ARM: bL_switcher: add a simple /dev user interface for debugging purposes

Only the basic to aid debugging.

Usage:

	echo <cpuid>,<clusterid> > /dev/b.L_switcher

where <cpuid> is between 0 and 3, and <clusterid> is 0 for the
A15 cluster and 1 for the A7 cluster.

Signed-off-by: nicolas Pitre <nico@linaro.org>

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 93a1d2594e2ed3ae6778ce7be989aef19d17bdc3..b3fc1fd233499ad19dd704c02af10260d04b34ae 100644 (file)
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1514,6 +1514,14 @@ config BL_SWITCHER
          transparently handle transition between a cluster of A15's
          and a cluster of A7's in a big.LITTLE system.
 
+config BL_SWITCHER_DUMMY_IF
+       tristate "Simple big.LITTLE switcher user interface"
+       depends on BL_SWITCHER && DEBUG_KERNEL
+       help
+         This is a simple and dummy char dev interface to control
+         the big.LITTLE switcher core code.  It is meant for
+         debugging purposes only.
+
 choice
        prompt "Memory split"
        default VMSPLIT_3G

diff --git a/arch/arm/common/Makefile b/arch/arm/common/Makefile
index 483c04fa83c4ba95cc9ae41763bf7d7aad8bb41c..6073ffb8906ea4731aa7a7b9efe1b03e6e4af330 100644 (file)
--- a/arch/arm/common/Makefile
+++ b/arch/arm/common/Makefile
@@ -17,3 +17,4 @@ obj-$(CONFIG_MCPM)            += mcpm_head.o mcpm_entry.o mcpm_platsmp.o vlock.o
 AFLAGS_mcpm_head.o             := -march=armv7-a
 AFLAGS_vlock.o                 := -march=armv7-a
 obj-$(CONFIG_BL_SWITCHER)      += bL_switcher.o
+obj-$(CONFIG_BL_SWITCHER_DUMMY_IF) += bL_switcher_dummy_if.o

diff --git a/arch/arm/common/bL_switcher_dummy_if.c b/arch/arm/common/bL_switcher_dummy_if.c
new file mode 100644 (file)
index 0000000..5e2dd19
--- /dev/null
+++ b/arch/arm/common/bL_switcher_dummy_if.c
@@ -0,0 +1,71 @@
+/*
+ * arch/arm/common/bL_switcher_dummy_if.c -- b.L switcher dummy interface
+ *
+ * Created by: Nicolas Pitre, November 2012
+ * Copyright:  (C) 2012  Linaro Limited
+ *
+ * Dummy interface to user space for debugging purpose only.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/miscdevice.h>
+#include <asm/uaccess.h>
+#include <asm/bL_switcher.h>
+
+static ssize_t bL_switcher_write(struct file *file, const char __user *buf,
+                       size_t len, loff_t *pos)
+{
+       unsigned char val[3];
+       unsigned int cpu, cluster;
+       int ret;
+
+       pr_debug("%s\n", __func__);
+
+       if (len < 3)
+               return -EINVAL;
+
+       if (copy_from_user(val, buf, 3))
+               return -EFAULT;
+
+       /* format: <cpu#>,<cluster#> */
+       if (val[0] < '0' || val[0] > '4' ||
+           val[1] != ',' ||
+           val[2] < '0' || val[2] > '1')
+               return -EINVAL;
+
+       cpu = val[0] - '0';
+       cluster = val[2] - '0';
+       ret = bL_switch_request(cpu, cluster);
+
+       return ret ? : len;
+}
+
+static const struct file_operations bL_switcher_fops = {
+       .write          = bL_switcher_write,
+       .owner  = THIS_MODULE,
+};
+
+static struct miscdevice bL_switcher_device = {
+        MISC_DYNAMIC_MINOR,
+        "b.L_switcher",
+        &bL_switcher_fops
+};
+
+static int __init bL_switcher_dummy_if_init(void)
+{
+       return misc_register(&bL_switcher_device);
+}
+
+static void __exit bL_switcher_dummy_if_exit(void)
+{
+       misc_deregister(&bL_switcher_device);
+}
+
+module_init(bL_switcher_dummy_if_init);
+module_exit(bL_switcher_dummy_if_exit);