[Xen-devel] [PATCH V3 4/5] xen/arm: Extend SCIF early prink code to handle other interfaces

[Oleksandr Tyshchenko <olekstysh@xxxxxxxxx>]

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
---
 xen/arch/arm/Rules.mk             |  7 +++++++
 xen/arch/arm/arm32/debug-scif.inc | 13 +++++++++----
 2 files changed, 16 insertions(+), 4 deletions(-)

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
 
 /*
-- 
2.7.4


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