rtc: cpcap: new rtc driver

This driver supports the Motorola CPCAP PMIC found on
some of Motorola's mobile phones, such as the Droid 4.

Tested-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Sebastian Reichel <sre@kernel.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

4 files changed, 358 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/rtc/cpcap-rtc.txt b/Documentation/devicetree/bindings/rtc/cpcap-rtc.txt
new file mode 100644
index 000000000000..45750ff3112d
--- /dev/null
+++ b/Documentation/devicetree/bindings/rtc/cpcap-rtc.txt
@@ -0,0 +1,18 @@
+Motorola CPCAP PMIC RTC
+-----------------------
+
+This module is part of the CPCAP. For more details about the whole
+chip see Documentation/devicetree/bindings/mfd/motorola-cpcap.txt.
+
+Requires node properties:
+- compatible: should contain "motorola,cpcap-rtc"
+- interrupts: An interrupt specifier for alarm and 1 Hz irq
+
+Example:
+
+&cpcap {
+        cpcap_rtc: rtc {
+                compatible = "motorola,cpcap-rtc";
+                interrupts = <39 IRQ_TYPE_NONE>, <26 IRQ_TYPE_NONE>;
+        };
+};
diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index ee1b0e9dde79..050bec749fae 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -1731,6 +1731,13 @@ config RTC_DRV_STM32
            This driver can also be built as a module, if so, the module
            will be called "rtc-stm32".
 
+config RTC_DRV_CPCAP
+        depends on MFD_CPCAP
+        tristate "Motorola CPCAP RTC"
+        help
+           Say y here for CPCAP rtc found on some Motorola phones
+           and tablets such as Droid 4.
+
 comment "HID Sensor RTC drivers"
 
 config RTC_DRV_HID_SENSOR_TIME
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index f07297b1460a..13857d2fce09 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -40,6 +40,7 @@ obj-$(CONFIG_RTC_DRV_BQ32K)	+= rtc-bq32k.o
 obj-$(CONFIG_RTC_DRV_BQ4802)    += rtc-bq4802.o
 obj-$(CONFIG_RTC_DRV_CMOS)      += rtc-cmos.o
 obj-$(CONFIG_RTC_DRV_COH901331) += rtc-coh901331.o
+obj-$(CONFIG_RTC_DRV_CPCAP)     += rtc-cpcap.o
 obj-$(CONFIG_RTC_DRV_DA9052)    += rtc-da9052.o
 obj-$(CONFIG_RTC_DRV_DA9055)    += rtc-da9055.o
 obj-$(CONFIG_RTC_DRV_DA9063)    += rtc-da9063.o
diff --git a/drivers/rtc/rtc-cpcap.c b/drivers/rtc/rtc-cpcap.c
new file mode 100644
index 000000000000..7c6a3c3167bd
--- /dev/null
+++ b/drivers/rtc/rtc-cpcap.c
@@ -0,0 +1,332 @@
+/*
+ * Motorola CPCAP PMIC RTC driver
+ *
+ * Based on cpcap-regulator.c from Motorola Linux kernel tree
+ * Copyright (C) 2009 Motorola, Inc.
+ *
+ * Rewritten for mainline kernel
+ *  - use DT
+ *  - use regmap
+ *  - use standard interrupt framework
+ *  - use managed device resources
+ *  - remove custom "secure clock daemon" helpers
+ *
+ * Copyright (C) 2017 Sebastian Reichel <sre@kernel.org>
+ *
+ * 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.
+ *
+ * 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/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/device.h>
+#include <linux/platform_device.h>
+#include <linux/rtc.h>
+#include <linux/err.h>
+#include <linux/regmap.h>
+#include <linux/mfd/motorola-cpcap.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+
+#define SECS_PER_DAY 86400
+#define DAY_MASK  0x7FFF
+#define TOD1_MASK 0x00FF
+#define TOD2_MASK 0x01FF
+
+struct cpcap_time {
+        int day;
+        int tod1;
+        int tod2;
+};
+
+struct cpcap_rtc {
+        struct regmap *regmap;
+        struct rtc_device *rtc_dev;
+        u16 vendor;
+        int alarm_irq;
+        bool alarm_enabled;
+        int update_irq;
+        bool update_enabled;
+};
+
+static void cpcap2rtc_time(struct rtc_time *rtc, struct cpcap_time *cpcap)
+{
+        unsigned long int tod;
+        unsigned long int time;
+
+        tod = (cpcap->tod1 & TOD1_MASK) | ((cpcap->tod2 & TOD2_MASK) << 8);
+        time = tod + ((cpcap->day & DAY_MASK) * SECS_PER_DAY);
+
+        rtc_time_to_tm(time, rtc);
+}
+
+static void rtc2cpcap_time(struct cpcap_time *cpcap, struct rtc_time *rtc)
+{
+        unsigned long time;
+
+        rtc_tm_to_time(rtc, &time);
+
+        cpcap->day = time / SECS_PER_DAY;
+        time %= SECS_PER_DAY;
+        cpcap->tod2 = (time >> 8) & TOD2_MASK;
+        cpcap->tod1 = time & TOD1_MASK;
+}
+
+static int cpcap_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
+{
+        struct cpcap_rtc *rtc = dev_get_drvdata(dev);
+
+        if (rtc->alarm_enabled == enabled)
+                return 0;
+
+        if (enabled)
+                enable_irq(rtc->alarm_irq);
+        else
+                disable_irq(rtc->alarm_irq);
+
+        rtc->alarm_enabled = !!enabled;
+
+        return 0;
+}
+
+static int cpcap_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+        struct cpcap_rtc *rtc;
+        struct cpcap_time cpcap_tm;
+        int temp_tod2;
+        int ret;
+
+        rtc = dev_get_drvdata(dev);
+
+        ret = regmap_read(rtc->regmap, CPCAP_REG_TOD2, &temp_tod2);
+        ret |= regmap_read(rtc->regmap, CPCAP_REG_DAY, &cpcap_tm.day);
+        ret |= regmap_read(rtc->regmap, CPCAP_REG_TOD1, &cpcap_tm.tod1);
+        ret |= regmap_read(rtc->regmap, CPCAP_REG_TOD2, &cpcap_tm.tod2);
+
+        if (temp_tod2 > cpcap_tm.tod2)
+                ret |= regmap_read(rtc->regmap, CPCAP_REG_DAY, &cpcap_tm.day);
+
+        if (ret) {
+                dev_err(dev, "Failed to read time\n");
+                return -EIO;
+        }
+
+        cpcap2rtc_time(tm, &cpcap_tm);
+
+        return rtc_valid_tm(tm);
+}
+
+static int cpcap_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+        struct cpcap_rtc *rtc;
+        struct cpcap_time cpcap_tm;
+        int ret = 0;
+
+        rtc = dev_get_drvdata(dev);
+
+        rtc2cpcap_time(&cpcap_tm, tm);
+
+        if (rtc->alarm_enabled)
+                disable_irq(rtc->alarm_irq);
+        if (rtc->update_enabled)
+                disable_irq(rtc->update_irq);
+
+        if (rtc->vendor == CPCAP_VENDOR_ST) {
+                /* The TOD1 and TOD2 registers MUST be written in this order
+                 * for the change to properly set.
+                 */
+                ret |= regmap_update_bits(rtc->regmap, CPCAP_REG_TOD1,
+                                          TOD1_MASK, cpcap_tm.tod1);
+                ret |= regmap_update_bits(rtc->regmap, CPCAP_REG_TOD2,
+                                          TOD2_MASK, cpcap_tm.tod2);
+                ret |= regmap_update_bits(rtc->regmap, CPCAP_REG_DAY,
+                                          DAY_MASK, cpcap_tm.day);
+        } else {
+                /* Clearing the upper lower 8 bits of the TOD guarantees that
+                 * the upper half of TOD (TOD2) will not increment for 0xFF RTC
+                 * ticks (255 seconds).  During this time we can safely write
+                 * to DAY, TOD2, then TOD1 (in that order) and expect RTC to be
+                 * synchronized to the exact time requested upon the final write
+                 * to TOD1.
+                 */
+                ret |= regmap_update_bits(rtc->regmap, CPCAP_REG_TOD1,
+                                          TOD1_MASK, 0);
+                ret |= regmap_update_bits(rtc->regmap, CPCAP_REG_DAY,
+                                          DAY_MASK, cpcap_tm.day);
+                ret |= regmap_update_bits(rtc->regmap, CPCAP_REG_TOD2,
+                                          TOD2_MASK, cpcap_tm.tod2);
+                ret |= regmap_update_bits(rtc->regmap, CPCAP_REG_TOD1,
+                                          TOD1_MASK, cpcap_tm.tod1);
+        }
+
+        if (rtc->update_enabled)
+                enable_irq(rtc->update_irq);
+        if (rtc->alarm_enabled)
+                enable_irq(rtc->alarm_irq);
+
+        return ret;
+}
+
+static int cpcap_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+        struct cpcap_rtc *rtc;
+        struct cpcap_time cpcap_tm;
+        int ret;
+
+        rtc = dev_get_drvdata(dev);
+
+        alrm->enabled = rtc->alarm_enabled;
+
+        ret = regmap_read(rtc->regmap, CPCAP_REG_DAYA, &cpcap_tm.day);
+        ret |= regmap_read(rtc->regmap, CPCAP_REG_TODA2, &cpcap_tm.tod2);
+        ret |= regmap_read(rtc->regmap, CPCAP_REG_TODA1, &cpcap_tm.tod1);
+
+        if (ret) {
+                dev_err(dev, "Failed to read time\n");
+                return -EIO;
+        }
+
+        cpcap2rtc_time(&alrm->time, &cpcap_tm);
+        return rtc_valid_tm(&alrm->time);
+}
+
+static int cpcap_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+        struct cpcap_rtc *rtc;
+        struct cpcap_time cpcap_tm;
+        int ret;
+
+        rtc = dev_get_drvdata(dev);
+
+        rtc2cpcap_time(&cpcap_tm, &alrm->time);
+
+        if (rtc->alarm_enabled)
+                disable_irq(rtc->alarm_irq);
+
+        ret = regmap_update_bits(rtc->regmap, CPCAP_REG_DAYA, DAY_MASK,
+                                 cpcap_tm.day);
+        ret |= regmap_update_bits(rtc->regmap, CPCAP_REG_TODA2, TOD2_MASK,
+                                  cpcap_tm.tod2);
+        ret |= regmap_update_bits(rtc->regmap, CPCAP_REG_TODA1, TOD1_MASK,
+                                  cpcap_tm.tod1);
+
+        if (!ret) {
+                enable_irq(rtc->alarm_irq);
+                rtc->alarm_enabled = true;
+        }
+
+        return ret;
+}
+
+static const struct rtc_class_ops cpcap_rtc_ops = {
+        .read_time              = cpcap_rtc_read_time,
+        .set_time               = cpcap_rtc_set_time,
+        .read_alarm             = cpcap_rtc_read_alarm,
+        .set_alarm              = cpcap_rtc_set_alarm,
+        .alarm_irq_enable       = cpcap_rtc_alarm_irq_enable,
+};
+
+static irqreturn_t cpcap_rtc_alarm_irq(int irq, void *data)
+{
+        struct cpcap_rtc *rtc = data;
+
+        rtc_update_irq(rtc->rtc_dev, 1, RTC_AF | RTC_IRQF);
+        return IRQ_HANDLED;
+}
+
+static irqreturn_t cpcap_rtc_update_irq(int irq, void *data)
+{
+        struct cpcap_rtc *rtc = data;
+
+        rtc_update_irq(rtc->rtc_dev, 1, RTC_UF | RTC_IRQF);
+        return IRQ_HANDLED;
+}
+
+static int cpcap_rtc_probe(struct platform_device *pdev)
+{
+        struct device *dev = &pdev->dev;
+        struct cpcap_rtc *rtc;
+        int err;
+
+        rtc = devm_kzalloc(dev, sizeof(*rtc), GFP_KERNEL);
+        if (!rtc)
+                return -ENOMEM;
+
+        rtc->regmap = dev_get_regmap(dev->parent, NULL);
+        if (!rtc->regmap)
+                return -ENODEV;
+
+        platform_set_drvdata(pdev, rtc);
+        rtc->rtc_dev = devm_rtc_device_register(dev, "cpcap_rtc",
+                                                &cpcap_rtc_ops, THIS_MODULE);
+
+        if (IS_ERR(rtc->rtc_dev)) {
+                kfree(rtc);
+                return PTR_ERR(rtc->rtc_dev);
+        }
+
+        err = cpcap_get_vendor(dev, rtc->regmap, &rtc->vendor);
+        if (err)
+                return err;
+
+        rtc->alarm_irq = platform_get_irq(pdev, 0);
+        err = devm_request_threaded_irq(dev, rtc->alarm_irq, NULL,
+                                        cpcap_rtc_alarm_irq, IRQ_NONE,
+                                        "rtc_alarm", rtc);
+        if (err) {
+                dev_err(dev, "Could not request alarm irq: %d\n", err);
+                return err;
+        }
+        disable_irq(rtc->alarm_irq);
+
+        /* Stock Android uses the 1 Hz interrupt for "secure clock daemon",
+         * which is not supported by the mainline kernel. The mainline kernel
+         * does not use the irq at the moment, but we explicitly request and
+         * disable it, so that its masked and does not wake up the processor
+         * every second.
+         */
+        rtc->update_irq = platform_get_irq(pdev, 1);
+        err = devm_request_threaded_irq(dev, rtc->update_irq, NULL,
+                                        cpcap_rtc_update_irq, IRQ_NONE,
+                                        "rtc_1hz", rtc);
+        if (err) {
+                dev_err(dev, "Could not request update irq: %d\n", err);
+                return err;
+        }
+        disable_irq(rtc->update_irq);
+
+        err = device_init_wakeup(dev, 1);
+        if (err) {
+                dev_err(dev, "wakeup initialization failed (%d)\n", err);
+                /* ignore error and continue without wakeup support */
+        }
+
+        return 0;
+}
+
+static const struct of_device_id cpcap_rtc_of_match[] = {
+        { .compatible = "motorola,cpcap-rtc", },
+        {},
+};
+MODULE_DEVICE_TABLE(of, cpcap_rtc_of_match);
+
+static struct platform_driver cpcap_rtc_driver = {
+        .probe          = cpcap_rtc_probe,
+        .driver         = {
+                .name   = "cpcap-rtc",
+                .of_match_table = cpcap_rtc_of_match,
+        },
+};
+
+module_platform_driver(cpcap_rtc_driver);
+
+MODULE_ALIAS("platform:cpcap-rtc");
+MODULE_DESCRIPTION("CPCAP RTC driver");
+MODULE_AUTHOR("Sebastian Reichel <sre@kernel.org>");
+MODULE_LICENSE("GPL");