v4.19.13 snapshot.
diff --git a/arch/mips/kernel/segment.c b/arch/mips/kernel/segment.c
new file mode 100644
index 0000000..2703f21
--- /dev/null
+++ b/arch/mips/kernel/segment.c
@@ -0,0 +1,113 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2013 Imagination Technologies Ltd.
+ */
+
+#include <linux/kernel.h>
+#include <linux/debugfs.h>
+#include <linux/seq_file.h>
+#include <asm/cpu.h>
+#include <asm/debug.h>
+#include <asm/mipsregs.h>
+
+static void build_segment_config(char *str, unsigned int cfg)
+{
+ unsigned int am;
+ static const char * const am_str[] = {
+ "UK", "MK", "MSK", "MUSK", "MUSUK", "USK",
+ "RSRVD", "UUSK"};
+
+ /* Segment access mode. */
+ am = (cfg & MIPS_SEGCFG_AM) >> MIPS_SEGCFG_AM_SHIFT;
+ str += sprintf(str, "%-5s", am_str[am]);
+
+ /*
+ * Access modes MK, MSK and MUSK are mapped segments. Therefore
+ * there is no direct physical address mapping unless it becomes
+ * unmapped uncached at error level due to EU.
+ */
+ if ((am == 0) || (am > 3) || (cfg & MIPS_SEGCFG_EU))
+ str += sprintf(str, " %03lx",
+ ((cfg & MIPS_SEGCFG_PA) >> MIPS_SEGCFG_PA_SHIFT));
+ else
+ str += sprintf(str, " UND");
+
+ if ((am == 0) || (am > 3))
+ str += sprintf(str, " %01ld",
+ ((cfg & MIPS_SEGCFG_C) >> MIPS_SEGCFG_C_SHIFT));
+ else
+ str += sprintf(str, " U");
+
+ /* Exception configuration. */
+ str += sprintf(str, " %01ld\n",
+ ((cfg & MIPS_SEGCFG_EU) >> MIPS_SEGCFG_EU_SHIFT));
+}
+
+static int show_segments(struct seq_file *m, void *v)
+{
+ unsigned int segcfg;
+ char str[42];
+
+ seq_puts(m, "Segment Virtual Size Access Mode Physical Caching EU\n");
+ seq_puts(m, "------- ------- ---- ----------- -------- ------- --\n");
+
+ segcfg = read_c0_segctl0();
+ build_segment_config(str, segcfg);
+ seq_printf(m, " 0 e0000000 512M %s", str);
+
+ segcfg >>= 16;
+ build_segment_config(str, segcfg);
+ seq_printf(m, " 1 c0000000 512M %s", str);
+
+ segcfg = read_c0_segctl1();
+ build_segment_config(str, segcfg);
+ seq_printf(m, " 2 a0000000 512M %s", str);
+
+ segcfg >>= 16;
+ build_segment_config(str, segcfg);
+ seq_printf(m, " 3 80000000 512M %s", str);
+
+ segcfg = read_c0_segctl2();
+ build_segment_config(str, segcfg);
+ seq_printf(m, " 4 40000000 1G %s", str);
+
+ segcfg >>= 16;
+ build_segment_config(str, segcfg);
+ seq_printf(m, " 5 00000000 1G %s\n", str);
+
+ return 0;
+}
+
+static int segments_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, show_segments, NULL);
+}
+
+static const struct file_operations segments_fops = {
+ .open = segments_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+};
+
+static int __init segments_info(void)
+{
+ struct dentry *segments;
+
+ if (cpu_has_segments) {
+ if (!mips_debugfs_dir)
+ return -ENODEV;
+
+ segments = debugfs_create_file("segments", S_IRUGO,
+ mips_debugfs_dir, NULL,
+ &segments_fops);
+ if (!segments)
+ return -ENOMEM;
+ }
+ return 0;
+}
+
+device_initcall(segments_info);