@@ -89,4 +89,12 @@ config CORESIGHT_STM
logging useful software events or data coming from various entities
in the system, possibly running different OSs
+config CORESIGHT_DEBUG
+ bool "CoreSight debug driver"
+ depends on ARM || ARM64
+ help
+ This driver provides support for coresight debugging module. This
+ is primarily used for printing out debug registers for panic and
+ soft and hard lockup.
+
endif
@@ -16,3 +16,4 @@ obj-$(CONFIG_CORESIGHT_SOURCE_ETM4X) += coresight-etm4x.o \
coresight-etm4x-sysfs.o
obj-$(CONFIG_CORESIGHT_QCOM_REPLICATOR) += coresight-replicator-qcom.o
obj-$(CONFIG_CORESIGHT_STM) += coresight-stm.o
+obj-$(CONFIG_CORESIGHT_DEBUG) += coresight-debug.o
new file mode 100644
@@ -0,0 +1,169 @@
+/*
+ * Copyright(C) 2017 Linaro Limited. All rights reserved.
+ * Author: Leo Yan <leo.yan@linaro.org>
+ *
+ * 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.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/kernel.h>
+#include <linux/moduleparam.h>
+#include <linux/init.h>
+#include <linux/types.h>
+#include <linux/device.h>
+#include <linux/io.h>
+#include <linux/err.h>
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/delay.h>
+#include <linux/smp.h>
+#include <linux/sysfs.h>
+#include <linux/stat.h>
+#include <linux/clk.h>
+#include <linux/cpu.h>
+#include <linux/coresight.h>
+#include <linux/amba/bus.h>
+#include <linux/uaccess.h>
+
+#include "coresight-priv.h"
+
+#define EDPCSR_LO 0x0A0
+#define EDPCSR_HI 0x0AC
+#define EDOSLAR 0x300
+#define EDOSLSR 0x304
+#define EDPDCR 0x310
+#define EDPDSR 0x314
+
+struct debug_drvdata {
+ void __iomem *base;
+ struct device *dev;
+ int cpu;
+};
+
+static struct debug_drvdata *debug_drvdata[NR_CPUS];
+
+static void debug_os_unlock(struct debug_drvdata *drvdata)
+{
+ /* Unlocks the debug registers */
+ writel_relaxed(0x0, drvdata->base + EDOSLAR);
+ isb();
+}
+
+static void debug_read_pcsr(struct debug_drvdata *drvdata)
+{
+ u32 pcsr_hi, pcsr_lo;
+
+ CS_UNLOCK(drvdata->base);
+
+ debug_os_unlock(drvdata);
+
+#ifdef CONFIG_64BIT
+ pcsr_lo = readl_relaxed(drvdata->base + EDPCSR_LO);
+ pcsr_hi = readl_relaxed(drvdata->base + EDPCSR_HI);
+
+ pr_emerg("CPU[%d]: PSCR=0x%lx\n", drvdata->cpu,
+ ((unsigned long)pcsr_hi << 32 | (unsigned long)pcsr_lo));
+#else
+ pcsr_lo = readl_relaxed(drvdata->base + EDPCSR_LO);
+
+ pr_emerg("CPU[%d]: PSCR=0x%lx\n", drvdata->cpu, pcsr_lo);
+#endif
+
+ CS_LOCK(drvdata->base);
+}
+
+/*
+ * Dump out memory limit information on panic.
+ */
+static int dump_debug(struct notifier_block *self, unsigned long v, void *p)
+{
+ int i;
+
+ pr_emerg("Coresight debug module:\n");
+
+ for_each_possible_cpu(i) {
+
+ if (!debug_drvdata[i])
+ continue;
+
+ debug_read_pcsr(debug_drvdata[i]);
+ }
+
+ return 0;
+}
+
+static struct notifier_block debug_notifier = {
+ .notifier_call = dump_debug,
+};
+
+static int __init register_coresight_debug_dumper(void)
+{
+ atomic_notifier_chain_register(&panic_notifier_list,
+ &debug_notifier);
+ return 0;
+}
+__initcall(register_coresight_debug_dumper);
+
+static int debug_probe(struct amba_device *adev, const struct amba_id *id)
+{
+ void __iomem *base;
+ struct device *dev = &adev->dev;
+ struct coresight_platform_data *pdata = NULL;
+ struct debug_drvdata *drvdata;
+ struct resource *res = &adev->res;
+ struct device_node *np = adev->dev.of_node;
+
+ drvdata = devm_kzalloc(dev, sizeof(*drvdata), GFP_KERNEL);
+ if (!drvdata)
+ return -ENOMEM;
+
+ if (np) {
+ pdata = of_get_coresight_platform_data(dev, np);
+ if (IS_ERR(pdata))
+ return PTR_ERR(pdata);
+ adev->dev.platform_data = pdata;
+ }
+
+ drvdata->dev = &adev->dev;
+ dev_set_drvdata(dev, drvdata);
+
+ /* Validity for the resource is already checked by the AMBA core */
+ base = devm_ioremap_resource(dev, res);
+ if (IS_ERR(base))
+ return PTR_ERR(base);
+
+ drvdata->base = base;
+ drvdata->cpu = pdata ? pdata->cpu : 0;
+ debug_drvdata[drvdata->cpu] = drvdata;
+
+ dev_info(dev, "%s initialized\n", (char *)id->data);
+ return 0;
+}
+
+static struct amba_id debug_ids[] = {
+ { /* Debug for Cortex-A53 */
+ .id = 0x000bbd03,
+ .mask = 0x000fffff,
+ .data = "debug",
+ },
+ { 0, 0},
+};
+
+static struct amba_driver debug_driver = {
+ .drv = {
+ .name = "coresight-debug",
+ .suppress_bind_attrs = true,
+ },
+ .probe = debug_probe,
+ .id_table = debug_ids,
+};
+builtin_amba_driver(debug_driver);
Coresight includes debug module and usually the module connects with CPU debug logic. ARMv8 architecture reference manual (ARMv8-ARM) has defined the debug registers in the chapter "H9: External Debug Register Descriptions". After enable the debug module we can check CPU state and PC value, etc. So this is helpful for some CPU lockup bugs, e.g. if one CPU has run into infinite loop with IRQ disabled. So the CPU cannot switch context and handle any interrupt, so it cannot handle SMP call for stack dump, etc. Furthermore, now ARMv8 introduces some other runtime firmwares like ARM trusted firmware BL31, so sometime CPU hard lock may happen in the firmware and cannot return back to kernel. This patch is to enable coresight debug module and register callback notifier for panic; so when system detect the CPU lockup we can utilize debug module registers to get to know PC value for all CPUs; so we can quickly know the hang address for CPUs. This is initial driver for coresight debug module and could enhance it later according to debugging requirement. Signed-off-by: Leo Yan <leo.yan@linaro.org> --- drivers/hwtracing/coresight/Kconfig | 8 ++ drivers/hwtracing/coresight/Makefile | 1 + drivers/hwtracing/coresight/coresight-debug.c | 169 ++++++++++++++++++++++++++ 3 files changed, 178 insertions(+) create mode 100644 drivers/hwtracing/coresight/coresight-debug.c -- 2.7.4