[PATCH 5/7] soc: brcmstb: add wake-timer driver

Brian Norris
2015-06-19T00:11:34Z

Useful for waking the system from suspend after a specified period of
time.

This IP could potentially be supported as an RTC driver (for use with
the 'rtcwake' utility), but it is not battery backed, so that's not a
great fit. Implement a custom sysfs interface instead.

Signed-off-by: Brian Norris <computersforpeace@gmail.com>
---
.../ABI/testing/sysfs-driver-wktmr-brcmstb | 12 +
drivers/soc/brcmstb/Kconfig | 3 +
drivers/soc/brcmstb/Makefile | 1 +
drivers/soc/brcmstb/wktmr.c | 242 +++++++++++++++++++++
4 files changed, 258 insertions(+)
create mode 100644 Documentation/ABI/testing/sysfs-driver-wktmr-brcmstb
create mode 100644 drivers/soc/brcmstb/wktmr.c

diff --git a/Documentation/ABI/testing/sysfs-driver-wktmr-brcmstb b/Documentation/ABI/testing/sysfs-driver-wktmr-brcmstb
new file mode 100644
index 000000000000..e563f8b8d969
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-driver-wktmr-brcmstb
@@ -0,0 +1,12 @@
+What: /sys/bus/platform/drivers/brcm-waketimer/<MMIO-address>.waketimer/timeout
+Date: November 21, 2014
+KernelVersion: 3.14
+Contact: Brian Norris <norris@broadcom.com>
+Description: The control file for the wakeup timer. This integer value
+ represents the number of seconds between a suspend operation
+ (e.g., S3 suspend-to-RAM) and the time at which the wakeup
+ timer should fire.
+
+ Values are -1 (default) or any non-negative integer. Units are
+ in seconds. The special value of -1 means the timer should not
+ wake up the system.
diff --git a/drivers/soc/brcmstb/Kconfig b/drivers/soc/brcmstb/Kconfig
index 5025dacce6f0..e818eca7e847 100644
--- a/drivers/soc/brcmstb/Kconfig
+++ b/drivers/soc/brcmstb/Kconfig
@@ -16,4 +16,7 @@ config BRCMSTB_PM
depends on PM
depends on ARM && ARCH_BRCMSTB

+config BRCMSTB_WKTMR
+ tristate "Support wake-up timer"
+
endif # SOC_BRCMSTB
diff --git a/drivers/soc/brcmstb/Makefile b/drivers/soc/brcmstb/Makefile
index 677e3fa0d042..6ecba0644229 100644
--- a/drivers/soc/brcmstb/Makefile
+++ b/drivers/soc/brcmstb/Makefile
@@ -1,3 +1,4 @@
obj-$(CONFIG_BRCMSTB_PM) += pm/

obj-y += common.o
+obj-$(CONFIG_BRCMSTB_WKTMR) += wktmr.o
diff --git a/drivers/soc/brcmstb/wktmr.c b/drivers/soc/brcmstb/wktmr.c
new file mode 100644
index 000000000000..89f989724d3c
--- /dev/null
+++ b/drivers/soc/brcmstb/wktmr.c
@@ -0,0 +1,242 @@
+/*
+ * Copyright ? 2014-2015 Broadcom Corporation
+ *
+ * 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/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/stat.h>
+#include <linux/device.h>
+#include <linux/platform_device.h>
+#include <linux/suspend.h>
+#include <linux/err.h>
+#include <linux/of.h>
+#include <linux/pm.h>
+#include <linux/io.h>
+#include <linux/interrupt.h>
+#include <linux/irqreturn.h>
+#include <linux/pm_wakeup.h>
+#include <linux/reboot.h>
+
+#define DRV_NAME "brcm-waketimer"
+
+struct brcmstb_waketmr {
+ struct device *dev;
+ void __iomem *base;
+ unsigned int irq;
+
+ int wake_timeout;
+ struct notifier_block reboot_notifier;
+};
+
+/* No timeout */
+#define BRCMSTB_WKTMR_DEFAULT_TIMEOUT (-1)
+
+#define BRCMSTB_WKTMR_EVENT 0x00
+#define BRCMSTB_WKTMR_COUNTER 0x04
+#define BRCMSTB_WKTMR_ALARM 0x08
+#define BRCMSTB_WKTMR_PRESCALER 0x0C
+#define BRCMSTB_WKTMR_PRESACALER_VAL 0x10
+
+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)
+{
+ unsigned int t;
+
+ brcmstb_waketmr_clear_alarm(timer);
+
+ t = readl_relaxed(timer->base + BRCMSTB_WKTMR_COUNTER);
+ writel_relaxed(t + 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;
+}
+
+static ssize_t brcmstb_waketmr_timeout_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
+
+ return snprintf(buf, PAGE_SIZE, "%d\n", timer->wake_timeout);
+}
+
+static ssize_t brcmstb_waketmr_timeout_store(struct device *dev,
+ struct device_attribute *attr, const char *buf, size_t count)
+{
+ struct brcmstb_waketmr *timer = dev_get_drvdata(dev);
+ int timeout;
+ int ret;
+
+ ret = kstrtoint(buf, 0, &timeout);
+ if (ret < 0)
+ return ret;
+
+ /* Allow -1 as "no timeout" */
+ if (timeout < -1)
+ return -EINVAL;
+
+ timer->wake_timeout = timeout;
+
+ return count;
+}
+
+static const DEVICE_ATTR(timeout, S_IRUGO | S_IWUSR,
+ brcmstb_waketmr_timeout_show,
+ brcmstb_waketmr_timeout_store);
+
+static int brcmstb_waketmr_prepare_suspend(struct brcmstb_waketmr *timer)
+{
+ struct device *dev = timer->dev;
+ int ret;
+
+ if (device_may_wakeup(dev) && timer->wake_timeout >= 0) {
+ ret = enable_irq_wake(timer->irq);
+ if (ret) {
+ dev_err(dev, "failed to enable wake-up interrupt\n");
+ return ret;
+ }
+
+ brcmstb_waketmr_set_alarm(timer, timer->wake_timeout);
+ }
+ return 0;
+}
+
+/* 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_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 ((int)timer->irq < 0)
+ return -ENODEV;
+
+ ret = devm_request_irq(dev, timer->irq, brcmstb_waketmr_irq, 0,
+ DRV_NAME, timer);
+ if (ret < 0)
+ return ret;
+
+ timer->reboot_notifier.notifier_call = brcmstb_waketmr_reboot;
+ register_reboot_notifier(&timer->reboot_notifier);
+
+ timer->wake_timeout = BRCMSTB_WKTMR_DEFAULT_TIMEOUT;
+
+ ret = device_create_file(dev, &dev_attr_timeout);
+ if (ret)
+ unregister_reboot_notifier(&timer->reboot_notifier);
+ else
+ 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);
+
+ device_remove_file(&pdev->dev, &dev_attr_timeout);
+ unregister_reboot_notifier(&timer->reboot_notifier);
+
+ 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) || timer->wake_timeout < 0)
+ 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" },
+ {},
+};
+
+static struct platform_driver brcmstb_waketmr_driver = {
+ .probe = brcmstb_waketmr_probe,
+ .remove = brcmstb_waketmr_remove,
+ .driver = {
+ .name = DRV_NAME,
+ .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_DESCRIPTION("Wake-up timer driver for STB chips");
--
1.9.1