[PATCH 1/2] xen: Add support for initializing 16550 UART using ACPI

[Bhupinder Thakur <bhupinder.thakur@linaro.org>]

Currently, Xen supports only DT based initialization of 16550 UART.
This patch adds support for initializing 16550 UART using ACPI SPCR table.

Signed-off-by: Bhupinder Thakur <bhupinder.thakur@linaro.org>
---
CC: Andrew Cooper <andrew.cooper3@citrix.com>
CC: George Dunlap <George.Dunlap@eu.citrix.com>
CC: Ian Jackson <ian.jackson@eu.citrix.com>
CC: Jan Beulich <jbeulich@suse.com>
CC: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
CC: Stefano Stabellini <sstabellini@kernel.org>
CC: Tim Deegan <tim@xen.org>
CC: Wei Liu <wei.liu2@citrix.com>
CC: Julien Grall <julien.grall@arm.com>

 xen/drivers/char/ns16550.c  | 57 +++++++++++++++++++++++++++++++++++++++++++++
 xen/include/xen/8250-uart.h |  1 +
 2 files changed, 58 insertions(+)

diff --git a/xen/drivers/char/ns16550.c b/xen/drivers/char/ns16550.c
index e0f8199..b3f6d85 100644
--- a/xen/drivers/char/ns16550.c
+++ b/xen/drivers/char/ns16550.c
@@ -1538,6 +1538,63 @@ DT_DEVICE_START(ns16550, "NS16550 UART", DEVICE_SERIAL)
 DT_DEVICE_END
 
 #endif /* HAS_DEVICE_TREE */
+
+#ifdef CONFIG_ACPI
+#include <xen/acpi.h>
+
+static int __init ns16550_acpi_uart_init(const void *data)
+{
+    struct ns16550 *uart;
+    acpi_status status;
+    struct acpi_table_spcr *spcr = NULL;
+
+    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;
+    }
+
+    uart = &ns16550_com[0];
+
+    ns16550_init_common(uart);
+
+    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->irq = spcr->interrupt;
+    uart->reg_width = spcr->serial_port.bit_width/8;
+    uart->reg_shift = 0;
+    uart->io_size = UART_MAX_REG<<uart->reg_shift;
+
+    irq_set_type(spcr->interrupt, spcr->interrupt_type);
+
+    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(ns16550c, "16550 COMPAT UART", DEVICE_SERIAL)
+        .class_type = ACPI_DBG2_16550_COMPATIBLE,
+        .init = ns16550_acpi_uart_init,
+ACPI_DEVICE_END
+ACPI_DEVICE_START(ns16550s, "16550 SUBSET UART", DEVICE_SERIAL)
+        .class_type = ACPI_DBG2_16550_SUBSET,
+        .init = ns16550_acpi_uart_init,
+ACPI_DEVICE_END
+
+#endif
 /*
  * Local variables:
  * mode: C
diff --git a/xen/include/xen/8250-uart.h b/xen/include/xen/8250-uart.h
index 5c3bac3..1b3e137 100644
--- a/xen/include/xen/8250-uart.h
+++ b/xen/include/xen/8250-uart.h
@@ -35,6 +35,7 @@
 #define UART_USR          0x1f    /* Status register (DW) */
 #define UART_DLL          0x00    /* divisor latch (ls) (DLAB=1) */
 #define UART_DLM          0x01    /* divisor latch (ms) (DLAB=1) */
+#define UART_MAX_REG      (UART_USR+1)
 
 /* Interrupt Enable Register */
 #define UART_IER_ERDAI    0x01    /* rx data recv'd       */
-- 
2.7.4


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