[PATCH v2 16/16] xen/riscv: add basic UART support

[Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>]

Update Kconfig to select GENERIC_UART_INIT for basic UART init ( find a dt node
and call device specific device_init() ).

Drop `default n if RISCV` statement for config HAS_NS16550 as now ns16550 is
ready to be compiled and used by RISC-V. Also, make the config user selectable
for everyone except X86.

Initialize a minimal amount of stuff to have UART and Xen console:
 - Initialize uart by calling uart_init().
 - Initialize Xen console by calling console_init_{pre,post}irq().
 - Initialize timer and its internal lists which are used by
   init_timer() which is called by ns16550_init_postirq(); otherwise
   "Unhandled exception: Store/AMO Page Fault" occurs.
 - Enable local interrupt to recieve an input from UART

Signed-off-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
---
Changes in v2:
 - Drop #include <xen/keyhandler.h> in setup.c, isn't needed anymore.
 - Drop call of percpu_init_areas() as it was needed when I used polling
   mode for UART,  for this case percpu is used to receive serial port info:
     struct serial_port *port = this_cpu(poll_port);
   So percpu isn't really needed at the current development state.
 - Make HAS_NS16550 user selectable for everyone, except X86.
 - Update the commit message.
---
 xen/arch/riscv/Kconfig   |  1 +
 xen/arch/riscv/setup.c   | 13 +++++++++++++
 xen/drivers/char/Kconfig |  3 +--
 3 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/xen/arch/riscv/Kconfig b/xen/arch/riscv/Kconfig
index 60520dab57..eb44318dda 100644
--- a/xen/arch/riscv/Kconfig
+++ b/xen/arch/riscv/Kconfig
@@ -2,6 +2,7 @@ config RISCV
        def_bool y
        select FUNCTION_ALIGNMENT_16B
        select GENERIC_BUG_FRAME
+       select GENERIC_UART_INIT
        select HAS_DEVICE_TREE
        select HAS_PMAP
        select HAS_UBSAN
diff --git a/xen/arch/riscv/setup.c b/xen/arch/riscv/setup.c
index 4f92266224..5c7cd568f0 100644
--- a/xen/arch/riscv/setup.c
+++ b/xen/arch/riscv/setup.c
@@ -4,12 +4,16 @@
 #include <xen/bug.h>
 #include <xen/bootfdt.h>
 #include <xen/compile.h>
+#include <xen/console.h>
 #include <xen/device_tree.h>
 #include <xen/init.h>
 #include <xen/irq.h>
 #include <xen/mm.h>
+#include <xen/percpu.h>
+#include <xen/serial.h>
 #include <xen/shutdown.h>
 #include <xen/smp.h>
+#include <xen/timer.h>
 #include <xen/vmap.h>
 #include <xen/xvmalloc.h>
 
@@ -136,8 +140,17 @@ void __init noreturn start_xen(unsigned long bootcpu_id,
 
     intc_preinit();
 
+    uart_init();
+    console_init_preirq();
+
     intc_init();
 
+    timer_init();
+
+    local_irq_enable();
+
+    console_init_postirq();
+
     printk("All set up\n");
 
     machine_halt();
diff --git a/xen/drivers/char/Kconfig b/xen/drivers/char/Kconfig
index e6e12bb413..8e49a52c73 100644
--- a/xen/drivers/char/Kconfig
+++ b/xen/drivers/char/Kconfig
@@ -2,8 +2,7 @@ config GENERIC_UART_INIT
        bool
 
 config HAS_NS16550
-       bool "NS16550 UART driver" if ARM
-       default n if RISCV
+       bool "NS16550 UART driver" if !X86
        default y
        help
          This selects the 16550-series UART support. For most systems, say Y.
-- 
2.49.0