rtc-ds1307.c: add DT property 'wakeup-source' to indicate the rtc can wakeup the device without an IRQ

Author: vitalogy

drivers/rtc/rtc-ds1307.c

@@ -11,21 +11,22 @@
  * published by the Free Software Foundation.
  */
 
-#include <linux/module.h>
+#include <linux/bcd.h>
+#include <linux/i2c.h>
 #include <linux/init.h>
+#include <linux/module.h>
+#include <linux/rtc/ds1307.h>
+#include <linux/rtc.h>
 #include <linux/slab.h>
-#include <linux/i2c.h>
 #include <linux/string.h>
-#include <linux/rtc.h>
-#include <linux/bcd.h>
-#include <linux/rtc/ds1307.h>
 
 /*
  * We can't determine type by probing, but if we expect pre-Linux code
  * to have set the chip up as a clock (turning on the oscillator and
  * setting the date and time), Linux can ignore the non-clock features.
  * That's a natural job for a factory or repair bench.
  */
+
 enum ds_type {
 	ds_1307,
 	ds_1337,
@@ -41,7 +42,6 @@ enum ds_type {
 	/* rs5c372 too?  different address... */
 };
 
-
 /* RTC registers don't differ much, except for the century flag */
 #define DS1307_REG_SECS		0x00	/* 00-59 */
 #	define DS1307_BIT_CH		0x80
@@ -114,7 +114,6 @@ struct ds1307 {
 #define HAS_ALARM	1		/* bit 1 == irq claimed */
 	struct i2c_client	*client;
 	struct rtc_device	*rtc;
-	struct work_struct	work;
 	s32 (*read_block_data)(const struct i2c_client *client, u8 command,
 			       u8 length, u8 *values);
 	s32 (*write_block_data)(const struct i2c_client *client, u8 command,
@@ -311,27 +310,17 @@ static s32 ds1307_native_smbus_read_block_data(const struct i2c_client *client,
 /*----------------------------------------------------------------------*/
 
 /*
- * The IRQ logic includes a "real" handler running in IRQ context just
- * long enough to schedule this workqueue entry.   We need a task context
- * to talk to the RTC, since I2C I/O calls require that; and disable the
- * IRQ until we clear its status on the chip, so that this handler can
- * work with any type of triggering (not just falling edge).
- *
  * The ds1337 and ds1339 both have two alarms, but we only use the first
  * one (with a "seconds" field).  For ds1337 we expect nINTA is our alarm
  * signal; ds1339 chips have only one alarm signal.
  */
-static void ds1307_work(struct work_struct *work)
+static irqreturn_t ds1307_irq(int irq, void *dev_id)
 {
-	struct ds1307		*ds1307;
-	struct i2c_client	*client;
-	struct mutex		*lock;
+	struct i2c_client	*client = dev_id;
+	struct ds1307		*ds1307 = i2c_get_clientdata(client);
+	struct mutex		*lock = &ds1307->rtc->ops_lock;
 	int			stat, control;
 
-	ds1307 = container_of(work, struct ds1307, work);
-	client = ds1307->client;
-	lock = &ds1307->rtc->ops_lock;
-
 	mutex_lock(lock);
 	stat = i2c_smbus_read_byte_data(client, DS1337_REG_STATUS);
 	if (stat < 0)
@@ -352,18 +341,8 @@ static void ds1307_work(struct work_struct *work)
 	}
 
 out:
-	if (test_bit(HAS_ALARM, &ds1307->flags))
-		enable_irq(client->irq);
 	mutex_unlock(lock);
-}
 
-static irqreturn_t ds1307_irq(int irq, void *dev_id)
-{
-	struct i2c_client	*client = dev_id;
-	struct ds1307		*ds1307 = i2c_get_clientdata(client);
-
-	disable_irq_nosync(irq);
-	schedule_work(&ds1307->work);
 	return IRQ_HANDLED;
 }
 
@@ -634,13 +613,14 @@ static const struct rtc_class_ops ds13xx_rtc_ops = {
 					 MCP794XX_BIT_ALMX_C1 | \
 					 MCP794XX_BIT_ALMX_C2)
 
-static void mcp794xx_work(struct work_struct *work)
+static irqreturn_t mcp794xx_irq(int irq, void *dev_id)
 {
-	struct ds1307 *ds1307 = container_of(work, struct ds1307, work);
-	struct i2c_client *client = ds1307->client;
+	struct i2c_client       *client = dev_id;
+	struct ds1307           *ds1307 = i2c_get_clientdata(client);
+	struct mutex            *lock = &ds1307->rtc->ops_lock;
 	int reg, ret;
 
-	mutex_lock(&ds1307->rtc->ops_lock);
+	mutex_lock(lock);
 
 	/* Check and clear alarm 0 interrupt flag. */
 	reg = i2c_smbus_read_byte_data(client, MCP794XX_REG_ALARM0_CTRL);
@@ -665,9 +645,9 @@ static void mcp794xx_work(struct work_struct *work)
 	rtc_update_irq(ds1307->rtc, 1, RTC_AF | RTC_IRQF);
 
 out:
-	if (test_bit(HAS_ALARM, &ds1307->flags))
-		enable_irq(client->irq);
-	mutex_unlock(&ds1307->rtc->ops_lock);
+	mutex_unlock(lock);
+
+	return IRQ_HANDLED;
 }
 
 static int mcp794xx_read_alarm(struct device *dev, struct rtc_wkalrm *t)
@@ -734,25 +714,25 @@ static int mcp794xx_set_alarm(struct device *dev, struct rtc_wkalrm *t)
 	regs[3] = bin2bcd(t->time.tm_sec);
 	regs[4] = bin2bcd(t->time.tm_min);
 	regs[5] = bin2bcd(t->time.tm_hour);
-	regs[6] = bin2bcd(t->time.tm_wday) + 1;
+	regs[6] = bin2bcd(t->time.tm_wday + 1);
 	regs[7] = bin2bcd(t->time.tm_mday);
-	regs[8] = bin2bcd(t->time.tm_mon) + 1;
+	regs[8] = bin2bcd(t->time.tm_mon + 1);
 
 	/* Clear the alarm 0 interrupt flag. */
 	regs[6] &= ~MCP794XX_BIT_ALMX_IF;
 	/* Set alarm match: second, minute, hour, day, date, month. */
 	regs[6] |= MCP794XX_MSK_ALMX_MATCH;
-
-	if (t->enabled)
-		regs[0] |= MCP794XX_BIT_ALM0_EN;
-	else
-		regs[0] &= ~MCP794XX_BIT_ALM0_EN;
+	/* Disable interrupt. We will not enable until completely programmed */
+	regs[0] &= ~MCP794XX_BIT_ALM0_EN;
 
 	ret = ds1307->write_block_data(client, MCP794XX_REG_CONTROL, 10, regs);
 	if (ret < 0)
 		return ret;
 
-	return 0;
+	if (!t->enabled)
+		return 0;
+	regs[0] |= MCP794XX_BIT_ALM0_EN;
+	return i2c_smbus_write_byte_data(client, MCP794XX_REG_CONTROL, regs[0]);
 }
 
 static int mcp794xx_alarm_irq_enable(struct device *dev, unsigned int enabled)
@@ -798,13 +778,6 @@ ds1307_nvram_read(struct file *filp, struct kobject *kobj,
 	client = kobj_to_i2c_client(kobj);
 	ds1307 = i2c_get_clientdata(client);
 
-	if (unlikely(off >= ds1307->nvram->size))
-		return 0;
-	if ((off + count) > ds1307->nvram->size)
-		count = ds1307->nvram->size - off;
-	if (unlikely(!count))
-		return count;
-
 	result = ds1307->read_block_data(client, ds1307->nvram_offset + off,
 								count, buf);
 	if (result < 0)
@@ -824,13 +797,6 @@ ds1307_nvram_write(struct file *filp, struct kobject *kobj,
 	client = kobj_to_i2c_client(kobj);
 	ds1307 = i2c_get_clientdata(client);
 
-	if (unlikely(off >= ds1307->nvram->size))
-		return -EFBIG;
-	if ((off + count) > ds1307->nvram->size)
-		count = ds1307->nvram->size - off;
-	if (unlikely(!count))
-		return count;
-
 	result = ds1307->write_block_data(client, ds1307->nvram_offset + off,
 								count, buf);
 	if (result < 0) {
@@ -894,8 +860,11 @@ static int ds1307_probe(struct i2c_client *client,
 	struct chip_desc	*chip = &chips[id->driver_data];
 	struct i2c_adapter	*adapter = to_i2c_adapter(client->dev.parent);
 	bool			want_irq = false;
+	bool			ds1307_can_wakeup_device = false;
 	unsigned char		*buf;
 	struct ds1307_platform_data *pdata = dev_get_platdata(&client->dev);
+	irq_handler_t	irq_handler = ds1307_irq;
+
 	static const int	bbsqi_bitpos[] = {
 		[ds_1337] = 0,
 		[ds_1339] = DS1339_BIT_BBSQI,
@@ -939,6 +908,24 @@ static int ds1307_probe(struct i2c_client *client,
 		ds1307->write_block_data = ds1307_write_block_data;
 	}
 
+#ifdef CONFIG_OF
+/*
+ * One would expect the device to be marked as a wakeup source only
+ * when an IRQ pin of the RTC is routed to an interrupt line of the
+ * CPU. In practice, such an IRQ pin can be connected to a PMIC and
+ * this allows the device to be powered up when RTC alarm rings. This
+ * is for instance the case on the Witty Pi extension board. On this
+ * device with no IRQ driectly connected to the SoC, the RTC chip
+ * can be forced as a wakeup source by stating that explicitly in
+ * the device's .dts file using the "wakeup-source" boolean property.
+ * If "wakeup-source is set, don't request an IRQ.
+ * This will guarantee 'wakealarm' sysfs entry is available on the device.
+ */
+	if (of_property_read_bool(client->dev.of_node, "wakeup-source")) {
+		ds1307_can_wakeup_device = true;
+	}
+#endif
+
 	switch (ds1307->type) {
 	case ds_1337:
 	case ds_1339:
@@ -957,13 +944,12 @@ static int ds1307_probe(struct i2c_client *client,
 			ds1307->regs[0] &= ~DS1337_BIT_nEOSC;
 
 		/*
-		 * Using IRQ?  Disable the square wave and both alarms.
+		 * Using IRQ or set wakeup-source in .dts file?
+		 * Disable the square wave and both alarms.
 		 * For some variants, be sure alarms can trigger when we're
 		 * running on Vbackup (BBSQI/BBSQW)
 		 */
-		if (ds1307->client->irq > 0 && chip->alarm) {
-			INIT_WORK(&ds1307->work, ds1307_work);
-
+		if (chip->alarm & (ds1307->client->irq > 0 || ds1307_can_wakeup_device)) {
 			ds1307->regs[0] |= DS1337_BIT_INTCN
 					| bbsqi_bitpos[ds1307->type];
 			ds1307->regs[0] &= ~(DS1337_BIT_A2IE | DS1337_BIT_A1IE);
@@ -1053,7 +1039,7 @@ static int ds1307_probe(struct i2c_client *client,
 	case mcp794xx:
 		rtc_ops = &mcp794xx_rtc_ops;
 		if (ds1307->client->irq > 0 && chip->alarm) {
-			INIT_WORK(&ds1307->work, mcp794xx_work);
+			irq_handler = mcp794xx_irq;
 			want_irq = true;
 		}
 		break;
@@ -1168,24 +1154,36 @@ static int ds1307_probe(struct i2c_client *client,
 				bin2bcd(tmp));
 	}
 
-	device_set_wakeup_capable(&client->dev, want_irq);
+	if (want_irq) {
+		device_set_wakeup_capable(&client->dev, true);
+		set_bit(HAS_ALARM, &ds1307->flags);
+	}
 	ds1307->rtc = devm_rtc_device_register(&client->dev, client->name,
 				rtc_ops, THIS_MODULE);
 	if (IS_ERR(ds1307->rtc)) {
 		return PTR_ERR(ds1307->rtc);
 	}
 
+	if (ds1307_can_wakeup_device) {
+		/* Disable request for an IRQ */
+		want_irq = false;
+		dev_info(&client->dev, "'wakeup-source' is set, request for an IRQ is disabled!\n");
+		/* We cannot support UIE mode if we do not have an IRQ line */
+		ds1307->rtc->uie_unsupported = 1;
+	}
+
 	if (want_irq) {
-		err = request_irq(client->irq, ds1307_irq, IRQF_SHARED,
-			  ds1307->rtc->name, client);
+		err = devm_request_threaded_irq(&client->dev,
+						client->irq, NULL, irq_handler,
+						IRQF_SHARED | IRQF_ONESHOT,
+						ds1307->rtc->name, client);
 		if (err) {
 			client->irq = 0;
+			device_set_wakeup_capable(&client->dev, false);
+			clear_bit(HAS_ALARM, &ds1307->flags);
 			dev_err(&client->dev, "unable to request IRQ!\n");
-		} else {
-
-			set_bit(HAS_ALARM, &ds1307->flags);
+		} else
 			dev_dbg(&client->dev, "got IRQ %d\n", client->irq);
-		}
 	}
 
 	if (chip->nvram_size) {
@@ -1231,11 +1229,6 @@ static int ds1307_remove(struct i2c_client *client)
 {
 	struct ds1307 *ds1307 = i2c_get_clientdata(client);
 
-	if (test_and_clear_bit(HAS_ALARM, &ds1307->flags)) {
-		free_irq(client->irq, client);
-		cancel_work_sync(&ds1307->work);
-	}
-
 	if (test_and_clear_bit(HAS_NVRAM, &ds1307->flags))
 		sysfs_remove_bin_file(&client->dev.kobj, ds1307->nvram);