thr3ads.net - Xen devel - [PATCH v2 0/5] arm/early-printk: Improve reusability and add Calxeda support [May 2013]

If this information is useful, please help other people find it:
Share via:

Andre Przywara

2013-May-24 13:47 UTC

[PATCH v2 0/5] arm/early-printk: Improve reusability and add Calxeda support

The current early-printk support for ARM is rather hard-coded, making
it hard to add machines or tweak settings.
This series slightly moves some code to gather UART settings in
xen/arch/arm/Rules.mk instead of the actual .c files. Also it allows
two different machines with different settings to share the same
driver, which the last patch exploits to add support the Calxeda
Midway hardware.

This haven''t been extensively tested, but I looked at the generated
assembly and did some quick checks on Versatile Express.

Signed-off-by: Andre Przywara <andre.przywara@calxeda.com>

Changes from v1:
	- add documentation
	- add extra support for ARM Fastmodel software emulators

Andre Przywara (5):
  arm/early-printk: calculate baud rate divisor from user provided
    value
  arm/early-printk: allow skipping of UART init
  arm/early-printk: move UART base address to Rules.mk
  arm/early-printk: add support for ARM Fastmodel
  arm/early-printk: add Calxeda Midway UART support

 docs/misc/arm/early-printk.txt          |  9 +++++++++
 xen/arch/arm/Rules.mk                   | 20 +++++++++++++++++++-
 xen/arch/arm/arm32/debug-exynos4210.inc |  6 ++----
 xen/arch/arm/arm32/debug-pl011.inc      |  6 ++----
 xen/arch/arm/arm32/head.S               |  2 ++
 xen/arch/arm/arm64/debug-pl011.inc      |  6 ++----
 xen/arch/arm/arm64/head.S               |  2 ++
 7 files changed, 38 insertions(+), 13 deletions(-)

-- 
1.7.12.1

Andre Przywara

2013-May-24 13:47 UTC

head link

[PATCH v2 1/5] arm/early-printk: calculate baud rate divisor from user provided value

For early-printk the used baud rate was hardcoded in the code, using
precalculated divisor values.
Let the calculation of these values be done by the preprocessor and
use a human readable value in xen/arch/arm/Rules.mk to drive this.

Signed-off-by: Andre Przywara <andre.przywara@calxeda.com>
---
 docs/misc/arm/early-printk.txt          | 3 +++
 xen/arch/arm/Rules.mk                   | 3 +++
 xen/arch/arm/arm32/debug-exynos4210.inc | 4 ++--
 xen/arch/arm/arm32/debug-pl011.inc      | 4 ++--
 xen/arch/arm/arm64/debug-pl011.inc      | 4 ++--
 5 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/docs/misc/arm/early-printk.txt b/docs/misc/arm/early-printk.txt
index d5cae85..10c3053 100644
--- a/docs/misc/arm/early-printk.txt
+++ b/docs/misc/arm/early-printk.txt
@@ -12,4 +12,7 @@ where mach is the name of the machine:
   - vexpress: printk with pl011 for versatile express
   - exynos5250: printk with the second UART
 
+The baud rate is hardcoded in xen/arch/arm/Rules.mk,
+see there when adding support for new machines.
+
 By default early printk is disabled.
diff --git a/xen/arch/arm/Rules.mk b/xen/arch/arm/Rules.mk
index b6a6890..b4d6907 100644
--- a/xen/arch/arm/Rules.mk
+++ b/xen/arch/arm/Rules.mk
@@ -45,9 +45,11 @@ ifeq ($(debug),y)
 # TODO handle UART base address from make command line
 ifeq ($(CONFIG_EARLY_PRINTK), vexpress)
 EARLY_PRINTK_INC := pl011
+EARLY_PRINTK_BAUD := 38400
 endif
 ifeq ($(CONFIG_EARLY_PRINTK), exynos5250)
 EARLY_PRINTK_INC := exynos4210
+EARLY_PRINTK_BAUD := 115200
 endif
 
 ifneq ($(EARLY_PRINTK_INC),)
@@ -56,4 +58,5 @@ endif
 
 CFLAGS-$(EARLY_PRINTK) += -DEARLY_PRINTK
 CFLAGS-$(EARLY_PRINTK) +=
-DEARLY_PRINTK_INC=\"debug-$(EARLY_PRINTK_INC).inc\"
+CFLAGS-$(EARLY_PRINTK) += -DEARLY_PRINTK_BAUD=$(EARLY_PRINTK_BAUD)
 endif
diff --git a/xen/arch/arm/arm32/debug-exynos4210.inc
b/xen/arch/arm/arm32/debug-exynos4210.inc
index 4241640..4922148 100644
--- a/xen/arch/arm/arm32/debug-exynos4210.inc
+++ b/xen/arch/arm/arm32/debug-exynos4210.inc
@@ -38,9 +38,9 @@
         orr   \rd, \rd, #(0x7<<8)
         str   \rd, [\rc, #0x558]
 
-        mov   \rc, #4
+        mov   \rc, #(100000000 / EARLY_PRINTK_BAUD % 16)
         str   \rc, [\rb, #UFRACVAL]     /* -> UFRACVAL (Baud divisor
fraction) */
-        mov   \rc, #53
+        mov   \rc, #(100000000 / EARLY_PRINTK_BAUD / 16 - 1)
         str   \rc, [\rb, #UBRDIV]       /* -> UBRDIV (Baud divisor integer)
*/
         mov   \rc, #3                   /* 8n1 */
         str   \rc, [\rb, #ULCON]        /* -> (Line control) */
diff --git a/xen/arch/arm/arm32/debug-pl011.inc
b/xen/arch/arm/arm32/debug-pl011.inc
index 6954aeb..2d970ea 100644
--- a/xen/arch/arm/arm32/debug-pl011.inc
+++ b/xen/arch/arm/arm32/debug-pl011.inc
@@ -23,9 +23,9 @@
  * rc: scratch register 1
  * rd: scratch register 2 (unused here) */
 .macro early_uart_init rb, rc, rd
-        mov   \rc, #0x0
+        mov   \rc, #(7372800 / EARLY_PRINTK_BAUD % 16)
         str   \rc, [\rb, #0x28]     /* -> UARTFBRD (Baud divisor fraction)
*/
-        mov   \rc, #0x4             /* 7.3728MHz / 0x4 == 16 * 115200 */
+        mov   \rc, #(7372800 / EARLY_PRINTK_BAUD / 16)
         str   \rc, [\rb, #0x24]     /* -> UARTIBRD (Baud divisor integer) */
         mov   \rc, #0x60            /* 8n1 */
         str   \rc, [\rb, #0x2C]     /* -> UARTLCR_H (Line control) */
diff --git a/xen/arch/arm/arm64/debug-pl011.inc
b/xen/arch/arm/arm64/debug-pl011.inc
index ee6e0e0..7220940 100644
--- a/xen/arch/arm/arm64/debug-pl011.inc
+++ b/xen/arch/arm/arm64/debug-pl011.inc
@@ -24,9 +24,9 @@
  * xb: register which containts the UART base address
  * c: scratch register number */
 .macro early_uart_init xb, c
-        mov   x\c, #0x0
+        mov   x\c, #(7372800 / EARLY_PRINTK_BAUD % 16)
         strh  w\c, [\xb, #0x28]      /* -> UARTFBRD (Baud divisor fraction)
*/
-        mov   x\c, #0x4              /* 7.3728MHz / 0x4 == 16 * 115200 */
+        mov   x\c, #(7372800 / EARLY_PRINTK_BAUD / 16)
         strh  w\c, [\xb, #0x24]      /* -> UARTIBRD (Baud divisor integer)
*/
         mov   x\c, #0x60             /* 8n1 */
         str   w\c, [\xb, #0x2C]      /* -> UARTLCR_H (Line control) */
-- 
1.7.12.1

Andre Przywara

2013-May-24 13:47 UTC

head link

[PATCH v2 2/5] arm/early-printk: allow skipping of UART init

While it seems obvious to initialize the UART before using it, chances
are that some firmware code or the bootloader already did this.
So it may actually be a good idea to skip the initialization, in fact
this fixes early printk on my TC2 Versatile Express.
So provide an option in xen/arch/arm/Rules.mk to only initialize the
UART when needed.

Signed-off-by: Andre Przywara <andre.przywara@calxeda.com>
---
 docs/misc/arm/early-printk.txt | 4 ++++
 xen/arch/arm/Rules.mk          | 2 ++
 xen/arch/arm/arm32/head.S      | 2 ++
 xen/arch/arm/arm64/head.S      | 2 ++
 4 files changed, 10 insertions(+)

diff --git a/docs/misc/arm/early-printk.txt b/docs/misc/arm/early-printk.txt
index 10c3053..965add5 100644
--- a/docs/misc/arm/early-printk.txt
+++ b/docs/misc/arm/early-printk.txt
@@ -14,5 +14,9 @@ where mach is the name of the machine:
 
 The baud rate is hardcoded in xen/arch/arm/Rules.mk,
 see there when adding support for new machines.
+If not explicitly requested with "EARLY_PRINTK_INIT_UART := y" in
Rules.mk,
+the code will not try to initialize the UART, so that bootloader or
+firmware settings can be used for maximum compatibility. The baud rate
+parameter is ignored in this case.
 
 By default early printk is disabled.
diff --git a/xen/arch/arm/Rules.mk b/xen/arch/arm/Rules.mk
index b4d6907..fdcf73e 100644
--- a/xen/arch/arm/Rules.mk
+++ b/xen/arch/arm/Rules.mk
@@ -49,6 +49,7 @@ EARLY_PRINTK_BAUD := 38400
 endif
 ifeq ($(CONFIG_EARLY_PRINTK), exynos5250)
 EARLY_PRINTK_INC := exynos4210
+EARLY_PRINTK_INIT_UART := y
 EARLY_PRINTK_BAUD := 115200
 endif
 
@@ -57,6 +58,7 @@ EARLY_PRINTK := y
 endif
 
 CFLAGS-$(EARLY_PRINTK) += -DEARLY_PRINTK
+CFLAGS-$(EARLY_PRINTK_INIT_UART) += -DEARLY_PRINTK_INIT_UART
 CFLAGS-$(EARLY_PRINTK) +=
-DEARLY_PRINTK_INC=\"debug-$(EARLY_PRINTK_INC).inc\"
 CFLAGS-$(EARLY_PRINTK) += -DEARLY_PRINTK_BAUD=$(EARLY_PRINTK_BAUD)
 endif
diff --git a/xen/arch/arm/arm32/head.S b/xen/arch/arm/arm32/head.S
index ec7f640..0588d54 100644
--- a/xen/arch/arm/arm32/head.S
+++ b/xen/arch/arm/arm32/head.S
@@ -369,7 +369,9 @@ fail:   PRINT("- Boot failed -\r\n")
  * r11: Early UART base address
  * Clobbers r0-r2 */
 init_uart:
+#ifdef EARLY_PRINTK_INIT_UART
         early_uart_init r11, r1, r2
+#endif
         adr   r0, 1f
         b     puts                  /* Jump to puts */
 1:      .asciz "- UART enabled -\r\n"
diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S
index 8955946..21b7e4d 100644
--- a/xen/arch/arm/arm64/head.S
+++ b/xen/arch/arm/arm64/head.S
@@ -116,7 +116,9 @@ boot_cpu:
 #ifdef EARLY_PRINTK
         ldr   x23, =EARLY_UART_BASE_ADDRESS /* x23 := UART base address */
         cbnz  x22, 1f
+#ifdef EARLY_PRINTK_INIT_UART
         bl    init_uart                 /* CPU 0 sets up the UART too */
+#endif
 1:      PRINT("- CPU ")
         mov   x0, x22
         bl    putn
-- 
1.7.12.1

Andre Przywara

2013-May-24 13:47 UTC

head link

[PATCH v2 3/5] arm/early-printk: move UART base address to Rules.mk

The UART memory mapped base address is currently hardcoded in the
early-printk UART driver, which denies the driver to be used by
two machines with a different mapping.
Move this definition out to xen/arch/arm/Rules.mk, allowing easier
user access and later sharing of the driver.

Signed-off-by: Andre Przywara <andre.przywara@calxeda.com>
---
 docs/misc/arm/early-printk.txt          | 2 +-
 xen/arch/arm/Rules.mk                   | 4 +++-
 xen/arch/arm/arm32/debug-exynos4210.inc | 2 --
 xen/arch/arm/arm32/debug-pl011.inc      | 2 --
 xen/arch/arm/arm64/debug-pl011.inc      | 2 --
 5 files changed, 4 insertions(+), 8 deletions(-)

diff --git a/docs/misc/arm/early-printk.txt b/docs/misc/arm/early-printk.txt
index 965add5..9220113 100644
--- a/docs/misc/arm/early-printk.txt
+++ b/docs/misc/arm/early-printk.txt
@@ -12,7 +12,7 @@ where mach is the name of the machine:
   - vexpress: printk with pl011 for versatile express
   - exynos5250: printk with the second UART
 
-The baud rate is hardcoded in xen/arch/arm/Rules.mk,
+The base address and baud rate is hardcoded in xen/arch/arm/Rules.mk,
 see there when adding support for new machines.
 If not explicitly requested with "EARLY_PRINTK_INIT_UART := y" in
Rules.mk,
 the code will not try to initialize the UART, so that bootloader or
diff --git a/xen/arch/arm/Rules.mk b/xen/arch/arm/Rules.mk
index fdcf73e..902bddb 100644
--- a/xen/arch/arm/Rules.mk
+++ b/xen/arch/arm/Rules.mk
@@ -42,15 +42,16 @@ EARLY_PRINTK := n
 ifeq ($(debug),y)
 
 # Early printk for versatile express
-# TODO handle UART base address from make command line
 ifeq ($(CONFIG_EARLY_PRINTK), vexpress)
 EARLY_PRINTK_INC := pl011
 EARLY_PRINTK_BAUD := 38400
+EARLY_UART_BASE_ADDRESS := 0x1c090000
 endif
 ifeq ($(CONFIG_EARLY_PRINTK), exynos5250)
 EARLY_PRINTK_INC := exynos4210
 EARLY_PRINTK_INIT_UART := y
 EARLY_PRINTK_BAUD := 115200
+EARLY_UART_BASE_ADDRESS := 0x12c20000
 endif
 
 ifneq ($(EARLY_PRINTK_INC),)
@@ -61,4 +62,5 @@ CFLAGS-$(EARLY_PRINTK) += -DEARLY_PRINTK
 CFLAGS-$(EARLY_PRINTK_INIT_UART) += -DEARLY_PRINTK_INIT_UART
 CFLAGS-$(EARLY_PRINTK) +=
-DEARLY_PRINTK_INC=\"debug-$(EARLY_PRINTK_INC).inc\"
 CFLAGS-$(EARLY_PRINTK) += -DEARLY_PRINTK_BAUD=$(EARLY_PRINTK_BAUD)
+CFLAGS-$(EARLY_PRINTK) += -DEARLY_UART_BASE_ADDRESS=$(EARLY_UART_BASE_ADDRESS)
 endif
diff --git a/xen/arch/arm/arm32/debug-exynos4210.inc
b/xen/arch/arm/arm32/debug-exynos4210.inc
index 4922148..d746c35 100644
--- a/xen/arch/arm/arm32/debug-exynos4210.inc
+++ b/xen/arch/arm/arm32/debug-exynos4210.inc
@@ -18,8 +18,6 @@
 
 #include <asm/exynos4210-uart.h>
 
-#define EARLY_UART_BASE_ADDRESS 0x12c20000
-
 /* Exynos 5 UART initialization
  * rb: register which contains the UART base address
  * rc: scratch register 1
diff --git a/xen/arch/arm/arm32/debug-pl011.inc
b/xen/arch/arm/arm32/debug-pl011.inc
index 2d970ea..8b085b8 100644
--- a/xen/arch/arm/arm32/debug-pl011.inc
+++ b/xen/arch/arm/arm32/debug-pl011.inc
@@ -16,8 +16,6 @@
  * GNU General Public License for more details.
  */
 
-#define EARLY_UART_BASE_ADDRESS 0x1c090000
-
 /* PL011 UART initialization
  * rb: register which contains the UART base address
  * rc: scratch register 1
diff --git a/xen/arch/arm/arm64/debug-pl011.inc
b/xen/arch/arm/arm64/debug-pl011.inc
index 7220940..b416235 100644
--- a/xen/arch/arm/arm64/debug-pl011.inc
+++ b/xen/arch/arm/arm64/debug-pl011.inc
@@ -18,8 +18,6 @@
 
 #include <asm/asm_defns.h>
 
-#define EARLY_UART_BASE_ADDRESS 0x1c090000
-
 /* PL011 UART initialization
  * xb: register which containts the UART base address
  * c: scratch register number */
-- 
1.7.12.1

Andre Przywara

2013-May-24 13:47 UTC

head link

[PATCH v2 4/5] arm/early-printk: add support for ARM Fastmodel

Though the ARM Fastmodel software emulator mimics a Versatile Express
board, the boot process is different compared to the real hardware,
so the early printk differs slightly. Create a new early-printk
target to model this correctly.

Signed-off-by: Andre Przywara <andre.przywara@calxeda.com>
---
 docs/misc/arm/early-printk.txt | 1 +
 xen/arch/arm/Rules.mk          | 6 ++++++
 2 files changed, 7 insertions(+)

diff --git a/docs/misc/arm/early-printk.txt b/docs/misc/arm/early-printk.txt
index 9220113..e423cc4 100644
--- a/docs/misc/arm/early-printk.txt
+++ b/docs/misc/arm/early-printk.txt
@@ -11,6 +11,7 @@ CONFIG_EARLY_PRINTK=mach
 where mach is the name of the machine:
   - vexpress: printk with pl011 for versatile express
   - exynos5250: printk with the second UART
+  - fastmodel: printk on ARM Fastmodel software emulators
 
 The base address and baud rate is hardcoded in xen/arch/arm/Rules.mk,
 see there when adding support for new machines.
diff --git a/xen/arch/arm/Rules.mk b/xen/arch/arm/Rules.mk
index 902bddb..d010c69 100644
--- a/xen/arch/arm/Rules.mk
+++ b/xen/arch/arm/Rules.mk
@@ -47,6 +47,12 @@ EARLY_PRINTK_INC := pl011
 EARLY_PRINTK_BAUD := 38400
 EARLY_UART_BASE_ADDRESS := 0x1c090000
 endif
+ifeq ($(CONFIG_EARLY_PRINTK), fastmodel)
+EARLY_PRINTK_INC := pl011
+EARLY_PRINTK_INIT_UART := y
+EARLY_PRINTK_BAUD := 115200
+EARLY_UART_BASE_ADDRESS := 0x1c090000
+endif
 ifeq ($(CONFIG_EARLY_PRINTK), exynos5250)
 EARLY_PRINTK_INC := exynos4210
 EARLY_PRINTK_INIT_UART := y
-- 
1.7.12.1

Andre Przywara

2013-May-24 13:47 UTC

head link

[PATCH v2 5/5] arm/early-printk: add Calxeda Midway UART support

With the help of the previous patches add a stanza to
xen/arch/arm/Rules.mk to specify the UART configuration of the
Calxeda Midway machine.
The information has been taken from the Linux kernel''s .dts file.
This can be enabled by adding "CONFIG_EARLY_PRINTK=midway" to
Config.mk.

Signed-off-by: Andre Przywara <andre.przywara@calxeda.com>
---
 docs/misc/arm/early-printk.txt | 1 +
 xen/arch/arm/Rules.mk          | 5 +++++
 2 files changed, 6 insertions(+)

diff --git a/docs/misc/arm/early-printk.txt b/docs/misc/arm/early-printk.txt
index e423cc4..fbc3208 100644
--- a/docs/misc/arm/early-printk.txt
+++ b/docs/misc/arm/early-printk.txt
@@ -11,6 +11,7 @@ CONFIG_EARLY_PRINTK=mach
 where mach is the name of the machine:
   - vexpress: printk with pl011 for versatile express
   - exynos5250: printk with the second UART
+  - midway: printk with the pl011 on Calxeda Midway processors
   - fastmodel: printk on ARM Fastmodel software emulators
 
 The base address and baud rate is hardcoded in xen/arch/arm/Rules.mk,
diff --git a/xen/arch/arm/Rules.mk b/xen/arch/arm/Rules.mk
index d010c69..422ed04 100644
--- a/xen/arch/arm/Rules.mk
+++ b/xen/arch/arm/Rules.mk
@@ -59,6 +59,11 @@ EARLY_PRINTK_INIT_UART := y
 EARLY_PRINTK_BAUD := 115200
 EARLY_UART_BASE_ADDRESS := 0x12c20000
 endif
+ifeq ($(CONFIG_EARLY_PRINTK), midway)
+EARLY_PRINTK_INC := pl011
+EARLY_PRINTK_BAUD := 115200
+EARLY_UART_BASE_ADDRESS := 0xfff36000
+endif
 
 ifneq ($(EARLY_PRINTK_INC),)
 EARLY_PRINTK := y
-- 
1.7.12.1

Julien Grall

2013-May-24 14:01 UTC

head link

Re: [PATCH v2 1/5] arm/early-printk: calculate baud rate divisor from user provided value

On 05/24/2013 02:47 PM, Andre Przywara wrote:
> For early-printk the used baud rate was hardcoded in the code, using
> precalculated divisor values.
> Let the calculation of these values be done by the preprocessor and
> use a human readable value in xen/arch/arm/Rules.mk to drive this.
> 
> Signed-off-by: Andre Przywara <andre.przywara@calxeda.com>
Reviewed-by: Julien Grall <julien.grall@linaro.org>
> ---
>  docs/misc/arm/early-printk.txt          | 3 +++
>  xen/arch/arm/Rules.mk                   | 3 +++
>  xen/arch/arm/arm32/debug-exynos4210.inc | 4 ++--
>  xen/arch/arm/arm32/debug-pl011.inc      | 4 ++--
>  xen/arch/arm/arm64/debug-pl011.inc      | 4 ++--
>  5 files changed, 12 insertions(+), 6 deletions(-)
> 
> diff --git a/docs/misc/arm/early-printk.txt
b/docs/misc/arm/early-printk.txt
> index d5cae85..10c3053 100644
> --- a/docs/misc/arm/early-printk.txt
> +++ b/docs/misc/arm/early-printk.txt
> @@ -12,4 +12,7 @@ where mach is the name of the machine:
>    - vexpress: printk with pl011 for versatile express
>    - exynos5250: printk with the second UART
>  
> +The baud rate is hardcoded in xen/arch/arm/Rules.mk,
> +see there when adding support for new machines.
> +
>  By default early printk is disabled.
> diff --git a/xen/arch/arm/Rules.mk b/xen/arch/arm/Rules.mk
> index b6a6890..b4d6907 100644
> --- a/xen/arch/arm/Rules.mk
> +++ b/xen/arch/arm/Rules.mk
> @@ -45,9 +45,11 @@ ifeq ($(debug),y)
>  # TODO handle UART base address from make command line
>  ifeq ($(CONFIG_EARLY_PRINTK), vexpress)
>  EARLY_PRINTK_INC := pl011
> +EARLY_PRINTK_BAUD := 38400
>  endif
>  ifeq ($(CONFIG_EARLY_PRINTK), exynos5250)
>  EARLY_PRINTK_INC := exynos4210
> +EARLY_PRINTK_BAUD := 115200
>  endif
>  
>  ifneq ($(EARLY_PRINTK_INC),)
> @@ -56,4 +58,5 @@ endif
>  
>  CFLAGS-$(EARLY_PRINTK) += -DEARLY_PRINTK
>  CFLAGS-$(EARLY_PRINTK) +=
-DEARLY_PRINTK_INC=\"debug-$(EARLY_PRINTK_INC).inc\"
> +CFLAGS-$(EARLY_PRINTK) += -DEARLY_PRINTK_BAUD=$(EARLY_PRINTK_BAUD)
>  endif
> diff --git a/xen/arch/arm/arm32/debug-exynos4210.inc
b/xen/arch/arm/arm32/debug-exynos4210.inc
> index 4241640..4922148 100644
> --- a/xen/arch/arm/arm32/debug-exynos4210.inc
> +++ b/xen/arch/arm/arm32/debug-exynos4210.inc
> @@ -38,9 +38,9 @@
>          orr   \rd, \rd, #(0x7<<8)
>          str   \rd, [\rc, #0x558]
>  
> -        mov   \rc, #4
> +        mov   \rc, #(100000000 / EARLY_PRINTK_BAUD % 16)
>          str   \rc, [\rb, #UFRACVAL]     /* -> UFRACVAL (Baud divisor
fraction) */
> -        mov   \rc, #53
> +        mov   \rc, #(100000000 / EARLY_PRINTK_BAUD / 16 - 1)
>          str   \rc, [\rb, #UBRDIV]       /* -> UBRDIV (Baud divisor
integer) */
>          mov   \rc, #3                   /* 8n1 */
>          str   \rc, [\rb, #ULCON]        /* -> (Line control) */
> diff --git a/xen/arch/arm/arm32/debug-pl011.inc
b/xen/arch/arm/arm32/debug-pl011.inc
> index 6954aeb..2d970ea 100644
> --- a/xen/arch/arm/arm32/debug-pl011.inc
> +++ b/xen/arch/arm/arm32/debug-pl011.inc
> @@ -23,9 +23,9 @@
>   * rc: scratch register 1
>   * rd: scratch register 2 (unused here) */
>  .macro early_uart_init rb, rc, rd
> -        mov   \rc, #0x0
> +        mov   \rc, #(7372800 / EARLY_PRINTK_BAUD % 16)
>          str   \rc, [\rb, #0x28]     /* -> UARTFBRD (Baud divisor
fraction) */
> -        mov   \rc, #0x4             /* 7.3728MHz / 0x4 == 16 * 115200 */
> +        mov   \rc, #(7372800 / EARLY_PRINTK_BAUD / 16)
>          str   \rc, [\rb, #0x24]     /* -> UARTIBRD (Baud divisor
integer) */
>          mov   \rc, #0x60            /* 8n1 */
>          str   \rc, [\rb, #0x2C]     /* -> UARTLCR_H (Line control) */
> diff --git a/xen/arch/arm/arm64/debug-pl011.inc
b/xen/arch/arm/arm64/debug-pl011.inc
> index ee6e0e0..7220940 100644
> --- a/xen/arch/arm/arm64/debug-pl011.inc
> +++ b/xen/arch/arm/arm64/debug-pl011.inc
> @@ -24,9 +24,9 @@
>   * xb: register which containts the UART base address
>   * c: scratch register number */
>  .macro early_uart_init xb, c
> -        mov   x\c, #0x0
> +        mov   x\c, #(7372800 / EARLY_PRINTK_BAUD % 16)
>          strh  w\c, [\xb, #0x28]      /* -> UARTFBRD (Baud divisor
fraction) */
> -        mov   x\c, #0x4              /* 7.3728MHz / 0x4 == 16 * 115200 */
> +        mov   x\c, #(7372800 / EARLY_PRINTK_BAUD / 16)
>          strh  w\c, [\xb, #0x24]      /* -> UARTIBRD (Baud divisor
integer) */
>          mov   x\c, #0x60             /* 8n1 */
>          str   w\c, [\xb, #0x2C]      /* -> UARTLCR_H (Line control) */

Julien Grall

2013-May-24 14:02 UTC

head link

Re: [PATCH v2 2/5] arm/early-printk: allow skipping of UART init

On 05/24/2013 02:47 PM, Andre Przywara wrote:
> While it seems obvious to initialize the UART before using it, chances
> are that some firmware code or the bootloader already did this.
> So it may actually be a good idea to skip the initialization, in fact
> this fixes early printk on my TC2 Versatile Express.
> So provide an option in xen/arch/arm/Rules.mk to only initialize the
> UART when needed.
> 
> Signed-off-by: Andre Przywara <andre.przywara@calxeda.com>
Reviewed-by: Julien Grall <julien.grall@linaro.org>
> ---
>  docs/misc/arm/early-printk.txt | 4 ++++
>  xen/arch/arm/Rules.mk          | 2 ++
>  xen/arch/arm/arm32/head.S      | 2 ++
>  xen/arch/arm/arm64/head.S      | 2 ++
>  4 files changed, 10 insertions(+)
> 
> diff --git a/docs/misc/arm/early-printk.txt
b/docs/misc/arm/early-printk.txt
> index 10c3053..965add5 100644
> --- a/docs/misc/arm/early-printk.txt
> +++ b/docs/misc/arm/early-printk.txt
> @@ -14,5 +14,9 @@ where mach is the name of the machine:
>  
>  The baud rate is hardcoded in xen/arch/arm/Rules.mk,
>  see there when adding support for new machines.
> +If not explicitly requested with "EARLY_PRINTK_INIT_UART := y"
in Rules.mk,
> +the code will not try to initialize the UART, so that bootloader or
> +firmware settings can be used for maximum compatibility. The baud rate
> +parameter is ignored in this case.
>  
>  By default early printk is disabled.
> diff --git a/xen/arch/arm/Rules.mk b/xen/arch/arm/Rules.mk
> index b4d6907..fdcf73e 100644
> --- a/xen/arch/arm/Rules.mk
> +++ b/xen/arch/arm/Rules.mk
> @@ -49,6 +49,7 @@ EARLY_PRINTK_BAUD := 38400
>  endif
>  ifeq ($(CONFIG_EARLY_PRINTK), exynos5250)
>  EARLY_PRINTK_INC := exynos4210
> +EARLY_PRINTK_INIT_UART := y
>  EARLY_PRINTK_BAUD := 115200
>  endif
>  
> @@ -57,6 +58,7 @@ EARLY_PRINTK := y
>  endif
>  
>  CFLAGS-$(EARLY_PRINTK) += -DEARLY_PRINTK
> +CFLAGS-$(EARLY_PRINTK_INIT_UART) += -DEARLY_PRINTK_INIT_UART
>  CFLAGS-$(EARLY_PRINTK) +=
-DEARLY_PRINTK_INC=\"debug-$(EARLY_PRINTK_INC).inc\"
>  CFLAGS-$(EARLY_PRINTK) += -DEARLY_PRINTK_BAUD=$(EARLY_PRINTK_BAUD)
>  endif
> diff --git a/xen/arch/arm/arm32/head.S b/xen/arch/arm/arm32/head.S
> index ec7f640..0588d54 100644
> --- a/xen/arch/arm/arm32/head.S
> +++ b/xen/arch/arm/arm32/head.S
> @@ -369,7 +369,9 @@ fail:   PRINT("- Boot failed -\r\n")
>   * r11: Early UART base address
>   * Clobbers r0-r2 */
>  init_uart:
> +#ifdef EARLY_PRINTK_INIT_UART
>          early_uart_init r11, r1, r2
> +#endif
>          adr   r0, 1f
>          b     puts                  /* Jump to puts */
>  1:      .asciz "- UART enabled -\r\n"
> diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S
> index 8955946..21b7e4d 100644
> --- a/xen/arch/arm/arm64/head.S
> +++ b/xen/arch/arm/arm64/head.S
> @@ -116,7 +116,9 @@ boot_cpu:
>  #ifdef EARLY_PRINTK
>          ldr   x23, =EARLY_UART_BASE_ADDRESS /* x23 := UART base address */
>          cbnz  x22, 1f
> +#ifdef EARLY_PRINTK_INIT_UART
>          bl    init_uart                 /* CPU 0 sets up the UART too */
> +#endif
>  1:      PRINT("- CPU ")
>          mov   x0, x22
>          bl    putn

Julien Grall

2013-May-24 14:02 UTC

head link

Re: [PATCH v2 3/5] arm/early-printk: move UART base address to Rules.mk

On 05/24/2013 02:47 PM, Andre Przywara wrote:
> The UART memory mapped base address is currently hardcoded in the
> early-printk UART driver, which denies the driver to be used by
> two machines with a different mapping.
> Move this definition out to xen/arch/arm/Rules.mk, allowing easier
> user access and later sharing of the driver.
> 
> Signed-off-by: Andre Przywara <andre.przywara@calxeda.com>
Reviewed-by: Julien Grall <julien.grall@linaro.org>
> ---
>  docs/misc/arm/early-printk.txt          | 2 +-
>  xen/arch/arm/Rules.mk                   | 4 +++-
>  xen/arch/arm/arm32/debug-exynos4210.inc | 2 --
>  xen/arch/arm/arm32/debug-pl011.inc      | 2 --
>  xen/arch/arm/arm64/debug-pl011.inc      | 2 --
>  5 files changed, 4 insertions(+), 8 deletions(-)
> 
> diff --git a/docs/misc/arm/early-printk.txt
b/docs/misc/arm/early-printk.txt
> index 965add5..9220113 100644
> --- a/docs/misc/arm/early-printk.txt
> +++ b/docs/misc/arm/early-printk.txt
> @@ -12,7 +12,7 @@ where mach is the name of the machine:
>    - vexpress: printk with pl011 for versatile express
>    - exynos5250: printk with the second UART
>  
> -The baud rate is hardcoded in xen/arch/arm/Rules.mk,
> +The base address and baud rate is hardcoded in xen/arch/arm/Rules.mk,
>  see there when adding support for new machines.
>  If not explicitly requested with "EARLY_PRINTK_INIT_UART := y"
in Rules.mk,
>  the code will not try to initialize the UART, so that bootloader or
> diff --git a/xen/arch/arm/Rules.mk b/xen/arch/arm/Rules.mk
> index fdcf73e..902bddb 100644
> --- a/xen/arch/arm/Rules.mk
> +++ b/xen/arch/arm/Rules.mk
> @@ -42,15 +42,16 @@ EARLY_PRINTK := n
>  ifeq ($(debug),y)
>  
>  # Early printk for versatile express
> -# TODO handle UART base address from make command line
>  ifeq ($(CONFIG_EARLY_PRINTK), vexpress)
>  EARLY_PRINTK_INC := pl011
>  EARLY_PRINTK_BAUD := 38400
> +EARLY_UART_BASE_ADDRESS := 0x1c090000
>  endif
>  ifeq ($(CONFIG_EARLY_PRINTK), exynos5250)
>  EARLY_PRINTK_INC := exynos4210
>  EARLY_PRINTK_INIT_UART := y
>  EARLY_PRINTK_BAUD := 115200
> +EARLY_UART_BASE_ADDRESS := 0x12c20000
>  endif
>  
>  ifneq ($(EARLY_PRINTK_INC),)
> @@ -61,4 +62,5 @@ CFLAGS-$(EARLY_PRINTK) += -DEARLY_PRINTK
>  CFLAGS-$(EARLY_PRINTK_INIT_UART) += -DEARLY_PRINTK_INIT_UART
>  CFLAGS-$(EARLY_PRINTK) +=
-DEARLY_PRINTK_INC=\"debug-$(EARLY_PRINTK_INC).inc\"
>  CFLAGS-$(EARLY_PRINTK) += -DEARLY_PRINTK_BAUD=$(EARLY_PRINTK_BAUD)
> +CFLAGS-$(EARLY_PRINTK) +=
-DEARLY_UART_BASE_ADDRESS=$(EARLY_UART_BASE_ADDRESS)
>  endif
> diff --git a/xen/arch/arm/arm32/debug-exynos4210.inc
b/xen/arch/arm/arm32/debug-exynos4210.inc
> index 4922148..d746c35 100644
> --- a/xen/arch/arm/arm32/debug-exynos4210.inc
> +++ b/xen/arch/arm/arm32/debug-exynos4210.inc
> @@ -18,8 +18,6 @@
>  
>  #include <asm/exynos4210-uart.h>
>  
> -#define EARLY_UART_BASE_ADDRESS 0x12c20000
> -
>  /* Exynos 5 UART initialization
>   * rb: register which contains the UART base address
>   * rc: scratch register 1
> diff --git a/xen/arch/arm/arm32/debug-pl011.inc
b/xen/arch/arm/arm32/debug-pl011.inc
> index 2d970ea..8b085b8 100644
> --- a/xen/arch/arm/arm32/debug-pl011.inc
> +++ b/xen/arch/arm/arm32/debug-pl011.inc
> @@ -16,8 +16,6 @@
>   * GNU General Public License for more details.
>   */
>  
> -#define EARLY_UART_BASE_ADDRESS 0x1c090000
> -
>  /* PL011 UART initialization
>   * rb: register which contains the UART base address
>   * rc: scratch register 1
> diff --git a/xen/arch/arm/arm64/debug-pl011.inc
b/xen/arch/arm/arm64/debug-pl011.inc
> index 7220940..b416235 100644
> --- a/xen/arch/arm/arm64/debug-pl011.inc
> +++ b/xen/arch/arm/arm64/debug-pl011.inc
> @@ -18,8 +18,6 @@
>  
>  #include <asm/asm_defns.h>
>  
> -#define EARLY_UART_BASE_ADDRESS 0x1c090000
> -
>  /* PL011 UART initialization
>   * xb: register which containts the UART base address
>   * c: scratch register number */

Julien Grall

2013-May-24 14:03 UTC

head link

Re: [PATCH v2 4/5] arm/early-printk: add support for ARM Fastmodel

On 05/24/2013 02:47 PM, Andre Przywara wrote:
> Though the ARM Fastmodel software emulator mimics a Versatile Express
> board, the boot process is different compared to the real hardware,
> so the early printk differs slightly. Create a new early-printk
> target to model this correctly.
> 
> Signed-off-by: Andre Przywara <andre.przywara@calxeda.com>
Reviewed-by: Julien Grall <julien.grall@linaro.org>
> ---
>  docs/misc/arm/early-printk.txt | 1 +
>  xen/arch/arm/Rules.mk          | 6 ++++++
>  2 files changed, 7 insertions(+)
> 
> diff --git a/docs/misc/arm/early-printk.txt
b/docs/misc/arm/early-printk.txt
> index 9220113..e423cc4 100644
> --- a/docs/misc/arm/early-printk.txt
> +++ b/docs/misc/arm/early-printk.txt
> @@ -11,6 +11,7 @@ CONFIG_EARLY_PRINTK=mach
>  where mach is the name of the machine:
>    - vexpress: printk with pl011 for versatile express
>    - exynos5250: printk with the second UART
> +  - fastmodel: printk on ARM Fastmodel software emulators
>  
>  The base address and baud rate is hardcoded in xen/arch/arm/Rules.mk,
>  see there when adding support for new machines.
> diff --git a/xen/arch/arm/Rules.mk b/xen/arch/arm/Rules.mk
> index 902bddb..d010c69 100644
> --- a/xen/arch/arm/Rules.mk
> +++ b/xen/arch/arm/Rules.mk
> @@ -47,6 +47,12 @@ EARLY_PRINTK_INC := pl011
>  EARLY_PRINTK_BAUD := 38400
>  EARLY_UART_BASE_ADDRESS := 0x1c090000
>  endif
> +ifeq ($(CONFIG_EARLY_PRINTK), fastmodel)
> +EARLY_PRINTK_INC := pl011
> +EARLY_PRINTK_INIT_UART := y
> +EARLY_PRINTK_BAUD := 115200
> +EARLY_UART_BASE_ADDRESS := 0x1c090000
> +endif
>  ifeq ($(CONFIG_EARLY_PRINTK), exynos5250)
>  EARLY_PRINTK_INC := exynos4210
>  EARLY_PRINTK_INIT_UART := y

Julien Grall

2013-May-24 14:03 UTC

head link

Re: [PATCH v2 5/5] arm/early-printk: add Calxeda Midway UART support

On 05/24/2013 02:47 PM, Andre Przywara wrote:
> With the help of the previous patches add a stanza to
> xen/arch/arm/Rules.mk to specify the UART configuration of the
> Calxeda Midway machine.
> The information has been taken from the Linux kernel''s .dts file.
> This can be enabled by adding "CONFIG_EARLY_PRINTK=midway" to
> Config.mk.
> 
> Signed-off-by: Andre Przywara <andre.przywara@calxeda.com>
Reviewed-by: Julien Grall <julien.grall@linaro.org>
> ---
>  docs/misc/arm/early-printk.txt | 1 +
>  xen/arch/arm/Rules.mk          | 5 +++++
>  2 files changed, 6 insertions(+)
> 
> diff --git a/docs/misc/arm/early-printk.txt
b/docs/misc/arm/early-printk.txt
> index e423cc4..fbc3208 100644
> --- a/docs/misc/arm/early-printk.txt
> +++ b/docs/misc/arm/early-printk.txt
> @@ -11,6 +11,7 @@ CONFIG_EARLY_PRINTK=mach
>  where mach is the name of the machine:
>    - vexpress: printk with pl011 for versatile express
>    - exynos5250: printk with the second UART
> +  - midway: printk with the pl011 on Calxeda Midway processors
>    - fastmodel: printk on ARM Fastmodel software emulators
>  
>  The base address and baud rate is hardcoded in xen/arch/arm/Rules.mk,
> diff --git a/xen/arch/arm/Rules.mk b/xen/arch/arm/Rules.mk
> index d010c69..422ed04 100644
> --- a/xen/arch/arm/Rules.mk
> +++ b/xen/arch/arm/Rules.mk
> @@ -59,6 +59,11 @@ EARLY_PRINTK_INIT_UART := y
>  EARLY_PRINTK_BAUD := 115200
>  EARLY_UART_BASE_ADDRESS := 0x12c20000
>  endif
> +ifeq ($(CONFIG_EARLY_PRINTK), midway)
> +EARLY_PRINTK_INC := pl011
> +EARLY_PRINTK_BAUD := 115200
> +EARLY_UART_BASE_ADDRESS := 0xfff36000
> +endif
>  
>  ifneq ($(EARLY_PRINTK_INC),)
>  EARLY_PRINTK := y

Ian Campbell

2013-May-30 08:59 UTC

head link

Re: [PATCH v2 0/5] arm/early-printk: Improve reusability and add Calxeda support

On Fri, 2013-05-24 at 15:47 +0200, Andre Przywara wrote:> The current early-printk support for ARM is rather hard-coded, making
> it hard to add machines or tweak settings.
> This series slightly moves some code to gather UART settings in
> xen/arch/arm/Rules.mk instead of the actual .c files. Also it allows
> two different machines with different settings to share the same
> driver, which the last patch exploits to add support the Calxeda
> Midway hardware.
> 
> This haven''t been extensively tested, but I looked at the
generated
> assembly and did some quick checks on Versatile Express.
> 
> Signed-off-by: Andre Przywara <andre.przywara@calxeda.com>
All Acked + applied, thanks.

I did wonder vaguely about:

pulling the per board configs out of Rules.mk into
earlyprintk-<board>.mk and doing:
        ifneq($(CONFIG_EARLY_PRINTK),)
        include earlyprintk-$(CONFIG_EARLY_PRINTK).mk
        endif

and

using the presence or absence of EARLY_PRINTK_BAUD instead of using a
separate EARLY_PRINTK_INIT_UART.

Neither of which affect the correctness of this series though.

Andre Przywara

2013-May-30 09:14 UTC

head link

Re: [PATCH v2 0/5] arm/early-printk: Improve reusability and add Calxeda support

On 05/30/2013 10:59 AM, Ian Campbell wrote:> On Fri, 2013-05-24 at 15:47 +0200, Andre Przywara wrote:
>> The current early-printk support for ARM is rather hard-coded, making
>> it hard to add machines or tweak settings.
>> This series slightly moves some code to gather UART settings in
>> xen/arch/arm/Rules.mk instead of the actual .c files. Also it allows
>> two different machines with different settings to share the same
>> driver, which the last patch exploits to add support the Calxeda
>> Midway hardware.
>>
>> This haven''t been extensively tested, but I looked at the
generated
>> assembly and did some quick checks on Versatile Express.
>>
>> Signed-off-by: Andre Przywara <andre.przywara@calxeda.com>
>
> All Acked + applied, thanks.
Thanks!
> I did wonder vaguely about:
>
> pulling the per board configs out of Rules.mk into
> earlyprintk-<board>.mk and doing:
>          ifneq($(CONFIG_EARLY_PRINTK),)
>          include earlyprintk-$(CONFIG_EARLY_PRINTK).mk
>          endif
Yeah, I also found it being in kind of the wrong place.
Just wasn''t sure if early_printk justifies <n> extra files to be 
created. What about moving all the boards definitions into one file and 
including this? This keeps Rules.mk clean and avoids too much clutter.
> and
>
> using the presence or absence of EARLY_PRINTK_BAUD instead of using a
> separate EARLY_PRINTK_INIT_UART.
I was also wondering about this redundancy, this seems to be a nice 
solution for this. Thanks, will make a patch.

Regards,
Andre.

Ian Campbell

2013-May-30 09:22 UTC

head link

Re: [PATCH v2 0/5] arm/early-printk: Improve reusability and add Calxeda support

On Thu, 2013-05-30 at 11:14 +0200, Andre Przywara wrote:> On 05/30/2013 10:59 AM, Ian Campbell wrote:
> > On Fri, 2013-05-24 at 15:47 +0200, Andre Przywara wrote:
> >> The current early-printk support for ARM is rather hard-coded,
making
> >> it hard to add machines or tweak settings.
> >> This series slightly moves some code to gather UART settings in
> >> xen/arch/arm/Rules.mk instead of the actual .c files. Also it
allows
> >> two different machines with different settings to share the same
> >> driver, which the last patch exploits to add support the Calxeda
> >> Midway hardware.
> >>
> >> This haven''t been extensively tested, but I looked at the
generated
> >> assembly and did some quick checks on Versatile Express.
> >>
> >> Signed-off-by: Andre Przywara <andre.przywara@calxeda.com>
> >
> > All Acked + applied, thanks.
> 
> Thanks!
> 
> > I did wonder vaguely about:
> >
> > pulling the per board configs out of Rules.mk into
> > earlyprintk-<board>.mk and doing:
> >          ifneq($(CONFIG_EARLY_PRINTK),)
> >          include earlyprintk-$(CONFIG_EARLY_PRINTK).mk
> >          endif
> 
> Yeah, I also found it being in kind of the wrong place.
> Just wasn''t sure if early_printk justifies <n> extra files
to be
> created. What about moving all the boards definitions into one file and 
> including this? This keeps Rules.mk clean and avoids too much clutter.
That sounds reasonable.
> 
> > and
> >
> > using the presence or absence of EARLY_PRINTK_BAUD instead of using a
> > separate EARLY_PRINTK_INIT_UART.
> 
> I was also wondering about this redundancy, this seems to be a nice 
> solution for this. Thanks, will make a patch.
Cheers!

Lets hope we don''t have to implement 9n1 vs 7n0 and stuff too, things
other than 8n1 are pretty uncommon now though I think...

Ian.

Xen devel - May 2013 - [PATCH v2 0/5] arm/early-printk: Improve reusability and add Calxeda support

[PATCH v2 0/5] arm/early-printk: Improve reusability and add Calxeda support

[PATCH v2 1/5] arm/early-printk: calculate baud rate divisor from user provided value

[PATCH v2 2/5] arm/early-printk: allow skipping of UART init

[PATCH v2 3/5] arm/early-printk: move UART base address to Rules.mk

[PATCH v2 4/5] arm/early-printk: add support for ARM Fastmodel

[PATCH v2 5/5] arm/early-printk: add Calxeda Midway UART support

Re: [PATCH v2 1/5] arm/early-printk: calculate baud rate divisor from user provided value

Re: [PATCH v2 2/5] arm/early-printk: allow skipping of UART init

Re: [PATCH v2 3/5] arm/early-printk: move UART base address to Rules.mk

Re: [PATCH v2 4/5] arm/early-printk: add support for ARM Fastmodel

Re: [PATCH v2 5/5] arm/early-printk: add Calxeda Midway UART support

Re: [PATCH v2 0/5] arm/early-printk: Improve reusability and add Calxeda support

Re: [PATCH v2 0/5] arm/early-printk: Improve reusability and add Calxeda support

Re: [PATCH v2 0/5] arm/early-printk: Improve reusability and add Calxeda support