Re: [Xen-devel] [PATCH V2 3/3] xen/arm: Add SCIFA UART support for early printk

[Oleksandr <olekstysh@xxxxxxxxx>]

Hi Julien

> > > > Actually, the main difference for the "early printk" support is in 
> > > > two reg offsets:
> > > > +#define SCIFA_SCASSR   0x14    /* Serial status register */
> > > > +#define SCIFA_SCAFTDR  0x20    /* Transmit FIFO data register */
> > > >
> > > > +#define SCIF_SCFSR             0x10    /* Serial status register */
> > > > +#define SCIF_SCFTDR            0x0c    /* Transmit FIFO data 
> > > > register */
> > > >
> > > > I am not mistaken, we will have to introduce two options to cover 
> > > > this case, as the offsets are not correlated with each other, no?
> > You don't need two options. For instance, you can only introduce an 
> > option SCIF_VERSION that would be 0 for SCIF and 61 (ascii 'a') for 
> > SCIFA.
> > Then in the code, you can use SCIF_VERSION to decides which sets of 
> > macros you are using.
> I think I understand the idea. Will try.

Is it something you would like to see?

[Sorry for formatting]


---
 xen/arch/arm/Rules.mk             |  7 +++++++
 xen/arch/arm/arm32/debug-scif.inc | 22 +++++++++++++++-------
 2 files changed, 22 insertions(+), 7 deletions(-)

diff --git a/xen/arch/arm/Rules.mk b/xen/arch/arm/Rules.mk
index f264592..b29bd60 100644
--- a/xen/arch/arm/Rules.mk
+++ b/xen/arch/arm/Rules.mk
@@ -69,6 +69,12 @@ EARLY_PRINTK_BAUD := $(word 3,$(EARLY_PRINTK_CFG))
 endif
 endif

+# For the debug-scif.inc to recognize which UART offsets to apply
+ifeq ($(EARLY_PRINTK_INC),scifa)
+EARLY_PRINTK_SCIFA_OPTION := y
+EARLY_PRINTK_INC := scif
+endif
+
 ifneq ($(EARLY_PRINTK_INC),)
 EARLY_PRINTK := y
 endif
@@ -79,6 +85,7 @@ 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)
 CFLAGS-$(EARLY_PRINTK) += -DEARLY_UART_REG_SHIFT=$(EARLY_UART_REG_SHIFT)
+CFLAGS-$(EARLY_PRINTK_SCIFA_OPTION) += -DEARLY_PRINTK_SCIFA_OPTION

 else # !CONFIG_DEBUG

diff --git a/xen/arch/arm/arm32/debug-scif.inc 
b/xen/arch/arm/arm32/debug-scif.inc
index 143f05d..49df616 100644
--- a/xen/arch/arm/arm32/debug-scif.inc
+++ b/xen/arch/arm/arm32/debug-scif.inc
@@ -1,7 +1,7 @@
 /*
  * xen/arch/arm/arm32/debug-scif.inc
  *
- * SCIF specific debug code
+ * SCIF(A) specific debug code
  *
  * Oleksandr Tyshchenko <oleksandr.tyshchenko@xxxxxxxxxxxxxxx>
  * Copyright (C) 2014, Globallogic.
@@ -19,28 +19,36 @@

 #include <asm/scif-uart.h>

+#ifdef EARLY_PRINTK_SCIFA_OPTION
+#define STATUS_REG    SCIFA_SCASSR
+#define TX_FIFO_REG   SCIFA_SCAFTDR
+#else
+#define STATUS_REG    SCIF_SCFSR
+#define TX_FIFO_REG   SCIF_SCFTDR
+#endif
+
 /*
- * SCIF UART wait UART to be ready to transmit
+ * SCIF(A) UART wait UART to be ready to transmit
  * rb: register which contains the UART base address
  * rc: scratch register
  */
 .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

 /*
- * SCIF UART transmit character
+ * SCIF(A) UART transmit character
  * rb: register which contains the UART base address
  * 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


>
--
Regards,

Oleksandr Tyshchenko


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