MIPS: generic/yamon-dt: Pull YAMON DT shim code out of SEAD-3 board

In preparation for supporting other YAMON-using boards (Malta) & sharing
code to translate information from YAMON into device tree properties,
pull the code doing so for the kernel command line, system memory &
serial configuration out of the SEAD-3 board code.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/16181/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 190 insertions, 0 deletions

diff --git a/arch/mips/generic/yamon-dt.c b/arch/mips/generic/yamon-dt.c
new file mode 100644
index 000000000000..9a0c8da5a796
--- /dev/null
+++ b/arch/mips/generic/yamon-dt.c
@@ -0,0 +1,190 @@
+/*
+ * Copyright (C) 2016 Imagination Technologies
+ * Author: Paul Burton <paul.burton@imgtec.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation;  either version 2 of the  License, or (at your
+ * option) any later version.
+ */
+
+#define pr_fmt(fmt) "yamon-dt: " fmt
+
+#include <linux/bug.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/libfdt.h>
+#include <linux/printk.h>
+
+#include <asm/fw/fw.h>
+
+__init int yamon_dt_append_cmdline(void *fdt)
+{
+	int err, chosen_off;
+
+	/* find or add chosen node */
+	chosen_off = fdt_path_offset(fdt, "/chosen");
+	if (chosen_off == -FDT_ERR_NOTFOUND)
+		chosen_off = fdt_path_offset(fdt, "/chosen@0");
+	if (chosen_off == -FDT_ERR_NOTFOUND)
+		chosen_off = fdt_add_subnode(fdt, 0, "chosen");
+	if (chosen_off < 0) {
+		pr_err("Unable to find or add DT chosen node: %d\n",
+		       chosen_off);
+		return chosen_off;
+	}
+
+	err = fdt_setprop_string(fdt, chosen_off, "bootargs", fw_getcmdline());
+	if (err) {
+		pr_err("Unable to set bootargs property: %d\n", err);
+		return err;
+	}
+
+	return 0;
+}
+
+__init int yamon_dt_append_memory(void *fdt)
+{
+	unsigned long phys_memsize, memsize;
+	__be32 mem_array[2];
+	int err, mem_off;
+	char *var;
+
+	/* find memory size from the bootloader environment */
+	var = fw_getenv("memsize");
+	if (var) {
+		err = kstrtoul(var, 0, &phys_memsize);
+		if (err) {
+			pr_err("Failed to read memsize env variable '%s'\n",
+			       var);
+			return -EINVAL;
+		}
+	} else {
+		pr_warn("The bootloader didn't provide memsize: defaulting to 32MB\n");
+		phys_memsize = 32 << 20;
+	}
+
+	/* default to using all available RAM */
+	memsize = phys_memsize;
+
+	/* allow the user to override the usable memory */
+	var = strstr(arcs_cmdline, "memsize=");
+	if (var)
+		memsize = memparse(var + strlen("memsize="), NULL);
+
+	/* if the user says there's more RAM than we thought, believe them */
+	phys_memsize = max_t(unsigned long, phys_memsize, memsize);
+
+	/* find or add a memory node */
+	mem_off = fdt_path_offset(fdt, "/memory");
+	if (mem_off == -FDT_ERR_NOTFOUND)
+		mem_off = fdt_add_subnode(fdt, 0, "memory");
+	if (mem_off < 0) {
+		pr_err("Unable to find or add memory DT node: %d\n", mem_off);
+		return mem_off;
+	}
+
+	err = fdt_setprop_string(fdt, mem_off, "device_type", "memory");
+	if (err) {
+		pr_err("Unable to set memory node device_type: %d\n", err);
+		return err;
+	}
+
+	mem_array[0] = 0;
+	mem_array[1] = cpu_to_be32(phys_memsize);
+	err = fdt_setprop(fdt, mem_off, "reg", mem_array, sizeof(mem_array));
+	if (err) {
+		pr_err("Unable to set memory regs property: %d\n", err);
+		return err;
+	}
+
+	mem_array[0] = 0;
+	mem_array[1] = cpu_to_be32(memsize);
+	err = fdt_setprop(fdt, mem_off, "linux,usable-memory",
+			  mem_array, sizeof(mem_array));
+	if (err) {
+		pr_err("Unable to set linux,usable-memory property: %d\n", err);
+		return err;
+	}
+
+	return 0;
+}
+
+__init int yamon_dt_serial_config(void *fdt)
+{
+	const char *yamontty, *mode_var;
+	char mode_var_name[9], path[18], parity;
+	unsigned int uart, baud, stop_bits;
+	bool hw_flow;
+	int chosen_off, err;
+
+	yamontty = fw_getenv("yamontty");
+	if (!yamontty || !strcmp(yamontty, "tty0")) {
+		uart = 0;
+	} else if (!strcmp(yamontty, "tty1")) {
+		uart = 1;
+	} else {
+		pr_warn("yamontty environment variable '%s' invalid\n",
+			yamontty);
+		uart = 0;
+	}
+
+	baud = stop_bits = 0;
+	parity = 0;
+	hw_flow = false;
+
+	snprintf(mode_var_name, sizeof(mode_var_name), "modetty%u", uart);
+	mode_var = fw_getenv(mode_var_name);
+	if (mode_var) {
+		while (mode_var[0] >= '0' && mode_var[0] <= '9') {
+			baud *= 10;
+			baud += mode_var[0] - '0';
+			mode_var++;
+		}
+		if (mode_var[0] == ',')
+			mode_var++;
+		if (mode_var[0])
+			parity = mode_var[0];
+		if (mode_var[0] == ',')
+			mode_var++;
+		if (mode_var[0])
+			stop_bits = mode_var[0] - '0';
+		if (mode_var[0] == ',')
+			mode_var++;
+		if (!strcmp(mode_var, "hw"))
+			hw_flow = true;
+	}
+
+	if (!baud)
+		baud = 38400;
+
+	if (parity != 'e' && parity != 'n' && parity != 'o')
+		parity = 'n';
+
+	if (stop_bits != 7 && stop_bits != 8)
+		stop_bits = 8;
+
+	WARN_ON(snprintf(path, sizeof(path), "uart%u:%u%c%u%s",
+			 uart, baud, parity, stop_bits,
+			 hw_flow ? "r" : "") >= sizeof(path));
+
+	/* find or add chosen node */
+	chosen_off = fdt_path_offset(fdt, "/chosen");
+	if (chosen_off == -FDT_ERR_NOTFOUND)
+		chosen_off = fdt_path_offset(fdt, "/chosen@0");
+	if (chosen_off == -FDT_ERR_NOTFOUND)
+		chosen_off = fdt_add_subnode(fdt, 0, "chosen");
+	if (chosen_off < 0) {
+		pr_err("Unable to find or add DT chosen node: %d\n",
+		       chosen_off);
+		return chosen_off;
+	}
+
+	err = fdt_setprop_string(fdt, chosen_off, "stdout-path", path);
+	if (err) {
+		pr_err("Unable to set stdout-path property: %d\n", err);
+		return err;
+	}
+
+	return 0;
+}