direction_mask(const unsigned long offset)
+static int i8255_direction_mask(const unsigned int offset)
{
- const unsigned long port_offset = offset % 8;
- const unsigned long io_port = offset / 8;
- const unsigned long ppi_port = io_port % 3;
+ const unsigned int stride = offset / I8255_NGPIO_PER_REG;
+ const unsigned int line = offset % I8255_NGPIO_PER_REG;

- switch (ppi_port) {
+ switch (stride) {
case I8255_PORTA:
return I8255_CONTROL_PORTA_DIRECTION;
case I8255_PORTB:
return I8255_CONTROL_PORTB_DIRECTION;
case I8255_PORTC:
/* Port C can be configured by nibble */
- if (port_offset >= 4)
+ if (line >= 4)
return I8255_CONTROL_PORTC_UPPER_DIRECTION;
return I8255_CONTROL_PORTC_LOWER_DIRECTION;
default:
@@ -53,6 +60,49 @@ static u8 i8255_direction_mask(const unsigned long offset)
}
}

+static int i8255_ppi_init(struct regmap *const map, const unsigned int base)
+{
+ int err;
+
+ /* Configure all ports to MODE 0 output mode */
+ err = regmap_write(map, base + I8255_CONTROL, I8255_CONTROL_MODE_SET);
+ if (err)
+ return err;
+
+ /* Initialize all GPIO to output 0 */
+ err = regmap_write(map, base + I8255_PORTA, 0x00);
+ if (err)
+ return err;
+ err = regmap_write(map, base + I8255_PORTB, 0x00);
+ if (err)
+ return err;
+ return regmap_write(map, base + I8255_PORTC, 0x00);
+}
+
+static int i8255_reg_mask_xlate(struct gpio_regmap *gpio, unsigned int base,
+ unsigned int offset, unsigned int *reg,
+ unsigned int *mask)
+{
+ const unsigned int ppi = offset / I8255_NGPIO;
+ const unsigned int ppi_offset = offset % I8255_NGPIO;
+ const unsigned int stride = ppi_offset / I8255_NGPIO_PER_REG;
+ const unsigned int line = ppi_offset % I8255_NGPIO_PER_REG;
+
+ switch (base) {
+ case I8255_REG_DAT_BASE:
+ *reg = base + stride + ppi * 4;
+ *mask = BIT(line);
+ return 0;
+ case I8255_REG_DIR_IN_BASE:
+ *reg = base + ppi * 4;
+ *mask = i8255_direction_mask(ppi_offset);
+ return 0;
+ default:
+ /* Should never reach this path */
+ return -EINVAL;
+ }
+}
+
static void i8255_set_port(struct i8255 __iomem *const ppi,
struct i8255_state *const state,
const unsigned long io_port,
@@ -93,7 +143,7 @@ void i8255_direction_input(struct i8255 __iomem *const ppi,
spin_lock_irqsave(&state[bank].lock, flags);

state[bank].control_state |= I8255_CONTROL_MODE_SET;
- state[bank].control_state |= i8255_direction_mask(offset);
+ state[bank].control_state |= i8255_direction_mask(offset % 24);

iowrite8(state[bank].control_state, &ppi[bank].control);

@@ -125,7 +175,7 @@ void i8255_direction_output(struct i8255 __iomem *const ppi,
spin_lock_irqsave(&state[bank].lock, flags);

state[bank].control_state |= I8255_CONTROL_MODE_SET;
- state[bank].control_state &= ~i8255_direction_mask(offset);
+ state[bank].control_state &= ~i8255_direction_mask(offset % 24);

iowrite8(state[bank].control_state, &ppi[bank].control);

@@ -165,7 +215,7 @@ int i8255_get_direction(const struct i8255_state *const state,
const unsigned long io_port = offset / 8;
const unsigned long bank = io_port / 3;

- return !!(state[bank].control_state & i8255_direction_mask(offset));
+ return !!(state[bank].control_state & i8255_direction_mask(offset % 24));
}
EXPORT_SYMBOL_NS_GPL(i8255_get_direction, I8255);

@@ -282,6 +332,51 @@ void i8255_state_init(struct i8255_state *const state,
}
EXPORT_SYMBOL_NS_GPL(i8255_state_init, I8255);

+/**
+ * devm_i8255_regmap_register - Register an i8255 GPIO controller
+ * @dev: device that is registering this i8255 GPIO device
+ * @config: configuration for i8255_regmap_config
+ *
+ * Registers an Intel 8255 Programmable Peripheral Interface GPIO controller.
+ * Returns 0 on success and negative error number on failure.
+ */
+int devm_i8255_regmap_register(struct device *const dev,
+ const struct i8255_regmap_config *const config)
+{
+ struct gpio_regmap_config gpio_config = {0};
+ unsigned long i;
+ int err;
+
+ if (!config->parent)
+ return -EINVAL;
+
+ if (!config->map)
+ return -EINVAL;
+
+ if (!config->num_ppi)
+ return -EINVAL;
+
+ for (i = 0; i < config->num_ppi; i++) {
+ err = i8255_ppi_init(config->map, i * 4);
+ if (err)
+ return err;
+ }
+
+ gpio_config.parent = config->parent;
+ gpio_config.regmap = config->map;
+ gpio_config.ngpio = I8255_NGPIO * config->num_ppi;
+ gpio_config.names = config->names;
+ gpio_config.reg_dat_base = GPIO_REGMAP_ADDR(I8255_REG_DAT_BASE);
+ gpio_config.reg_set_base = GPIO_REGMAP_ADDR(I8255_REG_DAT_BASE);
+ gpio_config.reg_dir_in_base = GPIO_REGMAP_ADDR(I8255_REG_DIR_IN_BASE);
+ gpio_config.ngpio_per_reg = I8255_NGPIO_PER_REG;
+ gpio_config.irq_domain = config->domain;
+ gpio_config.reg_mask_xlate = i8255_reg_mask_xlate;
+
+ return PTR_ERR_OR_ZERO(devm_gpio_regmap_register(dev, &gpio_config));
+}
+EXPORT_SYMBOL_NS_GPL(devm_i8255_regmap_register, I8255);
+
MODULE_AUTHOR("William Breathitt Gray");
MODULE_DESCRIPTION("Intel 8255 Programmable Peripheral Interface");
MODULE_LICENSE("GPL");
diff --git a/drivers/gpio/gpio-i8255.h b/drivers/gpio/gpio-i8255.h
index d9084aae9446..3daa0b145890 100644
--- a/drivers/gpio/gpio-i8255.h
+++ b/drivers/gpio/gpio-i8255.h
@@ -26,6 +26,34 @@ struct i8255_state {
u8 control_state;
};

+struct device;
+struct irq_domain;
+struct regmap;
+
+#define i8255_volatile_regmap_range(_base) regmap_reg_range(_base, _base + 0x2)
+
+/**
+ * struct i8255_regmap_config - Configuration for the register map of an i8255
+ * @parent: parent device
+ * @map: regmap for the i8255
+ * @num_ppi: number of i8255 Programmable Peripheral Interface
+ * @names: (optional) array of names for gpios
+ * @domain: (optional) IRQ domain if the controller is interrupt-capable
+ *
+ * Note: The regmap is expected to have cache enabled and i8255 control
+ * registers not marked as volatile.
+ */
+struct i8255_regmap_config {
+ struct device *parent;
+ struct regmap *map;
+ int num_ppi;
+ const char *const *names;
+ struct irq_domain *domain;
+};
+
+int devm_i8255_regmap_register(struct device *dev,
+ const struct i8255_regmap_config *config);
+
void i8255_direction_input(struct i8255 __iomem *ppi, struct i8255_state *state,
unsigned long offset);
void i8255_direction_output(struct i8255 __iomem *ppi,
--
2.38.1