From: Melin Tomas <tomas.melin@vaisala.com>
To: "linux@roeck-us.net" <linux@roeck-us.net>,
"wim@linux-watchdog.org" <wim@linux-watchdog.org>
Cc: "linux-watchdog@vger.kernel.org" <linux-watchdog@vger.kernel.org>,
Melin Tomas <tomas.melin@vaisala.com>
Subject: [PATCH v3 4/4] watchdog: cadence_wdt: Support all available prescaler values
Date: Tue, 9 Jul 2019 20:09:06 +0000 [thread overview]
Message-ID: <20190709200801.42313-5-tomas.melin@vaisala.com> (raw)
In-Reply-To: <20190709200801.42313-1-tomas.melin@vaisala.com>
Cadence watchdog HW supports prescaler values of
8, 64, 512 and 4096.
Add support to select prescaler values of 8 and 64 for lower
input clock frequencies.
Prescaler value is selected to keep timeout resolution of 1 second.
For clock frequencies below 32kHz, 1 second resolution does
no longer hold, thereby returning an error.
Signed-off-by: Tomas Melin <tomas.melin@vaisala.com>
---
drivers/watchdog/cadence_wdt.c | 21 +++++++++++++++------
1 file changed, 15 insertions(+), 6 deletions(-)
diff --git a/drivers/watchdog/cadence_wdt.c b/drivers/watchdog/cadence_wdt.c
index 0bdb275d904a..037faf557f9d 100644
--- a/drivers/watchdog/cadence_wdt.c
+++ b/drivers/watchdog/cadence_wdt.c
@@ -33,16 +33,17 @@
#define CDNS_WDT_COUNTER_VALUE_DIVISOR 0x1000
/* Clock prescaler value and selection */
+#define CDNS_WDT_PRESCALE_8 8
#define CDNS_WDT_PRESCALE_64 64
#define CDNS_WDT_PRESCALE_512 512
#define CDNS_WDT_PRESCALE_4096 4096
+#define CDNS_WDT_PRESCALE_SELECT_8 0
#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
+/* Base input clock frequency */
+#define CDNS_WDT_CLK_32KHZ 32768
/* Counter maximum value */
#define CDNS_WDT_COUNTER_MAX 0xFFF
@@ -318,10 +319,18 @@ static int cdns_wdt_probe(struct platform_device *pdev)
return ret;
clock_f = clk_get_rate(wdt->clk);
- if (clock_f == 0) {
- dev_err(dev, "invalid clock frequency, (f=%lu)\n", clock_f);
+ if (clock_f < CDNS_WDT_CLK_32KHZ) {
+ dev_err(dev,
+ "cannot find suitable clock prescaler, (f=%lu)\n",
+ clock_f);
return -EINVAL;
- } else if (clock_f <= CDNS_WDT_CLK_75MHZ) {
+ } else if (clock_f <= CDNS_WDT_CLK_32KHZ * CDNS_WDT_PRESCALE_8) {
+ wdt->prescaler = CDNS_WDT_PRESCALE_8;
+ wdt->ctrl_clksel = CDNS_WDT_PRESCALE_SELECT_8;
+ } else if (clock_f <= CDNS_WDT_CLK_32KHZ * CDNS_WDT_PRESCALE_64) {
+ wdt->prescaler = CDNS_WDT_PRESCALE_64;
+ wdt->ctrl_clksel = CDNS_WDT_PRESCALE_SELECT_64;
+ } else if (clock_f <= CDNS_WDT_CLK_32KHZ * CDNS_WDT_PRESCALE_512) {
wdt->prescaler = CDNS_WDT_PRESCALE_512;
wdt->ctrl_clksel = CDNS_WDT_PRESCALE_SELECT_512;
} else {
--
2.17.2
next prev parent reply other threads:[~2019-07-09 20:09 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-09 20:09 [PATCH v3 0/4] watchdog: cadence_wdt: Support all available prescaler values Melin Tomas
2019-07-09 20:09 ` [PATCH v3 1/4] watchdog: cadence_wdt: Move clock detection earlier in probe Melin Tomas
2019-07-09 20:15 ` Guenter Roeck
2019-07-09 20:09 ` [PATCH v3 2/4] watchdog: cadence_wdt: Calculate actual timeout limits Melin Tomas
2019-07-09 20:14 ` Guenter Roeck
2019-07-09 20:09 ` Melin Tomas [this message]
2019-07-09 20:21 ` [PATCH v3 4/4] watchdog: cadence_wdt: Support all available prescaler values Guenter Roeck
2019-07-09 20:49 ` Melin Tomas
2019-07-09 21:07 ` Guenter Roeck
2019-07-10 19:20 ` Melin Tomas
2019-07-10 20:39 ` Guenter Roeck
2019-07-11 20:10 ` Melin Tomas
2019-07-09 20:09 ` [PATCH v3 3/4] watchdog: cadence_wdt: Group struct member init statements Melin Tomas
2019-07-09 20:16 ` Guenter Roeck
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