[Xen-devel] [PATCH V2 20/33] xen/arm: Add generic UART to get the device in the device tree

[Julien Grall <julien.grall@xxxxxxxxxx>]

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@xxxxxxxxxx>

Changes in v2:
    - Use dtuart parameter instead of com1. The first one is more arm
    while the latter is more x86
---
 xen/arch/arm/setup.c         |    3 +-
 xen/drivers/char/Makefile    |    1 +
 xen/drivers/char/arm-uart.c  |   81 ++++++++++++++++++++++++++++++++++++++++++
 xen/drivers/char/serial.c    |    6 ++++
 xen/include/asm-arm/config.h |    2 +-
 xen/include/xen/serial.h     |    7 ++++
 6 files changed, 98 insertions(+), 2 deletions(-)
 create mode 100644 xen/drivers/char/arm-uart.c

diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c
index e4228f7..7b2df8b 100644
--- a/xen/arch/arm/setup.c
+++ b/xen/arch/arm/setup.c
@@ -435,8 +435,9 @@ 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
+    arm_uart_init();
+    console_init_preirq();
 
     /* FIXME: Do something smarter */
     dt_switch_to_printk();
diff --git a/xen/drivers/char/Makefile b/xen/drivers/char/Makefile
index ab2246d..e68a54a 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) += arm-uart.o
 obj-y += serial.o
diff --git a/xen/drivers/char/arm-uart.c b/xen/drivers/char/arm-uart.c
new file mode 100644
index 0000000..c76875e
--- /dev/null
+++ b/xen/drivers/char/arm-uart.c
@@ -0,0 +1,81 @@
+/*
+ * xen/drivers/char/arm-uart.c
+ *
+ * Generic ARM uart retrieved via the device tree
+ *
+ * Julien Grall <julien.grall@xxxxxxxxxx>
+ * 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/mm.h>
+#include <xen/serial.h>
+
+/*
+ * Configure UART port with a string:
+ * alias
+ *
+ * @alias: alias used in the device tree for the UART
+ * TODO: Implement config  in each UART driver.
+ */
+static char __initdata opt_dtuart[30] = "";
+string_param("dtuart", opt_dtuart);
+
+void __init arm_uart_init(void)
+{
+    struct dt_device_node *dev;
+    int ret;
+    u64 addr, size;
+    struct serial_arm_defaults defaults;
+    const char *devalias = opt_dtuart;
+
+    if ( !console_has("dtuart") || !strcmp(opt_dtuart, "") )
+    {
+        early_printk("No console\n");
+        return;
+    }
+
+    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;
+    }
+
+    /* TODO: Handle UART with 0 or multiple base address */
+    ret = dt_device_get_address(dev, 0, &addr, &size);
+    if ( ret )
+    {
+        early_printk("Unable to retrieve the base address of the serial\n");
+        return;
+    }
+
+    clear_fixmap(FIXMAP_CONSOLE);
+    set_fixmap(FIXMAP_CONSOLE, addr >> PAGE_SHIFT, DEV_SHARED);
+
+    addr = FIXMAP_ADDR(FIXMAP_CONSOLE) + (addr & (PAGE_SIZE - 1));
+
+    defaults.index = 0;
+    defaults.register_base_address = addr;
+
+    ret = device_init(dev, DEVICE_SERIAL, &defaults);
+
+    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 0ae7e4d..c4c4a84 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_COM1;
+        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 98a3a43..8ed72f5 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 5de5171..f548f8b 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;
@@ -156,6 +157,12 @@ void ns16550_init(int index, struct ns16550_defaults 
*defaults);
 void ehci_dbgp_init(void);
 
 void pl011_init(int index, unsigned long register_base_address);
+/* Default value for UART on ARM boards */
+struct serial_arm_defaults {
+    int index;                              /* Serial index */
+    unsigned long register_base_address;    /* Virtual base address */
+};
+void __init arm_uart_init(void);
 
 struct physdev_dbgp_op;
 int dbgp_op(const struct physdev_dbgp_op *);
-- 
Julien Grall


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