On 03/28/2014 03:31 AM, Harini Katakam wrote:
Add Cadence WDT driver. This is used by Xilinx Zynq.
Signed-off-by: Harini Katakam <harinik@xxxxxxxxxx>
---
drivers/watchdog/Kconfig | 7 +
drivers/watchdog/Makefile | 1 +
drivers/watchdog/cadence_wdt.c | 530 ++++++++++++++++++++++++++++++++++++++++
3 files changed, 538 insertions(+)
create mode 100644 drivers/watchdog/cadence_wdt.c
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 79d2589..13c61d8 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -138,6 +138,13 @@ config AT91SAM9X_WATCHDOG
Watchdog timer embedded into AT91SAM9X and AT91CAP9 chips. This will
reboot your system when the timeout is reached.
+config CADENCE_WATCHDOG
+ tristate "Cadence Watchdog Timer"
+ select WATCHDOG_CORE
+ help
+ Say Y here if you want to include support for the watchdog
+ timer in the Xilinx Zynq.
+
config 21285_WATCHDOG
tristate "DC21285 watchdog"
depends on FOOTBRIDGE
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 985a66c..49e3e77 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -32,6 +32,7 @@ obj-$(CONFIG_USBPCWATCHDOG) += pcwd_usb.o
obj-$(CONFIG_ARM_SP805_WATCHDOG) += sp805_wdt.o
obj-$(CONFIG_AT91RM9200_WATCHDOG) += at91rm9200_wdt.o
obj-$(CONFIG_AT91SAM9X_WATCHDOG) += at91sam9_wdt.o
+obj-$(CONFIG_CADENCE_WATCHDOG) += cadence_wdt.o
obj-$(CONFIG_OMAP_WATCHDOG) += omap_wdt.o
obj-$(CONFIG_TWL4030_WATCHDOG) += twl4030_wdt.o
obj-$(CONFIG_21285_WATCHDOG) += wdt285.o
diff --git a/drivers/watchdog/cadence_wdt.c b/drivers/watchdog/cadence_wdt.c
new file mode 100644
index 0000000..01e8c78
--- /dev/null
+++ b/drivers/watchdog/cadence_wdt.c
@@ -0,0 +1,530 @@
+/*
+ * Cadence WDT driver - Used by Xilinx Zynq
+ *
+ * Copyright (C) 2010 - 2014 Xilinx, 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.
+ */
+
+#include <linux/clk.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/irq.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/reboot.h>
+#include <linux/watchdog.h>
+
+#define CDNS_WDT_DEFAULT_TIMEOUT 10
+/* Supports 1 - 516 sec */
+#define CDNS_WDT_MIN_TIMEOUT 1
+#define CDNS_WDT_MAX_TIMEOUT 516
+
+/* Restart key */
+#define CDNS_WDT_RESTART_KEY 0x00001999
+
+/* Counter register access key */
+#define CDNS_WDT_REGISTER_ACCESS_KEY 0x00920000
+
+/* Counter value divisor */
+#define CDNS_WDT_COUNTER_VALUE_DIVISOR 0x1000
+
+/* Clock prescaler value and selection */
+#define CDNS_WDT_PRESCALE_64 64
+#define CDNS_WDT_PRESCALE_512 512
+#define CDNS_WDT_PRESCALE_4096 4096
+#define CDNS_WDT_PRESCALE_SELECT_64 1
+#define CDNS_WDT_PRESCALE_SELECT_512 2
+#define CDNS_WDT_PRESCALE_SELECT_4096 3
+
+/* Input clock frequency */
+#define CDNS_WDT_CLK_10MHZ 10000000
+#define CDNS_WDT_CLK_75MHZ 75000000
+
+/* Counter maximum value */
+#define CDNS_WDT_COUNTER_MAX 0xFFF
+
+static int wdt_timeout = CDNS_WDT_DEFAULT_TIMEOUT;
+static int nowayout = WATCHDOG_NOWAYOUT;
+
+module_param(wdt_timeout, int, 0);
+MODULE_PARM_DESC(wdt_timeout,
+ "Watchdog time in seconds. (default="
+ __MODULE_STRING(CDNS_WDT_DEFAULT_TIMEOUT) ")");
+
+module_param(nowayout, int, 0);
+MODULE_PARM_DESC(nowayout,
+ "Watchdog cannot be stopped once started (default="
+ __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+/**
+ * struct cdns_wdt - Watchdog device structure
+ * @regs: baseaddress of device
+ * @rst: reset flag
+ * @clk: struct clk * of a clock source
+ * @prescaler: for saving prescaler value
+ * @ctrl_clksel: counter clock prescaler selection
+ * @io_lock: spinlock for IO register access
+ * @cdns_wdt_device: watchdog device structure
+ * @cdns_wdt_notifier: notifier structure
+ *
+ * Structure containing parameters specific to cadence watchdog.
+ */
+struct cdns_wdt {
+ void __iomem *regs;
+ u32 rst;
+ struct clk *clk;
+ u32 prescaler;
+ u32 ctrl_clksel;
+ spinlock_t io_lock;
+ struct watchdog_device cdns_wdt_device;
+ struct notifier_block cdns_wdt_notifier;
+};
+
+/* Write access to Registers */
+static inline void cdns_wdt_writereg(void __iomem *offset, u32 val)
+{
+ writel_relaxed(val, offset);
+}
+
Not really sure if this function provides any value.
+/*************************Register Map**************************************/
+
+/* Register Offsets for the WDT */
+#define CDNS_WDT_ZMR_OFFSET 0x0 /* Zero Mode Register */
+#define CDNS_WDT_CCR_OFFSET 0x4 /* Counter Control Register */
+#define CDNS_WDT_RESTART_OFFSET 0x8 /* Restart Register */
+#define CDNS_WDT_SR_OFFSET 0xC /* Status Register */
+
+/*
+ * Zero Mode Register - This register controls how the time out is indicated
+ * and also contains the access code to allow writes to the register (0xABC).
+ */
+#define CDNS_WDT_ZMR_WDEN_MASK 0x00000001 /* Enable the WDT */
+#define CDNS_WDT_ZMR_RSTEN_MASK 0x00000002 /* Enable the reset output */
+#define CDNS_WDT_ZMR_IRQEN_MASK 0x00000004 /* Enable IRQ output */
+#define CDNS_WDT_ZMR_RSTLEN_16 0x00000030 /* Reset pulse of 16 pclk cycles */
+#define CDNS_WDT_ZMR_ZKEY_VAL 0x00ABC000 /* Access key, 0xABC << 12 */
+/*
+ * Counter Control register - This register controls how fast the timer runs
+ * and the reset value and also contains the access code to allow writes to
+ * the register.
+ */
+#define CDNS_WDT_CCR_CRV_MASK 0x00003FFC /* Counter reset value */
+
+/**
+ * cdns_wdt_stop - Stop the watchdog.
+ *
+ * @wdd: watchdog device
+ *
+ * Read the contents of the ZMR register, clear the WDEN bit
+ * in the register and set the access key for successful write.
+ *
+ * Return: always 0
+ */
+static int cdns_wdt_stop(struct watchdog_device *wdd)
+{
+ struct cdns_wdt *wdt = watchdog_get_drvdata(wdd);
+
+ spin_lock(&wdt->io_lock);
+ cdns_wdt_writereg(wdt->regs + CDNS_WDT_ZMR_OFFSET,
+ CDNS_WDT_ZMR_ZKEY_VAL & (~CDNS_WDT_ZMR_WDEN_MASK));
+ spin_unlock(&wdt->io_lock);
+
+ return 0;
+}
+
+/**
+ * cdns_wdt_reload - Reload the watchdog timer (i.e. pat the watchdog).
+ *
+ * @wdd: watchdog device
+ *
+ * Write the restart key value (0x00001999) to the restart register.
+ *
+ * Return: always 0
+ */
+static int cdns_wdt_reload(struct watchdog_device *wdd)
+{
+ struct cdns_wdt *wdt = watchdog_get_drvdata(wdd);
+
+ spin_lock(&wdt->io_lock);
+ cdns_wdt_writereg(wdt->regs + CDNS_WDT_RESTART_OFFSET,
+ CDNS_WDT_RESTART_KEY);
+ spin_unlock(&wdt->io_lock);
+
+ return 0;
+}
+
+/**
+ * cdns_wdt_start - Enable and start the watchdog.
+ *
+ * @wdd: watchdog device
+ *
+ * The counter value is calculated according to the formula:
+ * calculated count = (timeout * clock) / prescaler + 1.
+ * The calculated count is divided by 0x1000 to obtain the field value
+ * to write to counter control register.
+ * Clears the contents of prescaler and counter reset value. Sets the
+ * prescaler to 4096 and the calculated count and access key
+ * to write to CCR Register.
+ * Sets the WDT (WDEN bit) and either the Reset signal(RSTEN bit)
+ * or Interrupt signal(IRQEN) with a specified cycles and the access
+ * key to write to ZMR Register.
+ *
+ * Return: always 0
+ */
+static int cdns_wdt_start(struct watchdog_device *wdd)
+{
+ struct cdns_wdt *wdt = watchdog_get_drvdata(wdd);
+ unsigned int data = 0;
+ unsigned short count;
+ unsigned long clock_f = clk_get_rate(wdt->clk);
+
+ /*
+ * Counter value divisor to obtain the value of
+ * counter reset to be written to control register.
+ */
+ count = (wdd->timeout * (clock_f / wdt->prescaler)) /
+ CDNS_WDT_COUNTER_VALUE_DIVISOR + 1;
+
+ /* Check for boundary conditions of counter value */
+ if (count > CDNS_WDT_COUNTER_MAX)
+ count = CDNS_WDT_COUNTER_MAX;
+
+ spin_lock(&wdt->io_lock);
+ cdns_wdt_writereg(wdt->regs + CDNS_WDT_ZMR_OFFSET,
+ CDNS_WDT_ZMR_ZKEY_VAL);
+
+ /* Shift the count value to correct bit positions */
+ count = (count << 2) & CDNS_WDT_CCR_CRV_MASK;
+
+ /* Write counter access key first to be able write to register */
+ data = count | CDNS_WDT_REGISTER_ACCESS_KEY | wdt->ctrl_clksel;
+ cdns_wdt_writereg(wdt->regs + CDNS_WDT_CCR_OFFSET, data);
+ data = CDNS_WDT_ZMR_WDEN_MASK | CDNS_WDT_ZMR_RSTLEN_16 |
+ CDNS_WDT_ZMR_ZKEY_VAL;
+
+ /* Reset on timeout if specified in device tree. */
+ if (wdt->rst) {
+ data |= CDNS_WDT_ZMR_RSTEN_MASK;
+ data &= ~CDNS_WDT_ZMR_IRQEN_MASK;
+ } else {
+ data &= ~CDNS_WDT_ZMR_RSTEN_MASK;
+ data |= CDNS_WDT_ZMR_IRQEN_MASK;
+ }
+ cdns_wdt_writereg(wdt->regs + CDNS_WDT_ZMR_OFFSET, data);
+ spin_unlock(&wdt->io_lock);
+ cdns_wdt_writereg(wdt->regs + CDNS_WDT_RESTART_OFFSET,
+ CDNS_WDT_RESTART_KEY);
+
Sometimes you write into this register with lock protection, here without.
How comes (or, in other words, why does the write have to be spinlock
protected above but not here) ?
+ return 0;
+}
+
+/**
+ * cdns_wdt_settimeout - Set a new timeout value for the watchdog device.
+ *
+ * @wdd: watchdog device
+ * @new_time: new timeout value that needs to be set
+ * Return: 0 on success
+ *
+ * Update the watchdog_device timeout with new value which is used when
+ * cdns_wdt_start is called.
+ */
+static int cdns_wdt_settimeout(struct watchdog_device *wdd,
+ unsigned int new_time)
+{
+ wdd->timeout = new_time;
+
+ return cdns_wdt_start(wdd);
+}
+
+/**
+ * cdns_wdt_irq_handler - Notifies of watchdog timeout.
+ *
+ * @irq: interrupt number
+ * @dev_id: pointer to a platform device structure
+ * Return: IRQ_HANDLED
+ *
+ * The handler is invoked when the watchdog times out and a
+ * reset on timeout has not been enabled.
+ */
+static irqreturn_t cdns_wdt_irq_handler(int irq, void *dev_id)
+{
+ struct platform_device *pdev = dev_id;
+
+ dev_info(&pdev->dev, "Watchdog timed out.\n");
+
Does that really make sense ? What is the purpose of a watchdog
which does not do anything but display "I timed out" ?
+ return IRQ_HANDLED;
+}
+
+/*
+ * Info structure used to indicate the features supported by the device
+ * to the upper layers. This is defined in watchdog.h header file.
+ */
+static struct watchdog_info cdns_wdt_info = {
+ .identity = "cdns_wdt watchdog",
+ .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
+ WDIOF_MAGICCLOSE,
+};
+
+/* Watchdog Core Ops */
+static struct watchdog_ops cdns_wdt_ops = {
+ .owner = THIS_MODULE,
+ .start = cdns_wdt_start,
+ .stop = cdns_wdt_stop,
+ .ping = cdns_wdt_reload,
+ .set_timeout = cdns_wdt_settimeout,
+};
+
+/**
+ * cdns_wdt_notify_sys - Notifier for reboot or shutdown.
+ *
+ * @this: handle to notifier block
+ * @code: turn off indicator
+ * @unused: unused
+ * Return: NOTIFY_DONE
+ *
+ * This notifier is invoked whenever the system reboot or shutdown occur
+ * because we need to disable the WDT before system goes down as WDT might
+ * reset on the next boot.
+ */
+static int cdns_wdt_notify_sys(struct notifier_block *this, unsigned long code,
+ void *unused)
+{
+ struct cdns_wdt *wdt = container_of(this, struct cdns_wdt,
+ cdns_wdt_notifier);
+ if (code == SYS_DOWN || code == SYS_HALT)
+ /* Stop the watchdog */
+ cdns_wdt_stop(&wdt->cdns_wdt_device);
+
+ return NOTIFY_DONE;
+}
+
+/************************Platform Operations*****************************/
+/**
+ * cdns_wdt_probe - Probe call for the device.
+ *
+ * @pdev: handle to the platform device structure.
+ * Return: 0 on success, negative error otherwise.
+ *
+ * It does all the memory allocation and registration for the device.
+ */
+static int cdns_wdt_probe(struct platform_device *pdev)
+{
+ struct resource *res;
+ int ret, irq;
+ unsigned long clock_f;
+ struct cdns_wdt *wdt;
+ struct watchdog_device *cdns_wdt_device;
+
+ /* Allocate an instance of the cdns_wdt structure */
+ wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
+ if (!wdt)
+ return -ENOMEM;
+
+ cdns_wdt_device = &wdt->cdns_wdt_device;
+ cdns_wdt_device->info = &cdns_wdt_info;
+ cdns_wdt_device->ops = &cdns_wdt_ops;
+ cdns_wdt_device->timeout = CDNS_WDT_DEFAULT_TIMEOUT;
+ cdns_wdt_device->min_timeout = CDNS_WDT_MIN_TIMEOUT;
+ cdns_wdt_device->max_timeout = CDNS_WDT_MAX_TIMEOUT;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ wdt->regs = devm_ioremap_resource(&pdev->dev, res);
+ if (IS_ERR(wdt->regs))
+ return PTR_ERR(wdt->regs);
+
+ /* Register the interrupt */
+ of_property_read_u32(pdev->dev.of_node, "reset", &wdt->rst);
+ irq = platform_get_irq(pdev, 0);
+ if (!wdt->rst && irq >= 0) {
+ ret = devm_request_irq(&pdev->dev, irq, cdns_wdt_irq_handler, 0,
+ pdev->name, pdev);
+ if (ret) {
+ dev_err(&pdev->dev,
+ "cannot register interrupt handler err=%d\n",
+ ret);
+ return ret;
+ }
+ }
+
+ wdt->cdns_wdt_notifier.notifier_call = &cdns_wdt_notify_sys;
+ /* Register the reboot notifier */
+ ret = register_reboot_notifier(&wdt->cdns_wdt_notifier);
+ if (ret != 0) {
+ dev_err(&pdev->dev, "cannot register reboot notifier err=%d)\n",
+ ret);
+ return ret;
+ }
+
+ /* Initialize the members of cdns_wdt structure */
+ cdns_wdt_device->parent = &pdev->dev;
+ of_get_property(pdev->dev.of_node, "timeout-sec",
+ &cdns_wdt_device->timeout);
+ if (wdt_timeout < CDNS_WDT_MAX_TIMEOUT &&
+ wdt_timeout > CDNS_WDT_MIN_TIMEOUT)
Why are CDNS_WDT_MAX_TIMEOUT and CDNS_WDT_MIN_TIMEOUT not acceptable ?
Why don't you use watchdog_init_timeout() anyway ?
+ cdns_wdt_device->timeout = wdt_timeout;
+ else
+ dev_info(&pdev->dev,
+ "timeout limited to 1 - %d sec, using default=%d\n",
+ CDNS_WDT_MAX_TIMEOUT, CDNS_WDT_DEFAULT_TIMEOUT);
+
+ watchdog_set_nowayout(cdns_wdt_device, nowayout);
+ watchdog_set_drvdata(cdns_wdt_device, wdt);
+
Set too late (see other e-mail)
+ wdt->clk = devm_clk_get(&pdev->dev, NULL);
+ if (IS_ERR(wdt->clk)) {
+ dev_err(&pdev->dev, "input clock not found\n");
+ ret = PTR_ERR(wdt->clk);
+ goto err_notifier;
+ }
+
+ ret = clk_prepare_enable(wdt->clk);
+ if (ret) {
+ dev_err(&pdev->dev, "unable to enable clock\n");
+ goto err_notifier;
+ }
+
+ clock_f = clk_get_rate(wdt->clk);
+ if (clock_f <= CDNS_WDT_CLK_75MHZ) {
+ wdt->prescaler = CDNS_WDT_PRESCALE_512;
+ wdt->ctrl_clksel = CDNS_WDT_PRESCALE_SELECT_512;
+ } else {
+ wdt->prescaler = CDNS_WDT_PRESCALE_4096;
+ wdt->ctrl_clksel = CDNS_WDT_PRESCALE_SELECT_4096;
+ }
+
+ spin_lock_init(&wdt->io_lock);
+
+ /* Register the WDT */
+ ret = watchdog_register_device(cdns_wdt_device);
+ if (ret) {
+ dev_err(&pdev->dev, "Failed to register wdt device\n");
+ goto err_clk_disable;
+ }
+ platform_set_drvdata(pdev, wdt);
+
+ dev_info(&pdev->dev, "Xilinx Watchdog Timer at %p with timeout %ds%s\n",
+ wdt->regs, cdns_wdt_device->timeout,
+ nowayout ? ", nowayout" : "");
+
+ return 0;
+
+err_clk_disable:
+ clk_disable_unprepare(wdt->clk);
+err_notifier:
+ unregister_reboot_notifier(&wdt->cdns_wdt_notifier);
+
+ return ret;
+}
+
+/**
+ * cdns_wdt_remove - Probe call for the device.
+ *
+ * @pdev: handle to the platform device structure.
+ * Return: 0 on success, otherwise negative error.
+ *
+ * Unregister the device after releasing the resources.
+ */
+static int cdns_wdt_remove(struct platform_device *pdev)
+{
+ struct cdns_wdt *wdt = platform_get_drvdata(pdev);
+
+ cdns_wdt_stop(&wdt->cdns_wdt_device);
+ watchdog_unregister_device(&wdt->cdns_wdt_device);
+ unregister_reboot_notifier(&wdt->cdns_wdt_notifier);
+ clk_disable_unprepare(wdt->clk);
+
+ return 0;
+}
+
+/**
+ * cdns_wdt_shutdown - Stop the device.
+ *
+ * @pdev: handle to the platform structure.
+ *
+ */
+static void cdns_wdt_shutdown(struct platform_device *pdev)
+{
+ struct cdns_wdt *wdt = platform_get_drvdata(pdev);
+
+ /* Stop the device */
Is this cmment really necessary ? Sems to me the function name
already says it all.
+ cdns_wdt_stop(&wdt->cdns_wdt_device);
+ clk_disable_unprepare(wdt->clk);
+}
+
+/**
+ * cdns_wdt_suspend - Stop the device.
+ *
+ * @dev: handle to the device structure.
+ * Return: 0 always.
+ */
+static int __maybe_unused cdns_wdt_suspend(struct device *dev)
+{
+ struct platform_device *pdev = container_of(dev,
+ struct platform_device, dev);
+ struct cdns_wdt *wdt = platform_get_drvdata(pdev);
+
+ /* Stop the device */
Pretty value-free comment.
+ cdns_wdt_stop(&wdt->cdns_wdt_device);
+ clk_disable(wdt->clk);
+
+ return 0;
+}
+
+/**
+ * cdns_wdt_resume - Resume the device.
+ *
+ * @dev: handle to the device structure.
+ * Return: 0 on success, errno otherwise.
+ */
+static int __maybe_unused cdns_wdt_resume(struct device *dev)
+{
+ int ret;
+ struct platform_device *pdev = container_of(dev,
+ struct platform_device, dev);
+ struct cdns_wdt *wdt = platform_get_drvdata(pdev);
+
+ ret = clk_enable(wdt->clk);
+ if (ret) {
+ dev_err(dev, "unable to enable clock\n");
+ return ret;
+ }
+ /* Start the device */
Same here.
+ cdns_wdt_start(&wdt->cdns_wdt_device);
+
+ return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(cdns_wdt_pm_ops, cdns_wdt_suspend, cdns_wdt_resume);
+
+static struct of_device_id cdns_wdt_of_match[] = {
+ { .compatible = "xlnx,zynq-wdt-r1p2", },
+ { .compatible = "cdns,wdt-r1p2", },
+ { /* end of table */ }
+};
+MODULE_DEVICE_TABLE(of, cdns_wdt_of_match);
+
+/* Driver Structure */
+static struct platform_driver cdns_wdt_driver = {
+ .probe = cdns_wdt_probe,
+ .remove = cdns_wdt_remove,
+ .shutdown = cdns_wdt_shutdown,
+ .driver = {
+ .name = "cdns-wdt",
+ .owner = THIS_MODULE,
+ .of_match_table = cdns_wdt_of_match,
+ .pm = &cdns_wdt_pm_ops,
+ },
+};
+
+module_platform_driver(cdns_wdt_driver);
+
+MODULE_AUTHOR("Xilinx, Inc.");
+MODULE_DESCRIPTION("Watchdog driver for Cadence WDT");
+MODULE_LICENSE("GPL");
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