[PATCH v2 3/7] serial: exar: add support for config/set single MPIO

parker
2024-04-11T20:26:03Z

From: Parker Newman <pnewman@connecttech.com>

Adds support for configuring and setting a single MPIO

Signed-off-by: Parker Newman <pnewman@connecttech.com>
---
drivers/tty/serial/8250/8250_exar.c | 88 +++++++++++++++++++++++++++++
1 file changed, 88 insertions(+)

diff --git a/drivers/tty/serial/8250/8250_exar.c b/drivers/tty/serial/8250/8250_exar.c
index 49d690344e65..9915a99cb7c6 100644
--- a/drivers/tty/serial/8250/8250_exar.c
+++ b/drivers/tty/serial/8250/8250_exar.c
@@ -305,6 +305,94 @@ static int exar_ee_read(struct exar8250 *priv, uint8_t ee_addr)
return data;
}

+/**
+ * exar_mpio_config() - Configure an EXar MPIO as input or output
+ * @priv: Device's private structure
+ * @mpio_num: MPIO number/offset to configure
+ * @output: Configure as output if true, inout if false
+ *
+ * Configure a single MPIO as an input or output and disable trisate.
+ * If configuring as output it is reccomended to set value with
+ * exar_mpio_set prior to calling this function to ensure default state.
+ *
+ * Return: 0 on success, negative error code on failure
+ */
+static int exar_mpio_config(struct exar8250 *priv,
+ unsigned int mpio_num, bool output)
+{
+ uint8_t sel_reg; //MPIO Select register (input/output)
+ uint8_t tri_reg; //MPIO Tristate register
+ uint8_t value;
+ unsigned int bit;
+
+ if (mpio_num < 8) {
+ sel_reg = UART_EXAR_MPIOSEL_7_0;
+ tri_reg = UART_EXAR_MPIO3T_7_0;
+ bit = mpio_num;
+ } else if (mpio_num >= 8 && mpio_num < 16) {
+ sel_reg = UART_EXAR_MPIOSEL_15_8;
+ tri_reg = UART_EXAR_MPIO3T_15_8;
+ bit = mpio_num - 8;
+ } else {
+ return -EINVAL;
+ }
+
+ //Disable MPIO pin tri-state
+ value = exar_read_reg(priv, tri_reg);
+ value &= ~(BIT(bit));
+ exar_write_reg(priv, tri_reg, value);
+
+ value = exar_read_reg(priv, sel_reg);
+ //Set MPIO as input (1) or output (0)
+ if (output)
+ value &= ~(BIT(bit));
+ else
+ value |= BIT(bit);
+
+ exar_write_reg(priv, sel_reg, value);
+
+ return 0;
+}
+/**
+ * exar_mpio_set() - Set an Exar MPIO output high or low
+ * @priv: Device's private structure
+ * @mpio_num: MPIO number/offset to set
+ * @high: Set MPIO high if true, low if false
+ *
+ * Set a single MPIO high or low. exar_mpio_config must also be called
+ * to configure the pin as an output.
+ *
+ * Return: 0 on success, negative error code on failure
+ */
+static int exar_mpio_set(struct exar8250 *priv,
+ unsigned int mpio_num, bool high)
+{
+ uint8_t reg;
+ uint8_t value;
+ unsigned int bit;
+
+ if (mpio_num < 8) {
+ reg = UART_EXAR_MPIOSEL_7_0;
+ bit = mpio_num;
+ } else if (mpio_num >= 8 && mpio_num < 16) {
+ reg = UART_EXAR_MPIOSEL_15_8;
+ bit = mpio_num - 8;
+ } else {
+ return -EINVAL;
+ }
+
+ value = exar_read_reg(priv, reg);
+
+ if (high)
+ value |= BIT(bit);
+ else
+ value &= ~(BIT(bit));
+
+ exar_write_reg(priv, reg, value);
+
+ return 0;
+}
+
static void exar_pm(struct uart_port *port, unsigned int state, unsigned int old)
{
/*
--
2.43.2