Introduce a device tree binding for specifying the trickle charger
configuration for ds1339.
Signed-off-by: Ivan Grimaldi <grimaldi.i...@gmail.com>
---
.../devicetree/bindings/rtc/dallas,ds1390.txt | 18 +++++++
drivers/rtc/rtc-ds1390.c | 63 ++++++++++++++++++++++
2 files changed, 81 insertions(+)
create mode 100644 Documentation/devicetree/bindings/rtc/dallas,ds1390.txt
diff --git a/Documentation/devicetree/bindings/rtc/dallas,ds1390.txt
b/Documentation/devicetree/bindings/rtc/dallas,ds1390.txt
new file mode 100644
index 0000000..8e76f26
--- /dev/null
+++ b/Documentation/devicetree/bindings/rtc/dallas,ds1390.txt
@@ -0,0 +1,18 @@
+* Dallas DS1390 SPI Serial Real-Time Clock
+
+Required properties:
+- compatible: Should contain "dallas,ds1390".
+- reg: SPI address for chip
+
+Optional properties:
+- trickle-resistor-ohms : Selected resistor for trickle charger
+ Values usable for ds1390 are 250, 2000, 4000
+ Should be given if trickle charger should be enabled
+- trickle-diode-disable : Do not use internal trickle charger diode
+ Should be given if internal trickle charger diode should be disabled
+Example:
+ ds1390: rtc@68 {
+ compatible = "dallas,ds1390";
+ trickle-resistor-ohms = <250>;
+ reg = <0>;
+ };
diff --git a/drivers/rtc/rtc-ds1390.c b/drivers/rtc/rtc-ds1390.c
index a4303b4..9bcf6f9 100644
--- a/drivers/rtc/rtc-ds1390.c
+++ b/drivers/rtc/rtc-ds1390.c
@@ -20,6 +20,7 @@
#include <linux/spi/spi.h>
#include <linux/bcd.h>
#include <linux/slab.h>
+#include <linux/of.h>
#define DS1390_REG_100THS 0x00
#define DS1390_REG_SECONDS 0x01
@@ -40,11 +41,31 @@
#define DS1390_REG_STATUS 0x0E
#define DS1390_REG_TRICKLE 0x0F
+#define DS1390_TRICKLE_ENABLE_CHARGER 0xA0
+#define DS1390_TRICKLE_CHARGER_250_OHM 0x01
+#define DS1390_TRICKLE_CHARGER_2K_OHM 0x02
+#define DS1390_TRICKLE_CHARGER_4K_OHM 0x03
+#define DS1390_TRICKLE_CHARGER_NO_DIODE 0x04
+#define DS1390_TRICKLE_CHARGER_DIODE 0x08
+
struct ds1390 {
struct rtc_device *rtc;
u8 txrx_buf[9]; /* cmd + 8 registers */
};
+static void ds1390_set_reg(struct device *dev, unsigned char address,
+ unsigned char data)
+{
+ struct spi_device *spi = to_spi_device(dev);
+ unsigned char buf[2];
+
+ /* MSB must be '1' to write */
+ buf[0] = address | 0x80;
+ buf[1] = data;
+
+ spi_write(spi, buf, 2);
+}
+
static int ds1390_get_reg(struct device *dev, unsigned char address,
unsigned char *data)
{
@@ -67,6 +88,44 @@ static int ds1390_get_reg(struct device *dev, unsigned char
address,
return 0;
}
+static void ds1390_trickle_of_init(struct spi_device *spi)
+{
+ uint32_t ohms = 0;
+ uint8_t value;
+
+ if (of_property_read_u32(spi->dev.of_node, "trickle-resistor-ohms",
&ohms))
+ goto out;
+
+ /* Enable charger */
+ value = DS1390_TRICKLE_ENABLE_CHARGER;
+ if (of_property_read_bool(spi->dev.of_node, "trickle-diode-disable"))
+ value |= DS1390_TRICKLE_CHARGER_NO_DIODE;
+ else
+ value |= DS1390_TRICKLE_CHARGER_DIODE;
+
+ /* Resistor select */
+ switch (ohms) {
+ case 250:
+ value |= DS1390_TRICKLE_CHARGER_250_OHM;
+ break;
+ case 2000:
+ value |= DS1390_TRICKLE_CHARGER_2K_OHM;
+ break;
+ case 4000:
+ value |= DS1390_TRICKLE_CHARGER_4K_OHM;
+ break;
+ default:
+ dev_warn(&spi->dev,
+ "Unsupported ohm value %02ux in dt\n", ohms);
+ return;
+ }
+
+ ds1390_set_reg(&spi->dev, DS1390_REG_TRICKLE, value);
+
+out:
+ return;
+}
+
static int ds1390_read_time(struct device *dev, struct rtc_time *dt)
{
struct spi_device *spi = to_spi_device(dev);
@@ -143,6 +202,9 @@ static int ds1390_probe(struct spi_device *spi)
return res;
}
+ if (spi->dev.of_node)
+ ds1390_trickle_of_init(spi);
+
chip->rtc = devm_rtc_device_register(&spi->dev, "ds1390",
&ds1390_rtc_ops, THIS_MODULE);
if (IS_ERR(chip->rtc)) {
@@ -165,5 +227,6 @@ module_spi_driver(ds1390_driver);
MODULE_DESCRIPTION("Dallas/Maxim DS1390/93/94 SPI RTC driver");
MODULE_AUTHOR("Mark Jackson <m...@mimc.co.uk>");
+MODULE_AUTHOR("Ivan Grimaldi <ivan.grima...@siaemic.com>");
MODULE_LICENSE("GPL");
MODULE_ALIAS("spi:rtc-ds1390");
--
2.5.2
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