[PATCH 1/4] xen/arm: debug-pl011: Use correct accessors

[Michal Orzel <michal.orzel@xxxxxxx>]

Although most PL011 UARTs can cope with 32-bit accesses, some of the old
legacy ones might not. PL011 registers are 8/16-bit wide and this shall
be perceived as the normal behavior.

Modify early printk pl011 code for arm32/arm64 to use the correct
accessors depending on the register size (refer ARM DDI 0183G, Table 3.1).

Signed-off-by: Michal Orzel <michal.orzel@xxxxxxx>
---
Next patch will override strX,ldrX with macros but I prefer to keep the
history clean (+ possibiltity for a backport if needed).
---
 xen/arch/arm/arm32/debug-pl011.inc | 12 ++++++------
 xen/arch/arm/arm64/debug-pl011.inc |  6 +++---
 2 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/xen/arch/arm/arm32/debug-pl011.inc 
b/xen/arch/arm/arm32/debug-pl011.inc
index c527f1d4424d..9fe0c2503831 100644
--- a/xen/arch/arm/arm32/debug-pl011.inc
+++ b/xen/arch/arm/arm32/debug-pl011.inc
@@ -26,13 +26,13 @@
  */
 .macro early_uart_init rb, rc, rd
         mov   \rc, #(7372800 / CONFIG_EARLY_UART_PL011_BAUD_RATE % 16)
-        str   \rc, [\rb, #FBRD]     /* -> UARTFBRD (Baud divisor fraction) */
+        strb  \rc, [\rb, #FBRD]     /* -> UARTFBRD (Baud divisor fraction) */
         mov   \rc, #(7372800 / CONFIG_EARLY_UART_PL011_BAUD_RATE / 16)
-        str   \rc, [\rb, #IBRD]     /* -> UARTIBRD (Baud divisor integer) */
+        strh  \rc, [\rb, #IBRD]     /* -> UARTIBRD (Baud divisor integer) */
         mov   \rc, #WLEN_8          /* 8n1 */
-        str   \rc, [\rb, #LCR_H]     /* -> UARTLCR_H (Line control) */
+        strb  \rc, [\rb, #LCR_H]     /* -> UARTLCR_H (Line control) */
         ldr   \rc, =(RXE | TXE | UARTEN)      /* RXE | TXE | UARTEN */
-        str   \rc, [\rb, #CR]     /* -> UARTCR (Control Register) */
+        strh  \rc, [\rb, #CR]     /* -> UARTCR (Control Register) */
 .endm
 
 /*
@@ -42,7 +42,7 @@
  */
 .macro early_uart_ready rb, rc
 1:
-        ldr   \rc, [\rb, #FR]       /* <- UARTFR (Flag register) */
+        ldrh  \rc, [\rb, #FR]       /* <- UARTFR (Flag register) */
         tst   \rc, #BUSY             /* Check BUSY bit */
         bne   1b                    /* Wait for the UART to be ready */
 .endm
@@ -53,7 +53,7 @@
  * rt: register which contains the character to transmit
  */
 .macro early_uart_transmit rb, rt
-        str   \rt, [\rb, #DR]            /* -> UARTDR (Data Register) */
+        strb  \rt, [\rb, #DR]            /* -> UARTDR (Data Register) */
 .endm
 
 /*
diff --git a/xen/arch/arm/arm64/debug-pl011.inc 
b/xen/arch/arm/arm64/debug-pl011.inc
index 6d60e78c8ba3..df713eff4922 100644
--- a/xen/arch/arm/arm64/debug-pl011.inc
+++ b/xen/arch/arm/arm64/debug-pl011.inc
@@ -25,13 +25,13 @@
  */
 .macro early_uart_init xb, c
         mov   x\c, #(7372800 / CONFIG_EARLY_UART_PL011_BAUD_RATE % 16)
-        strh  w\c, [\xb, #FBRD]      /* -> UARTFBRD (Baud divisor fraction) */
+        strb  w\c, [\xb, #FBRD]      /* -> UARTFBRD (Baud divisor fraction) */
         mov   x\c, #(7372800 / CONFIG_EARLY_UART_PL011_BAUD_RATE / 16)
         strh  w\c, [\xb, #IBRD]      /* -> UARTIBRD (Baud divisor integer) */
         mov   x\c, #WLEN_8           /* 8n1 */
-        str   w\c, [\xb, #LCR_H]     /* -> UARTLCR_H (Line control) */
+        strb  w\c, [\xb, #LCR_H]     /* -> UARTLCR_H (Line control) */
         ldr   x\c, =(RXE | TXE | UARTEN)
-        str   w\c, [\xb, #CR]        /* -> UARTCR (Control Register) */
+        strh  w\c, [\xb, #CR]        /* -> UARTCR (Control Register) */
 .endm
 
 /*
-- 
2.25.1