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Date: Fri, 3 Jul 2020 15:04:04 +0300
From: Tero Kristo <t-kristo@...com>
To: <wim@...ux-watchdog.org>, <linux@...ck-us.net>,
<linux-watchdog@...r.kernel.org>
CC: <linux-kernel@...r.kernel.org>, <jan.kiszka@...mens.com>
Subject: [PATCHv2 3/5] watchdog: rti-wdt: add support for window size configuration
RTI watchdog can support different open window sizes. Add support for
these and add a new module parameter to configure it. The default open
window size for the driver still remains at 50%.
Also, modify the margin calculation logic a bit for 32k source clock,
instead of adding a margin to every window config, assume the 32k source
clock is running slower.
Signed-off-by: Tero Kristo <t-kristo@...com>
---
drivers/watchdog/rti_wdt.c | 112 +++++++++++++++++++++++++++++++------
1 file changed, 95 insertions(+), 17 deletions(-)
diff --git a/drivers/watchdog/rti_wdt.c b/drivers/watchdog/rti_wdt.c
index d456dd72d99a..110bfc8d0bb3 100644
--- a/drivers/watchdog/rti_wdt.c
+++ b/drivers/watchdog/rti_wdt.c
@@ -19,7 +19,8 @@
#include <linux/types.h>
#include <linux/watchdog.h>
-#define DEFAULT_HEARTBEAT 60
+#define DEFAULT_HEARTBEAT 60
+#define DEFAULT_WINDOWSIZE 50
/* Max heartbeat is calculated at 32kHz source clock */
#define MAX_HEARTBEAT 1000
@@ -35,9 +36,13 @@
#define RTIWWDRX_NMI 0xa
-#define RTIWWDSIZE_50P 0x50
+#define RTIWWDSIZE_50P 0x50
+#define RTIWWDSIZE_25P 0x500
+#define RTIWWDSIZE_12P5 0x5000
+#define RTIWWDSIZE_6P25 0x50000
+#define RTIWWDSIZE_3P125 0x500000
-#define WDENABLE_KEY 0xa98559da
+#define WDENABLE_KEY 0xa98559da
#define WDKEY_SEQ0 0xe51a
#define WDKEY_SEQ1 0xa35c
@@ -48,7 +53,8 @@
#define DWDST BIT(1)
-static int heartbeat;
+static int heartbeat = DEFAULT_HEARTBEAT;
+static u32 wsize = DEFAULT_WINDOWSIZE;
/*
* struct to hold data for each WDT device
@@ -62,34 +68,93 @@ struct rti_wdt_device {
struct watchdog_device wdd;
};
+static int rti_wdt_convert_wsize(void)
+{
+ if (wsize >= 50) {
+ wsize = RTIWWDSIZE_50P;
+ } else if (wsize >= 25) {
+ wsize = RTIWWDSIZE_25P;
+ } else if (wsize > 12) {
+ wsize = RTIWWDSIZE_12P5;
+ } else if (wsize > 6) {
+ wsize = RTIWWDSIZE_6P25;
+ } else if (wsize > 3) {
+ wsize = RTIWWDSIZE_3P125;
+ } else {
+ pr_err("%s: bad windowsize: %d\n", __func__, wsize);
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static int rti_wdt_setup_hw_hb(struct watchdog_device *wdd)
+{
+ /*
+ * 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.
+ */
+ switch (wsize) {
+ case RTIWWDSIZE_50P:
+ /* 50% open window => 50% min heartbeat */
+ wdd->min_hw_heartbeat_ms = 500 * heartbeat;
+ break;
+
+ case RTIWWDSIZE_25P:
+ /* 25% open window => 75% min heartbeat */
+ wdd->min_hw_heartbeat_ms = 750 * heartbeat;
+ break;
+
+ case RTIWWDSIZE_12P5:
+ /* 12.5% open window => 87.5% min heartbeat */
+ wdd->min_hw_heartbeat_ms = 875 * heartbeat;
+ break;
+
+ case RTIWWDSIZE_6P25:
+ /* 6.5% open window => 93.5% min heartbeat */
+ wdd->min_hw_heartbeat_ms = 935 * heartbeat;
+ break;
+
+ case RTIWWDSIZE_3P125:
+ /* 3.125% open window => 96.9% min heartbeat */
+ wdd->min_hw_heartbeat_ms = 969 * heartbeat;
+ break;
+
+ default:
+ pr_err("%s: Bad watchdog window size!\n", __func__);
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
static int rti_wdt_start(struct watchdog_device *wdd)
{
u32 timer_margin;
struct rti_wdt_device *wdt = watchdog_get_drvdata(wdd);
+ int ret;
/* set timeout period */
- timer_margin = (u64)wdd->timeout * wdt->freq;
+ timer_margin = (u64)heartbeat * 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;
+ ret = rti_wdt_convert_wsize();
+ if (ret)
+ return ret;
+
+ ret = rti_wdt_setup_hw_hb(wdd);
+ if (ret)
+ return ret;
/* 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);
+ writel_relaxed(wsize, wdt->base + RTIWWDSIZECTRL);
readl_relaxed(wdt->base + RTIWWDSIZECTRL);
@@ -169,6 +234,14 @@ static int rti_wdt_probe(struct platform_device *pdev)
return -EINVAL;
}
+ /*
+ * If watchdog is running at 32k clock, it is not accurate.
+ * Adjust frequency down in this case so that we don't pet
+ * the watchdog too often.
+ */
+ if (wdt->freq > 30000 && wdt->freq < 32768)
+ wdt->freq = 30000;
+
pm_runtime_enable(dev);
ret = pm_runtime_get_sync(dev);
if (ret) {
@@ -251,5 +324,10 @@ MODULE_PARM_DESC(heartbeat,
__MODULE_STRING(MAX_HEARTBEAT) ", default "
__MODULE_STRING(DEFAULT_HEARTBEAT));
+module_param(wsize, uint, 0);
+MODULE_PARM_DESC(wsize,
+ "Watchdog open window size in percentage from 3 to 50, "
+ "default " __MODULE_STRING(DEFAULT_WINDOW_SIZE));
+
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:rti-wdt");
--
2.17.1
--
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