Add initial RISC-V architecture support

Signed-off-by: Antony Pavlov <antonynpavlov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

5 files changed, 158 insertions, 0 deletions

diff --git a/arch/riscv/lib/.gitignore b/arch/riscv/lib/.gitignore
new file mode 100644
index 0000000000..d1165788c9
--- /dev/null
+++ b/arch/riscv/lib/.gitignore
@@ -0,0 +1 @@
+barebox.lds
diff --git a/arch/riscv/lib/Makefile b/arch/riscv/lib/Makefile
new file mode 100644
index 0000000000..a1df0b7dc7
--- /dev/null
+++ b/arch/riscv/lib/Makefile
@@ -0,0 +1,3 @@
+extra-y += barebox.lds
+
+obj-y += riscv_timer.o
diff --git a/arch/riscv/lib/asm-offsets.c b/arch/riscv/lib/asm-offsets.c
new file mode 100644
index 0000000000..22f382b71e
--- /dev/null
+++ b/arch/riscv/lib/asm-offsets.c
@@ -0,0 +1,12 @@
+/*
+ * Generate definitions needed by assembly language modules.
+ * This code generates raw asm output which is post-processed to extract
+ * and format the required data.
+ */
+
+#include <linux/kbuild.h>
+
+int main(void)
+{
+	return 0;
+}
diff --git a/arch/riscv/lib/barebox.lds.S b/arch/riscv/lib/barebox.lds.S
new file mode 100644
index 0000000000..ffb97f40e8
--- /dev/null
+++ b/arch/riscv/lib/barebox.lds.S
@@ -0,0 +1,79 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2016 Antony Pavlov <antonynpavlov@gmail.com>
+ *
+ * This file is part of barebox.
+ *
+ * This program 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 General Public License for more details.
+ *
+ */
+
+#include <asm-generic/barebox.lds.h>
+
+OUTPUT_ARCH(riscv)
+ENTRY(_start)
+SECTIONS
+{
+	. = TEXT_BASE;
+
+	. = ALIGN(8);
+	.text      :
+	{
+		_stext = .;
+		_start = .;
+		KEEP(*(.text_entry*))
+		_text = .;
+		*(.text*)
+	}
+
+	. = ALIGN(8);
+	.rodata : { *(.rodata*) }
+
+	_etext = .;			/* End of text and rodata section */
+	_sdata = .;
+
+	. = ALIGN(8);
+	.data : { *(.data*) }
+
+	.barebox_imd : { BAREBOX_IMD }
+
+	. = ALIGN(8);
+	.got : { *(.got*) }
+
+	. = .;
+	__barebox_cmd_start = .;
+	.barebox_cmd : { BAREBOX_CMDS }
+	__barebox_cmd_end = .;
+
+	__barebox_magicvar_start = .;
+	.barebox_magicvar : { BAREBOX_MAGICVARS }
+	__barebox_magicvar_end = .;
+
+	__barebox_initcalls_start = .;
+	.barebox_initcalls : { INITCALLS }
+	__barebox_initcalls_end = .;
+
+	__barebox_exitcalls_start = .;
+	.barebox_exitcalls : { EXITCALLS }
+	__barebox_exitcalls_end = .;
+
+	__usymtab_start = .;
+	__usymtab : { BAREBOX_SYMS }
+	__usymtab_end = .;
+
+	.rela.dyn : { *(.rela*) }
+
+	.oftables : { BAREBOX_CLK_TABLE() }
+
+	.dtb : { BAREBOX_DTB() }
+
+	_edata = .;
+	. = ALIGN(8);
+	__bss_start = .;
+	.bss : { *(.bss*) *(.sbss*) }
+	__bss_stop = .;
+	_end = .;
+}
diff --git a/arch/riscv/lib/riscv_timer.c b/arch/riscv/lib/riscv_timer.c
new file mode 100644
index 0000000000..919d77d4b5
--- /dev/null
+++ b/arch/riscv/lib/riscv_timer.c
@@ -0,0 +1,63 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2017 Antony Pavlov <antonynpavlov@gmail.com>
+ *
+ * This file is part of barebox.
+ *
+ * This program 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 General Public License for more details.
+ *
+ */
+
+/**
+ * @file
+ * @brief Clocksource based on RISC-V cycle CSR timer
+ */
+
+#include <init.h>
+#include <of.h>
+#include <linux/clk.h>
+#include <clock.h>
+
+static uint64_t rdcycle_read(void)
+{
+	register unsigned long __v;
+
+	__asm__ __volatile__ ("rdcycle %0" : "=r" (__v));
+
+	return __v;
+}
+
+static struct clocksource rdcycle_cs = {
+	.read	= rdcycle_read,
+	.mask	= CLOCKSOURCE_MASK(32),
+};
+
+static int rdcycle_cs_init(void)
+{
+	unsigned int cycle_frequency;
+
+	/* default rate: 100 MHz */
+	cycle_frequency = 100000000;
+
+	if (IS_ENABLED(CONFIG_OFTREE)) {
+		struct device_node *np;
+		struct clk *clk;
+
+		np = of_get_cpu_node(0, NULL);
+		if (np) {
+			clk = of_clk_get(np, 0);
+			if (!IS_ERR(clk)) {
+				cycle_frequency = clk_get_rate(clk);
+			}
+		}
+	}
+
+	clocks_calc_mult_shift(&rdcycle_cs.mult, &rdcycle_cs.shift,
+		cycle_frequency, NSEC_PER_SEC, 10);
+
+	return init_clock(&rdcycle_cs);
+}
+postcore_initcall(rdcycle_cs_init);