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Subject[PATCH] serial: 8250_fintek: Add using BIOS IRQ default setting
Date
In 8250_fintek.c probe_setup_port(), we'll detect the IRQ trigger mode by
irq_get_irq_data() and pass it to fintek_8250_set_irq_mode(). If detected
Edge mode, we'll set the UART with Edge/High mode, otherwise Level/Low.

But in some motherboard, The APIC maybe setting to Level/High. In this case
the driver will setting wrong configuration into UART. So we add a option
to kernel parameter to control the driver as following:

fintek_uart_irq_mode_override= [SERIAL]
{default, bios}
If the parameter is "default", the driver will using
former IRQ override methed(By IRQ trigger type).
otherwise, we'll don't change the UART IRQ setting.

Signed-off-by: Ji-Ze Hong (Peter Hong) <hpeter+linux_kernel@gmail.com>
---
drivers/tty/serial/8250/8250_fintek.c | 27 +++++++++++++++++++++++++++
1 file changed, 27 insertions(+)

diff --git a/drivers/tty/serial/8250/8250_fintek.c b/drivers/tty/serial/8250/8250_fintek.c
index dba5950b8d0e..c5fea0a7c79b 100644
--- a/drivers/tty/serial/8250/8250_fintek.c
+++ b/drivers/tty/serial/8250/8250_fintek.c
@@ -92,6 +92,9 @@
#define F81866_UART_CLK_18_432MHZ BIT(0)
#define F81866_UART_CLK_24MHZ BIT(1)

+#define FINTEK_IRQ_MODE_BY_DETECT 0
+#define FINTEK_IRQ_MODE_BY_BIOS 1
+
struct fintek_8250 {
u16 pid;
u16 base_port;
@@ -99,6 +102,24 @@ struct fintek_8250 {
u8 key;
};

+static int not_override_irq_mode = FINTEK_IRQ_MODE_BY_DETECT;
+
+static int __init parse_uart_irq_mode_override(char *arg)
+{
+ if (!arg)
+ return -EINVAL;
+
+ if (strcmp(arg, "bios") == 0)
+ not_override_irq_mode = FINTEK_IRQ_MODE_BY_BIOS;
+ else if (strcmp(arg, "default") == 0)
+ not_override_irq_mode = FINTEK_IRQ_MODE_BY_DETECT;
+ else
+ return -EINVAL;
+
+ return 0;
+}
+early_param("fintek_uart_irq_mode_override", parse_uart_irq_mode_override);
+
static u8 sio_read_reg(struct fintek_8250 *pdata, u8 reg)
{
outb(reg, pdata->base_port + ADDR_PORT);
@@ -248,6 +269,12 @@ static int fintek_8250_rs485_config(struct uart_port *port,

static void fintek_8250_set_irq_mode(struct fintek_8250 *pdata, bool is_level)
{
+ if (not_override_irq_mode == FINTEK_IRQ_MODE_BY_BIOS) {
+ pr_info("Fintek UART(%04x) irq mode is using BIOS default",
+ pdata->pid);
+ return;
+ }
+
sio_write_reg(pdata, LDN, pdata->index);

switch (pdata->pid) {
--
2.17.1
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