Parse the ACPI SPCR table and initialize the 16550 compatible serial port
for ARM only. Currently we only support one UART on ARM. Some fields like
PCI, flow control and so on we do not care yet on ARM are ignored.
Signed-off-by: Wei Xu <xuwei5@xxxxxxxxxxxxx>
---
Changes in v2:
- improve commit message
- remove the spcr initialization
- add comments for the uart initialization and configuration
- adjust the code style issue
- limit the code only built on ACPI and ARM
---
xen/drivers/char/ns16550.c | 60 ++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 60 insertions(+)
diff --git a/xen/drivers/char/ns16550.c b/xen/drivers/char/ns16550.c
index aa87c57..a193f74 100644
--- a/xen/drivers/char/ns16550.c
+++ b/xen/drivers/char/ns16550.c
@@ -1620,6 +1620,66 @@ DT_DEVICE_START(ns16550, "NS16550 UART", DEVICE_SERIAL)
DT_DEVICE_END
#endif /* HAS_DEVICE_TREE */
+#if defined(CONFIG_ACPI) && defined(CONFIG_ARM)
+#include <xen/acpi.h>
+
+static int __init ns16550_acpi_uart_init(const void *data)
+{
+ struct acpi_table_spcr *spcr;
+ acpi_status status;
+
+ /* Same as the DT part.
+ * Only support one UART on ARM which happen to be ns16550_com[0].
+ */
+ struct ns16550 *uart = &ns16550_com[0];
+
+ status = acpi_get_table(ACPI_SIG_SPCR, 0,
+ (struct acpi_table_header **)&spcr);
+
+ if ( ACPI_FAILURE(status) )
+ {
+ printk("ns16550: Failed to get SPCR table\n");
+ return -EINVAL;
+ }
+
+ ns16550_init_common(uart);
+
+ /* The baud rate is pre-configured by the firmware.
+ * And currently the ACPI part is only targeting ARM so some fields
+ * like PCI, flow control and so on we do not care yet are ignored.
+ */
+ uart->baud = BAUD_AUTO;
+ uart->data_bits = 8;
+ uart->parity = spcr->parity;
+ uart->stop_bits = spcr->stop_bits;
+ uart->io_base = spcr->serial_port.address;
+ uart->io_size = 8;
+ uart->reg_shift = spcr->serial_port.bit_offset;
+ uart->reg_width = 1;
+
+ /* The trigger/polarity information is not available in spcr. */
+ irq_set_type(spcr->interrupt, IRQ_TYPE_LEVEL_HIGH);
+ uart->irq = spcr->interrupt;
+
+ uart->vuart.base_addr = uart->io_base;
+ uart->vuart.size = uart->io_size;
+ uart->vuart.data_off = UART_THR << uart->reg_shift;
+ uart->vuart.status_off = UART_LSR << uart->reg_shift;
+ uart->vuart.status = UART_LSR_THRE | UART_LSR_TEMT;
+
+ /* Register with generic serial driver. */
+ serial_register_uart(uart - ns16550_com, &ns16550_driver, uart);
+
+ return 0;
+}
+
+ACPI_DEVICE_START(ans16550, "NS16550 UART", DEVICE_SERIAL)
+ .class_type = ACPI_DBG2_16550_COMPATIBLE,
+ .init = ns16550_acpi_uart_init,
+ACPI_DEVICE_END
+
+#endif /* CONFIG_ACPI && CONFIG_ARM */
+
/*
* Local variables:
* mode: C
--
2.8.1
.
