On Tue, Jan 22, 2019 at 07:10:23PM +0200, Matti Vaittinen wrote:

On Tue, Jan 22, 2019 at 07:47:50AM -0800, Guenter Roeck wrote:

quoted

On Tue, Jan 22, 2019 at 11:48:36AM +0200, Matti Vaittinen wrote:

quoted

Initial support for watchdog block included in ROHM BD70528
power management IC.

Configurations for low power states are still to be checked.

Signed-off-by: Matti Vaittinen <redacted>
---
 drivers/watchdog/Kconfig       |  12 +++
 drivers/watchdog/Makefile      |   1 +
 drivers/watchdog/bd70528_wdt.c | 161 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 174 insertions(+)
 create mode 100644 drivers/watchdog/bd70528_wdt.c

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 57f017d74a97..f30e3a3e886e 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig

@@ -90,6 +90,18 @@ config SOFT_WATCHDOG_PRETIMEOUT
 	  watchdog. Be aware that governors might affect the watchdog because it
 	  is purely software, e.g. the panic governor will stall it!
 
+config BD70528_WATCHDOG
+	tristate "ROHM BD70528 PMIC Watchdog"
+	depends on MFD_ROHM_BD70528
+	select WATCHDOG_CORE
+	help
+	  Support for the watchdog in the ROHM BD70528 PMIC. Watchdog trigger
+	  cause system reset.
+
+	  Say Y here to include support for the ROHM BD70528 watchdog.
+	  Alternatively say M to compile the driver as a module,
+	  which will be called bd70528_wdt.
+
 config DA9052_WATCHDOG
 	tristate "Dialog DA9052 Watchdog"
 	depends on PMIC_DA9052 || COMPILE_TEST

diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index a0917ef28e07..1ce87a3b1172 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile

@@ -204,6 +204,7 @@ obj-$(CONFIG_WATCHDOG_SUN4V)		+= sun4v_wdt.o
 obj-$(CONFIG_XEN_WDT) += xen_wdt.o
 
 # Architecture Independent
+obj-$(CONFIG_BD70528_WATCHDOG) += bd70528_wdt.o
 obj-$(CONFIG_DA9052_WATCHDOG) += da9052_wdt.o
 obj-$(CONFIG_DA9055_WATCHDOG) += da9055_wdt.o
 obj-$(CONFIG_DA9062_WATCHDOG) += da9062_wdt.o

diff --git a/drivers/watchdog/bd70528_wdt.c b/drivers/watchdog/bd70528_wdt.c
new file mode 100644
index 000000000000..e9a32566f595
--- /dev/null
+++ b/drivers/watchdog/bd70528_wdt.c

@@ -0,0 +1,161 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2018 ROHM Semiconductors
+// ROHM BD70528MWV watchdog driver
+
+#include <linux/bcd.h>
+#include <linux/kernel.h>
+#include <linux/mfd/rohm-bd70528.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/watchdog.h>
+
+static int bd70528_wdt_set(struct bd70528 *bd70528, int enable)
+{
+	int ret;
+
+	if (bd70528->rtc_timer_lock)
+		mutex_lock(bd70528->rtc_timer_lock);

This looks awkward. I don't think the if() is necessary.

Right. Now when only bd70528 MFD driver uses this WDT this if is not
required.

That doesn't warrant the conditional. It just bloats the code.
If there is only one user, the mutex will always be acquired.

quoted

quoted

+
+	ret = bd70528->wdt_set(bd70528, enable, NULL);
+
+	if (bd70528->rtc_timer_lock)
+		mutex_unlock(bd70528->rtc_timer_lock);
+	return ret;
+}
+
+static int bd70528_wdt_start(struct watchdog_device *wdt)
+{
+	struct bd70528 *bd70528 = watchdog_get_drvdata(wdt);
+
+	return bd70528_wdt_set(bd70528, 1);
+}
+
+static int bd70528_wdt_stop(struct watchdog_device *wdt)
+{
+	struct bd70528 *bd70528 = watchdog_get_drvdata(wdt);
+
+	return bd70528_wdt_set(bd70528, 0);
+}
+
+static int bd70528_wdt_set_timeout(struct watchdog_device *wdt,
+				    unsigned int timeout)
+{
+	unsigned int hours;
+	unsigned int minutes;
+	unsigned int seconds;
+	int ret;
+	struct bd70528 *bd70528 = watchdog_get_drvdata(wdt);
+
+	seconds = timeout;
+	hours = timeout / (60 * 60);
+	/* Maximum timeout is 1h 59m 59s => hours is 1 or 0 */
+	if (hours)
+		seconds -= (60 * 60);
+	minutes = seconds / 60;
+	seconds = seconds % 60;
+
+	if (bd70528->rtc_timer_lock)
+		mutex_lock(bd70528->rtc_timer_lock);
+
+	ret = bd70528->wdt_set(bd70528, 0, NULL);
+	if (ret)
+		goto out_unlock;
+
+	ret = regmap_update_bits(bd70528->chip.regmap, BD70528_REG_WDT_HOUR,
+				 BD70528_MASK_WDT_HOUR, hours);
+	if (ret) {
+		dev_err(bd70528->chip.dev, "Failed to set WDT hours\n");
+		goto out_en_unlock;
+	}
+	ret = regmap_update_bits(bd70528->chip.regmap, BD70528_REG_WDT_MINUTE,
+				 BD70528_MASK_WDT_MINUTE, bin2bcd(minutes));
+	if (ret) {
+		dev_err(bd70528->chip.dev, "Failed to set WDT minutes\n");
+		goto out_en_unlock;
+	}
+	ret = regmap_update_bits(bd70528->chip.regmap, BD70528_REG_WDT_SEC,
+				 BD70528_MASK_WDT_SEC, bin2bcd(seconds));
+	if (ret) {
+		dev_err(bd70528->chip.dev, "Failed to set WDT seconds\n");
+		goto out_en_unlock;

Unnecessary goto.

True. I'll drop this.

quoted

quoted

+	}
+
+out_en_unlock:
+	ret = bd70528->wdt_set(bd70528, 1, NULL);
+out_unlock:
+	if (bd70528->rtc_timer_lock)
+		mutex_lock(bd70528->rtc_timer_lock);

I don't think this code was ever tested.

Yep. This should be unlock. What comes to testingI'll quote the
cover-sheet for the patch set:

quoted

Currently only MFD core, clk, RTC and regulator portions are
somehow tested. The RFC series also include initial gpio, power-supply
and watchdog patches in order to provide better overview on chip
and to collect initial feedback. Reset and ADC are not supported by
this series.

I think having the wdt_set and rtc_timer_lock in MFD would have been
completely mysterious if watchdog draft was not included =)

quoted

quoted

+static const struct watchdog_info bd70528_wdt_info = {
+	.identity = "bd70528-wdt",
+	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
+};
+
+static const struct watchdog_ops bd70528_wdt_ops = {
+	.start		= bd70528_wdt_start,
+	.stop		= bd70528_wdt_stop,
+	/*
+	 *  bd70528 WDT ping is same as enable. Eg, writing 'enable' to enabled
+	 * WDT will restart the timeout
+	 */

Unnecessary comment.

Ok. I will remove the comment if this is obvious to others. For me it
was not obvious. I was first writing a separate ping and start functions
untill I realized that it is the same operation. But this was my first
WDT driver so I don't know if this is a normal for all WDTs.

It is documented as part of the API.

"Most hardware that does not support this as a separate function uses the
start function to restart the watchdog timer hardware"

Repeating the API for each driver doesn't really add value.

quoted

quoted

+	.ping		= bd70528_wdt_start,
+	.set_timeout	= bd70528_wdt_set_timeout,
+};
+
+/* Max time we can set is 1 hour, 59 minutes and 59 seconds */
+#define WDT_MAX_MS ((2 * 60 * 60 - 1) * 1000)
+/* Minimum time is 1 second */
+#define WDT_MIN_MS 1000
+static struct watchdog_device bd70528_wd = {
+	.info = &bd70528_wdt_info,
+	.ops =  &bd70528_wdt_ops,
+	.min_hw_heartbeat_ms = WDT_MIN_MS,
+	.max_hw_heartbeat_ms = WDT_MAX_MS,
+};
+
+static int bd70528_wdt_probe(struct platform_device *pdev)
+{
+	struct bd70528 *tmp;
+	struct bd70528 *bd70528;
+	int ret;
+
+	tmp = dev_get_drvdata(pdev->dev.parent);
+	if (!tmp) {
+		dev_err(&pdev->dev, "No MFD driver data\n");
+		return -EINVAL;
+	}
+	bd70528 = devm_kzalloc(&pdev->dev, sizeof(*bd70528), GFP_KERNEL);
+	if (!bd70528)
+		return -ENOMEM;
+
+	*bd70528 = *tmp;
+	bd70528->chip.dev = &pdev->dev;

This is wrong.
You should not copy the parent's driver data but have local driver
data as needed which then points to the parent's driver data if
needed. I assume this is why the mutex is a pointer, but that
just shows that the whole approach is wrong.

Mutex is a pointer because we want to use same mutex from WDT and RTC.
We can sure point to parent data but then we still need our own dev
pointer. So we can have a struct with pointer to parent data and dev
pointer - but I'm not at all sure it is any clearer.

As I said, that is wrong. To say it in plaintext, I won't accept
the driver if it copies the parent's driver data. The driver should
have and use its own driver data, and only maintain a pointer to
its parent's driver data. And most definitely you don't want to
copy and use any device data structure from the parent.

quoted

quoted

+
+	/*
+	 * TODO: Set the initial state and timeout.

Confused. Why don't you just do it ?

I will. But it's not ready yet. I still wanted to include the WDT for
this RFC. And I hope I could get the MFD core part included in Lee's
tree at early phase so that the include/linux/mfd/rohm-bd70528.h would
be in other sub trees when they're finalized for upstreaming.

quoted

quoted

+	 * See whether the low power states require special handling
+	 */
+	watchdog_set_drvdata(&bd70528_wd, bd70528);

At least in theory there can be more than one of those devices
in the system, since it is an i2c device. With that in mind, bd70528_wd
should be locally allocated.

Point taken, thanks.

quoted

Also, bd70528_wd should be fully initialized. For example, the parent
device is not set.

Thanks for this point too =) I will see what are all the missing
initializations before sending out the final version.

I do really appreciate that you see the trouble of doing the review and
giving me the push to right direction!

Br,
	Matti Vaittinen

-- 
Matti Vaittinen
ROHM Semiconductors

~~~ "I don't think so," said Rene Descartes.  Just then, he vanished ~~~