Re: [PATCH v2 2/2] watchdog: pic32-dmt: Add PIC32 deadman timer driver
From: Guenter Roeck <hidden>
Date: 2016-02-26 14:12:06
Also in:
linux-mips, linux-watchdog, lkml
On 02/25/2016 10:30 AM, Joshua Henderson wrote:
quoted hunk ↗ jump to hunk
From: Purna Chandra Mandal <redacted> Adds support for the deadman timer peripheral found on PIC32 class devices. The primary function of the deadman timer (DMT) is to reset the processor in the event of a software malfunction. The DMT is a free-running instruction fetch timer, which is clocked whenever an instruction fetch occurs until a count match occurs. Instructions are not fetched when the processor is in sleep mode. Signed-off-by: Purna Chandra Mandal <redacted> Signed-off-by: Joshua Henderson <redacted> Cc: Ralf Baechle <ralf-6z/3iImG2C8G8FEW9MqTrA@public.gmane.org> --- Note: Please merge this patch series through the MIPS tree. Changes since v1: - Drop default y in Kconfig - Alphabetical include files - Use BIT() where appropriate - Replace cpu_relax() with nop() and comment why it's needed - Return bool on functions where appropriate - Add a way to break out of a tight loop - Remove static unused function - Remove redundant spinlock already covered by watchdog core - Remove unecessary error handling when enabling DMT - Drop implementation of .get_timeleft - Drop calculation of max_timeout - Cleanup dev_err() message contents - Fix race condition with watchdog device register - Unregister watchdog before disabling clock - Fix typo in driver name --- drivers/watchdog/Kconfig | 13 +++ drivers/watchdog/Makefile | 1 + drivers/watchdog/pic32-dmt.c | 260 ++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 274 insertions(+) create mode 100644 drivers/watchdog/pic32-dmt.cdiff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig index 543fa81..53747e9 100644 --- a/drivers/watchdog/Kconfig +++ b/drivers/watchdog/Kconfig@@ -1427,6 +1427,19 @@ config PIC32_WDT To compile this driver as a loadable module, choose M here. The module will be called pic32-wdt. +config PIC32_DMT + tristate "Microchip PIC32 Deadman Timer" + select WATCHDOG_CORE + depends on MACH_PIC32 + help + Watchdog driver for PIC32 instruction fetch counting timer. This specific + timer is typically be used in misson critical and safety critical + applications, where any single failure of the software functionality + and sequencing must be detected. + + To compile this driver as a loadable module, choose M here. + The module will be called pic32-dmt. + # PARISC Architecture # POWERPC Architecturediff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile index 244ed80..d051c9c 100644 --- a/drivers/watchdog/Makefile +++ b/drivers/watchdog/Makefile@@ -154,6 +154,7 @@ obj-$(CONFIG_RALINK_WDT) += rt2880_wdt.o obj-$(CONFIG_IMGPDC_WDT) += imgpdc_wdt.o obj-$(CONFIG_MT7621_WDT) += mt7621_wdt.o obj-$(CONFIG_PIC32_WDT) += pic32-wdt.o +obj-$(CONFIG_PIC32_DMT) += pic32-dmt.o # PARISC Architecturediff --git a/drivers/watchdog/pic32-dmt.c b/drivers/watchdog/pic32-dmt.c new file mode 100644 index 0000000..91801fa --- /dev/null +++ b/drivers/watchdog/pic32-dmt.c@@ -0,0 +1,260 @@ +/* + * PIC32 deadman timer driver + * + * Purna Chandra Mandal <purna.mandal-UWL1GkI3JZL3oGB3hsPCZA@public.gmane.org> + * Copyright (c) 2016, Microchip Technology Inc. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt +
No pr_ function left, so this define can be removed.
+#include <linux/clk.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/pm.h>
+#include <linux/watchdog.h>
+
+#include <asm/mach-pic32/pic32.h>
+
+/* Deadman Timer Regs */
+#define DMTCON_REG 0x00
+#define DMTPRECLR_REG 0x10
+#define DMTCLR_REG 0x20
+#define DMTSTAT_REG 0x30
+#define DMTCNT_REG 0x40
+#define DMTPSCNT_REG 0x60
+#define DMTPSINTV_REG 0x70
+
+/* Deadman Timer Regs fields */
+#define DMT_ON BIT(15)
+#define DMT_STEP1_KEY BIT(6)
+#define DMT_STEP2_KEY BIT(3)
+#define DMTSTAT_WINOPN BIT(0)
+#define DMTSTAT_EVENT BIT(5)
+#define DMTSTAT_BAD2 BIT(6)
+#define DMTSTAT_BAD1 BIT(7)
+
+/* Reset Control Register fields for watchdog */
+#define RESETCON_DMT_TIMEOUT BIT(5)
+
+struct pic32_dmt {
+ void __iomem *regs;
+ struct clk *clk;
+};
+
+static inline void dmt_enable(struct pic32_dmt *dmt)
+{
+ writel(DMT_ON, PIC32_SET(dmt->regs + DMTCON_REG));
+}
+
+static inline void dmt_disable(struct pic32_dmt *dmt)
+{
+ writel(DMT_ON, PIC32_CLR(dmt->regs + DMTCON_REG));
+ /*
+ * Cannot touch registers in the CPU cycle following clearing the
+ * ON bit.
+ */
+ nop();
+}
+
+static inline int dmt_bad_status(struct pic32_dmt *dmt)
+{
+ u32 val;
+
+ val = readl(dmt->regs + DMTSTAT_REG);
+ val &= (DMTSTAT_BAD1 | DMTSTAT_BAD2 | DMTSTAT_EVENT);
+ if (val)
+ return -EAGAIN;
+
+ return 0;
+}
+
+static inline int dmt_keepalive(struct pic32_dmt *dmt)
+{
+ u32 v;
+ u32 timeout = 500;
+
+ /* set pre-clear key */
+ writel(DMT_STEP1_KEY << 8, dmt->regs + DMTPRECLR_REG);
+
+ /* wait for DMT window to open */
+ while (--timeout) {
+ v = readl(dmt->regs + DMTSTAT_REG) & DMTSTAT_WINOPN;
+ if (v == DMTSTAT_WINOPN)
+ break;
+ }
+
+ /* apply key2 */
+ writel(DMT_STEP2_KEY, dmt->regs + DMTCLR_REG);
+
+ /* check whether keys are latched correctly */
+ return dmt_bad_status(dmt);
+}
+
+static inline u32 pic32_dmt_get_timeout_secs(struct pic32_dmt *dmt)
+{
+ unsigned long rate;
+
+ rate = clk_get_rate(dmt->clk);
+ if (rate)
+ return readl(dmt->regs + DMTPSCNT_REG) / rate;
+
+ return -EINVAL;Return value is unsigned, and the caller checks for 0 to identify an error, so you need to return 0 here. With that fixed, and the pr_fmt dropped, feel free to add Reviewed-by: Guenter Roeck <redacted> to the next revision of this patch. Thanks, Guenter -- To unsubscribe from this list: send the line "unsubscribe linux-watchdog" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html