[PATCH] AB3100 RTC support v4

Linus Walleij
2009-08-30T21:49:16Z

This adds support for the RTC found inside the AB3100 Mixed Signal chip.
The symbols used for communicating with the chip is found in the
mfd/ab3100-core.c driver that also provides the platform device.

Signed-off-by: Linus Walleij <linus.walleij@stericsson.com>
Acked-by: Alessandro Zummo <alessandro.zummo@towertech.it>
Cc: Samuel Ortiz <sameo@linux.intel.com>
---
Changelog v3->v4
- Remove error message that will be given by the RTC core anyway.
- Suggest to push this through Sam's MFD tree if it's OK with Sam.
Changelog v2->v3
- Oneliner bug found by colleague during integration test.
Changelog v1->v2
- Renamed accessor functions to match the symbols queued in Samuel
Ortiz' MFD for-next tree.
- Check return errors from accessor functions where missing.
- Use rtc_valid_tm() when returning alarm time.
- Remove needless initialization message.
- No saving of clock from kernelspace in .remove or .shutdown.
Use hwclock from userspace shutdown scripts instead.
---
drivers/rtc/Kconfig | 9 ++
drivers/rtc/Makefile | 1 +
drivers/rtc/rtc-ab3100.c | 281 ++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 291 insertions(+), 0 deletions(-)
create mode 100644 drivers/rtc/rtc-ab3100.c

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 81adbdb..a36dffd 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -535,6 +535,15 @@ config RTC_DRV_PCF50633
If you say yes here you get support for the RTC subsystem of the
NXP PCF50633 used in embedded systems.

+config RTC_DRV_AB3100
+ tristate "ST-Ericsson AB3100 RTC"
+ depends on AB3100_CORE
+ default y if AB3100_CORE
+ help
+ Select this to enable the ST-Ericsson AB3100 Mixed Signal IC RTC
+ support. This chip contains a battery- and capacitor-backed RTC.
+
+
comment "on-CPU RTC drivers"

config RTC_DRV_OMAP
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 3c0f2b2..fe85afb 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -17,6 +17,7 @@ rtc-core-$(CONFIG_RTC_INTF_SYSFS) += rtc-sysfs.o

# Keep the list ordered.

+obj-$(CONFIG_RTC_DRV_AB3100) += rtc-ab3100.o
obj-$(CONFIG_RTC_DRV_AT32AP700X)+= rtc-at32ap700x.o
obj-$(CONFIG_RTC_DRV_AT91RM9200)+= rtc-at91rm9200.o
obj-$(CONFIG_RTC_DRV_AT91SAM9) += rtc-at91sam9.o
diff --git a/drivers/rtc/rtc-ab3100.c b/drivers/rtc/rtc-ab3100.c
new file mode 100644
index 0000000..4704aac
--- /dev/null
+++ b/drivers/rtc/rtc-ab3100.c
@@ -0,0 +1,281 @@
+/*
+ * Copyright (C) 2007-2009 ST-Ericsson AB
+ * License terms: GNU General Public License (GPL) version 2
+ * RTC clock driver for the AB3100 Analog Baseband Chip
+ * Author: Linus Walleij <linus.walleij@stericsson.com>
+ */
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/platform_device.h>
+#include <linux/rtc.h>
+#include <linux/mfd/ab3100.h>
+
+/* Clock rate in Hz */
+#define AB3100_RTC_CLOCK_RATE 32768
+
+/*
+ * The AB3100 RTC registers. These are the same for
+ * AB3000 and AB3100.
+ * Control register:
+ * Bit 0: RTC Monitor cleared=0, active=1, if you set it
+ * to 1 it remains active until RTC power is lost.
+ * Bit 1: 32 kHz Oscillator, 0 = on, 1 = bypass
+ * Bit 2: Alarm on, 0 = off, 1 = on
+ * Bit 3: 32 kHz buffer disabling, 0 = enabled, 1 = disabled
+ */
+#define AB3100_RTC 0x53
+/* default setting, buffer disabled, alarm on */
+#define RTC_SETTING 0x30
+/* Alarm when AL0-AL3 == TI0-TI3 */
+#define AB3100_AL0 0x56
+#define AB3100_AL1 0x57
+#define AB3100_AL2 0x58
+#define AB3100_AL3 0x59
+/* This 48-bit register that counts up at 32768 Hz */
+#define AB3100_TI0 0x5a
+#define AB3100_TI1 0x5b
+#define AB3100_TI2 0x5c
+#define AB3100_TI3 0x5d
+#define AB3100_TI4 0x5e
+#define AB3100_TI5 0x5f
+
+/*
+ * RTC clock functions and device struct declaration
+ */
+static int ab3100_rtc_set_mmss(struct device *dev, unsigned long secs)
+{
+ struct ab3100 *ab3100_data = dev_get_drvdata(dev);
+ u8 regs[] = {AB3100_TI0, AB3100_TI1, AB3100_TI2,
+ AB3100_TI3, AB3100_TI4, AB3100_TI5};
+ unsigned char buf[6];
+ u64 fat_time = (u64) secs * AB3100_RTC_CLOCK_RATE * 2;
+ int err = 0;
+ int i;
+
+ buf[0] = (fat_time) & 0xFF;
+ buf[1] = (fat_time >> 8) & 0xFF;
+ buf[2] = (fat_time >> 16) & 0xFF;
+ buf[3] = (fat_time >> 24) & 0xFF;
+ buf[4] = (fat_time >> 32) & 0xFF;
+ buf[5] = (fat_time >> 40) & 0xFF;
+
+ for (i = 0; i < 6; i++) {
+ err = ab3100_set_register_interruptible(ab3100_data,
+ regs[i], buf[i]);
+ if (err)
+ return err;
+ }
+
+ /* Set the flag to mark that the clock is now set */
+ return ab3100_mask_and_set_register_interruptible(ab3100_data,
+ AB3100_RTC,
+ 0xFE, 0x01);
+
+}
+
+static int ab3100_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+ struct ab3100 *ab3100_data = dev_get_drvdata(dev);
+ unsigned long time;
+ u8 rtcval;
+ int err;
+
+ err = ab3100_get_register_interruptible(ab3100_data,
+ AB3100_RTC, &rtcval);
+ if (err)
+ return err;
+
+ if (!(rtcval & 0x01)) {
+ dev_info(dev, "clock not set (lost power)");
+ return -EINVAL;
+ } else {
+ u64 fat_time;
+ u8 buf[6];
+
+ /* Read out time registers */
+ err = ab3100_get_register_page_interruptible(ab3100_data,
+ AB3100_TI0,
+ buf, 6);
+ if (err != 0)
+ return err;
+
+ fat_time = ((u64) buf[5] << 40) | ((u64) buf[4] << 32) |
+ ((u64) buf[3] << 24) | ((u64) buf[2] << 16) |
+ ((u64) buf[1] << 8) | (u64) buf[0];
+ time = (unsigned long) (fat_time /
+ (u64) (AB3100_RTC_CLOCK_RATE * 2));
+ }
+
+ rtc_time_to_tm(time, tm);
+
+ return rtc_valid_tm(tm);
+}
+
+static int ab3100_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
+{
+ struct ab3100 *ab3100_data = dev_get_drvdata(dev);
+ unsigned long time;
+ u64 fat_time;
+ u8 buf[6];
+ u8 rtcval;
+ int err;
+
+ /* Figure out if alarm is enabled or not */
+ err = ab3100_get_register_interruptible(ab3100_data,
+ AB3100_RTC, &rtcval);
+ if (err)
+ return err;
+ if (rtcval & 0x04)
+ alarm->enabled = 1;
+ else
+ alarm->enabled = 0;
+ /* No idea how this could be represented */
+ alarm->pending = 0;
+ /* Read out alarm registers, only 4 bytes */
+ err = ab3100_get_register_page_interruptible(ab3100_data,
+ AB3100_AL0, buf, 4);
+ if (err)
+ return err;
+ fat_time = ((u64) buf[3] << 40) | ((u64) buf[2] << 32) |
+ ((u64) buf[1] << 24) | ((u64) buf[0] << 16);
+ time = (unsigned long) (fat_time / (u64) (AB3100_RTC_CLOCK_RATE * 2));
+
+ rtc_time_to_tm(time, &alarm->time);
+
+ return rtc_valid_tm(&alarm->time);
+}
+
+static int ab3100_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
+{
+ struct ab3100 *ab3100_data = dev_get_drvdata(dev);
+ u8 regs[] = {AB3100_AL0, AB3100_AL1, AB3100_AL2, AB3100_AL3};
+ unsigned char buf[4];
+ unsigned long secs;
+ u64 fat_time;
+ int err;
+ int i;
+
+ rtc_tm_to_time(&alarm->time, &secs);
+ fat_time = (u64) secs * AB3100_RTC_CLOCK_RATE * 2;
+ buf[0] = (fat_time >> 16) & 0xFF;
+ buf[1] = (fat_time >> 24) & 0xFF;
+ buf[2] = (fat_time >> 32) & 0xFF;
+ buf[3] = (fat_time >> 40) & 0xFF;
+
+ /* Set the alarm */
+ for (i = 0; i < 4; i++) {
+ err = ab3100_set_register_interruptible(ab3100_data,
+ regs[i], buf[i]);
+ if (err)
+ return err;
+ }
+ /* Then enable the alarm */
+ return ab3100_mask_and_set_register_interruptible(ab3100_data,
+ AB3100_RTC, ~(1 << 2),
+ alarm->enabled << 2);
+}
+
+static int ab3100_rtc_irq_enable(struct device *dev, unsigned int enabled)
+{
+ struct ab3100 *ab3100_data = dev_get_drvdata(dev);
+
+ /*
+ * It's not possible to enable/disable the alarm IRQ for this RTC.
+ * It does not actually trigger any IRQ: instead its only function is
+ * to power up the system, if it wasn't on. This will manifest as
+ * a "power up cause" in the AB3100 power driver (battery charging etc)
+ * and need to be handled there instead.
+ */
+ if (enabled)
+ return ab3100_mask_and_set_register_interruptible(ab3100_data,
+ AB3100_RTC, ~(1 << 2),
+ 1 << 2);
+ else
+ return ab3100_mask_and_set_register_interruptible(ab3100_data,
+ AB3100_RTC, ~(1 << 2),
+ 0);
+}
+
+static const struct rtc_class_ops ab3100_rtc_ops = {
+ .read_time = ab3100_rtc_read_time,
+ .set_mmss = ab3100_rtc_set_mmss,
+ .read_alarm = ab3100_rtc_read_alarm,
+ .set_alarm = ab3100_rtc_set_alarm,
+ .alarm_irq_enable = ab3100_rtc_irq_enable,
+};
+
+static int __init ab3100_rtc_probe(struct platform_device *pdev)
+{
+ int err;
+ u8 regval;
+ struct rtc_device *rtc;
+ struct ab3100 *ab3100_data = platform_get_drvdata(pdev);
+
+ /* The first RTC register needs special treatment */
+ err = ab3100_get_register_interruptible(ab3100_data,
+ AB3100_RTC, &regval);
+ if (err) {
+ dev_err(&pdev->dev, "unable to read RTC register\n");
+ return -ENODEV;
+ }
+
+ if ((regval & 0xFE) != RTC_SETTING) {
+ dev_warn(&pdev->dev, "not default value in RTC reg 0x%x\n",
+ regval);
+ }
+
+ if ((regval & 1) == 0) {
+ /*
+ * Set bit to detect power loss.
+ * This bit remains until RTC power is lost.
+ */
+ regval = 1 | RTC_SETTING;
+ err = ab3100_set_register_interruptible(ab3100_data,
+ AB3100_RTC, regval);
+ /* Ignore any error on this write */
+ }
+
+ rtc = rtc_device_register("ab3100-rtc", &pdev->dev, &ab3100_rtc_ops,
+ THIS_MODULE);
+ if (IS_ERR(rtc)) {
+ err = PTR_ERR(rtc);
+ return err;
+ }
+
+ return 0;
+}
+
+static int __exit ab3100_rtc_remove(struct platform_device *pdev)
+{
+ struct rtc_device *rtc = platform_get_drvdata(pdev);
+
+ rtc_device_unregister(rtc);
+ return 0;
+}
+
+static struct platform_driver ab3100_rtc_driver = {
+ .driver = {
+ .name = "ab3100-rtc",
+ .owner = THIS_MODULE,
+ },
+ .remove = __exit_p(ab3100_rtc_remove),
+};
+
+static int __init ab3100_rtc_init(void)
+{
+ return platform_driver_probe(&ab3100_rtc_driver,
+ ab3100_rtc_probe);
+}
+
+static void __exit ab3100_rtc_exit(void)
+{
+ platform_driver_unregister(&ab3100_rtc_driver);
+}
+
+module_init(ab3100_rtc_init);
+module_exit(ab3100_rtc_exit);
+
+MODULE_AUTHOR("Linus Walleij <linus.walleij@stericsson.com>");
+MODULE_DESCRIPTION("AB3100 RTC Driver");
+MODULE_LICENSE("GPL");
--
1.6.2.1