cpu/microwatt: add initial software support

litex/soc/cores/cpu/microwatt/core.py

@@ -18,7 +18,7 @@ class Microwatt(CPU):
     data_width           = 64
     endianness           = "little"
     gcc_triple           = ("powerpc64le-linux")
-    linker_output_format = "elf64-powerpc64le"
+    linker_output_format = "elf64-powerpcle"
     io_regions           = {0xc0000000: 0x10000000} # origin, length
 
     @property

litex/soc/integration/soc_core.py

@@ -170,6 +170,8 @@ class SoCCore(Module):
                 raise ValueError("Unsupported CPU type: {}".format(cpu_type))
             # Declare the CPU
             self.submodules.cpu = cpu.CPUS[cpu_type](platform, self.cpu_variant)
+            if cpu_type == "microwatt":
+                self.add_constant("UART_POLLING", None)
 
             # Update Memory Map (if defined by CPU)
             self.soc_mem_map.update(self.cpu.mem_map)

litex/soc/software/bios/boot-helper-microwatt.S

@@ -0,0 +1,4 @@
+.section    .text, "ax", @progbits
+.global     boot_helper
+boot_helper:
+	nop # FIXME

litex/soc/software/bios/isr.c

@@ -56,7 +56,9 @@ void isr(void)
 
 	irqs = irq_pending() & irq_getmask();
 
+#ifndef UART_POLLING
 	if(irqs & (1 << UART_INTERRUPT))
 		uart_isr();
+#endif
 }
 #endif

litex/soc/software/bios/sdram.c

@@ -46,6 +46,8 @@ __attribute__((unused)) static void cdelay(int i)
 		__asm__ volatile("nop");
 #elif defined (__powerpc__)
 		__asm__ volatile("nop");
+#elif defined (__microwatt__)
+		__asm__ volatile("nop");
 #else
 #error Unsupported architecture
 #endif

litex/soc/software/include/base/irq.h

@@ -56,6 +56,8 @@ static inline unsigned int irq_getie(void)
 	return (csrr(mstatus) & CSR_MSTATUS_MIE) != 0;
 #elif defined (__rocket__)
 	return (csrr(mstatus) & CSR_MSTATUS_MIE) != 0;
+#elif defined (__microwatt__)
+	return 0; // FIXME
 #else
 #error Unsupported architecture
 #endif
@@ -81,6 +83,8 @@ static inline void irq_setie(unsigned int ie)
 	if(ie) csrs(mstatus,CSR_MSTATUS_MIE); else csrc(mstatus,CSR_MSTATUS_MIE);
 #elif defined (__rocket__)
 	if(ie) csrs(mstatus,CSR_MSTATUS_MIE); else csrc(mstatus,CSR_MSTATUS_MIE);
+#elif defined (__microwatt__)
+	// FIXME
 #else
 #error Unsupported architecture
 #endif
@@ -108,6 +112,8 @@ static inline unsigned int irq_getmask(void)
 	return mask;
 #elif defined (__rocket__)
 	return csr_readl(PLIC_ENABLED) >> 1;
+#elif defined (__microwatt__)
+	return 0; // FIXME
 #else
 #error Unsupported architecture
 #endif
@@ -129,6 +135,8 @@ static inline void irq_setmask(unsigned int mask)
 	asm volatile ("csrw %0, %1" :: "i"(CSR_IRQ_MASK), "r"(mask));
 #elif defined (__rocket__)
 	csr_writel(mask << 1, PLIC_ENABLED);
+#elif defined (__microwatt__)
+	// FIXME
 #else
 #error Unsupported architecture
 #endif
@@ -154,6 +162,8 @@ static inline unsigned int irq_pending(void)
 	return pending;
 #elif defined (__rocket__)
 	return csr_readl(PLIC_PENDING) >> 1;
+#elif defined (__microwatt__)
+	return 0; // FIXME
 #else
 #error Unsupported architecture
 #endif

litex/soc/software/libbase/crt0-microwatt.S

@@ -0,0 +1,102 @@
+/* Copyright 2013-2014 IBM Corp.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * 	http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+ * implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define STACK_TOP	0xffff4000
+
+#define FIXUP_ENDIAN						   \
+	tdi   0,0,0x48;	  /* Reverse endian of b . + 8		*/ \
+	b     191f;	  /* Skip trampoline if endian is good	*/ \
+	.long 0xa600607d; /* mfmsr r11				*/ \
+	.long 0x01006b69; /* xori r11,r11,1			*/ \
+	.long 0x05009f42; /* bcl 20,31,$+4			*/ \
+	.long 0xa602487d; /* mflr r10				*/ \
+	.long 0x14004a39; /* addi r10,r10,20			*/ \
+	.long 0xa64b5a7d; /* mthsrr0 r10			*/ \
+	.long 0xa64b7b7d; /* mthsrr1 r11			*/ \
+	.long 0x2402004c; /* hrfid				*/ \
+191:
+
+
+/* Load an immediate 64-bit value into a register */
+#define LOAD_IMM64(r, e)			\
+	lis     r,(e)@highest;			\
+	ori     r,r,(e)@higher;			\
+	rldicr  r,r, 32, 31;			\
+	oris    r,r, (e)@h;			\
+	ori     r,r, (e)@l;
+
+	.section ".head","ax"
+
+	. = 0
+.global _start
+_start:
+	FIXUP_ENDIAN
+
+	/* setup stack */
+	LOAD_IMM64(%r1, STACK_TOP - 0x100)
+	LOAD_IMM64(%r12, main)
+	mtctr	%r12,
+	bctrl
+	ba	0
+
+	/* XXX: litedram init should not take exceptions, maybe we could get
+	 *      rid of these to save space, along with a core tweak to suppress
+	 *      exceptions in case they happen (just terminate ?)
+	 */
+
+#define EXCEPTION(nr)		\
+	.=  nr;      \
+	b	.
+
+	/* More exception stubs */
+	EXCEPTION(0x100)
+	EXCEPTION(0x200)
+	EXCEPTION(0x300)
+	EXCEPTION(0x380)
+	EXCEPTION(0x400)
+	EXCEPTION(0x480)
+	EXCEPTION(0x500)
+	EXCEPTION(0x600)
+	EXCEPTION(0x700)
+	EXCEPTION(0x800)
+	EXCEPTION(0x900)
+	EXCEPTION(0x980)
+	EXCEPTION(0xa00)
+	EXCEPTION(0xb00)
+	EXCEPTION(0xc00)
+	EXCEPTION(0xd00)
+	EXCEPTION(0xe00)
+	EXCEPTION(0xe20)
+	EXCEPTION(0xe40)
+	EXCEPTION(0xe60)
+	EXCEPTION(0xe80)
+	EXCEPTION(0xf00)
+	EXCEPTION(0xf20)
+	EXCEPTION(0xf40)
+	EXCEPTION(0xf60)
+	EXCEPTION(0xf80)
+#if 0
+	EXCEPTION(0x1000)
+	EXCEPTION(0x1100)
+	EXCEPTION(0x1200)
+	EXCEPTION(0x1300)
+	EXCEPTION(0x1400)
+	EXCEPTION(0x1500)
+	EXCEPTION(0x1600)
+#endif
+
+	.text
+

litex/soc/software/libbase/system.c

@@ -56,6 +56,9 @@ void flush_cpu_icache(void)
 #elif defined (__rocket__)
 	/* FIXME: do something useful here! */
 	asm volatile("nop");
+#elif defined (__microwatt__)
+	/* FIXME: do something useful here! */
+	asm volatile("nop");
 #else
 #error Unsupported architecture
 #endif
@@ -101,6 +104,9 @@ void flush_cpu_dcache(void)
 #elif defined (__rocket__)
 	/* FIXME: do something useful here! */
 	asm volatile("nop");
+#elif defined (__microwatt__)
+	/* FIXME: do something useful here! */
+	asm volatile("nop");
 #else
 #error Unsupported architecture
 #endif