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Subject[PATCH 4/5] gpio: gpio-mm: Implement and utilize register structures
Date
Reduce magic numbers and improve code readability by implementing and
utilizing named register data structures.

Signed-off-by: William Breathitt Gray <william.gray@linaro.org>
---
drivers/gpio/gpio-gpio-mm.c | 116 ++++++++++++++++++++++--------------
1 file changed, 72 insertions(+), 44 deletions(-)

diff --git a/drivers/gpio/gpio-gpio-mm.c b/drivers/gpio/gpio-gpio-mm.c
index 097a06463d01..8f67442b8715 100644
--- a/drivers/gpio/gpio-gpio-mm.c
+++ b/drivers/gpio/gpio-gpio-mm.c
@@ -27,6 +27,16 @@ 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");

+/**
+ * struct i8255_reg - Intel 8255 register structure
+ * @port: Port A, B, and C
+ * @control: Control register
+ */
+struct i8255_reg {
+ u8 port[3];
+ u8 control;
+};
+
/**
* struct gpiomm_gpio - GPIO device private data structure
* @chip: instance of the gpio_chip
@@ -34,7 +44,7 @@ MODULE_PARM_DESC(base, "Diamond Systems GPIO-MM base addresses");
* @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
+ * @dio: Digital I/O register groups
*/
struct gpiomm_gpio {
struct gpio_chip chip;
@@ -42,7 +52,7 @@ struct gpiomm_gpio {
unsigned char out_state[6];
unsigned char control[2];
spinlock_t lock;
- void __iomem *base;
+ struct i8255_reg __iomem *dio;
};

static int gpiomm_gpio_get_direction(struct gpio_chip *chip,
@@ -63,32 +73,33 @@ static int gpiomm_gpio_direction_input(struct gpio_chip *chip,
{
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 long group = io_port / 3;
+ const unsigned long port = io_port - (group * 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) {
+ if (port == 2) {
/* Port C can be configured by nibble */
if (offset % 8 > 3) {
gpiommgpio->io_state[io_port] |= 0xF0;
- gpiommgpio->control[control_port] |= BIT(3);
+ gpiommgpio->control[group] |= BIT(3);
} else {
gpiommgpio->io_state[io_port] |= 0x0F;
- gpiommgpio->control[control_port] |= BIT(0);
+ gpiommgpio->control[group] |= BIT(0);
}
} else {
gpiommgpio->io_state[io_port] |= 0xFF;
- if (io_port == 0 || io_port == 3)
- gpiommgpio->control[control_port] |= BIT(4);
+ if (port == 0)
+ gpiommgpio->control[group] |= BIT(4);
else
- gpiommgpio->control[control_port] |= BIT(1);
+ gpiommgpio->control[group] |= BIT(1);
}

- control = BIT(7) | gpiommgpio->control[control_port];
- iowrite8(control, gpiommgpio->base + 3 + control_port*4);
+ control = BIT(7) | gpiommgpio->control[group];
+ iowrite8(control, &gpiommgpio->dio[group].control);

spin_unlock_irqrestore(&gpiommgpio->lock, flags);

@@ -100,30 +111,31 @@ static int gpiomm_gpio_direction_output(struct gpio_chip *chip,
{
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 long group = io_port / 3;
+ const unsigned long port = io_port - (group * 3);
const unsigned int mask = BIT(offset % 8);
- const unsigned int out_port = (io_port > 2) ? io_port + 1 : io_port;
+ struct i8255_reg __iomem *const dio = gpiommgpio->dio + group;
unsigned long flags;
unsigned int control;

spin_lock_irqsave(&gpiommgpio->lock, flags);

/* Check if configuring Port C */
- if (io_port == 2 || io_port == 5) {
+ if (port == 2) {
/* Port C can be configured by nibble */
if (offset % 8 > 3) {
gpiommgpio->io_state[io_port] &= 0x0F;
- gpiommgpio->control[control_port] &= ~BIT(3);
+ gpiommgpio->control[group] &= ~BIT(3);
} else {
gpiommgpio->io_state[io_port] &= 0xF0;
- gpiommgpio->control[control_port] &= ~BIT(0);
+ gpiommgpio->control[group] &= ~BIT(0);
}
} else {
gpiommgpio->io_state[io_port] &= 0x00;
- if (io_port == 0 || io_port == 3)
- gpiommgpio->control[control_port] &= ~BIT(4);
+ if (port == 0)
+ gpiommgpio->control[group] &= ~BIT(4);
else
- gpiommgpio->control[control_port] &= ~BIT(1);
+ gpiommgpio->control[group] &= ~BIT(1);
}

if (value)
@@ -131,10 +143,10 @@ static int gpiomm_gpio_direction_output(struct gpio_chip *chip,
else
gpiommgpio->out_state[io_port] &= ~mask;

- control = BIT(7) | gpiommgpio->control[control_port];
- iowrite8(control, gpiommgpio->base + 3 + control_port*4);
+ control = BIT(7) | gpiommgpio->control[group];
+ iowrite8(control, &dio->control);

- iowrite8(gpiommgpio->out_state[io_port], gpiommgpio->base + out_port);
+ iowrite8(gpiommgpio->out_state[io_port], dio->port + port);

spin_unlock_irqrestore(&gpiommgpio->lock, flags);

@@ -146,7 +158,8 @@ 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;
+ const unsigned long group = port / 3;
+ const unsigned long in_port = port - (group * 3);
unsigned long flags;
unsigned int port_state;

@@ -158,29 +171,33 @@ static int gpiomm_gpio_get(struct gpio_chip *chip, unsigned int offset)
return -EINVAL;
}

- port_state = ioread8(gpiommgpio->base + in_port);
+ port_state = ioread8(gpiommgpio->dio[group].port + in_port);

spin_unlock_irqrestore(&gpiommgpio->lock, flags);

return !!(port_state & mask);
}

-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;
+ unsigned long group;
+ unsigned long in_port;
+ u8 __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];
+ for_each_set_clump8(offset, gpio_mask, mask, chip->ngpio) {
+ port = offset / 8;
+ group = port / 3;
+ in_port = port - (group * 3);
+ port_addr = gpiommgpio->dio[group].port + in_port;
port_state = ioread8(port_addr) & gpio_mask;

bitmap_set_value8(bits, port_state, offset);
@@ -195,7 +212,8 @@ static void gpiomm_gpio_set(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 out_port = (port > 2) ? port + 1 : port;
+ const unsigned long group = port / 3;
+ const unsigned long out_port = port - (group * 3);
unsigned long flags;

spin_lock_irqsave(&gpiommgpio->lock, flags);
@@ -205,7 +223,8 @@ static void gpiomm_gpio_set(struct gpio_chip *chip, unsigned int offset,
else
gpiommgpio->out_state[port] &= ~mask;

- iowrite8(gpiommgpio->out_state[port], gpiommgpio->base + out_port);
+ iowrite8(gpiommgpio->out_state[port],
+ gpiommgpio->dio[group].port + out_port);

spin_unlock_irqrestore(&gpiommgpio->lock, flags);
}
@@ -217,13 +236,17 @@ static void gpiomm_gpio_set_multiple(struct gpio_chip *chip,
unsigned long offset;
unsigned long gpio_mask;
size_t index;
- void __iomem *port_addr;
+ size_t group;
+ size_t out_port;
+ u8 __iomem *port_addr;
unsigned long bitmask;
unsigned long flags;

- for_each_set_clump8(offset, gpio_mask, mask, ARRAY_SIZE(ports) * 8) {
+ for_each_set_clump8(offset, gpio_mask, mask, chip->ngpio) {
index = offset / 8;
- port_addr = gpiommgpio->base + ports[index];
+ group = index / 3;
+ out_port = index - (group * 3);
+ port_addr = gpiommgpio->dio[group].port + out_port;

bitmask = bitmap_get_value8(bits, offset) & gpio_mask;

@@ -250,6 +273,17 @@ 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_reg __iomem *const dio)
+{
+ /* Activate Mode Set; set Mode 0 output mode for Port A, B, and C */
+ iowrite8(0x80, &dio->control);
+
+ /* Initialize all GPIO to 0 */
+ iowrite8(0x00, &dio->port[0]);
+ iowrite8(0x00, &dio->port[1]);
+ iowrite8(0x00, &dio->port[2]);
+}
+
static int gpiomm_probe(struct device *dev, unsigned int id)
{
struct gpiomm_gpio *gpiommgpio;
@@ -266,8 +300,8 @@ 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->dio = devm_ioport_map(dev, base[id], GPIOMM_EXTENT);
+ if (!gpiommgpio->dio)
return -ENOMEM;

gpiommgpio->chip.label = name;
@@ -293,14 +327,8 @@ static int gpiomm_probe(struct device *dev, unsigned int id)
}

/* 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);
+ gpiomm_init_dio(&gpiommgpio->dio[0]);
+ gpiomm_init_dio(&gpiommgpio->dio[1]);

return 0;
}
--
2.36.1
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