Division functionality for cores that dont have divide hardware.
Cortex a5 doesnt support hardware division such as sdiv and udiv commands.
This commit adds a software division function in assembly as well as include
appropriate files for software divison.
The software division algorithm is a modified version obtained from:
http://www.keil.com/support/man/docs/armasm/armasm_dom1359731155623.htm
Change-Id: Ib405a330da5f1cea1e68e07e7b520edeef9e2652
Signed-off-by: Usama Arif <usama.arif@arm.com>
diff --git a/drivers/arm/pl011/aarch32/pl011_console.S b/drivers/arm/pl011/aarch32/pl011_console.S
index ae613b1..e9f95f2 100644
--- a/drivers/arm/pl011/aarch32/pl011_console.S
+++ b/drivers/arm/pl011/aarch32/pl011_console.S
@@ -63,7 +63,14 @@
/* Program the baudrate */
/* Divisor = (Uart clock * 4) / baudrate */
lsl r1, r1, #2
+#if (ARM_ARCH_MAJOR == 7) && !defined(ARMV7_SUPPORTS_VIRTUALIZATION)
+ push {r0,r3}
+ softudiv r0,r1,r2,r3
+ mov r1, r0
+ pop {r0,r3}
+#else
udiv r2, r1, r2
+#endif
/* IBRD = Divisor >> 6 */
lsr r1, r2, #6
/* Write the IBRD */
diff --git a/include/arch/aarch32/asm_macros.S b/include/arch/aarch32/asm_macros.S
index 8408804..8cfa212 100644
--- a/include/arch/aarch32/asm_macros.S
+++ b/include/arch/aarch32/asm_macros.S
@@ -78,7 +78,7 @@
* Clobber: r14, r1, r2
*/
.macro get_my_mp_stack _name, _size
- bl plat_my_core_pos
+ bl plat_my_core_pos
ldr r2, =(\_name + \_size)
mov r1, #\_size
mla r0, r0, r1, r2
@@ -189,4 +189,31 @@
.endif
.endm
+ /*
+ * Helper macro for carrying out division in software when
+ * hardware division is not suported. \top holds the dividend
+ * in the function call and the remainder after
+ * the function is executed. \bot holds the divisor. \div holds
+ * the quotient and \temp is a temporary registed used in calcualtion.
+ * The division algorithm has been obtained from:
+ * http://www.keil.com/support/man/docs/armasm/armasm_dom1359731155623.htm
+ */
+ .macro softudiv div:req,top:req,bot:req,temp:req
+
+ mov \temp, \bot
+ cmp \temp, \top, lsr #1
+div1:
+ movls \temp, \temp, lsl #1
+ cmp \temp, \top, lsr #1
+ bls div1
+ mov \div, #0
+
+div2:
+ cmp \top, \temp
+ subcs \top, \top,\temp
+ ADC \div, \div, \div
+ mov \temp, \temp, lsr #1
+ cmp \temp, \bot
+ bhs div2
+ .endm
#endif /* ASM_MACROS_S */