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From 83a8df1b7fff284fc3c2277c8051f53acde2e64f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Noralf=20Tr=C3=B8nnes?= <noralf@tronnes.org>
Date: Sat, 24 Feb 2018 13:41:25 +0100
Subject: [PATCH 234/454] firmware/raspberrypi: Add a get_throttled sysfs file
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Under-voltage due to inadequate power supplies is a recurring problem for
new Raspberry Pi users. There are visual indications that an
under-voltage situation is occuring like blinking power led and a
lightning icon on the desktop (not shown when using the vc4 driver), but
for new users it's not obvious that this signifies a critical situation.
This patch provides a twofold improvement to the situation:
Firstly it logs under-voltage events to the kernel log. This provides
information also for headless installations.
Secondly it provides a sysfs file to read the value. This improves on
'vcgencmd' by providing change notification. Userspace can poll on the
file and be notified of changes to the value.
A script can poll the file and use dbus notification to put a windows on
the desktop with information about the severity with a recommendation to
change the power supply. A link to more information can also be provided.
Only changes to the sticky bits are reported (cleared between readings).
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
---
drivers/firmware/raspberrypi.c | 108 +++++++++++++++++++++
include/soc/bcm2835/raspberrypi-firmware.h | 1 +
2 files changed, 109 insertions(+)
--- a/drivers/firmware/raspberrypi.c
+++ b/drivers/firmware/raspberrypi.c
@@ -14,6 +14,7 @@
#include <linux/module.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>
+#include <linux/workqueue.h>
#include <soc/bcm2835/raspberrypi-firmware.h>
#define MBOX_MSG(chan, data28) (((data28) & ~0xf) | ((chan) & 0xf))
@@ -21,11 +22,14 @@
#define MBOX_DATA28(msg) ((msg) & ~0xf)
#define MBOX_CHAN_PROPERTY 8
+#define UNDERVOLTAGE_BIT BIT(0)
+
struct rpi_firmware {
struct mbox_client cl;
struct mbox_chan *chan; /* The property channel. */
struct completion c;
u32 enabled;
+ struct delayed_work get_throttled_poll_work;
};
static struct platform_device *g_pdev;
@@ -166,6 +170,101 @@ int rpi_firmware_property(struct rpi_fir
}
EXPORT_SYMBOL_GPL(rpi_firmware_property);
+static int rpi_firmware_get_throttled(struct rpi_firmware *fw, u32 *value)
+{
+ static ktime_t old_timestamp;
+ static u32 old_value;
+ u32 new_sticky, old_sticky, new_uv, old_uv;
+ ktime_t new_timestamp;
+ s64 elapsed_ms;
+ int ret;
+
+ if (!fw)
+ return -EBUSY;
+
+ /*
+ * We can't run faster than the sticky shift (100ms) since we get
+ * flipping in the sticky bits that are cleared.
+ * This happens on polling, so just return the previous value.
+ */
+ new_timestamp = ktime_get();
+ elapsed_ms = ktime_ms_delta(new_timestamp, old_timestamp);
+ if (elapsed_ms < 150) {
+ *value = old_value;
+ return 0;
+ }
+ old_timestamp = new_timestamp;
+
+ /* Clear sticky bits */
+ *value = 0xffff;
+
+ ret = rpi_firmware_property(fw, RPI_FIRMWARE_GET_THROTTLED,
+ value, sizeof(*value));
+ if (ret)
+ return ret;
+
+ new_sticky = *value >> 16;
+ old_sticky = old_value >> 16;
+ old_value = *value;
+
+ /* Only notify about changes in the sticky bits */
+ if (new_sticky == old_sticky)
+ return 0;
+
+ new_uv = new_sticky & UNDERVOLTAGE_BIT;
+ old_uv = old_sticky & UNDERVOLTAGE_BIT;
+
+ if (new_uv != old_uv) {
+ if (new_uv)
+ pr_crit("Under-voltage detected! (0x%08x)\n", *value);
+ else
+ pr_info("Voltage normalised (0x%08x)\n", *value);
+ }
+
+ sysfs_notify(&fw->cl.dev->kobj, NULL, "get_throttled");
+
+ return 0;
+}
+
+static void get_throttled_poll(struct work_struct *work)
+{
+ struct rpi_firmware *fw = container_of(work, struct rpi_firmware,
+ get_throttled_poll_work.work);
+ u32 dummy;
+ int ret;
+
+ ret = rpi_firmware_get_throttled(fw, &dummy);
+ if (ret)
+ pr_debug("%s: Failed to read value (%d)", __func__, ret);
+
+ schedule_delayed_work(&fw->get_throttled_poll_work, 2 * HZ);
+}
+
+static ssize_t get_throttled_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct rpi_firmware *fw = dev_get_drvdata(dev);
+ u32 value;
+ int ret;
+
+ ret = rpi_firmware_get_throttled(fw, &value);
+ if (ret)
+ return ret;
+
+ return sprintf(buf, "%x\n", value);
+}
+
+static DEVICE_ATTR_RO(get_throttled);
+
+static struct attribute *rpi_firmware_dev_attrs[] = {
+ &dev_attr_get_throttled.attr,
+ NULL,
+};
+
+static const struct attribute_group rpi_firmware_dev_group = {
+ .attrs = rpi_firmware_dev_attrs,
+};
+
static void
rpi_firmware_print_firmware_revision(struct rpi_firmware *fw)
{
@@ -190,6 +289,11 @@ static int rpi_firmware_probe(struct pla
{
struct device *dev = &pdev->dev;
struct rpi_firmware *fw;
+ int ret;
+
+ ret = devm_device_add_group(dev, &rpi_firmware_dev_group);
+ if (ret)
+ return ret;
fw = devm_kzalloc(dev, sizeof(*fw), GFP_KERNEL);
if (!fw)
@@ -208,12 +312,15 @@ static int rpi_firmware_probe(struct pla
}
init_completion(&fw->c);
+ INIT_DELAYED_WORK(&fw->get_throttled_poll_work, get_throttled_poll);
platform_set_drvdata(pdev, fw);
g_pdev = pdev;
rpi_firmware_print_firmware_revision(fw);
+ schedule_delayed_work(&fw->get_throttled_poll_work, 0);
+
return 0;
}
@@ -221,6 +328,7 @@ static int rpi_firmware_remove(struct pl
{
struct rpi_firmware *fw = platform_get_drvdata(pdev);
+ cancel_delayed_work_sync(&fw->get_throttled_poll_work);
mbox_free_channel(fw->chan);
g_pdev = NULL;
--- a/include/soc/bcm2835/raspberrypi-firmware.h
+++ b/include/soc/bcm2835/raspberrypi-firmware.h
@@ -77,6 +77,7 @@ enum rpi_firmware_property_tag {
RPI_FIRMWARE_GET_EDID_BLOCK = 0x00030020,
RPI_FIRMWARE_GET_CUSTOMER_OTP = 0x00030021,
RPI_FIRMWARE_GET_DOMAIN_STATE = 0x00030030,
+ RPI_FIRMWARE_GET_THROTTLED = 0x00030046,
RPI_FIRMWARE_SET_CLOCK_STATE = 0x00038001,
RPI_FIRMWARE_SET_CLOCK_RATE = 0x00038002,
RPI_FIRMWARE_SET_VOLTAGE = 0x00038003,
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