[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-devel] [PATCH V4 4/5] xen/arm: Extend SCIF early prink code to handle other interfaces



Hi Oleksandr,

On 17/04/2019 15:59, Oleksandr Tyshchenko wrote:
From: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>

Extend early prink code to be able to handle other SCIF(X)
compatible interfaces as well. These interfaces have lot in common,
but mostly differ in offsets and bits for some registers.

Introduce "EARLY_PRINTK_VERSION" config option to choose which
interface version should be used (to properly apply register offsets).

Please note, nothing has been technically changed for Renesas "Lager"
and other supported boards (SCIF).

The "EARLY_PRINTK_VERSION" option for that board should be empty:
CONFIG_EARLY_PRINTK=scif,0xe6e60000

Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
CC: Julien Grall <julien.grall@xxxxxxx>

---
     Changes in v3:
         - It was decided not to introduce new debug-scifa.inc
           for handling SCIFA interface, but to extend existing
           debug-scif.inc for handling both interfaces.
           This patch is a result of splitting an initial patch
           "xen/arm: Add SCIFA UART support for early printk"
           and only reworks a code

         Changes in v4:
         - Update docs/misc/arm/early-printk.txt with the new option
---
  docs/misc/arm/early-printk.txt    |  6 ++++++
  xen/arch/arm/Rules.mk             |  7 +++++++
  xen/arch/arm/arm32/debug-scif.inc | 13 +++++++++----
  3 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/docs/misc/arm/early-printk.txt b/docs/misc/arm/early-printk.txt
index b23c54f..c054674 100644
--- a/docs/misc/arm/early-printk.txt
+++ b/docs/misc/arm/early-printk.txt
@@ -27,6 +27,12 @@ CONFIG_EARLY_PRINTK=<INC>,<BASE_ADDRESS>,<OTHER_OPTIONS>
        If <BAUD_RATE> is not given then the code will not try to
        initialize the UART, so that bootloader or firmware settings can
       be used for maximum compatibility.
+  - scif,<BASE_ADDRESS>,<VERSION>
+    - <VERSION> is a option to choose which interface version should be used

By "a option" did you intend to mean it is an optional parameter?

If so, how about:

"SCIF<VERSION> is, optionally, the interface version of the UART."

So you would also provide a way for the user to know how to specify it. Stefano any opinion?

+      If <VERSION> is not given then a default interface version (SCIF)

s/a/the/

+      will be used.
    - For all other uarts there are no additional options.
As a convenience it is also possible to select from a list of
diff --git a/xen/arch/arm/Rules.mk b/xen/arch/arm/Rules.mk
index f264592..3d9a0ed 100644
--- a/xen/arch/arm/Rules.mk
+++ b/xen/arch/arm/Rules.mk
@@ -68,6 +68,13 @@ EARLY_PRINTK_INIT_UART := y
  EARLY_PRINTK_BAUD := $(word 3,$(EARLY_PRINTK_CFG))
  endif
  endif
+ifeq ($(EARLY_PRINTK_INC),scif)
+ifneq ($(word 3,$(EARLY_PRINTK_CFG)),)
+CFLAGS-y += -DEARLY_PRINTK_VERSION_$(word 3,$(EARLY_PRINTK_CFG))
+else
+CFLAGS-y += -DEARLY_PRINTK_VERSION_NONE
+endif
+endif
ifneq ($(EARLY_PRINTK_INC),)
  EARLY_PRINTK := y
diff --git a/xen/arch/arm/arm32/debug-scif.inc 
b/xen/arch/arm/arm32/debug-scif.inc
index 143f05d..a8d2eae 100644
--- a/xen/arch/arm/arm32/debug-scif.inc
+++ b/xen/arch/arm/arm32/debug-scif.inc
@@ -19,6 +19,11 @@
#include <asm/scif-uart.h> +#ifdef EARLY_PRINTK_VERSION_NONE
+#define STATUS_REG    SCIF_SCFSR
+#define TX_FIFO_REG   SCIF_SCFTDR
+#endif
+
  /*
   * SCIF UART wait UART to be ready to transmit
   * rb: register which contains the UART base address
@@ -26,7 +31,7 @@
   */
  .macro early_uart_ready rb rc
  1:
-        ldrh   \rc, [\rb, #SCIF_SCFSR]   /* <- SCFSR (status register) */
+        ldrh   \rc, [\rb, #STATUS_REG]   /* Read status register */
          tst    \rc, #SCFSR_TDFE          /* Check TDFE bit */
          beq    1b                        /* Wait for the UART to be ready */
  .endm
@@ -37,10 +42,10 @@
   * rt: register which contains the character to transmit
   */
  .macro early_uart_transmit rb rt
-        strb   \rt, [\rb, #SCIF_SCFTDR]                  /* -> SCFTDR (data 
register) */
-        ldrh   \rt, [\rb, #SCIF_SCFSR]                   /* <- SCFSR (status 
register) */
+        strb   \rt, [\rb, #TX_FIFO_REG]                  /* Write data 
register */
+        ldrh   \rt, [\rb, #STATUS_REG]                   /* Read status 
register */
          and    \rt, \rt, #(~(SCFSR_TEND | SCFSR_TDFE))   /* Clear TEND and 
TDFE bits */
-        strh   \rt, [\rb, #SCIF_SCFSR]                   /* -> SCFSR (status 
register) */
+        strh   \rt, [\rb, #STATUS_REG]                   /* Write status 
register */
  .endm
/*


CHeers,

--
Julien Grall

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel

 


Rackspace

Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.