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Subject[PATCH v3] rtc: add rtc-abx80x, a driver for the Abracon AB x80x i2c rtc
Date
From: Philippe De Muyter <phdm@macqel.be>

This is a basic driver for the ultra-low-power Abracon AB x80x series of RTC
chips. It supports in particular, the supersets AB0805 and AB1805.
It allows reading and writing the time, and enables the supercapacitor/
battery charger.

[arnd@arndb.de: abx805 depends on i2c]
Signed-off-by: Philippe De Muyter <phdm@macqel.be>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
Changes in v3:
- renamed buffer from date to buf in abx80x_rtc_read_time()


drivers/rtc/Kconfig | 10 ++
drivers/rtc/Makefile | 1 +
drivers/rtc/rtc-abx80x.c | 307 +++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 318 insertions(+)
create mode 100644 drivers/rtc/rtc-abx80x.c

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index b5b5c3d485d6..89507c1858ec 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -164,6 +164,16 @@ config RTC_DRV_ABB5ZES3
This driver can also be built as a module. If so, the module
will be called rtc-ab-b5ze-s3.

+config RTC_DRV_ABX80X
+ tristate "Abracon ABx80x"
+ help
+ If you say yes here you get support for Abracon AB080X and AB180X
+ families of ultra-low-power battery- and capacitor-backed real-time
+ clock chips.
+
+ This driver can also be built as a module. If so, the module
+ will be called rtc-abx80x.
+
config RTC_DRV_AS3722
tristate "ams AS3722 RTC driver"
depends on MFD_AS3722
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 69c87062b098..7b20b0462cb6 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -25,6 +25,7 @@ obj-$(CONFIG_RTC_DRV_88PM80X) += rtc-88pm80x.o
obj-$(CONFIG_RTC_DRV_AB3100) += rtc-ab3100.o
obj-$(CONFIG_RTC_DRV_AB8500) += rtc-ab8500.o
obj-$(CONFIG_RTC_DRV_ABB5ZES3) += rtc-ab-b5ze-s3.o
+obj-$(CONFIG_RTC_DRV_ABX80X) += rtc-abx80x.o
obj-$(CONFIG_RTC_DRV_ARMADA38X) += rtc-armada38x.o
obj-$(CONFIG_RTC_DRV_AS3722) += rtc-as3722.o
obj-$(CONFIG_RTC_DRV_AT32AP700X)+= rtc-at32ap700x.o
diff --git a/drivers/rtc/rtc-abx80x.c b/drivers/rtc/rtc-abx80x.c
new file mode 100644
index 000000000000..4337c3bc6ace
--- /dev/null
+++ b/drivers/rtc/rtc-abx80x.c
@@ -0,0 +1,307 @@
+/*
+ * A driver for the I2C members of the Abracon AB x8xx RTC family,
+ * and compatible: AB 1805 and AB 0805
+ *
+ * Copyright 2014-2015 Macq S.A.
+ *
+ * Author: Philippe De Muyter <phdm@macqel.be>
+ * Author: Alexandre Belloni <alexandre.belloni@free-electrons.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#include <linux/bcd.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/rtc.h>
+
+#define ABX8XX_REG_HTH 0x00
+#define ABX8XX_REG_SC 0x01
+#define ABX8XX_REG_MN 0x02
+#define ABX8XX_REG_HR 0x03
+#define ABX8XX_REG_DA 0x04
+#define ABX8XX_REG_MO 0x05
+#define ABX8XX_REG_YR 0x06
+#define ABX8XX_REG_WD 0x07
+
+#define ABX8XX_REG_CTRL1 0x10
+#define ABX8XX_CTRL_WRITE BIT(1)
+#define ABX8XX_CTRL_12_24 BIT(6)
+
+#define ABX8XX_REG_CFG_KEY 0x1f
+#define ABX8XX_CFG_KEY_MISC 0x9d
+
+#define ABX8XX_REG_ID0 0x28
+
+#define ABX8XX_REG_TRICKLE 0x20
+#define ABX8XX_TRICKLE_CHARGE_ENABLE 0xa0
+#define ABX8XX_TRICKLE_STANDARD_DIODE 0x8
+#define ABX8XX_TRICKLE_SCHOTTKY_DIODE 0x4
+
+static u8 trickle_resistors[] = {0, 3, 6, 11};
+
+enum abx80x_chip {AB0801, AB0803, AB0804, AB0805,
+ AB1801, AB1803, AB1804, AB1805, ABX80X};
+
+struct abx80x_cap {
+ u16 pn;
+ bool has_tc;
+};
+
+static struct abx80x_cap abx80x_caps[] = {
+ [AB0801] = {.pn = 0x0801},
+ [AB0803] = {.pn = 0x0803},
+ [AB0804] = {.pn = 0x0804, .has_tc = true},
+ [AB0805] = {.pn = 0x0805, .has_tc = true},
+ [AB1801] = {.pn = 0x1801},
+ [AB1803] = {.pn = 0x1803},
+ [AB1804] = {.pn = 0x1804, .has_tc = true},
+ [AB1805] = {.pn = 0x1805, .has_tc = true},
+ [ABX80X] = {.pn = 0}
+};
+
+static struct i2c_driver abx80x_driver;
+
+static int abx80x_enable_trickle_charger(struct i2c_client *client,
+ u8 trickle_cfg)
+{
+ int err;
+
+ /*
+ * Write the configuration key register to enable access to the Trickle
+ * register
+ */
+ err = i2c_smbus_write_byte_data(client, ABX8XX_REG_CFG_KEY,
+ ABX8XX_CFG_KEY_MISC);
+ if (err < 0) {
+ dev_err(&client->dev, "Unable to write configuration key\n");
+ return -EIO;
+ }
+
+ err = i2c_smbus_write_byte_data(client, ABX8XX_REG_TRICKLE,
+ ABX8XX_TRICKLE_CHARGE_ENABLE |
+ trickle_cfg);
+ if (err < 0) {
+ dev_err(&client->dev, "Unable to write trickle register\n");
+ return -EIO;
+ }
+
+ return 0;
+}
+
+static int abx80x_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+ struct i2c_client *client = to_i2c_client(dev);
+ unsigned char buf[8];
+ int err;
+
+ err = i2c_smbus_read_i2c_block_data(client, ABX8XX_REG_HTH,
+ sizeof(buf), buf);
+ if (err < 0) {
+ dev_err(&client->dev, "Unable to read date\n");
+ return -EIO;
+ }
+
+ tm->tm_sec = bcd2bin(buf[ABX8XX_REG_SC] & 0x7F);
+ tm->tm_min = bcd2bin(buf[ABX8XX_REG_MN] & 0x7F);
+ tm->tm_hour = bcd2bin(buf[ABX8XX_REG_HR] & 0x3F);
+ tm->tm_wday = buf[ABX8XX_REG_WD] & 0x7;
+ tm->tm_mday = bcd2bin(buf[ABX8XX_REG_DA] & 0x3F);
+ tm->tm_mon = bcd2bin(buf[ABX8XX_REG_MO] & 0x1F) - 1;
+ tm->tm_year = bcd2bin(buf[ABX8XX_REG_YR]) + 100;
+
+ err = rtc_valid_tm(tm);
+ if (err < 0)
+ dev_err(&client->dev, "retrieved date/time is not valid.\n");
+
+ return err;
+}
+
+static int abx80x_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+ struct i2c_client *client = to_i2c_client(dev);
+ unsigned char buf[8];
+ int err;
+
+ if (tm->tm_year < 100)
+ return -EINVAL;
+
+ buf[ABX8XX_REG_HTH] = 0;
+ buf[ABX8XX_REG_SC] = bin2bcd(tm->tm_sec);
+ buf[ABX8XX_REG_MN] = bin2bcd(tm->tm_min);
+ buf[ABX8XX_REG_HR] = bin2bcd(tm->tm_hour);
+ buf[ABX8XX_REG_DA] = bin2bcd(tm->tm_mday);
+ buf[ABX8XX_REG_MO] = bin2bcd(tm->tm_mon + 1);
+ buf[ABX8XX_REG_YR] = bin2bcd(tm->tm_year - 100);
+ buf[ABX8XX_REG_WD] = tm->tm_wday;
+
+ err = i2c_smbus_write_i2c_block_data(client, ABX8XX_REG_HTH,
+ sizeof(buf), buf);
+ if (err < 0) {
+ dev_err(&client->dev, "Unable to write to date registers\n");
+ return -EIO;
+ }
+
+ return 0;
+}
+
+static const struct rtc_class_ops abx80x_rtc_ops = {
+ .read_time = abx80x_rtc_read_time,
+ .set_time = abx80x_rtc_set_time,
+};
+
+static int abx80x_dt_trickle_cfg(struct device_node *np)
+{
+ const char *diode;
+ int trickle_cfg = 0;
+ int i, ret;
+ u32 tmp;
+
+ ret = of_property_read_string(np, "abracon,tc-diode", &diode);
+ if (ret)
+ return ret;
+
+ if (!strcmp(diode, "standard"))
+ trickle_cfg |= ABX8XX_TRICKLE_STANDARD_DIODE;
+ else if (!strcmp(diode, "schottky"))
+ trickle_cfg |= ABX8XX_TRICKLE_SCHOTTKY_DIODE;
+ else
+ return -EINVAL;
+
+ ret = of_property_read_u32(np, "abracon,tc-resistor", &tmp);
+ if (ret)
+ return ret;
+
+ for (i = 0; i < sizeof(trickle_resistors); i++)
+ if (trickle_resistors[i] == tmp)
+ break;
+
+ if (i == sizeof(trickle_resistors))
+ return -EINVAL;
+
+ return (trickle_cfg | i);
+}
+
+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;
+ int i, data, err, trickle_cfg = -EINVAL;
+ char buf[7];
+ unsigned int part = id->driver_data;
+ unsigned int partnumber;
+ unsigned int majrev, minrev;
+ unsigned int lot;
+ unsigned int wafer;
+ unsigned int uid;
+
+ if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
+ return -ENODEV;
+
+ err = i2c_smbus_read_i2c_block_data(client, ABX8XX_REG_ID0,
+ sizeof(buf), buf);
+ if (err < 0) {
+ dev_err(&client->dev, "Unable to read partnumber\n");
+ return -EIO;
+ }
+
+ partnumber = (buf[0] << 8) | buf[1];
+ majrev = buf[2] >> 3;
+ minrev = buf[2] & 0x7;
+ lot = ((buf[4] & 0x80) << 2) | ((buf[6] & 0x80) << 1) | buf[3];
+ uid = ((buf[4] & 0x7f) << 8) | buf[5];
+ wafer = (buf[6] & 0x7c) >> 2;
+ dev_info(&client->dev, "model %04x, revision %u.%u, lot %x, wafer %x, uid %x\n",
+ partnumber, majrev, minrev, lot, wafer, uid);
+
+ data = i2c_smbus_read_byte_data(client, ABX8XX_REG_CTRL1);
+ if (data < 0) {
+ dev_err(&client->dev, "Unable to read control register\n");
+ return -EIO;
+ }
+
+ err = i2c_smbus_write_byte_data(client, ABX8XX_REG_CTRL1,
+ ((data & ~ABX8XX_CTRL_12_24) |
+ ABX8XX_CTRL_WRITE));
+ if (err < 0) {
+ dev_err(&client->dev, "Unable to write control register\n");
+ return -EIO;
+ }
+
+ /* part autodetection */
+ if (part == ABX80X) {
+ for (i = 0; abx80x_caps[i].pn; i++)
+ if (partnumber == abx80x_caps[i].pn)
+ break;
+ if (abx80x_caps[i].pn == 0) {
+ dev_err(&client->dev, "Unknown part: %04x\n",
+ partnumber);
+ return -EINVAL;
+ }
+ part = i;
+ }
+
+ if (partnumber != abx80x_caps[part].pn) {
+ dev_err(&client->dev, "partnumber mismatch %04x != %04x\n",
+ partnumber, abx80x_caps[part].pn);
+ return -EINVAL;
+ }
+
+ if (np && abx80x_caps[part].has_tc)
+ trickle_cfg = abx80x_dt_trickle_cfg(np);
+
+ if (trickle_cfg > 0) {
+ dev_info(&client->dev, "Enabling trickle charger: %02x\n",
+ trickle_cfg);
+ abx80x_enable_trickle_charger(client, trickle_cfg);
+ }
+
+ rtc = devm_rtc_device_register(&client->dev, abx80x_driver.driver.name,
+ &abx80x_rtc_ops, THIS_MODULE);
+
+ if (IS_ERR(rtc))
+ return PTR_ERR(rtc);
+
+ i2c_set_clientdata(client, rtc);
+
+ return 0;
+}
+
+static int abx80x_remove(struct i2c_client *client)
+{
+ return 0;
+}
+
+static const struct i2c_device_id abx80x_id[] = {
+ { "abx80x", ABX80X },
+ { "ab0801", AB0801 },
+ { "ab0803", AB0803 },
+ { "ab0804", AB0804 },
+ { "ab0805", AB0805 },
+ { "ab1801", AB1801 },
+ { "ab1803", AB1803 },
+ { "ab1804", AB1804 },
+ { "ab1805", AB1805 },
+ { }
+};
+MODULE_DEVICE_TABLE(i2c, abx80x_id);
+
+static struct i2c_driver abx80x_driver = {
+ .driver = {
+ .name = "rtc-abx80x",
+ },
+ .probe = abx80x_probe,
+ .remove = abx80x_remove,
+ .id_table = abx80x_id,
+};
+
+module_i2c_driver(abx80x_driver);
+
+MODULE_AUTHOR("Philippe De Muyter <phdm@macqel.be>");
+MODULE_AUTHOR("Alexandre Belloni <alexandre.belloni@free-electrons.com>");
+MODULE_DESCRIPTION("Abracon ABX80X RTC driver");
+MODULE_LICENSE("GPL v2");
--
2.1.0


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