[PATCH v5] watchdog: Add Broadcom BCM2835 watchdog timer driver

From: Lubomir Rintel
Date: Tue Jun 18 2013 - 13:45:08 EST

This adds a driver for watchdog timer hardware present on Broadcom BCM2835 SoC,
used in Raspberry Pi and Roku 2 devices.

Signed-off-by: Lubomir Rintel <lkundrak@xxxxx>
Tested-by: Stephen Warren <swarren@xxxxxxxxxxxxx>
Cc: Stephen Warren <swarren@xxxxxxxxxxxxx>
Cc: Wim Van Sebroeck <wim@xxxxxxxxx>
Cc: Guenter Roeck <linux@xxxxxxxxxxxx>
Cc: linux-rpi-kernel@xxxxxxxxxxxxxxxxxxx
Cc: linux-watchdog@xxxxxxxxxxxxxxx
Cc: devicetree-discuss@xxxxxxxxxxxxxxxx
---
Changes for v2:
- Use per-device structure instead of global variables for lock and memory base
- Fix default timeout setting
- Do not leak memory if probe fails
- Style fixes
- Split out defconfig into a separate commit
- Meaningful commit message with credit

Changes for v3:
- Add proper copyright notice to header
- Drop status constants, we don't use them
- Fix heartbeat parameter's type
- Log driver initialization message once the device is probed

Changes for v4:
- Drop an useless initializer
- Add a signoff from downstream
- Do not announce the driver to the log if we failed to probe
- Set platform data earlier and do not explicitly unset it

Changes for v5:
- Copyright clarification

.../bindings/watchdog/brcm,bcm2835-pm-wdog.txt | 5 +
drivers/watchdog/Kconfig | 11 ++
drivers/watchdog/Makefile | 1 +
drivers/watchdog/bcm2835_wdt.c | 189 ++++++++++++++++++++
4 files changed, 206 insertions(+), 0 deletions(-)
create mode 100644 drivers/watchdog/bcm2835_wdt.c

diff --git a/Documentation/devicetree/bindings/watchdog/brcm,bcm2835-pm-wdog.txt b/Documentation/devicetree/bindings/watchdog/brcm,bcm2835-pm-wdog.txt
index d209366..f801d71 100644
--- a/Documentation/devicetree/bindings/watchdog/brcm,bcm2835-pm-wdog.txt
+++ b/Documentation/devicetree/bindings/watchdog/brcm,bcm2835-pm-wdog.txt
@@ -5,9 +5,14 @@ Required properties:
- compatible : should be "brcm,bcm2835-pm-wdt"
- reg : Specifies base physical address and size of the registers.

+Optional properties:
+
+- timeout-sec : Contains the watchdog timeout in seconds
+
Example:

watchdog {
compatible = "brcm,bcm2835-pm-wdt";
reg = <0x7e100000 0x28>;
+ timeout-sec = <10>;
};
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index e89fc31..c3d3b16 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -1098,6 +1098,17 @@ config BCM63XX_WDT
To compile this driver as a loadable module, choose M here.
The module will be called bcm63xx_wdt.

+config BCM2835_WDT
+ tristate "Broadcom BCM2835 hardware watchdog"
+ depends on ARCH_BCM2835
+ select WATCHDOG_CORE
+ help
+ Watchdog driver for the built in watchdog hardware in Broadcom
+ BCM2835 SoC.
+
+ To compile this driver as a loadable module, choose M here.
+ The module will be called bcm2835_wdt.
+
config LANTIQ_WDT
tristate "Lantiq SoC watchdog"
depends on LANTIQ
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index a300b94..1bf5675 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -54,6 +54,7 @@ obj-$(CONFIG_TS72XX_WATCHDOG) += ts72xx_wdt.o
obj-$(CONFIG_IMX2_WDT) += imx2_wdt.o
obj-$(CONFIG_UX500_WATCHDOG) += ux500_wdt.o
obj-$(CONFIG_RETU_WATCHDOG) += retu_wdt.o
+obj-$(CONFIG_BCM2835_WDT) += bcm2835_wdt.o

# AVR32 Architecture
obj-$(CONFIG_AT32AP700X_WDT) += at32ap700x_wdt.o
diff --git a/drivers/watchdog/bcm2835_wdt.c b/drivers/watchdog/bcm2835_wdt.c
new file mode 100644
index 0000000..61566fc
--- /dev/null
+++ b/drivers/watchdog/bcm2835_wdt.c
@@ -0,0 +1,189 @@
+/*
+ * Watchdog driver for Broadcom BCM2835
+ *
+ * "bcm2708_wdog" driver written by Luke Diamand that was obtained from
+ * branch "rpi-3.6.y" of git://github.com/raspberrypi/linux.git was used
+ * as a hardware reference for the Broadcom BCM2835 watchdog timer.
+ *
+ * Copyright (C) 2013 Lubomir Rintel <lkundrak@xxxxx>
+ *
+ * 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.
+ */
+
+#include <linux/types.h>
+#include <linux/module.h>
+#include <linux/io.h>
+#include <linux/watchdog.h>
+#include <linux/platform_device.h>
+#include <linux/of_address.h>
+#include <linux/miscdevice.h>
+
+#define PM_RSTC 0x1c
+#define PM_WDOG 0x24
+
+#define PM_PASSWORD 0x5a000000
+
+#define PM_WDOG_TIME_SET 0x000fffff
+#define PM_RSTC_WRCFG_CLR 0xffffffcf
+#define PM_RSTC_WRCFG_SET 0x00000030
+#define PM_RSTC_WRCFG_FULL_RESET 0x00000020
+#define PM_RSTC_RESET 0x00000102
+
+#define SECS_TO_WDOG_TICKS(x) ((x) << 16)
+#define WDOG_TICKS_TO_SECS(x) ((x) >> 16)
+
+struct bcm2835_wdt {
+ void __iomem *base;
+ spinlock_t lock;
+};
+
+static unsigned int heartbeat;
+static bool nowayout = WATCHDOG_NOWAYOUT;
+
+static int bcm2835_wdt_start(struct watchdog_device *wdog)
+{
+ struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
+ uint32_t cur;
+ unsigned long flags;
+
+ spin_lock_irqsave(&wdt->lock, flags);
+
+ writel_relaxed(PM_PASSWORD | (SECS_TO_WDOG_TICKS(wdog->timeout) &
+ PM_WDOG_TIME_SET), wdt->base + PM_WDOG);
+ cur = readl_relaxed(wdt->base + PM_RSTC);
+ writel_relaxed(PM_PASSWORD | (cur & PM_RSTC_WRCFG_CLR) |
+ PM_RSTC_WRCFG_FULL_RESET, wdt->base + PM_RSTC);
+
+ spin_unlock_irqrestore(&wdt->lock, flags);
+
+ return 0;
+}
+
+static int bcm2835_wdt_stop(struct watchdog_device *wdog)
+{
+ struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
+
+ writel_relaxed(PM_PASSWORD | PM_RSTC_RESET, wdt->base + PM_RSTC);
+ dev_info(wdog->dev, "Watchdog timer stopped");
+ return 0;
+}
+
+static int bcm2835_wdt_set_timeout(struct watchdog_device *wdog, unsigned int t)
+{
+ wdog->timeout = t;
+ return 0;
+}
+
+static unsigned int bcm2835_wdt_get_timeleft(struct watchdog_device *wdog)
+{
+ struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
+
+ uint32_t ret = readl_relaxed(wdt->base + PM_WDOG);
+ return WDOG_TICKS_TO_SECS(ret & PM_WDOG_TIME_SET);
+}
+
+static struct watchdog_ops bcm2835_wdt_ops = {
+ .owner = THIS_MODULE,
+ .start = bcm2835_wdt_start,
+ .stop = bcm2835_wdt_stop,
+ .set_timeout = bcm2835_wdt_set_timeout,
+ .get_timeleft = bcm2835_wdt_get_timeleft,
+};
+
+static struct watchdog_info bcm2835_wdt_info = {
+ .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
+ WDIOF_KEEPALIVEPING,
+ .identity = "Broadcom BCM2835 Watchdog timer",
+};
+
+static struct watchdog_device bcm2835_wdt_wdd = {
+ .info = &bcm2835_wdt_info,
+ .ops = &bcm2835_wdt_ops,
+ .min_timeout = 1,
+ .max_timeout = WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
+ .timeout = WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
+};
+
+static int bcm2835_wdt_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct device_node *np = dev->of_node;
+ struct bcm2835_wdt *wdt;
+ int err;
+
+ wdt = devm_kzalloc(dev, sizeof(struct bcm2835_wdt), GFP_KERNEL);
+ if (!wdt) {
+ dev_err(dev, "Failed to allocate memory for watchdog device");
+ return -ENOMEM;
+ }
+ platform_set_drvdata(pdev, wdt);
+
+ spin_lock_init(&wdt->lock);
+
+ wdt->base = of_iomap(np, 0);
+ if (!wdt->base) {
+ dev_err(dev, "Failed to remap watchdog regs");
+ return -ENODEV;
+ }
+
+ watchdog_set_drvdata(&bcm2835_wdt_wdd, wdt);
+ watchdog_init_timeout(&bcm2835_wdt_wdd, heartbeat, dev);
+ watchdog_set_nowayout(&bcm2835_wdt_wdd, nowayout);
+ err = watchdog_register_device(&bcm2835_wdt_wdd);
+ if (err) {
+ dev_err(dev, "Failed to register watchdog device");
+ iounmap(wdt->base);
+ return err;
+ }
+
+ dev_info(dev, "Broadcom BCM2835 watchdog timer");
+ return 0;
+}
+
+static int bcm2835_wdt_remove(struct platform_device *pdev)
+{
+ struct bcm2835_wdt *wdt = platform_get_drvdata(pdev);
+
+ watchdog_unregister_device(&bcm2835_wdt_wdd);
+ iounmap(wdt->base);
+
+ return 0;
+}
+
+static void bcm2835_wdt_shutdown(struct platform_device *pdev)
+{
+ bcm2835_wdt_stop(&bcm2835_wdt_wdd);
+}
+
+static const struct of_device_id bcm2835_wdt_of_match[] = {
+ { .compatible = "brcm,bcm2835-pm-wdt", },
+ {},
+};
+MODULE_DEVICE_TABLE(of, bcm2835_wdt_of_match);
+
+static struct platform_driver bcm2835_wdt_driver = {
+ .probe = bcm2835_wdt_probe,
+ .remove = bcm2835_wdt_remove,
+ .shutdown = bcm2835_wdt_shutdown,
+ .driver = {
+ .name = "bcm2835-wdt",
+ .owner = THIS_MODULE,
+ .of_match_table = bcm2835_wdt_of_match,
+ },
+};
+module_platform_driver(bcm2835_wdt_driver);
+
+module_param(heartbeat, uint, 0);
+MODULE_PARM_DESC(heartbeat, "Initial watchdog heartbeat in seconds");
+
+module_param(nowayout, bool, 0);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
+ __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+MODULE_AUTHOR("Lubomir Rintel <lkundrak@xxxxx>");
+MODULE_DESCRIPTION("Driver for Broadcom BCM2835 watchdog timer");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
--
1.7.1

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