Commit 8bc2a407 authored by Michael Lange's avatar Michael Lange Committed by Alexandre Belloni
Browse files

rtc: ds1307: add support for the DT property 'wakeup-source' 



For RTC chips with no IRQ directly 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.
This will guarantee the 'wakealarm' sysfs entry is available on the
device, if supported by the RTC.

With these changes to the driver rtc-ds1307 and the necessary entries
in the .dts file, I get an working ds1337 RTC on the Witty Pi extension
board by UUGear for the Raspberry Pi.

An example for the entry in the .dts file:

	rtc: ds1337@68 {
		compatible = "dallas,ds1337";
		reg = <0x68>;
		wakeup-source;

If the "wakeup-source" property is set, do not request an IRQ.
Set also UIE mode to unsupported, to get a working 'hwclock' binary.

Signed-off-by: default avatarMichael Lange <linuxstuff@milaw.biz>
Signed-off-by: default avatarAlexandre Belloni <alexandre.belloni@free-electrons.com>
parent 04d3ba70

drivers/rtc/rtc-ds1307.c

+27 −2
Original line number Diff line number Diff line
@@ -851,6 +851,7 @@ 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;
@@ -898,6 +899,20 @@ static int ds1307_probe(struct i2c_client *client, 
		ds1307->write_block_data = ds1307_write_block_data;

	}



#ifdef CONFIG_OF

/*

 * For devices with no IRQ directly 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 the "wakeup-source" property is set, don't request an IRQ.

 * This will guarantee the 'wakealarm' sysfs entry is available on the device,

 * if supported by the RTC.

 */

	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:
@@ -916,11 +931,13 @@ 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 defined as wakeup-source?

		 * 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) {

		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);
@@ -1135,6 +1152,14 @@ read_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 = devm_request_threaded_irq(&client->dev,

						client->irq, NULL, irq_handler,

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