From 83a8df1b7fff284fc3c2277c8051f53acde2e64f Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Noralf=20Tr=C3=B8nnes?= 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 --- 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 #include #include +#include #include #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,