[PATCH 4/4] rtc: brcmstb-waketimer: Add Broadcom STB wake-timer

Florian Fainelli
2017-06-26T22:32:47Z

From: Brian Norris <computersforpeace@gmail.com>

This adds support for the Broadcom STB wake-timer which is a timer in
the chip's 27Mhz clock domain that offers the ability to wake the system
(wake-up source) from suspend states (S2, S3, S5). It is supported using
the rtc framework allowing us to configure alarms for system wake-up.

Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Markus Mayer <mmayer@broadcom.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
---
drivers/rtc/Kconfig | 11 ++
drivers/rtc/Makefile | 1 +
drivers/rtc/rtc-brcmstb-waketimer.c | 325 ++++++++++++++++++++++++++++++++++++
3 files changed, 337 insertions(+)
create mode 100644 drivers/rtc/rtc-brcmstb-waketimer.c

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 8d3b95728326..8e1aa67fe533 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -197,6 +197,17 @@ config RTC_DRV_AC100
This driver can also be built as a module. If so, the module
will be called rtc-ac100.

+config RTC_DRV_BRCMSTB
+ tristate "Broadcom STB wake-timer"
+ depends on ARCH_BRCMSTB || BMIPS_GENERIC || COMPILE_TEST
+ default ARCH_BRCMSTB || BMIPS_GENERIC
+ help
+ If you say yes here you get support for the wake-timer found on
+ Broadcom STB SoCs (BCM7xxx).
+
+ This driver can also be built as a module. If so, the module will
+ be called rtc-brcmstb-waketimer.
+
config RTC_DRV_AS3722
tristate "ams AS3722 RTC driver"
depends on MFD_AS3722
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 13857d2fce09..df89cac1f9ae 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -36,6 +36,7 @@ obj-$(CONFIG_RTC_DRV_AT91RM9200)+= rtc-at91rm9200.o
obj-$(CONFIG_RTC_DRV_AT91SAM9) += rtc-at91sam9.o
obj-$(CONFIG_RTC_DRV_AU1XXX) += rtc-au1xxx.o
obj-$(CONFIG_RTC_DRV_BFIN) += rtc-bfin.o
+obj-$(CONFIG_RTC_DRV_BRCMSTB) += rtc-brcmstb-waketimer.o
obj-$(CONFIG_RTC_DRV_BQ32K) += rtc-bq32k.o
obj-$(CONFIG_RTC_DRV_BQ4802) += rtc-bq4802.o
obj-$(CONFIG_RTC_DRV_CMOS) += rtc-cmos.o
diff --git a/drivers/rtc/rtc-brcmstb-waketimer.c b/drivers/rtc/rtc-brcmstb-waketimer.c
new file mode 100644
index 000000000000..5dea6d0627d8
--- /dev/null
+++ b/drivers/rtc/rtc-brcmstb-waketimer.c
@@ -0,0 +1,325 @@
+/*
+ * Copyright ? 2014-2017 Broadcom
+ *
+ * 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.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/clk.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/irqreturn.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pm.h>
+#include <linux/pm_wakeup.h>
+#include <linux/reboot.h>
+#include <linux/rtc.h>
+#include <linux/stat.h>
+#include <linux/suspend.h>
+
+struct brcmstb_waketmr {
+ struct rtc_device *rtc;
+ struct device *dev;
+ void __iomem *base;
+ int irq;
+ struct notifier_block reboot_notifier;
+ struct clk *clk;
+ u32 rate;
+};
+
+#define BRCMSTB_WKTMR_EVENT 0x00
+#define BRCMSTB_WKTMR_COUNTER 0x04
+#define BRCMSTB_WKTMR_ALARM 0x08
+#define BRCMSTB_WKTMR_PRESCALER 0x0C
+#define BRCMSTB_WKTMR_PRESCALER_VAL 0x10
+
+#define BRCMSTB_WKTMR_DEFAULT_FREQ 27000000
+
+static inline void brcmstb_waketmr_clear_alarm(struct brcmstb_waketmr *timer)
+{
+ writel_relaxed(1, timer->base + BRCMSTB_WKTMR_EVENT);
+ (void)readl_relaxed(timer->base + BRCMSTB_WKTMR_EVENT);
+}
+
+static void brcmstb_waketmr_set_alarm(struct brcmstb_waketmr *timer,
+ unsigned int secs)
+{
+ brcmstb_waketmr_clear_alarm(timer);
+
+ writel_relaxed(secs + 1, timer->base + BRCMSTB_WKTMR_ALARM);
+}
+
+static irqreturn_t brcmstb_waketmr_irq(int irq, void *data)
+{
+ struct brcmstb_waketmr *timer = data;
+
+ pm_wakeup_event(timer->dev, 0);
+
+ return IRQ_HANDLED;
+}
+
+struct wktmr_time {
+ u32 sec;
+ u32 pre;
+};
+
+static void wktmr_read(struct brcmstb_waketmr *timer,
+ struct wktmr_time *t)
+{
+ u32 tmp;
+
+ do {
+ t->sec = readl_relaxed(timer->base + BRCMSTB_WKTMR_COUNTER);
+ tmp = readl_relaxed(timer->base + BRCMSTB_WKTMR_PRESCALER_VAL);
+ } while (tmp >= timer->rate);
+
+ t->pre = timer->rate - tmp;
+}
+
+static int brcmstb_waketmr_prepare_suspend(struct brcmstb_waketmr *timer)
+{
+ struct device *dev = timer->dev;
+ int ret = 0;
+
+ if (device_may_wakeup(dev)) {
+ ret = enable_irq_wake(timer->irq);
+ if (ret) {
+ dev_err(dev, "failed to enable wake-up interrupt\n");
+ return ret;
+ }
+ }
+
+ return ret;
+}
+
+/* If enabled as a wakeup-source, arm the timer when powering off */
+static int brcmstb_waketmr_reboot(struct notifier_block *nb,
+ unsigned long action, void *data)
+{
+ struct brcmstb_waketmr *timer;
+
+ timer = container_of(nb, struct brcmstb_waketmr, reboot_notifier);
+
+ /* Set timer for cold boot */
+ if (action == SYS_POWER_OFF)
+ brcmstb_waketmr_prepare_suspend(timer);
+
+ return NOTIFY_DONE;
+}
+
+static int brcmstb_waketmr_gettime(struct device *dev,
+ struct rtc_time *tm)
+{
+ struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
+ struct wktmr_time now;
+
+ wktmr_read(timer, &now);
+
+ rtc_time_to_tm(now.sec, tm);
+
+ return 0;
+}
+
+static int brcmstb_waketmr_settime(struct device *dev,
+ struct rtc_time *tm)
+{
+ struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
+ unsigned long sec;
+ int ret;
+
+ rtc_tm_to_time(tm, &sec);
+
+ writel_relaxed(sec, timer->base + BRCMSTB_WKTMR_COUNTER);
+
+ return 0;
+}
+
+static int brcmstb_waketmr_getalarm(struct device *dev,
+ struct rtc_wkalrm *alarm)
+{
+ struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
+ unsigned long sec;
+ u32 reg;
+
+ sec = readl_relaxed(timer->base + BRCMSTB_WKTMR_ALARM);
+ if (sec != 0) {
+ /* Alarm is enabled */
+ alarm->enabled = 1;
+ rtc_time_to_tm(sec, &alarm->time);
+ }
+
+ reg = readl_relaxed(timer->base + BRCMSTB_WKTMR_EVENT);
+ alarm->pending = !!(reg & 1);
+
+ return 0;
+}
+
+static int brcmstb_waketmr_setalarm(struct device *dev,
+ struct rtc_wkalrm *alarm)
+{
+ struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
+ unsigned long sec;
+
+ if (alarm->enabled)
+ rtc_tm_to_time(&alarm->time, &sec);
+ else
+ sec = 0;
+
+ brcmstb_waketmr_set_alarm(timer, sec);
+
+ return 0;
+}
+
+/*
+ * Does not do much but keep the RTC class happy. We always support
+ * alarms.
+ */
+static int brcmstb_waketmr_alarm_enable(struct device *dev,
+ unsigned int enabled)
+{
+ return 0;
+}
+
+static const struct rtc_class_ops brcmstb_waketmr_ops = {
+ .read_time = brcmstb_waketmr_gettime,
+ .set_time = brcmstb_waketmr_settime,
+ .read_alarm = brcmstb_waketmr_getalarm,
+ .set_alarm = brcmstb_waketmr_setalarm,
+ .alarm_irq_enable = brcmstb_waketmr_alarm_enable,
+};
+
+static int brcmstb_waketmr_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct brcmstb_waketmr *timer;
+ struct resource *res;
+ int ret;
+
+ timer = devm_kzalloc(dev, sizeof(*timer), GFP_KERNEL);
+ if (!timer)
+ return -ENOMEM;
+
+ platform_set_drvdata(pdev, timer);
+ timer->dev = dev;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ timer->base = devm_ioremap_resource(dev, res);
+ if (IS_ERR(timer->base))
+ return PTR_ERR(timer->base);
+
+ /*
+ * Set wakeup capability before requesting wakeup interrupt, so we can
+ * process boot-time "wakeups" (e.g., from S5 soft-off)
+ */
+ device_set_wakeup_capable(dev, true);
+ device_wakeup_enable(dev);
+
+ timer->irq = platform_get_irq(pdev, 0);
+ if (timer->irq < 0)
+ return -ENODEV;
+
+ timer->clk = devm_clk_get(dev, NULL);
+ if (!IS_ERR(timer->clk)) {
+ ret = clk_prepare_enable(timer->clk);
+ if (ret)
+ return ret;
+ timer->rate = clk_get_rate(timer->clk);
+ if (!timer->rate)
+ timer->rate = BRCMSTB_WKTMR_DEFAULT_FREQ;
+ } else {
+ timer->rate = BRCMSTB_WKTMR_DEFAULT_FREQ;
+ timer->clk = NULL;
+ }
+
+ ret = devm_request_irq(dev, timer->irq, brcmstb_waketmr_irq, 0,
+ "brcmstb-waketimer", timer);
+ if (ret < 0)
+ return ret;
+
+ timer->reboot_notifier.notifier_call = brcmstb_waketmr_reboot;
+ register_reboot_notifier(&timer->reboot_notifier);
+
+ timer->rtc = rtc_device_register("brcmstb-waketmr", dev,
+ &brcmstb_waketmr_ops, THIS_MODULE);
+ if (IS_ERR(timer->rtc)) {
+ dev_err(dev, "unable to register device\n");
+ unregister_reboot_notifier(&timer->reboot_notifier);
+ return PTR_ERR(timer->rtc);
+ }
+
+ dev_info(dev, "registered, with irq %d\n", timer->irq);
+
+ return ret;
+}
+
+static int brcmstb_waketmr_remove(struct platform_device *pdev)
+{
+ struct brcmstb_waketmr *timer = dev_get_drvdata(&pdev->dev);
+
+ unregister_reboot_notifier(&timer->reboot_notifier);
+ rtc_device_unregister(timer->rtc);
+
+ return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int brcmstb_waketmr_suspend(struct device *dev)
+{
+ struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
+
+ return brcmstb_waketmr_prepare_suspend(timer);
+}
+
+static int brcmstb_waketmr_resume(struct device *dev)
+{
+ struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
+ int ret;
+
+ if (!device_may_wakeup(dev))
+ return 0;
+
+ ret = disable_irq_wake(timer->irq);
+
+ brcmstb_waketmr_clear_alarm(timer);
+
+ return ret;
+}
+#endif /* CONFIG_PM_SLEEP */
+
+static SIMPLE_DEV_PM_OPS(brcmstb_waketmr_pm_ops,
+ brcmstb_waketmr_suspend, brcmstb_waketmr_resume);
+
+static const struct of_device_id brcmstb_waketmr_of_match[] = {
+ { .compatible = "brcm,brcmstb-waketimer" },
+ { /* sentinel */ },
+};
+
+static struct platform_driver brcmstb_waketmr_driver = {
+ .probe = brcmstb_waketmr_probe,
+ .remove = brcmstb_waketmr_remove,
+ .driver = {
+ .name = "brcmstb-waketimer",
+ .pm = &brcmstb_waketmr_pm_ops,
+ .of_match_table = of_match_ptr(brcmstb_waketmr_of_match),
+ }
+};
+module_platform_driver(brcmstb_waketmr_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Brian Norris");
+MODULE_AUTHOR("Markus Mayer");
+MODULE_DESCRIPTION("Wake-up timer driver for STB chips");
--
2.9.3