target/avr: Add basic parameters of the new platform

This includes definitions of various basic parameters needed
for integration of a new platform into QEMU.

[AM: Split a larger AVR introduction patch into logical units]
Suggested-by: Aleksandar Markovic <aleksandar.m.mail@gmail.com>
Co-developed-by: Michael Rolnik <mrolnik@gmail.com>
Co-developed-by: Sarah Harris <S.E.Harris@kent.ac.uk>
Signed-off-by: Michael Rolnik <mrolnik@gmail.com>
Signed-off-by: Sarah Harris <S.E.Harris@kent.ac.uk>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Aleksandar Markovic <aleksandar.m.mail@gmail.com>
Acked-by: Igor Mammedov <imammedo@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
[thuth: Simplify MAINTAINERS right from the start]
Signed-off-by: Thomas Huth <huth@tuxfamily.org>
Message-Id: <20200705140315.260514-2-huth@tuxfamily.org>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>

MAINTAINERS

@@ -167,6 +167,12 @@ S: Maintained
 F: hw/arm/smmu*
 F: include/hw/arm/smmu*
 
+AVR TCG CPUs
+M: Michael Rolnik <mrolnik@gmail.com>
+R: Sarah Harris <S.E.Harris@kent.ac.uk>
+S: Maintained
+F: target/avr/
+
 CRIS TCG CPUs
 M: Edgar E. Iglesias <edgar.iglesias@gmail.com>
 S: Maintained

target/avr/cpu-param.h

@@ -0,0 +1,36 @@
+/*
+ * QEMU AVR CPU
+ *
+ * Copyright (c) 2016-2020 Michael Rolnik
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see
+ * <http://www.gnu.org/licenses/lgpl-2.1.html>
+ */
+
+#ifndef AVR_CPU_PARAM_H
+#define AVR_CPU_PARAM_H
+
+#define TARGET_LONG_BITS 32
+/*
+ * TARGET_PAGE_BITS cannot be more than 8 bits because
+ * 1.  all IO registers occupy [0x0000 .. 0x00ff] address range, and they
+ *     should be implemented as a device and not memory
+ * 2.  SRAM starts at the address 0x0100
+ */
+#define TARGET_PAGE_BITS 8
+#define TARGET_PHYS_ADDR_SPACE_BITS 24
+#define TARGET_VIRT_ADDR_SPACE_BITS 24
+#define NB_MMU_MODES 2
+
+#endif

target/avr/cpu.h

@@ -0,0 +1,66 @@
+/*
+ * QEMU AVR CPU
+ *
+ * Copyright (c) 2016-2020 Michael Rolnik
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see
+ * <http://www.gnu.org/licenses/lgpl-2.1.html>
+ */
+
+#ifndef QEMU_AVR_CPU_H
+#define QEMU_AVR_CPU_H
+
+#include "exec/cpu-defs.h"
+
+#define TCG_GUEST_DEFAULT_MO 0
+
+/*
+ * AVR has two memory spaces, data & code.
+ * e.g. both have 0 address
+ * ST/LD instructions access data space
+ * LPM/SPM and instruction fetching access code memory space
+ */
+#define MMU_CODE_IDX 0
+#define MMU_DATA_IDX 1
+
+#define EXCP_RESET 1
+#define EXCP_INT(n) (EXCP_RESET + (n) + 1)
+
+/* Number of CPU registers */
+#define NUMBER_OF_CPU_REGISTERS 32
+/* Number of IO registers accessible by ld/st/in/out */
+#define NUMBER_OF_IO_REGISTERS 64
+
+/*
+ * Offsets of AVR memory regions in host memory space.
+ *
+ * This is needed because the AVR has separate code and data address
+ * spaces that both have start from zero but have to go somewhere in
+ * host memory.
+ *
+ * It's also useful to know where some things are, like the IO registers.
+ */
+/* Flash program memory */
+#define OFFSET_CODE 0x00000000
+/* CPU registers, IO registers, and SRAM */
+#define OFFSET_DATA 0x00800000
+/* CPU registers specifically, these are mapped at the start of data */
+#define OFFSET_CPU_REGISTERS OFFSET_DATA
+/*
+ * IO registers, including status register, stack pointer, and memory
+ * mapped peripherals, mapped just after CPU registers
+ */
+#define OFFSET_IO_REGISTERS (OFFSET_DATA + NUMBER_OF_CPU_REGISTERS)
+
+#endif /* !defined (QEMU_AVR_CPU_H) */