[PATCH v3 6/6] gpio: gpio-mm: Implement and utilize register structures

From: William Breathitt Gray
Date: Mon Jul 18 2022 - 16:57:23 EST


Reduce magic numbers and improve code readability by implementing and
utilizing named register data structures. The GPIO-MM device features an
Intel 8255 compatible GPIO interface, so the i8255 GPIO module is
selected and utilized as well.

Tested-by: Fred Eckert <Frede@xxxxxxxxxxxx>
Signed-off-by: William Breathitt Gray <william.gray@xxxxxxxxxx>
---
Changes in v3:
- Include "gpio-i8255.h" instead of <linux/gpio/i8255.h>
- Import I8255 symbol namespace
- Define GPIOMM_NUM_PPI as the number of PPI (2)
- Utilize i8255_state struct; replaces 'control_state' and 'lock' with
'ppi_state'
- Call i8255_state_init() to initialize 'ppi_state'

drivers/gpio/Kconfig | 1 +
drivers/gpio/gpio-gpio-mm.c | 202 +++++++-----------------------------
2 files changed, 41 insertions(+), 162 deletions(-)

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 253a03ee3fa4..5202e3b6f2c6 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -889,6 +889,7 @@ config GPIO_GPIO_MM
tristate "Diamond Systems GPIO-MM GPIO support"
depends on PC104
select ISA_BUS_API
+ select GPIO_I8255
help
Enables GPIO support for the Diamond Systems GPIO-MM and GPIO-MM-12.

diff --git a/drivers/gpio/gpio-gpio-mm.c b/drivers/gpio/gpio-gpio-mm.c
index 097a06463d01..75b3ceeddbaf 100644
--- a/drivers/gpio/gpio-gpio-mm.c
+++ b/drivers/gpio/gpio-gpio-mm.c
@@ -6,7 +6,7 @@
* This driver supports the following Diamond Systems devices: GPIO-MM and
* GPIO-MM-12.
*/
-#include <linux/bitmap.h>
+#include <linux/bits.h>
#include <linux/bitops.h>
#include <linux/device.h>
#include <linux/errno.h>
@@ -17,7 +17,10 @@
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
-#include <linux/spinlock.h>
+
+#include "gpio-i8255.h"
+
+MODULE_IMPORT_NS(I8255);

#define GPIOMM_EXTENT 8
#define MAX_NUM_GPIOMM max_num_isa_dev(GPIOMM_EXTENT)
@@ -27,32 +30,26 @@ static unsigned int num_gpiomm;
module_param_hw_array(base, uint, ioport, &num_gpiomm, 0);
MODULE_PARM_DESC(base, "Diamond Systems GPIO-MM base addresses");

+#define GPIOMM_NUM_PPI 2
+
/**
* struct gpiomm_gpio - GPIO device private data structure
- * @chip: instance of the gpio_chip
- * @io_state: bit I/O state (whether bit is set to input or output)
- * @out_state: output bits state
- * @control: Control registers state
- * @lock: synchronization lock to prevent I/O race conditions
- * @base: base port address of the GPIO device
+ * @chip: instance of the gpio_chip
+ * @ppi_state: Programmable Peripheral Interface group states
+ * @ppi: Programmable Peripheral Interface groups
*/
struct gpiomm_gpio {
struct gpio_chip chip;
- unsigned char io_state[6];
- unsigned char out_state[6];
- unsigned char control[2];
- spinlock_t lock;
- void __iomem *base;
+ struct i8255_state ppi_state[GPIOMM_NUM_PPI];
+ struct i8255 __iomem *ppi;
};

static int gpiomm_gpio_get_direction(struct gpio_chip *chip,
unsigned int offset)
{
struct gpiomm_gpio *const gpiommgpio = gpiochip_get_data(chip);
- const unsigned int port = offset / 8;
- const unsigned int mask = BIT(offset % 8);

- if (gpiommgpio->io_state[port] & mask)
+ if (i8255_get_direction(gpiommgpio->ppi_state, offset))
return GPIO_LINE_DIRECTION_IN;

return GPIO_LINE_DIRECTION_OUT;
@@ -62,35 +59,8 @@ static int gpiomm_gpio_direction_input(struct gpio_chip *chip,
unsigned int offset)
{
struct gpiomm_gpio *const gpiommgpio = gpiochip_get_data(chip);
- const unsigned int io_port = offset / 8;
- const unsigned int control_port = io_port / 3;
- unsigned long flags;
- unsigned int control;
-
- spin_lock_irqsave(&gpiommgpio->lock, flags);
-
- /* Check if configuring Port C */
- if (io_port == 2 || io_port == 5) {
- /* Port C can be configured by nibble */
- if (offset % 8 > 3) {
- gpiommgpio->io_state[io_port] |= 0xF0;
- gpiommgpio->control[control_port] |= BIT(3);
- } else {
- gpiommgpio->io_state[io_port] |= 0x0F;
- gpiommgpio->control[control_port] |= BIT(0);
- }
- } else {
- gpiommgpio->io_state[io_port] |= 0xFF;
- if (io_port == 0 || io_port == 3)
- gpiommgpio->control[control_port] |= BIT(4);
- else
- gpiommgpio->control[control_port] |= BIT(1);
- }

- control = BIT(7) | gpiommgpio->control[control_port];
- iowrite8(control, gpiommgpio->base + 3 + control_port*4);
-
- spin_unlock_irqrestore(&gpiommgpio->lock, flags);
+ i8255_direction_input(gpiommgpio->ppi, gpiommgpio->ppi_state, offset);

return 0;
}
@@ -99,44 +69,9 @@ static int gpiomm_gpio_direction_output(struct gpio_chip *chip,
unsigned int offset, int value)
{
struct gpiomm_gpio *const gpiommgpio = gpiochip_get_data(chip);
- const unsigned int io_port = offset / 8;
- const unsigned int control_port = io_port / 3;
- const unsigned int mask = BIT(offset % 8);
- const unsigned int out_port = (io_port > 2) ? io_port + 1 : io_port;
- unsigned long flags;
- unsigned int control;
-
- spin_lock_irqsave(&gpiommgpio->lock, flags);
-
- /* Check if configuring Port C */
- if (io_port == 2 || io_port == 5) {
- /* Port C can be configured by nibble */
- if (offset % 8 > 3) {
- gpiommgpio->io_state[io_port] &= 0x0F;
- gpiommgpio->control[control_port] &= ~BIT(3);
- } else {
- gpiommgpio->io_state[io_port] &= 0xF0;
- gpiommgpio->control[control_port] &= ~BIT(0);
- }
- } else {
- gpiommgpio->io_state[io_port] &= 0x00;
- if (io_port == 0 || io_port == 3)
- gpiommgpio->control[control_port] &= ~BIT(4);
- else
- gpiommgpio->control[control_port] &= ~BIT(1);
- }
-
- if (value)
- gpiommgpio->out_state[io_port] |= mask;
- else
- gpiommgpio->out_state[io_port] &= ~mask;
-
- control = BIT(7) | gpiommgpio->control[control_port];
- iowrite8(control, gpiommgpio->base + 3 + control_port*4);

- iowrite8(gpiommgpio->out_state[io_port], gpiommgpio->base + out_port);
-
- spin_unlock_irqrestore(&gpiommgpio->lock, flags);
+ i8255_direction_output(gpiommgpio->ppi, gpiommgpio->ppi_state, offset,
+ value);

return 0;
}
@@ -144,47 +79,16 @@ static int gpiomm_gpio_direction_output(struct gpio_chip *chip,
static int gpiomm_gpio_get(struct gpio_chip *chip, unsigned int offset)
{
struct gpiomm_gpio *const gpiommgpio = gpiochip_get_data(chip);
- const unsigned int port = offset / 8;
- const unsigned int mask = BIT(offset % 8);
- const unsigned int in_port = (port > 2) ? port + 1 : port;
- unsigned long flags;
- unsigned int port_state;
-
- spin_lock_irqsave(&gpiommgpio->lock, flags);
-
- /* ensure that GPIO is set for input */
- if (!(gpiommgpio->io_state[port] & mask)) {
- spin_unlock_irqrestore(&gpiommgpio->lock, flags);
- return -EINVAL;
- }
-
- port_state = ioread8(gpiommgpio->base + in_port);
-
- spin_unlock_irqrestore(&gpiommgpio->lock, flags);

- return !!(port_state & mask);
+ return i8255_get(gpiommgpio->ppi, offset);
}

-static const size_t ports[] = { 0, 1, 2, 4, 5, 6 };
-
static int gpiomm_gpio_get_multiple(struct gpio_chip *chip, unsigned long *mask,
unsigned long *bits)
{
struct gpiomm_gpio *const gpiommgpio = gpiochip_get_data(chip);
- unsigned long offset;
- unsigned long gpio_mask;
- void __iomem *port_addr;
- unsigned long port_state;
-
- /* clear bits array to a clean slate */
- bitmap_zero(bits, chip->ngpio);

- for_each_set_clump8(offset, gpio_mask, mask, ARRAY_SIZE(ports) * 8) {
- port_addr = gpiommgpio->base + ports[offset / 8];
- port_state = ioread8(port_addr) & gpio_mask;
-
- bitmap_set_value8(bits, port_state, offset);
- }
+ i8255_get_multiple(gpiommgpio->ppi, mask, bits, chip->ngpio);

return 0;
}
@@ -193,49 +97,17 @@ static void gpiomm_gpio_set(struct gpio_chip *chip, unsigned int offset,
int value)
{
struct gpiomm_gpio *const gpiommgpio = gpiochip_get_data(chip);
- const unsigned int port = offset / 8;
- const unsigned int mask = BIT(offset % 8);
- const unsigned int out_port = (port > 2) ? port + 1 : port;
- unsigned long flags;
-
- spin_lock_irqsave(&gpiommgpio->lock, flags);
-
- if (value)
- gpiommgpio->out_state[port] |= mask;
- else
- gpiommgpio->out_state[port] &= ~mask;
-
- iowrite8(gpiommgpio->out_state[port], gpiommgpio->base + out_port);

- spin_unlock_irqrestore(&gpiommgpio->lock, flags);
+ i8255_set(gpiommgpio->ppi, gpiommgpio->ppi_state, offset, value);
}

static void gpiomm_gpio_set_multiple(struct gpio_chip *chip,
unsigned long *mask, unsigned long *bits)
{
struct gpiomm_gpio *const gpiommgpio = gpiochip_get_data(chip);
- unsigned long offset;
- unsigned long gpio_mask;
- size_t index;
- void __iomem *port_addr;
- unsigned long bitmask;
- unsigned long flags;
-
- for_each_set_clump8(offset, gpio_mask, mask, ARRAY_SIZE(ports) * 8) {
- index = offset / 8;
- port_addr = gpiommgpio->base + ports[index];
-
- bitmask = bitmap_get_value8(bits, offset) & gpio_mask;
-
- spin_lock_irqsave(&gpiommgpio->lock, flags);

- /* update output state data and set device gpio register */
- gpiommgpio->out_state[index] &= ~gpio_mask;
- gpiommgpio->out_state[index] |= bitmask;
- iowrite8(gpiommgpio->out_state[index], port_addr);
-
- spin_unlock_irqrestore(&gpiommgpio->lock, flags);
- }
+ i8255_set_multiple(gpiommgpio->ppi, gpiommgpio->ppi_state, mask, bits,
+ chip->ngpio);
}

#define GPIOMM_NGPIO 48
@@ -250,6 +122,21 @@ static const char *gpiomm_names[GPIOMM_NGPIO] = {
"Port 2C2", "Port 2C3", "Port 2C4", "Port 2C5", "Port 2C6", "Port 2C7",
};

+static void gpiomm_init_dio(struct i8255 __iomem *const ppi,
+ struct i8255_state *const ppi_state)
+{
+ const unsigned long ngpio = 24;
+ const unsigned long mask = GENMASK(ngpio - 1, 0);
+ const unsigned long bits = 0;
+ unsigned long i;
+
+ /* Initialize all GPIO to output 0 */
+ for (i = 0; i < GPIOMM_NUM_PPI; i++) {
+ i8255_mode0_output(&ppi[i]);
+ i8255_set_multiple(&ppi[i], &ppi_state[i], &mask, &bits, ngpio);
+ }
+}
+
static int gpiomm_probe(struct device *dev, unsigned int id)
{
struct gpiomm_gpio *gpiommgpio;
@@ -266,8 +153,8 @@ static int gpiomm_probe(struct device *dev, unsigned int id)
return -EBUSY;
}

- gpiommgpio->base = devm_ioport_map(dev, base[id], GPIOMM_EXTENT);
- if (!gpiommgpio->base)
+ gpiommgpio->ppi = devm_ioport_map(dev, base[id], GPIOMM_EXTENT);
+ if (!gpiommgpio->ppi)
return -ENOMEM;

gpiommgpio->chip.label = name;
@@ -284,7 +171,8 @@ static int gpiomm_probe(struct device *dev, unsigned int id)
gpiommgpio->chip.set = gpiomm_gpio_set;
gpiommgpio->chip.set_multiple = gpiomm_gpio_set_multiple;

- spin_lock_init(&gpiommgpio->lock);
+ i8255_state_init(gpiommgpio->ppi_state, GPIOMM_NUM_PPI);
+ gpiomm_init_dio(gpiommgpio->ppi, gpiommgpio->ppi_state);

err = devm_gpiochip_add_data(dev, &gpiommgpio->chip, gpiommgpio);
if (err) {
@@ -292,16 +180,6 @@ static int gpiomm_probe(struct device *dev, unsigned int id)
return err;
}

- /* initialize all GPIO as output */
- iowrite8(0x80, gpiommgpio->base + 3);
- iowrite8(0x00, gpiommgpio->base);
- iowrite8(0x00, gpiommgpio->base + 1);
- iowrite8(0x00, gpiommgpio->base + 2);
- iowrite8(0x80, gpiommgpio->base + 7);
- iowrite8(0x00, gpiommgpio->base + 4);
- iowrite8(0x00, gpiommgpio->base + 5);
- iowrite8(0x00, gpiommgpio->base + 6);
-
return 0;
}

--
2.36.1