[PATCH v3 1/2] watchdog: add Alphascale asm9260-wdt driver

Oleksij Rempel
2015-11-24T21:41:00Z

Add WD support for Alphascale asm9260 SoC. This driver
provide support for different function modes:
- HW mode to trigger SoC reset on timeout
- SW mode do soft reset if needed
- DEBUG mode

Optional support for stopping watchdog. If reset binding are not provided
this driver will work in nowayout mode.

Signed-off-by: Oleksij Rempel <linux@rempel-privat.de>
---
drivers/watchdog/Kconfig | 10 ++
drivers/watchdog/Makefile | 1 +
drivers/watchdog/asm9260_wdt.c | 400 +++++++++++++++++++++++++++++++++++++++++
3 files changed, 411 insertions(+)
create mode 100644 drivers/watchdog/asm9260_wdt.c

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index c68edc1..9cd9b75 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -173,6 +173,16 @@ config ARM_SP805_WATCHDOG
ARM Primecell SP805 Watchdog timer. This will reboot your system when
the timeout is reached.

+config ASM9260_WATCHDOG
+ tristate "Alphascale ASM9260 watchdog"
+ depends on MACH_ASM9260
+ depends on OF
+ select WATCHDOG_CORE
+ select RESET_CONTROLLER
+ help
+ Watchdog timer embedded into Alphascale asm9260 chips. This will reboot your
+ system when the timeout is reached.
+
config AT91RM9200_WATCHDOG
tristate "AT91RM9200 watchdog"
depends on SOC_AT91RM9200 && MFD_SYSCON
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 0c616e3..bd7b0cd 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -30,6 +30,7 @@ obj-$(CONFIG_USBPCWATCHDOG) += pcwd_usb.o

# ARM Architecture
obj-$(CONFIG_ARM_SP805_WATCHDOG) += sp805_wdt.o
+obj-$(CONFIG_ASM9260_WATCHDOG) += asm9260_wdt.o
obj-$(CONFIG_AT91RM9200_WATCHDOG) += at91rm9200_wdt.o
obj-$(CONFIG_AT91SAM9X_WATCHDOG) += at91sam9_wdt.o
obj-$(CONFIG_CADENCE_WATCHDOG) += cadence_wdt.o
diff --git a/drivers/watchdog/asm9260_wdt.c b/drivers/watchdog/asm9260_wdt.c
new file mode 100644
index 0000000..c8daeff
--- /dev/null
+++ b/drivers/watchdog/asm9260_wdt.c
@@ -0,0 +1,400 @@
+/*
+ * Watchdog driver for Alphascale ASM9260.
+ *
+ * Copyright (c) 2014 Oleksij Rempel <linux@rempel-privat.de>
+ *
+ * Licensed under GPLv2 or later.
+ */
+
+#include <linux/bitops.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/reboot.h>
+#include <linux/reset.h>
+#include <linux/watchdog.h>
+
+#define CLOCK_FREQ 1000000
+
+/* Watchdog Mode register */
+#define HW_WDMOD 0x00
+/* Wake interrupt. Set by HW, can't be cleared. */
+#define BM_MOD_WDINT BIT(3)
+/* This bit set if timeout reached. Cleared by SW. */
+#define BM_MOD_WDTOF BIT(2)
+/* HW Reset on timeout */
+#define BM_MOD_WDRESET BIT(1)
+/* WD enable */
+#define BM_MOD_WDEN BIT(0)
+
+/*
+ * Watchdog Timer Constant register
+ * Minimal value is 0xff, the meaning of this value
+ * depends on used clock: T = WDCLK * (0xff + 1) * 4
+ */
+#define HW_WDTC 0x04
+#define BM_WDTC_MAX(freq) (0x7fffffff / (freq))
+
+/* Watchdog Feed register */
+#define HW_WDFEED 0x08
+
+/* Watchdog Timer Value register */
+#define HW_WDTV 0x0c
+
+#define ASM9260_WDT_DEFAULT_TIMEOUT 30
+
+enum asm9260_wdt_mode {
+ HW_RESET,
+ SW_RESET,
+ DEBUG,
+};
+
+struct asm9260_wdt_priv {
+ struct device *dev;
+ struct watchdog_device wdd;
+ struct clk *clk;
+ struct clk *clk_ahb;
+ struct reset_control *rst;
+ struct notifier_block restart_handler;
+
+ void __iomem *iobase;
+ int irq;
+ unsigned long wdt_freq;
+ enum asm9260_wdt_mode mode;
+};
+
+static int asm9260_wdt_feed(struct watchdog_device *wdd)
+{
+ struct asm9260_wdt_priv *priv = watchdog_get_drvdata(wdd);
+
+ iowrite32(0xaa, priv->iobase + HW_WDFEED);
+ iowrite32(0x55, priv->iobase + HW_WDFEED);
+
+ return 0;
+}
+
+static unsigned int asm9260_wdt_gettimeleft(struct watchdog_device *wdd)
+{
+ struct asm9260_wdt_priv *priv = watchdog_get_drvdata(wdd);
+ u32 counter;
+
+ counter = ioread32(priv->iobase + HW_WDTV);
+
+ return DIV_ROUND_CLOSEST(counter, priv->wdt_freq);
+}
+
+static int asm9260_wdt_updatetimeout(struct watchdog_device *wdd)
+{
+ struct asm9260_wdt_priv *priv = watchdog_get_drvdata(wdd);
+ u32 counter;
+
+ counter = wdd->timeout * priv->wdt_freq;
+
+ iowrite32(counter, priv->iobase + HW_WDTC);
+
+ return 0;
+}
+
+static int asm9260_wdt_enable(struct watchdog_device *wdd)
+{
+ struct asm9260_wdt_priv *priv = watchdog_get_drvdata(wdd);
+ u32 mode = 0;
+
+ if (priv->mode == HW_RESET)
+ mode = BM_MOD_WDRESET;
+
+ iowrite32(BM_MOD_WDEN | mode, priv->iobase + HW_WDMOD);
+
+ asm9260_wdt_updatetimeout(wdd);
+
+ asm9260_wdt_feed(wdd);
+
+ return 0;
+}
+
+static int asm9260_wdt_disable(struct watchdog_device *wdd)
+{
+ struct asm9260_wdt_priv *priv = watchdog_get_drvdata(wdd);
+
+ /* The only way to disable WD is to reset it. */
+ reset_control_assert(priv->rst);
+ reset_control_deassert(priv->rst);
+
+ return 0;
+}
+
+static int asm9260_wdt_settimeout(struct watchdog_device *wdd, unsigned int to)
+{
+ wdd->timeout = to;
+ asm9260_wdt_updatetimeout(wdd);
+
+ return 0;
+}
+
+static void asm9260_wdt_sys_reset(struct asm9260_wdt_priv *priv)
+{
+ /* init WD if it was not started */
+
+ iowrite32(BM_MOD_WDEN | BM_MOD_WDRESET, priv->iobase + HW_WDMOD);
+
+ iowrite32(0xff, priv->iobase + HW_WDTC);
+ /* first pass correct sequence */
+ asm9260_wdt_feed(&priv->wdd);
+ /*
+ * Then write wrong pattern to the feed to trigger reset
+ * ASAP.
+ */
+ iowrite32(0xff, priv->iobase + HW_WDFEED);
+
+ mdelay(1000);
+}
+
+static irqreturn_t asm9260_wdt_irq(int irq, void *devid)
+{
+ struct asm9260_wdt_priv *priv = devid;
+ u32 stat;
+
+ stat = ioread32(priv->iobase + HW_WDMOD);
+ if (!(stat & BM_MOD_WDINT))
+ return IRQ_NONE;
+
+ if (priv->mode == DEBUG)
+ dev_info(priv->dev, "Watchdog Timeout. Do nothing.\n");
+ else {
+ dev_info(priv->dev, "Watchdog Timeout. Doing SW Reset.\n");
+ asm9260_wdt_sys_reset(priv);
+ }
+
+ return IRQ_HANDLED;
+}
+
+static int asm9260_restart_handler(struct notifier_block *this,
+ unsigned long mode, void *cmd)
+{
+ struct asm9260_wdt_priv *priv =
+ container_of(this, struct asm9260_wdt_priv, restart_handler);
+
+ asm9260_wdt_sys_reset(priv);
+
+ return NOTIFY_DONE;
+}
+
+static const struct watchdog_info asm9260_wdt_ident = {
+ .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING
+ | WDIOF_MAGICCLOSE,
+ .identity = "Alphascale asm9260 Watchdog",
+};
+
+static struct watchdog_ops asm9260_wdt_ops = {
+ .owner = THIS_MODULE,
+ .start = asm9260_wdt_enable,
+ .stop = asm9260_wdt_disable,
+ .get_timeleft = asm9260_wdt_gettimeleft,
+ .ping = asm9260_wdt_feed,
+ .set_timeout = asm9260_wdt_settimeout,
+};
+
+static int __init asm9260_wdt_get_dt_clks(struct asm9260_wdt_priv *priv)
+{
+ int err;
+ unsigned long clk;
+
+ priv->clk = devm_clk_get(priv->dev, "mod");
+ if (IS_ERR(priv->clk)) {
+ dev_err(priv->dev, "Failed to get \"mod\" clk\n");
+ return PTR_ERR(priv->clk);
+ }
+
+ /* configure AHB clock */
+ priv->clk_ahb = devm_clk_get(priv->dev, "ahb");
+ if (IS_ERR(priv->clk_ahb)) {
+ dev_err(priv->dev, "Failed to get \"ahb\" clk\n");
+ return PTR_ERR(priv->clk_ahb);
+ }
+
+ err = clk_prepare_enable(priv->clk_ahb);
+ if (err) {
+ dev_err(priv->dev, "Failed to enable ahb_clk!\n");
+ return err;
+ }
+
+ err = clk_set_rate(priv->clk, CLOCK_FREQ);
+ if (err) {
+ clk_disable_unprepare(priv->clk_ahb);
+ dev_err(priv->dev, "Failed to set rate!\n");
+ return err;
+ }
+
+ err = clk_prepare_enable(priv->clk);
+ if (err) {
+ clk_disable_unprepare(priv->clk_ahb);
+ dev_err(priv->dev, "Failed to enable clk!\n");
+ return err;
+ }
+
+ /* wdt has internal divider */
+ clk = clk_get_rate(priv->clk);
+ if (!clk) {
+ clk_disable_unprepare(priv->clk);
+ clk_disable_unprepare(priv->clk_ahb);
+ dev_err(priv->dev, "Failed, clk is 0!\n");
+ return -EINVAL;
+ }
+
+ priv->wdt_freq = clk / 2;
+
+ return 0;
+}
+
+static void __init asm9260_wdt_get_dt_mode(struct asm9260_wdt_priv *priv)
+{
+ const char *tmp;
+ int ret;
+
+ /* default mode */
+ priv->mode = HW_RESET;
+
+ ret = of_property_read_string(priv->dev->of_node,
+ "alphascale,mode", &tmp);
+ if (ret < 0)
+ return;
+
+ if (!strcmp(tmp, "hw"))
+ priv->mode = HW_RESET;
+ else if (!strcmp(tmp, "sw"))
+ priv->mode = SW_RESET;
+ else if (!strcmp(tmp, "debug"))
+ priv->mode = DEBUG;
+ else
+ dev_warn(priv->dev, "unknown reset-type: %s. Using default \"hw\" mode.",
+ tmp);
+}
+
+static int __init asm9260_wdt_probe(struct platform_device *pdev)
+{
+ struct asm9260_wdt_priv *priv;
+ struct watchdog_device *wdd;
+ struct resource *res;
+ int ret;
+
+ priv = devm_kzalloc(&pdev->dev, sizeof(struct asm9260_wdt_priv),
+ GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+
+ priv->dev = &pdev->dev;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ priv->iobase = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(priv->iobase))
+ return PTR_ERR(priv->iobase);
+
+ ret = asm9260_wdt_get_dt_clks(priv);
+ if (ret)
+ return ret;
+
+ priv->rst = devm_reset_control_get(&pdev->dev, "wdt_rst");
+ if (IS_ERR(priv->rst))
+ return PTR_ERR(priv->rst);
+
+ wdd = &priv->wdd;
+ wdd->info = &asm9260_wdt_ident;
+ wdd->ops = &asm9260_wdt_ops;
+ wdd->min_timeout = 1;
+ wdd->max_timeout = BM_WDTC_MAX(priv->wdt_freq);
+ wdd->parent = &pdev->dev;
+
+ watchdog_set_drvdata(wdd, priv);
+
+ /*
+ * If 'timeout-sec' unspecified in devicetree, assume a 30 second
+ * default, unless the max timeout is less than 30 seconds, then use
+ * the max instead.
+ */
+ wdd->timeout = ASM9260_WDT_DEFAULT_TIMEOUT;
+ watchdog_init_timeout(wdd, 0, &pdev->dev);
+
+ asm9260_wdt_get_dt_mode(priv);
+
+ if (priv->mode != HW_RESET)
+ priv->irq = platform_get_irq(pdev, 0);
+
+ if (priv->irq > 0) {
+ /*
+ * Not all supported platforms specify an interrupt for the
+ * watchdog, so let's make it optional.
+ */
+ ret = devm_request_irq(&pdev->dev, priv->irq,
+ asm9260_wdt_irq, IRQF_SHARED,
+ pdev->name, priv);
+ if (ret < 0)
+ dev_warn(&pdev->dev, "failed to request IRQ\n");
+ }
+
+ ret = watchdog_register_device(wdd);
+ if (ret)
+ goto clk_off;
+
+ platform_set_drvdata(pdev, priv);
+
+ priv->restart_handler.notifier_call = asm9260_restart_handler;
+ priv->restart_handler.priority = 128;
+ ret = register_restart_handler(&priv->restart_handler);
+ if (ret)
+ dev_warn(&pdev->dev, "cannot register restart handler\n");
+
+ dev_info(&pdev->dev, "Watchdog enabled (to=%d, mode=%d)\n",
+ wdd->timeout, priv->mode);
+ return 0;
+
+clk_off:
+ clk_disable_unprepare(priv->clk);
+ clk_disable_unprepare(priv->clk_ahb);
+ return ret;
+}
+
+static void asm9260_wdt_shutdown(struct platform_device *pdev)
+{
+ struct asm9260_wdt_priv *priv = platform_get_drvdata(pdev);
+
+ asm9260_wdt_disable(&priv->wdd);
+}
+
+static int __exit asm9260_wdt_remove(struct platform_device *pdev)
+{
+ struct asm9260_wdt_priv *priv = platform_get_drvdata(pdev);
+
+ asm9260_wdt_disable(&priv->wdd);
+
+ unregister_restart_handler(&priv->restart_handler);
+ clk_disable_unprepare(priv->clk);
+ clk_disable_unprepare(priv->clk_ahb);
+
+ return 0;
+}
+
+static const struct of_device_id asm9260_wdt_of_match[] = {
+ { .compatible = "alphascale,asm9260-wdt"},
+ {},
+};
+MODULE_DEVICE_TABLE(of, asm9260_wdt_of_match);
+
+static struct platform_driver asm9260_wdt_driver = {
+ .driver = {
+ .name = "asm9260-wdt",
+ .owner = THIS_MODULE,
+ .of_match_table = asm9260_wdt_of_match,
+ },
+ .probe = asm9260_wdt_probe,
+ .remove = asm9260_wdt_remove,
+ .shutdown = asm9260_wdt_shutdown,
+};
+module_platform_driver(asm9260_wdt_driver);
+
+MODULE_DESCRIPTION("asm9260 WatchDog Timer Driver");
+MODULE_AUTHOR("Oleksij Rempel <linux@rempel-privat.de>");
+MODULE_LICENSE("GPL");
--
2.5.0