MIPS: Add debugfs file to print the segmentation control registers

Add a new mips/segments debugfs file to print the 6 segmentation
control registers for supported cores. A sample from a proAptiv core
is given below:

Signed-off-by: John Crispin <blogic@openwrt.org>
Patchwork: http://patchwork.linux-mips.org/patch/6137/
Segment   Virtual    Size   Access Mode   Physical   Caching   EU
-------   -------    ----   -----------   --------   -------   --
   0      e0000000   512M      MK           UND         U       0
   1      c0000000   512M      MSK          UND         U       0
   2      a0000000   512M      UK           000         2       0
   3      80000000   512M      UK           000         3       0
   4      40000000    1G       MUSK         UND         U       1
   5      00000000    1G       MUSK         UND         U       1

Reviewed-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

diff --git a/arch/mips/kernel/Makefile b/arch/mips/kernel/Makefile
index 1c1b71752c84cbc26dc2c0f81cc778e0a749a495..b95eb7411d0c1d384ba685af8218d6ef3779e2ad 100644 (file)
--- a/arch/mips/kernel/Makefile
+++ b/arch/mips/kernel/Makefile
@@ -30,6 +30,7 @@ obj-$(CONFIG_CSRC_R4K)                += csrc-r4k.o
 obj-$(CONFIG_CSRC_SB1250)      += csrc-sb1250.o
 obj-$(CONFIG_SYNC_R4K)         += sync-r4k.o
 
+obj-$(CONFIG_DEBUG_FS)         += segment.o
 obj-$(CONFIG_STACKTRACE)       += stacktrace.o
 obj-$(CONFIG_MODULES)          += mips_ksyms.o module.o
 obj-$(CONFIG_MODULES_USE_ELF_RELA) += module-rela.o

diff --git a/arch/mips/kernel/segment.c b/arch/mips/kernel/segment.c
new file mode 100644 (file)
index 0000000..076ead2
--- /dev/null
+++ b/arch/mips/kernel/segment.c
@@ -0,0 +1,110 @@
+/*
+ * 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/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.
+        */
+       if ((am == 0) || (am > 3)) {
+               str += sprintf(str, "         %03lx",
+                       ((cfg & MIPS_SEGCFG_PA) >> MIPS_SEGCFG_PA_SHIFT));
+               str += sprintf(str, "         %01ld",
+                       ((cfg & MIPS_SEGCFG_C) >> MIPS_SEGCFG_C_SHIFT));
+       } else {
+               str += sprintf(str, "         UND");
+               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)
+{
+       extern struct dentry *mips_debugfs_dir;
+       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);