Introduce a set of helper functions for accessing the on-board GPIO
registers on Moxa PCIe serial devices. These cover:
- Initializing all pins as outputs
- Setting the direction of individual pins
- Setting or clearing an output pin
- Bulk set/get operations on OUTPUT and DIRECTION registers
These functions do not change any existing behavior yet. They are added
as a preparation step for follow-up patches that will make use of the
GPIOs to control board-specific signals.
Signed-off-by: Crescent Hsieh <crescentcy.hsieh@moxa.com>
---
drivers/tty/serial/8250/8250_mxpcie.c | 91 +++++++++++++++++++++++++++
1 file changed, 91 insertions(+)
diff --git a/drivers/tty/serial/8250/8250_mxpcie.c b/drivers/tty/serial/8250/8250_mxpcie.c
index a0deb464a318..6e727b77c105 100644
--- a/drivers/tty/serial/8250/8250_mxpcie.c
+++ b/drivers/tty/serial/8250/8250_mxpcie.c
@@ -79,11 +79,18 @@
#define MOXA_PUART_RX_FIFO_MEM 0x100 /* Memory Space to Rx FIFO Data Register */
#define MOXA_PUART_TX_FIFO_MEM 0x100 /* Memory Space to Tx FIFO Data Register */
+/* GPIO */
#define MOXA_GPIO_DIRECTION 0x09
#define MOXA_GPIO_OUTPUT 0x0A
#define MOXA_GPIO_PIN2 BIT(2)
+#define MOXA_GPIO_STATE_INPUT 0
+#define MOXA_GPIO_STATE_OUTPUT 1
+
+#define MOXA_GPIO_LOW 0
+#define MOXA_GPIO_HIGH 1
+
#define MOXA_UIR_OFFSET 0x04
#define MOXA_UIR_RS232 0x00
#define MOXA_UIR_RS422 0x01
@@ -120,6 +127,90 @@ static const struct serial_rs485 mxpcie8250_rs485_supported = {
.flags = SER_RS485_ENABLED | SER_RS485_RTS_ON_SEND | SER_RS485_RX_DURING_TX | SER_RS485_MODE_RS422,
};
+/**
+ * mxpcie8250_gpio_init() - GPIO initialization routine
+ * @iobar_addr: The base address of the GPIO I/O region
+ *
+ * Initializes the GPIO direction. After calling this function, all GPIO
+ * pins will be set to output.
+ */
+static void mxpcie8250_gpio_init(resource_size_t iobar_addr)
+{
+ /* Initialize all the GPIO pins into output state */
+ outb(0xff, iobar_addr + MOXA_GPIO_DIRECTION);
+}
+
+/**
+ * mxpcie8250_gpio_set_direction() - Set GPIO pin direction
+ * @iobar_addr: The base address of the GPIO I/O region
+ * @pin: The target GPIO pin (MOXA_GPIO_PIN0 to MOXA_GPIO_PIN7)
+ * @direction: Desired direction (MOXA_GPIO_STATE_INPUT or MOXA_GPIO_STATE_OUTPUT)
+ *
+ * Sets the direction of the specified GPIO pin. This function should be called
+ * before performing GPIO set or get operations.
+ */
+static void mxpcie8250_gpio_set_direction(resource_size_t iobar_addr, int pin, int direction)
+{
+ u8 cval;
+
+ cval = inb(iobar_addr + MOXA_GPIO_DIRECTION);
+
+ if (direction == MOXA_GPIO_STATE_INPUT)
+ cval &= ~pin;
+ else
+ cval |= pin;
+
+ outb(cval, iobar_addr + MOXA_GPIO_DIRECTION);
+}
+
+/**
+ * mxpcie8250_gpio_set() - Set GPIO output state
+ * @iobar_addr: The base address of the GPIO I/O region
+ * @pin: The target GPIO pin (MOXA_GPIO_PIN0 to MOXA_GPIO_PIN7)
+ * @state: Desired output state (MOXA_GPIO_HIGH or MOXA_GPIO_LOW)
+ *
+ * Sets the output state of the specified GPIO pin.
+ */
+static void mxpcie8250_gpio_set(resource_size_t iobar_addr, int pin, int state)
+{
+ u8 cval;
+
+ cval = inb(iobar_addr + MOXA_GPIO_OUTPUT);
+
+ if (state == MOXA_GPIO_HIGH)
+ cval |= pin;
+ else
+ cval &= ~pin;
+
+ outb(cval, iobar_addr + MOXA_GPIO_OUTPUT);
+}
+
+/**
+ * mxpcie8250_gpio_set_all() - Set all GPIO output/direction pins at once
+ * @iobar_addr: The base address of the GPIO I/O region
+ * @data: The data to set for all pins
+ * @offset: Offset of the GPIO register (MOXA_GPIO_OUTPUT or MOXA_GPIO_DIRECTION)
+ *
+ * Sets the output state or direction of all GPIO pins at once.
+ */
+static void mxpcie8250_gpio_set_all(resource_size_t iobar_addr, u8 data, u8 offset)
+{
+ outb(data, iobar_addr + offset);
+}
+
+/**
+ * mxpcie8250_gpio_get_all() - Get all GPIO input/output pins state at once
+ * @iobar_addr: The base address of the GPIO I/O region
+ * @data: The buffer to store the states of all pins
+ * @offset: Offset of the GPIO register (MOXA_GPIO_INPUT or MOXA_GPIO_OUTPUT)
+ *
+ * Gets the input or output state of all GPIO pins at once.
+ */
+static void mxpcie8250_gpio_get_all(resource_size_t iobar_addr, u8 *data, u8 offset)
+{
+ *data = inb(iobar_addr + offset);
+}
+
static bool mxpcie8250_is_mini_pcie(unsigned short device)
{
if (device == PCI_DEVICE_ID_MOXA_CP102N ||
--
2.45.2