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Subject[PATCH] rtc: abx80x: add basic watchdog support
Date
The abx804 and abx805 chips have support for a simple watchdog
function that can trigger an external reset.

Signed-off-by: Jeremy Gebben <jgebben@sweptlaser.com>
---
drivers/rtc/Kconfig | 11 +++
drivers/rtc/rtc-abx80x.c | 160 ++++++++++++++++++++++++++++++++++++---
2 files changed, 159 insertions(+), 12 deletions(-)

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 7d7be60a2413..4771e3a89721 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -195,6 +195,17 @@ config RTC_DRV_ABX80X
This driver can also be built as a module. If so, the module
will be called rtc-abx80x.

+config RTC_DRV_ABX80X_WDT
+ bool "Abracon ABx80x Watchdog"
+ default y
+ depends on RTC_DRV_ABX80X
+ help
+ If you say yes here you get watchdog support for Abracon ABX804 and ABX805
+ clock chips. This watchdog supports timeouts up to 31 seconds with 1 second
+ granularity.
+
+ This watchdog device is part of the rtc-abx80x module.
+
config RTC_DRV_AC100
tristate "X-Powers AC100"
depends on MFD_AC100
diff --git a/drivers/rtc/rtc-abx80x.c b/drivers/rtc/rtc-abx80x.c
index 2cefa67a1132..fa558939e944 100644
--- a/drivers/rtc/rtc-abx80x.c
+++ b/drivers/rtc/rtc-abx80x.c
@@ -17,6 +17,7 @@
#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/rtc.h>
+#include <linux/watchdog.h>

#define ABX8XX_REG_HTH 0x00
#define ABX8XX_REG_SC 0x01
@@ -37,6 +38,7 @@

#define ABX8XX_REG_STATUS 0x0f
#define ABX8XX_STATUS_AF BIT(2)
+#define ABX8XX_STATUS_WDT BIT(6)

#define ABX8XX_REG_CTRL1 0x10
#define ABX8XX_CTRL_WRITE BIT(0)
@@ -61,6 +63,14 @@
#define ABX8XX_OSS_OF BIT(1)
#define ABX8XX_OSS_OMODE BIT(4)

+#define ABX8XX_REG_WDT 0x1b
+#define ABX8XX_WDT_WDS BIT(7)
+#define ABX8XX_WDT_BMB_MASK 0x7c
+#define ABX8XX_WDT_BMB_SHIFT 2
+#define ABX8XX_WDT_MAX_TIME (ABX8XX_WDT_BMB_MASK >> ABX8XX_WDT_BMB_SHIFT)
+#define ABX8XX_WDT_WRB_MASK 0x03
+#define ABX8XX_WDT_WRB_1HZ 0x02
+
#define ABX8XX_REG_CFG_KEY 0x1f
#define ABX8XX_CFG_KEY_OSC 0xa1
#define ABX8XX_CFG_KEY_MISC 0x9d
@@ -80,20 +90,27 @@ enum abx80x_chip {AB0801, AB0803, AB0804, AB0805,
struct abx80x_cap {
u16 pn;
bool has_tc;
+ bool has_wdog;
};

static struct abx80x_cap abx80x_caps[] = {
[AB0801] = {.pn = 0x0801},
[AB0803] = {.pn = 0x0803},
- [AB0804] = {.pn = 0x0804, .has_tc = true},
- [AB0805] = {.pn = 0x0805, .has_tc = true},
+ [AB0804] = {.pn = 0x0804, .has_tc = true, .has_wdog = true},
+ [AB0805] = {.pn = 0x0805, .has_tc = true, .has_wdog = true},
[AB1801] = {.pn = 0x1801},
[AB1803] = {.pn = 0x1803},
- [AB1804] = {.pn = 0x1804, .has_tc = true},
- [AB1805] = {.pn = 0x1805, .has_tc = true},
+ [AB1804] = {.pn = 0x1804, .has_tc = true, .has_wdog = true},
+ [AB1805] = {.pn = 0x1805, .has_tc = true, .has_wdog = true},
[ABX80X] = {.pn = 0}
};

+struct abx80x_priv {
+ struct rtc_device *rtc;
+ struct i2c_client *client;
+ struct watchdog_device wdog;
+};
+
static int abx80x_is_rc_mode(struct i2c_client *client)
{
int flags = 0;
@@ -218,7 +235,8 @@ static int abx80x_rtc_set_time(struct device *dev, struct rtc_time *tm)
static irqreturn_t abx80x_handle_irq(int irq, void *dev_id)
{
struct i2c_client *client = dev_id;
- struct rtc_device *rtc = i2c_get_clientdata(client);
+ struct abx80x_priv *priv = i2c_get_clientdata(client);
+ struct rtc_device *rtc = priv->rtc;
int status;

status = i2c_smbus_read_byte_data(client, ABX8XX_REG_STATUS);
@@ -228,6 +246,13 @@ static irqreturn_t abx80x_handle_irq(int irq, void *dev_id)
if (status & ABX8XX_STATUS_AF)
rtc_update_irq(rtc, 1, RTC_AF | RTC_IRQF);

+ /*
+ * It is unclear if we'll get an interrupt before the external
+ * reset kicks in.
+ */
+ if (status & ABX8XX_STATUS_WDT)
+ dev_err(&client->dev, "watchdog timeout interrupt!\n");
+
i2c_smbus_write_byte_data(client, ABX8XX_REG_STATUS, 0);

return IRQ_HANDLED;
@@ -529,11 +554,110 @@ static void rtc_calib_remove_sysfs_group(void *_dev)
sysfs_remove_group(&dev->kobj, &rtc_calib_attr_group);
}

+#ifdef CONFIG_RTC_DRV_ABX80X_WDT
+
+static inline u8 timeout_bits(unsigned int timeout)
+{
+ return ((timeout << ABX8XX_WDT_BMB_SHIFT) & ABX8XX_WDT_BMB_MASK) |
+ ABX8XX_WDT_WRB_1HZ;
+}
+
+static int __abx80x_wdog_set_timeout(struct watchdog_device *wdog,
+ unsigned int timeout)
+{
+ struct abx80x_priv *priv = watchdog_get_drvdata(wdog);
+ u8 val = ABX8XX_WDT_WDS | timeout_bits(timeout);
+
+ /*
+ * Writing any timeout to the WDT register resets the watchdog timer.
+ * Writing 0 disables it.
+ */
+ return i2c_smbus_write_byte_data(priv->client, ABX8XX_REG_WDT, val);
+}
+
+static int abx80x_wdog_set_timeout(struct watchdog_device *wdog,
+ unsigned int new_timeout)
+{
+ int err = __abx80x_wdog_set_timeout(wdog, new_timeout);
+
+ if (err)
+ return err;
+
+ wdog->timeout = new_timeout;
+ return 0;
+}
+
+static int abx80x_wdog_ping(struct watchdog_device *wdog)
+{
+ return __abx80x_wdog_set_timeout(wdog, wdog->timeout);
+}
+
+static int abx80x_wdog_start(struct watchdog_device *wdog)
+{
+ int err = __abx80x_wdog_set_timeout(wdog, wdog->timeout);
+
+ if (err)
+ return err;
+
+ set_bit(WDOG_HW_RUNNING, &wdog->status);
+ return 0;
+}
+
+static int abx80x_wdog_stop(struct watchdog_device *wdog)
+{
+ int err = __abx80x_wdog_set_timeout(wdog, 0);
+
+ if (err)
+ return err;
+
+ clear_bit(WDOG_HW_RUNNING, &wdog->status);
+ return 0;
+}
+
+static const struct watchdog_info abx80x_wdog_info = {
+ .identity = "abx80x watchdog",
+ .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
+};
+
+static const struct watchdog_ops abx80x_wdog_ops = {
+ .owner = THIS_MODULE,
+ .start = abx80x_wdog_start,
+ .stop = abx80x_wdog_stop,
+ .ping = abx80x_wdog_ping,
+ .set_timeout = abx80x_wdog_set_timeout,
+};
+
+static int abx80x_setup_watchdog(struct abx80x_priv *priv)
+{
+ int err;
+
+ priv->wdog.ops = &abx80x_wdog_ops;
+ priv->wdog.info = &abx80x_wdog_info;
+ priv->wdog.min_timeout = 1;
+ priv->wdog.max_timeout = ABX8XX_WDT_MAX_TIME;
+
+ err = devm_watchdog_register_device(&priv->client->dev,
+ &priv->wdog);
+ if (err)
+ return err;
+
+ watchdog_set_drvdata(&priv->wdog, priv);
+ watchdog_init_timeout(&priv->wdog, ABX8XX_WDT_MAX_TIME,
+ &priv->client->dev);
+ return 0;
+}
+#else
+static int abx80x_setup_watchdog(struct abx80x_priv *priv)
+{
+ return 0;
+}
+#endif
+
static int abx80x_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
struct device_node *np = client->dev.of_node;
- struct rtc_device *rtc;
+ struct abx80x_priv *priv;
int i, data, err, trickle_cfg = -EINVAL;
char buf[7];
unsigned int part = id->driver_data;
@@ -610,13 +734,25 @@ static int abx80x_probe(struct i2c_client *client,
if (err)
return err;

- rtc = devm_rtc_allocate_device(&client->dev);
- if (IS_ERR(rtc))
- return PTR_ERR(rtc);
+ priv = devm_kzalloc(&client->dev, sizeof(struct abx80x_priv),
+ GFP_KERNEL);
+ if (priv == NULL)
+ return -ENOMEM;
+
+ priv->rtc = devm_rtc_allocate_device(&client->dev);
+ if (IS_ERR(priv->rtc))
+ return PTR_ERR(priv->rtc);

- rtc->ops = &abx80x_rtc_ops;
+ priv->rtc->ops = &abx80x_rtc_ops;
+ priv->client = client;

- i2c_set_clientdata(client, rtc);
+ i2c_set_clientdata(client, priv);
+
+ if (abx80x_caps[part].has_wdog) {
+ err = abx80x_setup_watchdog(priv);
+ if (err)
+ return err;
+ }

if (client->irq > 0) {
dev_info(&client->dev, "IRQ %d supplied\n", client->irq);
@@ -649,7 +785,7 @@ static int abx80x_probe(struct i2c_client *client,
return err;
}

- err = rtc_register_device(rtc);
+ err = rtc_register_device(priv->rtc);

return err;
}
--
2.17.1
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