xen/arm: Add generic UART to get the device in the device tree

This generic UART will find the right UART via xen command line
with dtuart=myserial.

"myserial" is the alias of the UART in the device tree. Xen will retrieve
the information via the device tree and call the initialization function for
this specific UART thanks to the device API.

Signed-off-by: Julien Grall <julien.grall@linaro.org>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Keir Fraser <keir@xen.org>

6 files changed, 83 insertions, 3 deletions

diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c
index fc53117164..2e331d3800 100644
--- a/xen/arch/arm/setup.c
+++ b/xen/arch/arm/setup.c
@@ -436,8 +436,9 @@ void __init start_xen(unsigned long boot_phys_offset,
 #ifdef EARLY_UART_ADDRESS
     /* TODO Need to get device tree or command line for UART address */
     pl011_init(0, FIXMAP_ADDR(FIXMAP_CONSOLE));
-    console_init_preirq();
 #endif
+    dt_uart_init();
+    console_init_preirq();
 
     system_state = SYS_STATE_boot;
 
diff --git a/xen/drivers/char/Makefile b/xen/drivers/char/Makefile
index ab2246d61d..9c067f973c 100644
--- a/xen/drivers/char/Makefile
+++ b/xen/drivers/char/Makefile
@@ -2,4 +2,5 @@ obj-y += console.o
 obj-$(HAS_NS16550) += ns16550.o
 obj-$(HAS_PL011) += pl011.o
 obj-$(HAS_EHCI) += ehci-dbgp.o
+obj-$(CONFIG_ARM) += dt-uart.o
 obj-y += serial.o
diff --git a/xen/drivers/char/dt-uart.c b/xen/drivers/char/dt-uart.c
new file mode 100644
index 0000000000..93bb0f5845
--- /dev/null
+++ b/xen/drivers/char/dt-uart.c
@@ -0,0 +1,69 @@
+/*
+ * xen/drivers/char/dt-uart.c
+ *
+ * Generic uart retrieved via the device tree
+ *
+ * Julien Grall <julien.grall@linaro.org>
+ * Copyright (c) 2013 Linaro Limited.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <asm/device.h>
+#include <asm/early_printk.h>
+#include <asm/types.h>
+#include <xen/console.h>
+#include <xen/device_tree.h>
+#include <xen/serial.h>
+
+/*
+ * Configure UART port with a string:
+ * alias,options
+ *
+ * @alias: alias used in the device tree for the UART
+ * @options: UART speficic options (see in each UART driver)
+ */
+static char __initdata opt_dtuart[30] = "";
+string_param("dtuart", opt_dtuart);
+
+void __init dt_uart_init(void)
+{
+    struct dt_device_node *dev;
+    int ret;
+    const char *devalias = opt_dtuart;
+    char *options;
+
+    if ( !console_has("dtuart") || !strcmp(opt_dtuart, "") )
+    {
+        early_printk("No console\n");
+        return;
+    }
+
+    options = strchr(opt_dtuart, ',');
+    if ( options != NULL )
+        *(options++) = '\0';
+    else
+        options = "";
+
+    early_printk("Looking for UART console %s\n", devalias);
+    dev = dt_find_node_by_alias(devalias);
+
+    if ( !dev )
+    {
+        early_printk("Unable to find device \"%s\"\n", devalias);
+        return;
+    }
+
+    ret = device_init(dev, DEVICE_SERIAL, options);
+
+    if ( ret )
+        early_printk("Unable to initialize serial: %d\n", ret);
+}
diff --git a/xen/drivers/char/serial.c b/xen/drivers/char/serial.c
index 0ae7e4daeb..e1c3f475af 100644
--- a/xen/drivers/char/serial.c
+++ b/xen/drivers/char/serial.c
@@ -271,6 +271,12 @@ int __init serial_parse_handle(char *conf)
         goto common;
     }
 
+    if ( !strncmp(conf, "dtuart", 5) )
+    {
+        handle = SERHND_DTUART;
+        goto common;
+    }
+
     if ( strncmp(conf, "com", 3) )
         goto fail;
 
diff --git a/xen/include/asm-arm/config.h b/xen/include/asm-arm/config.h
index 98a3a434bf..8ed72f5188 100644
--- a/xen/include/asm-arm/config.h
+++ b/xen/include/asm-arm/config.h
@@ -39,7 +39,7 @@
 
 #define CONFIG_VIDEO 1
 
-#define OPT_CONSOLE_STR "com1"
+#define OPT_CONSOLE_STR "dtuart"
 
 #ifdef MAX_PHYS_CPUS
 #define NR_CPUS MAX_PHYS_CPUS
diff --git a/xen/include/xen/serial.h b/xen/include/xen/serial.h
index 5de517136b..8af3bc415a 100644
--- a/xen/include/xen/serial.h
+++ b/xen/include/xen/serial.h
@@ -9,6 +9,7 @@
 #ifndef __XEN_SERIAL_H__
 #define __XEN_SERIAL_H__
 
+#include <xen/init.h>
 #include <xen/spinlock.h>
 
 struct cpu_user_regs;
@@ -76,10 +77,11 @@ struct uart_driver {
 };
 
 /* 'Serial handles' are composed from the following fields. */
-#define SERHND_IDX      (3<<0) /* COM1, COM2, or DBGP?                    */
+#define SERHND_IDX      (3<<0) /* COM1, COM2, DBGP, DTUART?               */
 # define SERHND_COM1    (0<<0)
 # define SERHND_COM2    (1<<0)
 # define SERHND_DBGP    (2<<0)
+# define SERHND_DTUART  (0<<0) /* Steal SERHND_COM1 value */
 #define SERHND_HI       (1<<2) /* Mux/demux each transferred char by MSB. */
 #define SERHND_LO       (1<<3) /* Ditto, except that the MSB is cleared.  */
 #define SERHND_COOKED   (1<<4) /* Newline/carriage-return translation?    */
@@ -156,6 +158,7 @@ void ns16550_init(int index, struct ns16550_defaults *defaults);
 void ehci_dbgp_init(void);
 
 void pl011_init(int index, unsigned long register_base_address);
+void __init dt_uart_init(void);
 
 struct physdev_dbgp_op;
 int dbgp_op(const struct physdev_dbgp_op *);