Re: [PATCHv3 3/4] watchdog: Add K3 RTI watchdog support

From: Tero Kristo
Date: Wed Apr 01 2020 - 08:45:25 EST

On 05/03/2020 00:06, Guenter Roeck wrote:
On Wed, Mar 04, 2020 at 12:42:14PM +0200, Tero Kristo wrote:
Texas Instruments K3 SoCs contain an RTI (Real Time Interrupt) module
which can be used as a watchdog. This IP provides a support for
windowed watchdog mode, in which the watchdog must be petted within
a certain time window. If it is petted either too soon, or too late,
a watchdog error will be triggered.

Signed-off-by: Tero Kristo <t-kristo@xxxxxx>

Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>

Whats the plan for merging this one + the DT binding doc? I can't see this in linux-next yet at least, I do see the watchdog core change from this series though.

-Tero


---
v3:
* changed to use clk_get/put instead of devm_* versions of this

v2:
* Added better documentation within the driver code
* Dropped fck handle, instead get the fck rate during probe only
* Modified the max_hw_heartbeat calculation logic a bit

drivers/watchdog/Kconfig | 8 ++
drivers/watchdog/Makefile | 1 +
drivers/watchdog/rti_wdt.c | 255 +++++++++++++++++++++++++++++++++++++
3 files changed, 261 insertions(+)
create mode 100644 drivers/watchdog/rti_wdt.c

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index cec868f8db3f..81faf47d44a6 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -583,6 +583,14 @@ config DAVINCI_WATCHDOG
NOTE: once enabled, this timer cannot be disabled.
Say N if you are unsure.
+config K3_RTI_WATCHDOG
+ tristate "Texas Instruments K3 RTI watchdog"
+ depends on ARCH_K3 || COMPILE_TEST
+ select WATCHDOG_CORE
+ help
+ Say Y here if you want to include support for the K3 watchdog
+ timer (RTI module) available in the K3 generation of processors.
+
config ORION_WATCHDOG
tristate "Orion watchdog"
depends on ARCH_ORION5X || ARCH_DOVE || MACH_DOVE || ARCH_MVEBU || (COMPILE_TEST && !ARCH_EBSA110)
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 2ee352bf3372..6de2e4ceef19 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -57,6 +57,7 @@ obj-$(CONFIG_EP93XX_WATCHDOG) += ep93xx_wdt.o
obj-$(CONFIG_PNX4008_WATCHDOG) += pnx4008_wdt.o
obj-$(CONFIG_IOP_WATCHDOG) += iop_wdt.o
obj-$(CONFIG_DAVINCI_WATCHDOG) += davinci_wdt.o
+obj-$(CONFIG_K3_RTI_WATCHDOG) += rti_wdt.o
obj-$(CONFIG_ORION_WATCHDOG) += orion_wdt.o
obj-$(CONFIG_SUNXI_WATCHDOG) += sunxi_wdt.o
obj-$(CONFIG_RN5T618_WATCHDOG) += rn5t618_wdt.o
diff --git a/drivers/watchdog/rti_wdt.c b/drivers/watchdog/rti_wdt.c
new file mode 100644
index 000000000000..7a46c40891e2
--- /dev/null
+++ b/drivers/watchdog/rti_wdt.c
@@ -0,0 +1,255 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Watchdog driver for the K3 RTI module
+ *
+ * (c) Copyright 2019-2020 Texas Instruments Inc.
+ * All rights reserved.
+ */
+
+#include <linux/clk.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/types.h>
+#include <linux/watchdog.h>
+
+#define DEFAULT_HEARTBEAT 60
+
+/* Max heartbeat is calculated at 32kHz source clock */
+#define MAX_HEARTBEAT 1000
+
+/* Timer register set definition */
+#define RTIDWDCTRL 0x90
+#define RTIDWDPRLD 0x94
+#define RTIWDSTATUS 0x98
+#define RTIWDKEY 0x9c
+#define RTIDWDCNTR 0xa0
+#define RTIWWDRXCTRL 0xa4
+#define RTIWWDSIZECTRL 0xa8
+
+#define RTIWWDRX_NMI 0xa
+
+#define RTIWWDSIZE_50P 0x50
+
+#define WDENABLE_KEY 0xa98559da
+
+#define WDKEY_SEQ0 0xe51a
+#define WDKEY_SEQ1 0xa35c
+
+#define WDT_PRELOAD_SHIFT 13
+
+#define WDT_PRELOAD_MAX 0xfff
+
+#define DWDST BIT(1)
+
+static int heartbeat;
+
+/*
+ * struct to hold data for each WDT device
+ * @base - base io address of WD device
+ * @freq - source clock frequency of WDT
+ * @wdd - hold watchdog device as is in WDT core
+ */
+struct rti_wdt_device {
+ void __iomem *base;
+ unsigned long freq;
+ struct watchdog_device wdd;
+};
+
+static int rti_wdt_start(struct watchdog_device *wdd)
+{
+ u32 timer_margin;
+ struct rti_wdt_device *wdt = watchdog_get_drvdata(wdd);
+
+ /* set timeout period */
+ timer_margin = (u64)wdd->timeout * wdt->freq;
+ timer_margin >>= WDT_PRELOAD_SHIFT;
+ if (timer_margin > WDT_PRELOAD_MAX)
+ timer_margin = WDT_PRELOAD_MAX;
+ writel_relaxed(timer_margin, wdt->base + RTIDWDPRLD);
+
+ /*
+ * RTI only supports a windowed mode, where the watchdog can only
+ * be petted during the open window; not too early or not too late.
+ * The HW configuration options only allow for the open window size
+ * to be 50% or less than that; we obviouly want to configure the open
+ * window as large as possible so we select the 50% option. To avoid
+ * any glitches, we accommodate 5% safety margin also, so we setup
+ * the min_hw_hearbeat at 55% of the timeout period.
+ */
+ wdd->min_hw_heartbeat_ms = 11 * wdd->timeout * 1000 / 20;
+
+ /* Generate NMI when wdt expires */
+ writel_relaxed(RTIWWDRX_NMI, wdt->base + RTIWWDRXCTRL);
+
+ /* Open window size 50%; this is the largest window size available */
+ writel_relaxed(RTIWWDSIZE_50P, wdt->base + RTIWWDSIZECTRL);
+
+ readl_relaxed(wdt->base + RTIWWDSIZECTRL);
+
+ /* enable watchdog */
+ writel_relaxed(WDENABLE_KEY, wdt->base + RTIDWDCTRL);
+ return 0;
+}
+
+static int rti_wdt_ping(struct watchdog_device *wdd)
+{
+ struct rti_wdt_device *wdt = watchdog_get_drvdata(wdd);
+
+ /* put watchdog in service state */
+ writel_relaxed(WDKEY_SEQ0, wdt->base + RTIWDKEY);
+ /* put watchdog in active state */
+ writel_relaxed(WDKEY_SEQ1, wdt->base + RTIWDKEY);
+
+ return 0;
+}
+
+static unsigned int rti_wdt_get_timeleft(struct watchdog_device *wdd)
+{
+ u64 timer_counter;
+ u32 val;
+ struct rti_wdt_device *wdt = watchdog_get_drvdata(wdd);
+
+ /* if timeout has occurred then return 0 */
+ val = readl_relaxed(wdt->base + RTIWDSTATUS);
+ if (val & DWDST)
+ return 0;
+
+ timer_counter = readl_relaxed(wdt->base + RTIDWDCNTR);
+
+ do_div(timer_counter, wdt->freq);
+
+ return timer_counter;
+}
+
+static const struct watchdog_info rti_wdt_info = {
+ .options = WDIOF_KEEPALIVEPING,
+ .identity = "K3 RTI Watchdog",
+};
+
+static const struct watchdog_ops rti_wdt_ops = {
+ .owner = THIS_MODULE,
+ .start = rti_wdt_start,
+ .ping = rti_wdt_ping,
+ .get_timeleft = rti_wdt_get_timeleft,
+};
+
+static int rti_wdt_probe(struct platform_device *pdev)
+{
+ int ret = 0;
+ struct device *dev = &pdev->dev;
+ struct resource *wdt_mem;
+ struct watchdog_device *wdd;
+ struct rti_wdt_device *wdt;
+ struct clk *clk;
+
+ wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
+ if (!wdt)
+ return -ENOMEM;
+
+ clk = clk_get(dev, NULL);
+ if (IS_ERR(clk)) {
+ if (PTR_ERR(clk) != -EPROBE_DEFER)
+ dev_err(dev, "failed to get clock\n");
+ return PTR_ERR(clk);
+ }
+
+ wdt->freq = clk_get_rate(clk);
+
+ clk_put(clk);
+
+ if (!wdt->freq) {
+ dev_err(dev, "Failed to get fck rate.\n");
+ return -EINVAL;
+ }
+
+ pm_runtime_enable(dev);
+ ret = pm_runtime_get_sync(dev);
+ if (ret) {
+ if (ret != -EPROBE_DEFER)
+ dev_err(&pdev->dev, "runtime pm failed\n");
+ return ret;
+ }
+
+ platform_set_drvdata(pdev, wdt);
+
+ wdd = &wdt->wdd;
+ wdd->info = &rti_wdt_info;
+ wdd->ops = &rti_wdt_ops;
+ wdd->min_timeout = 1;
+ wdd->max_hw_heartbeat_ms = (WDT_PRELOAD_MAX << WDT_PRELOAD_SHIFT) /
+ wdt->freq * 1000;
+ wdd->timeout = DEFAULT_HEARTBEAT;
+ wdd->parent = dev;
+
+ watchdog_init_timeout(wdd, heartbeat, dev);
+
+ watchdog_set_drvdata(wdd, wdt);
+ watchdog_set_nowayout(wdd, 1);
+ watchdog_set_restart_priority(wdd, 128);
+
+ wdt_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ wdt->base = devm_ioremap_resource(dev, wdt_mem);
+ if (IS_ERR(wdt->base)) {
+ ret = PTR_ERR(wdt->base);
+ goto err_iomap;
+ }
+
+ ret = watchdog_register_device(wdd);
+ if (ret) {
+ dev_err(dev, "cannot register watchdog device\n");
+ goto err_iomap;
+ }
+
+ return 0;
+
+err_iomap:
+ pm_runtime_put_sync(&pdev->dev);
+
+ return ret;
+}
+
+static int rti_wdt_remove(struct platform_device *pdev)
+{
+ struct rti_wdt_device *wdt = platform_get_drvdata(pdev);
+
+ watchdog_unregister_device(&wdt->wdd);
+ pm_runtime_put(&pdev->dev);
+
+ return 0;
+}
+
+static const struct of_device_id rti_wdt_of_match[] = {
+ { .compatible = "ti,rti-wdt", },
+ {},
+};
+MODULE_DEVICE_TABLE(of, rti_wdt_of_match);
+
+static struct platform_driver rti_wdt_driver = {
+ .driver = {
+ .name = "rti-wdt",
+ .of_match_table = rti_wdt_of_match,
+ },
+ .probe = rti_wdt_probe,
+ .remove = rti_wdt_remove,
+};
+
+module_platform_driver(rti_wdt_driver);
+
+MODULE_AUTHOR("Tero Kristo <t-kristo@xxxxxx>");
+MODULE_DESCRIPTION("K3 RTI Watchdog Driver");
+
+module_param(heartbeat, int, 0);
+MODULE_PARM_DESC(heartbeat,
+ "Watchdog heartbeat period in seconds from 1 to "
+ __MODULE_STRING(MAX_HEARTBEAT) ", default "
+ __MODULE_STRING(DEFAULT_HEARTBEAT));
+
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:rti-wdt");
--
2.17.1

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