linux-kernel - [PATCH 3/3] ARM: versatile: Make able to use UART ports for KGDB FIQ debugger

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Message-Id: <1357521831-6053-3-git-send-email-anton.vorontsov@linaro.org>
Date:	Sun,  6 Jan 2013 17:23:51 -0800
From:	Anton Vorontsov <anton.vorontsov@...aro.org>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Russell King <linux@....linux.org.uk>,
	Jason Wessel <jason.wessel@...driver.com>,
	John Stultz <john.stultz@...aro.org>,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linaro-kernel@...ts.linaro.org, patches@...aro.org,
	kernel-team@...roid.com
Subject: [PATCH 3/3] ARM: versatile: Make able to use UART ports for KGDB FIQ debugger

If enabled, kernel will able to enter KGDB upon serial line activity on
UART ports.

Note that even with this patch and CONFIG_KGDB_FIQ is enabled, you still
need to pass kgdb_fiq.enable=1 kernel command line option, otherwise UART
will behave in a normal way.

By default UART0 is used, but this can be changed via kgdb_fiq.uart_num
kernel command line option.

Signed-off-by: Anton Vorontsov <anton.vorontsov@...aro.org>
---
 arch/arm/Kconfig                   |  1 +
 arch/arm/mach-versatile/Makefile   |  1 +
 arch/arm/mach-versatile/kgdb_fiq.c | 55 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 57 insertions(+)
 create mode 100644 arch/arm/mach-versatile/kgdb_fiq.c

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index bde27c1..8fea25d 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -338,6 +338,7 @@ config ARCH_VERSATILE
 	select PLAT_VERSATILE_CLCD
 	select PLAT_VERSATILE_CLOCK
 	select VERSATILE_FPGA_IRQ
+	select ARCH_MIGHT_HAVE_KGDB_FIQ
 	help
 	  This enables support for ARM Ltd Versatile board.
 
diff --git a/arch/arm/mach-versatile/Makefile b/arch/arm/mach-versatile/Makefile
index 81fa3fe..bfd761f 100644
--- a/arch/arm/mach-versatile/Makefile
+++ b/arch/arm/mach-versatile/Makefile
@@ -7,3 +7,4 @@ obj-$(CONFIG_ARCH_VERSATILE_PB)		+= versatile_pb.o
 obj-$(CONFIG_MACH_VERSATILE_AB)		+= versatile_ab.o
 obj-$(CONFIG_MACH_VERSATILE_DT)		+= versatile_dt.o
 obj-$(CONFIG_PCI)			+= pci.o
+obj-$(CONFIG_KGDB_FIQ)			+= kgdb_fiq.o
diff --git a/arch/arm/mach-versatile/kgdb_fiq.c b/arch/arm/mach-versatile/kgdb_fiq.c
new file mode 100644
index 0000000..dd92e40
--- /dev/null
+++ b/arch/arm/mach-versatile/kgdb_fiq.c
@@ -0,0 +1,55 @@
+/*
+ * KGDB FIQ board support
+ *
+ * Copyright 2012 Linaro Ltd.
+ *		  Anton Vorontsov <anton.vorontsov@...aro.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.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/kgdb.h>
+#include <mach/hardware.h>
+#include <mach/platform.h>
+#include <asm/hardware/vic.h>
+
+static void *kgdb_irq_base;
+
+static int kgdb_irq;
+module_param_named(uart_num, kgdb_irq, int, 0600);
+MODULE_PARM_DESC(uart_num, "UART<number> port to use for KGDB FIQ");
+
+static void kgdb_fiq_select(bool on)
+{
+	void __iomem *sel = kgdb_irq_base + VIC_INT_SELECT;
+	u32 msk = 1 << kgdb_irq;
+	u32 val;
+
+	pr_debug("rerouting VIC vector %d to %s\n", kgdb_irq,
+		 on ? "FIQ" : "IRQ");
+
+	val = readl(sel);
+	val &= ~msk;
+	if (on)
+		val |= msk;
+	writel(val, sel);
+}
+
+static bool kgdb_is_fiq_rised(void)
+{
+	return readl(kgdb_irq_base + VIC_FIQ_STATUS) & (1 << kgdb_irq);
+}
+
+static int __init kgdb_fiq_init(void)
+{
+	kgdb_irq_base = __io_address(VERSATILE_VIC_BASE);
+	kgdb_irq += INT_UARTINT0;
+	WARN_ON(kgdb_irq > INT_UARTINT2);
+
+	return kgdb_register_fiq(kgdb_fiq_select, kgdb_is_fiq_rised);
+}
+console_initcall(kgdb_fiq_init);
-- 
1.8.0.2

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