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The KEBA battery monitoring controller is found in the system FPGA of KEBA PLC devices. It puts a load on the coin cell battery to check the state of the battery. If the coin cell battery is nearly empty, then the user space is signaled with a hwmon alarm. The auxiliary device for this driver is instantiated by the cp500 misc driver. Signed-off-by: Gerhard Engleder <eg@keba.com> Link: https://lore.kernel.org/r/20250409190830.60489-1-gerhard@engleder-embedded.com Signed-off-by: Guenter Roeck <linux@roeck-us.net>
147 lines
3.4 KiB
C
147 lines
3.4 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2025 KEBA Industrial Automation GmbH
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*
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* Driver for KEBA battery monitoring controller FPGA IP core
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*/
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#include <linux/hwmon.h>
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#include <linux/io.h>
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#include <linux/delay.h>
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#include <linux/module.h>
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#include <linux/device.h>
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#include <linux/auxiliary_bus.h>
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#include <linux/misc/keba.h>
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#include <linux/mutex.h>
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#define KBATT "kbatt"
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#define KBATT_CONTROL_REG 0x4
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#define KBATT_CONTROL_BAT_TEST 0x01
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#define KBATT_STATUS_REG 0x8
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#define KBATT_STATUS_BAT_OK 0x01
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#define KBATT_MAX_UPD_INTERVAL (10 * HZ)
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#define KBATT_SETTLE_TIME_US (100 * USEC_PER_MSEC)
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struct kbatt {
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/* update lock */
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struct mutex lock;
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void __iomem *base;
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unsigned long next_update; /* in jiffies */
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bool alarm;
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};
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static bool kbatt_alarm(struct kbatt *kbatt)
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{
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mutex_lock(&kbatt->lock);
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if (!kbatt->next_update || time_after(jiffies, kbatt->next_update)) {
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/* switch load on */
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iowrite8(KBATT_CONTROL_BAT_TEST,
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kbatt->base + KBATT_CONTROL_REG);
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/* wait some time to let things settle */
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fsleep(KBATT_SETTLE_TIME_US);
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/* check battery state */
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if (ioread8(kbatt->base + KBATT_STATUS_REG) &
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KBATT_STATUS_BAT_OK)
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kbatt->alarm = false;
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else
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kbatt->alarm = true;
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/* switch load off */
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iowrite8(0, kbatt->base + KBATT_CONTROL_REG);
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kbatt->next_update = jiffies + KBATT_MAX_UPD_INTERVAL;
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}
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mutex_unlock(&kbatt->lock);
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return kbatt->alarm;
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}
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static int kbatt_read(struct device *dev, enum hwmon_sensor_types type,
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u32 attr, int channel, long *val)
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{
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struct kbatt *kbatt = dev_get_drvdata(dev);
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*val = kbatt_alarm(kbatt) ? 1 : 0;
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return 0;
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}
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static umode_t kbatt_is_visible(const void *data, enum hwmon_sensor_types type,
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u32 attr, int channel)
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{
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if (channel == 0 && attr == hwmon_in_min_alarm)
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return 0444;
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return 0;
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}
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static const struct hwmon_channel_info *kbatt_info[] = {
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HWMON_CHANNEL_INFO(in,
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/* 0: input minimum alarm channel */
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HWMON_I_MIN_ALARM),
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NULL
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};
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static const struct hwmon_ops kbatt_hwmon_ops = {
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.is_visible = kbatt_is_visible,
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.read = kbatt_read,
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};
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static const struct hwmon_chip_info kbatt_chip_info = {
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.ops = &kbatt_hwmon_ops,
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.info = kbatt_info,
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};
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static int kbatt_probe(struct auxiliary_device *auxdev,
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const struct auxiliary_device_id *id)
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{
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struct keba_batt_auxdev *kbatt_auxdev =
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container_of(auxdev, struct keba_batt_auxdev, auxdev);
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struct device *dev = &auxdev->dev;
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struct device *hwmon_dev;
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struct kbatt *kbatt;
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int retval;
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kbatt = devm_kzalloc(dev, sizeof(*kbatt), GFP_KERNEL);
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if (!kbatt)
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return -ENOMEM;
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retval = devm_mutex_init(dev, &kbatt->lock);
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if (retval)
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return retval;
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kbatt->base = devm_ioremap_resource(dev, &kbatt_auxdev->io);
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if (IS_ERR(kbatt->base))
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return PTR_ERR(kbatt->base);
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hwmon_dev = devm_hwmon_device_register_with_info(dev, KBATT, kbatt,
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&kbatt_chip_info,
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NULL);
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return PTR_ERR_OR_ZERO(hwmon_dev);
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}
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static const struct auxiliary_device_id kbatt_devtype_aux[] = {
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{ .name = "keba.batt" },
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{}
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};
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MODULE_DEVICE_TABLE(auxiliary, kbatt_devtype_aux);
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static struct auxiliary_driver kbatt_driver_aux = {
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.name = KBATT,
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.id_table = kbatt_devtype_aux,
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.probe = kbatt_probe,
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};
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module_auxiliary_driver(kbatt_driver_aux);
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MODULE_AUTHOR("Petar Bojanic <boja@keba.com>");
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MODULE_AUTHOR("Gerhard Engleder <eg@keba.com>");
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MODULE_DESCRIPTION("KEBA battery monitoring controller driver");
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MODULE_LICENSE("GPL");
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