Re: [kvm-unit-tests PATCH 18/18] arm/arm64: uart0_init: check /chosen/stdout-path

[Paolo Bonzini]

On 06/11/2015 01:24, Andrew Jones wrote:
> Arguably all of uart0_init() is unnecessary, as we're pretty sure
> that the address we initialize uart0_base to is correct. We go
> through the motions of finding the uart anyway though, because it's
> easy. It's also easy to check chosen/stdout-path first, so let's do
> that too. But, just to make all this stuff is a little less unnecessary,
> let's add a warning when we do actually find an address that doesn't
> match our initializer.
> 
> Signed-off-by: Andrew Jones 
> ---
>  lib/arm/io.c | 36 +++-
>  1 file changed, 27 insertions(+), 9 deletions(-)
> 
> diff --git a/lib/arm/io.c b/lib/arm/io.c
> index 8b1501886736a..a08d394e4aa1c 100644
> --- a/lib/arm/io.c
> +++ b/lib/arm/io.c
> @@ -19,12 +19,14 @@ extern void halt(int code);
>  /*
>   * Use this guess for the pl011 base in order to make an attempt at
>   * having earlier printf support. We'll overwrite it with the real
> - * base address that we read from the device tree later.
> + * base address that we read from the device tree later. This is
> + * the address we expect QEMU's mach-virt machine type to put in
> + * its generated device tree.
>   */
> -#define QEMU_MACH_VIRT_PL011_BASE 0x0900UL
> +#define UART_EARLY_BASE 0x0900UL
>  
>  static struct spinlock uart_lock;
> -static volatile u8 *uart0_base = (u8 *)QEMU_MACH_VIRT_PL011_BASE;
> +static volatile u8 *uart0_base = (u8 *)UART_EARLY_BASE;
>  
>  static void uart0_init(void)
>  {
> @@ -32,16 +34,32 @@ static void uart0_init(void)
>   struct dt_pbus_reg base;
>   int ret;
>  
> - ret = dt_pbus_get_base_compatible(compatible, );
> - assert(ret == 0 || ret == -FDT_ERR_NOTFOUND);
> + ret = dt_get_default_console_node();
> + assert(ret >= 0 || ret == -FDT_ERR_NOTFOUND);
>  
> - if (ret) {
> - printf("%s: %s not found in the device tree, aborting...\n",
> - __func__, compatible);
> - abort();
> + if (ret == -FDT_ERR_NOTFOUND) {
> +
> + ret = dt_pbus_get_base_compatible(compatible, );
> + assert(ret == 0 || ret == -FDT_ERR_NOTFOUND);
> +
> + if (ret) {
> + printf("%s: %s not found in the device tree, "
> + "aborting...\n",
> + __func__, compatible);
> + abort();
> + }
> +
> + } else {
> + assert(dt_pbus_translate_node(ret, 0, ) == 0);
>   }
>  
>   uart0_base = ioremap(base.addr, base.size);
> +
> + if (uart0_base != (u8 *)UART_EARLY_BASE) {
> + printf("WARNING: early print support may not work. "
> +"Found uart at %p, but early base is %p.\n",
> + uart0_base, (u8 *)UART_EARLY_BASE);
> + }
>  }
>  
>  void io_init(void)
> 

Applied, thanks.

Paolo
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[kvm-unit-tests PATCH 18/18] arm/arm64: uart0_init: check /chosen/stdout-path

[Andrew Jones]

Arguably all of uart0_init() is unnecessary, as we're pretty sure
that the address we initialize uart0_base to is correct. We go
through the motions of finding the uart anyway though, because it's
easy. It's also easy to check chosen/stdout-path first, so let's do
that too. But, just to make all this stuff is a little less unnecessary,
let's add a warning when we do actually find an address that doesn't
match our initializer.

Signed-off-by: Andrew Jones 
---
 lib/arm/io.c | 36 +++-
 1 file changed, 27 insertions(+), 9 deletions(-)

diff --git a/lib/arm/io.c b/lib/arm/io.c
index 8b1501886736a..a08d394e4aa1c 100644
--- a/lib/arm/io.c
+++ b/lib/arm/io.c
@@ -19,12 +19,14 @@ extern void halt(int code);
 /*
  * Use this guess for the pl011 base in order to make an attempt at
  * having earlier printf support. We'll overwrite it with the real
- * base address that we read from the device tree later.
+ * base address that we read from the device tree later. This is
+ * the address we expect QEMU's mach-virt machine type to put in
+ * its generated device tree.
  */
-#define QEMU_MACH_VIRT_PL011_BASE 0x0900UL
+#define UART_EARLY_BASE 0x0900UL
 
 static struct spinlock uart_lock;
-static volatile u8 *uart0_base = (u8 *)QEMU_MACH_VIRT_PL011_BASE;
+static volatile u8 *uart0_base = (u8 *)UART_EARLY_BASE;
 
 static void uart0_init(void)
 {
@@ -32,16 +34,32 @@ static void uart0_init(void)
struct dt_pbus_reg base;
int ret;
 
-   ret = dt_pbus_get_base_compatible(compatible, );
-   assert(ret == 0 || ret == -FDT_ERR_NOTFOUND);
+   ret = dt_get_default_console_node();
+   assert(ret >= 0 || ret == -FDT_ERR_NOTFOUND);
 
-   if (ret) {
-   printf("%s: %s not found in the device tree, aborting...\n",
-   __func__, compatible);
-   abort();
+   if (ret == -FDT_ERR_NOTFOUND) {
+
+   ret = dt_pbus_get_base_compatible(compatible, );
+   assert(ret == 0 || ret == -FDT_ERR_NOTFOUND);
+
+   if (ret) {
+   printf("%s: %s not found in the device tree, "
+   "aborting...\n",
+   __func__, compatible);
+   abort();
+   }
+
+   } else {
+   assert(dt_pbus_translate_node(ret, 0, ) == 0);
}
 
uart0_base = ioremap(base.addr, base.size);
+
+   if (uart0_base != (u8 *)UART_EARLY_BASE) {
+   printf("WARNING: early print support may not work. "
+  "Found uart at %p, but early base is %p.\n",
+   uart0_base, (u8 *)UART_EARLY_BASE);
+   }
 }
 
 void io_init(void)
-- 
2.4.3

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