[PATCHv7] rtc: Add support for Intersil ISL12057 I2C RTC chip

Arnaud Ebalard
2013-12-19T21:53:16Z

Intersil ISL12057 is an I2C RTC chip also supporting two alarms. This
patch only adds support for basic RTC functionalities (i.e. getting
and setting time). Tests have been performed on NETGEAR ReadyNAS 102
w/ startup/shutdown scripts, hwclock, ntpdate and openntpd.

Reviewed-by: Mark Brown <broonie@linaro.org>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Arnaud Ebalard <arno@natisbad.org>
---
Hi Jason,

In order to get at least some initial support for the chip available in
mainline kernel (v3.14 will have three users waiting for it: ReadyNAS
102, 104 and 2120), I decided to temporarily remove the alarm and IRQ
related code I pushed earlier (see [1] below).

I will submit a patch later to add back Alarm/IRQ support once I get
some feedback from RTC community on how to correctly handle the
specificities of the hardware (Alarm1 interrupt line connected to a power
component and not to the SoC).

Mark, Guenter, I modified this v7 to remove .proc handler but kept you
Reviewed-by. More sepcifically, Mark, I kept the protection around
regmap_* functions for the reason I gave in previous email. Do not
hesitate to tell if you disagree.

Comments welcome!

Cheers,

a+

[1]: http://thread.gmane.org/gmane.linux.drivers.devicetree/46581

Changes since previous v6 (comment from Alessandro Zummo)
- removed .proc handler

Changes since previous v5 (comments from Mark Brown):
- Added Reviewed-By from Mark

Changes since previous v4 (comments from Guenter Roeck):
- M-x tabified the whole driver and manually handled tab before
comments (after defines). In the long run, I will try and find
a way to make emacs wiser on that last point.
- Removed checkpatch false positive by cleaning header
- remove useless forward declaration of isl12057_driver
- added missing comment about lack of mutex protection
- typo (s/enable/unable/)
- removed forgotten data->rtc and associated field in 'data'

NOTE: I kept definitions of bits (Alarms, etc) to avoid sparse
info in the file. Additionally, those will be reused soon.

Changes since previous v3 (comments from Guenter Roeck):
- use BIT() instead of (1<<X)
- use dev_set_drvdata()/dev_get_drvdata() to simplify access to 'data'
- removed two (now) useless fields in private 'data' structure
- now use dev instead of &client->dev

Changes since previous v2 (Comments from Mark Brown):
- converted to regmap

Changes since previous v1 (Comments from Mark Rutland):
- fixed return values for isl12057_i2c_{read,set}_regs()
- checked associated return paths

Changes since previous v0:
- removed alarm and IRQ related code
- Switched to isl for intersil (no existing driver has any reference
to isil, even though this would be the recommended choice)
- Added intersil info in vendor-prefixes.txt file
- Added entry for ISL 12057 in I2C trivial-devices.txt file
- Added mutex protection for non atomic read/write

.../devicetree/bindings/i2c/trivial-devices.txt | 1 +
.../devicetree/bindings/vendor-prefixes.txt | 1 +
drivers/rtc/Kconfig | 11 +
drivers/rtc/Makefile | 1 +
drivers/rtc/rtc-isl12057.c | 310 +++++++++++++++++++++
5 files changed, 324 insertions(+)
create mode 100644 drivers/rtc/rtc-isl12057.c

diff --git a/Documentation/devicetree/bindings/i2c/trivial-devices.txt b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
index b1cb341..cdf1430 100644
--- a/Documentation/devicetree/bindings/i2c/trivial-devices.txt
+++ b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
@@ -39,6 +39,7 @@ fsl,sgtl5000 SGTL5000: Ultra Low-Power Audio Codec
gmt,g751 G751: Digital Temperature Sensor and Thermal Watchdog with Two-Wire Interface
infineon,slb9635tt Infineon SLB9635 (Soft-) I2C TPM (old protocol, max 100khz)
infineon,slb9645tt Infineon SLB9645 I2C TPM (new protocol, max 400khz)
+isl,isl12057 Intersil ISL12057 I2C RTC Chip
maxim,ds1050 5 Bit Programmable, Pulse-Width Modulator
maxim,max1237 Low-Power, 4-/12-Channel, 2-Wire Serial, 12-Bit ADCs
maxim,max6625 9-Bit/12-Bit Temperature Sensors with I?C-Compatible Serial Interface
diff --git a/Documentation/devicetree/bindings/vendor-prefixes.txt b/Documentation/devicetree/bindings/vendor-prefixes.txt
index edbb8d8..ed0f63f 100644
--- a/Documentation/devicetree/bindings/vendor-prefixes.txt
+++ b/Documentation/devicetree/bindings/vendor-prefixes.txt
@@ -39,6 +39,7 @@ ibm International Business Machines (IBM)
idt Integrated Device Technologies, Inc.
img Imagination Technologies Ltd.
intercontrol Inter Control Group
+isl Intersil
lg LG Corporation
linux Linux-specific binding
lsi LSI Corp. (LSI Logic)
diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 0077302..9608210 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -304,6 +304,17 @@ config RTC_DRV_ISL12022
This driver can also be built as a module. If so, the module
will be called rtc-isl12022.

+config RTC_DRV_ISL12057
+ depends on I2C
+ select REGMAP_I2C
+ tristate "Intersil ISL12057"
+ help
+ If you say yes here you get support for the Intersil ISL12057
+ I2C RTC chip.
+
+ This driver can also be built as a module. If so, the module
+ will be called rtc-isl12057.
+
config RTC_DRV_X1205
tristate "Xicor/Intersil X1205"
help
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 27b4bd8..d4089c0 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -58,6 +58,7 @@ obj-$(CONFIG_RTC_DRV_HID_SENSOR_TIME) += rtc-hid-sensor-time.o
obj-$(CONFIG_RTC_DRV_IMXDI) += rtc-imxdi.o
obj-$(CONFIG_RTC_DRV_ISL1208) += rtc-isl1208.o
obj-$(CONFIG_RTC_DRV_ISL12022) += rtc-isl12022.o
+obj-$(CONFIG_RTC_DRV_ISL12057) += rtc-isl12057.o
obj-$(CONFIG_RTC_DRV_JZ4740) += rtc-jz4740.o
obj-$(CONFIG_RTC_DRV_LP8788) += rtc-lp8788.o
obj-$(CONFIG_RTC_DRV_LPC32XX) += rtc-lpc32xx.o
diff --git a/drivers/rtc/rtc-isl12057.c b/drivers/rtc/rtc-isl12057.c
new file mode 100644
index 0000000..ef32f08
--- /dev/null
+++ b/drivers/rtc/rtc-isl12057.c
@@ -0,0 +1,310 @@
+/*
+ * rtc-isl12057 - Driver for Intersil ISL12057 I2C Real Time Clock
+ *
+ * Copyright (C) 2013, Arnaud EBALARD <arno@natisbad.org>
+ *
+ * This work is largely based on Intersil ISL1208 driver developed by
+ * Hebert Valerio Riedel <hvr@gnu.org>.
+ *
+ * Detailed datasheet on which this development is based is available here:
+ *
+ * http://natisbad.org/NAS2/refs/ISL12057.pdf
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/rtc.h>
+#include <linux/i2c.h>
+#include <linux/bcd.h>
+#include <linux/rtc.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/regmap.h>
+
+#define DRV_NAME "rtc-isl12057"
+
+/* RTC section */
+#define ISL12057_REG_RTC_SC 0x00 /* Seconds */
+#define ISL12057_REG_RTC_MN 0x01 /* Minutes */
+#define ISL12057_REG_RTC_HR 0x02 /* Hours */
+#define ISL12057_REG_RTC_HR_PM BIT(5) /* AM/PM bit in 12h format */
+#define ISL12057_REG_RTC_HR_MIL BIT(6) /* 24h/12h format */
+#define ISL12057_REG_RTC_DW 0x03 /* Day of the Week */
+#define ISL12057_REG_RTC_DT 0x04 /* Date */
+#define ISL12057_REG_RTC_MO 0x05 /* Month */
+#define ISL12057_REG_RTC_YR 0x06 /* Year */
+#define ISL12057_RTC_SEC_LEN 7
+
+/* Alarm 1 section */
+#define ISL12057_REG_A1_SC 0x07 /* Alarm 1 Seconds */
+#define ISL12057_REG_A1_MN 0x08 /* Alarm 1 Minutes */
+#define ISL12057_REG_A1_HR 0x09 /* Alarm 1 Hours */
+#define ISL12057_REG_A1_HR_PM BIT(5) /* AM/PM bit in 12h format */
+#define ISL12057_REG_A1_HR_MIL BIT(6) /* 24h/12h format */
+#define ISL12057_REG_A1_DWDT 0x0A /* Alarm 1 Date / Day of the week */
+#define ISL12057_REG_A1_DWDT_B BIT(6) /* DW / DT selection bit */
+#define ISL12057_A1_SEC_LEN 4
+
+/* Alarm 2 section */
+#define ISL12057_REG_A2_MN 0x0B /* Alarm 2 Minutes */
+#define ISL12057_REG_A2_HR 0x0C /* Alarm 2 Hours */
+#define ISL12057_REG_A2_DWDT 0x0D /* Alarm 2 Date / Day of the week */
+#define ISL12057_A2_SEC_LEN 3
+
+/* Control/Status registers */
+#define ISL12057_REG_INT 0x0E
+#define ISL12057_REG_INT_A1IE BIT(0) /* Alarm 1 interrupt enable bit */
+#define ISL12057_REG_INT_A2IE BIT(1) /* Alarm 2 interrupt enable bit */
+#define ISL12057_REG_INT_INTCN BIT(2) /* Interrupt control enable bit */
+#define ISL12057_REG_INT_RS1 BIT(3) /* Freq out control bit 1 */
+#define ISL12057_REG_INT_RS2 BIT(4) /* Freq out control bit 2 */
+#define ISL12057_REG_INT_EOSC BIT(7) /* Oscillator enable bit */
+
+#define ISL12057_REG_SR 0x0F
+#define ISL12057_REG_SR_A1F BIT(0) /* Alarm 1 interrupt bit */
+#define ISL12057_REG_SR_A2F BIT(1) /* Alarm 2 interrupt bit */
+#define ISL12057_REG_SR_OSF BIT(7) /* Oscillator failure bit */
+
+/* Register memory map length */
+#define ISL12057_MEM_MAP_LEN 0x10
+
+struct isl12057_rtc_data {
+ struct regmap *regmap;
+ struct mutex lock;
+};
+
+static void isl12057_rtc_regs_to_tm(struct rtc_time *tm, u8 *regs)
+{
+ tm->tm_sec = bcd2bin(regs[ISL12057_REG_RTC_SC]);
+ tm->tm_min = bcd2bin(regs[ISL12057_REG_RTC_MN]);
+
+ if (regs[ISL12057_REG_RTC_HR] & ISL12057_REG_RTC_HR_MIL) { /* AM/PM */
+ tm->tm_hour = bcd2bin(regs[ISL12057_REG_RTC_HR] & 0x0f);
+ if (regs[ISL12057_REG_RTC_HR] & ISL12057_REG_RTC_HR_PM)
+ tm->tm_hour += 12;
+ } else { /* 24 hour mode */
+ tm->tm_hour = bcd2bin(regs[ISL12057_REG_RTC_HR] & 0x3f);
+ }
+
+ tm->tm_mday = bcd2bin(regs[ISL12057_REG_RTC_DT]);
+ tm->tm_wday = bcd2bin(regs[ISL12057_REG_RTC_DW]) - 1; /* starts at 1 */
+ tm->tm_mon = bcd2bin(regs[ISL12057_REG_RTC_MO]) - 1; /* starts at 1 */
+ tm->tm_year = bcd2bin(regs[ISL12057_REG_RTC_YR]) + 100;
+}
+
+static int isl12057_rtc_tm_to_regs(u8 *regs, struct rtc_time *tm)
+{
+ /*
+ * The clock has an 8 bit wide bcd-coded register for the year.
+ * tm_year is an offset from 1900 and we are interested in the
+ * 2000-2099 range, so any value less than 100 is invalid.
+ */
+ if (tm->tm_year < 100)
+ return -EINVAL;
+
+ regs[ISL12057_REG_RTC_SC] = bin2bcd(tm->tm_sec);
+ regs[ISL12057_REG_RTC_MN] = bin2bcd(tm->tm_min);
+ regs[ISL12057_REG_RTC_HR] = bin2bcd(tm->tm_hour); /* 24-hour format */
+ regs[ISL12057_REG_RTC_DT] = bin2bcd(tm->tm_mday);
+ regs[ISL12057_REG_RTC_MO] = bin2bcd(tm->tm_mon + 1);
+ regs[ISL12057_REG_RTC_YR] = bin2bcd(tm->tm_year - 100);
+ regs[ISL12057_REG_RTC_DW] = bin2bcd(tm->tm_wday + 1);
+
+ return 0;
+}
+
+/*
+ * Try and match register bits w/ fixed null values to see whether we
+ * are dealing with an ISL12057. Note: this function is called early
+ * during init and hence does need mutex protection.
+ */
+static int isl12057_i2c_validate_chip(struct regmap *regmap)
+{
+ u8 regs[ISL12057_MEM_MAP_LEN];
+ u8 mask[ISL12057_MEM_MAP_LEN] = { 0x80, 0x80, 0x80, 0xf8,
+ 0xc0, 0x60, 0x00, 0x00,
+ 0x00, 0x00, 0x00, 0x00,
+ 0x00, 0x00, 0x60, 0x7c };
+ int ret, i;
+
+ ret = regmap_bulk_read(regmap, 0, regs, ISL12057_MEM_MAP_LEN);
+ if (ret)
+ return ret;
+
+ for (i = 0; i < ISL12057_MEM_MAP_LEN; ++i) {
+ if (regs[i] & mask[i]) /* check if bits are cleared */
+ return -ENODEV;
+ }
+
+ return 0;
+}
+
+static int isl12057_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+ struct isl12057_rtc_data *data = dev_get_drvdata(dev);
+ u8 regs[ISL12057_RTC_SEC_LEN];
+ int ret;
+
+ mutex_lock(&data->lock);
+ ret = regmap_bulk_read(data->regmap, ISL12057_REG_RTC_SC, regs,
+ ISL12057_RTC_SEC_LEN);
+ mutex_unlock(&data->lock);
+
+ if (ret) {
+ dev_err(dev, "%s: RTC read failed\n", __func__);
+ return ret;
+ }
+
+ isl12057_rtc_regs_to_tm(tm, regs);
+
+ return rtc_valid_tm(tm);
+}
+
+static int isl12057_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+ struct isl12057_rtc_data *data = dev_get_drvdata(dev);
+ u8 regs[ISL12057_RTC_SEC_LEN];
+ int ret;
+
+ ret = isl12057_rtc_tm_to_regs(regs, tm);
+ if (ret)
+ return ret;
+
+ mutex_lock(&data->lock);
+ ret = regmap_bulk_write(data->regmap, ISL12057_REG_RTC_SC, regs,
+ ISL12057_RTC_SEC_LEN);
+ mutex_unlock(&data->lock);
+
+ if (ret)
+ dev_err(dev, "%s: RTC write failed\n", __func__);
+
+ return ret;
+}
+
+/*
+ * Check current RTC status and enable/disable what needs to be. Return 0 if
+ * everything went ok and a negative value upon error. Note: this function
+ * is called early during init and hence does need mutex protection.
+ */
+static int isl12057_check_rtc_status(struct device *dev, struct regmap *regmap)
+{
+ int ret;
+
+ /* Enable oscillator if not already running */
+ ret = regmap_update_bits(regmap, ISL12057_REG_INT,
+ ISL12057_REG_INT_EOSC, 0);
+ if (ret < 0) {
+ dev_err(dev, "Unable to enable oscillator\n");
+ return ret;
+ }
+
+ /* Clear oscillator failure bit if needed */
+ ret = regmap_update_bits(regmap, ISL12057_REG_SR,
+ ISL12057_REG_SR_OSF, 0);
+ if (ret < 0) {
+ dev_err(dev, "Unable to clear oscillator failure bit\n");
+ return ret;
+ }
+
+ /* Clear alarm bit if needed */
+ ret = regmap_update_bits(regmap, ISL12057_REG_SR,
+ ISL12057_REG_SR_A1F, 0);
+ if (ret < 0) {
+ dev_err(dev, "Unable to clear alarm bit\n");
+ return ret;
+ }
+
+ return 0;
+}
+
+static const struct rtc_class_ops rtc_ops = {
+ .read_time = isl12057_rtc_read_time,
+ .set_time = isl12057_rtc_set_time,
+};
+
+static struct regmap_config isl12057_rtc_regmap_config = {
+ .reg_bits = 8,
+ .val_bits = 8,
+};
+
+static int isl12057_probe(struct i2c_client *client,
+ const struct i2c_device_id *id)
+{
+ struct device *dev = &client->dev;
+ struct isl12057_rtc_data *data;
+ struct rtc_device *rtc;
+ struct regmap *regmap;
+ int ret;
+
+ if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
+ I2C_FUNC_SMBUS_BYTE_DATA |
+ I2C_FUNC_SMBUS_I2C_BLOCK))
+ return -ENODEV;
+
+ regmap = devm_regmap_init_i2c(client, &isl12057_rtc_regmap_config);
+ if (IS_ERR(regmap)) {
+ ret = PTR_ERR(regmap);
+ dev_err(dev, "regmap allocation failed: %d\n", ret);
+ return ret;
+ }
+
+ ret = isl12057_i2c_validate_chip(regmap);
+ if (ret)
+ return ret;
+
+ ret = isl12057_check_rtc_status(dev, regmap);
+ if (ret)
+ return ret;
+
+ data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+
+ mutex_init(&data->lock);
+ data->regmap = regmap;
+ dev_set_drvdata(dev, data);
+
+ rtc = devm_rtc_device_register(dev, DRV_NAME, &rtc_ops, THIS_MODULE);
+ if (IS_ERR(rtc))
+ return PTR_ERR(rtc);
+
+ return 0;
+}
+
+#ifdef CONFIG_OF
+static struct of_device_id isl12057_dt_match[] = {
+ { .compatible = "isl,isl12057" },
+ { },
+};
+#endif
+
+static const struct i2c_device_id isl12057_id[] = {
+ { "isl12057", 0 },
+ { }
+};
+MODULE_DEVICE_TABLE(i2c, isl12057_id);
+
+static struct i2c_driver isl12057_driver = {
+ .driver = {
+ .name = DRV_NAME,
+ .owner = THIS_MODULE,
+ .of_match_table = of_match_ptr(isl12057_dt_match),
+ },
+ .probe = isl12057_probe,
+ .id_table = isl12057_id,
+};
+module_i2c_driver(isl12057_driver);
+
+MODULE_AUTHOR("Arnaud EBALARD <arno@natisbad.org>");
+MODULE_DESCRIPTION("Intersil ISL12057 RTC driver");
+MODULE_LICENSE("GPL");
--
1.8.4.4