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