On 23/08/17 07:38, Nikita Yushchenko wrote:
> This adds support for reading and writing date/time from/to ds1314 chip.
>
> Other functionality (alarms, inout clock, output clock) is not added
> yet, because availability of that depends on chip connections.
>
> Signed-off-by: Nikita Yushchenko <nikita.yo...@cogentembedded.com>
Tested this patch on a ZII RDU2 and it seems to work properly.
Tested-by: Aleksander Morgado <aleksan...@aleksander.es
> ---
> drivers/rtc/Kconfig | 10 +++++-----
> drivers/rtc/rtc-ds1307.c | 13 +++++++++++++
> 2 files changed, 18 insertions(+), 5 deletions(-)
> ===
> DS1341/1342 chips have additional features, namely
> - alarms,
> - input clock (can be used instead of intercal oscillator for better
> accuracy),
> - output clock ("square wave generation")
>
> However, not all of that is available at the same time. Same chip pins,
> CLKIN/nINTA and SQW/nINTB, can be used either for input/output clocks,
> or for alarm interrupts. Role of these pins on particular board depends
> on hardware wiring.
>
> We can add device tree properties that describe if each of pins is wired
> as clock, or as interrupt, or left unconnected, and enable support for
> corresponding functionality based on that. But that requires hardware setups
> for testing, and also is somewhat cumbersome. Additional complexity is
> caused by bit enabling/disabling output clock also affects which pins alarm
> interrupts are routed to.
>
> Another factor is that there are hardware setups (i.e. ZII RDU2) that
> power DS1341 from SuperCap, which makes power saving critical. For such
> setups, kernel driver should leave register bits that control mentioned
> pins in the state configured by bootloader.
>
> Given all that, it was decided to limit support to "only date/time" for
> now. That is enough for common use case. Full (and cumbersome) implementation
> can be added later if ever needed.
>
> diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
> index 72419ac2c52a..db63592a0f57 100644
> --- a/drivers/rtc/Kconfig
> +++ b/drivers/rtc/Kconfig
> @@ -227,14 +227,14 @@ config RTC_DRV_AS3722
> will be called rtc-as3722.
>
> config RTC_DRV_DS1307
> - tristate "Dallas/Maxim DS1307/37/38/39/40, ST M41T00, EPSON RX-8025,
> ISL12057"
> + tristate "Dallas/Maxim DS1307/37/38/39/40/41, ST M41T00, EPSON RX-8025,
> ISL12057"
> help
> If you say yes here you get support for various compatible RTC
> chips (often with battery backup) connected with I2C. This driver
> - should handle DS1307, DS1337, DS1338, DS1339, DS1340, ST M41T00,
> - EPSON RX-8025, Intersil ISL12057 and probably other chips. In some
> - cases the RTC must already have been initialized (by manufacturing or
> - a bootloader).
> + should handle DS1307, DS1337, DS1338, DS1339, DS1340, DS1341,
> + ST M41T00, EPSON RX-8025, Intersil ISL12057 and probably other chips.
> + In some cases the RTC must already have been initialized (by
> + manufacturing or a bootloader).
>
> The first seven registers on these chips hold an RTC, and other
> registers may add features such as NVRAM, a trickle charger for
> diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
> index 4fac49e55d47..1d11f8000f8a 100644
> --- a/drivers/rtc/rtc-ds1307.c
> +++ b/drivers/rtc/rtc-ds1307.c
> @@ -39,6 +39,7 @@ enum ds_type {
> ds_1338,
> ds_1339,
> ds_1340,
> + ds_1341,
> ds_1388,
> ds_3231,
> m41t0,
> @@ -179,6 +180,10 @@ static struct chip_desc chips[last_ds_type] = {
> .century_bit = DS1340_BIT_CENTURY,
> .trickle_charger_reg = 0x08,
> },
> + [ds_1341] = {
> + .century_reg = DS1307_REG_MONTH,
> + .century_bit = DS1337_BIT_CENTURY,
> + },
> [ds_1388] = {
> .trickle_charger_reg = 0x0a,
> },
> @@ -209,6 +214,7 @@ static const struct i2c_device_id ds1307_id[] = {
> { "ds1339", ds_1339 },
> { "ds1388", ds_1388 },
> { "ds1340", ds_1340 },
> + { "ds1341", ds_1341 },
> { "ds3231", ds_3231 },
> { "m41t0", m41t0 },
> { "m41t00", m41t00 },
> @@ -253,6 +259,10 @@ static const struct of_device_id ds1307_of_match[] = {
> .data = (void *)ds_1340
> },
> {
> + .compatible = "dallas,ds1341",
> + .data = (void *)ds_1341
> + },
> + {
> .compatible = "maxim,ds3231",
> .data = (void *)ds_3231
> },
> @@ -298,6 +308,7 @@ static const struct acpi_device_id ds1307_acpi_ids[] = {
> { .id = "DS1339", .driver_data = ds_1339 },
> { .id = "DS1388", .driver_data = ds_1388 },
> { .id = "DS1340", .driver_data = ds_1340 },
> + { .id = "DS1341", .driver_data = ds_1341 },
> { .id = "DS3231", .driver_data = ds_3231 },
> { .id = "M41T0", .driver_data = m41t0 },
> { .id = "M41T00", .driver_data = m41t00 },
> @@ -1323,6 +1334,7 @@ static int ds1307_probe(struct i2c_client *client,
> static const int bbsqi_bitpos[] = {
> [ds_1337] = 0,
> [ds_1339] = DS1339_BIT_BBSQI,
> + [ds_1341] = 0,
> [ds_3231] = DS3231_BIT_BBSQW,
> };
> const struct rtc_class_ops *rtc_ops = &ds13xx_rtc_ops;
> @@ -1401,6 +1413,7 @@ static int ds1307_probe(struct i2c_client *client,
> switch (ds1307->type) {
> case ds_1337:
> case ds_1339:
> + case ds_1341:
> case ds_3231:
> /* get registers that the "rtc" read below won't read... */
> err = regmap_bulk_read(ds1307->regmap, DS1337_REG_CONTROL,
>
--
Aleksander
https://aleksander.es
