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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2025 KEBA Industrial Automation GmbH
4 *
5 * Driver for KEBA battery monitoring controller FPGA IP core
6 */
7
8#include <linux/hwmon.h>
9#include <linux/io.h>
10#include <linux/delay.h>
11#include <linux/module.h>
12#include <linux/device.h>
13#include <linux/auxiliary_bus.h>
14#include <linux/misc/keba.h>
15#include <linux/mutex.h>
16
17#define KBATT "kbatt"
18
19#define KBATT_CONTROL_REG 0x4
20#define KBATT_CONTROL_BAT_TEST 0x01
21
22#define KBATT_STATUS_REG 0x8
23#define KBATT_STATUS_BAT_OK 0x01
24
25#define KBATT_MAX_UPD_INTERVAL (10 * HZ)
26#define KBATT_SETTLE_TIME_US (100 * USEC_PER_MSEC)
27
28struct kbatt {
29 /* update lock */
30 struct mutex lock;
31 void __iomem *base;
32
33 unsigned long next_update; /* in jiffies */
34 bool alarm;
35};
36
37static bool kbatt_alarm(struct kbatt *kbatt)
38{
39 mutex_lock(&kbatt->lock);
40
41 if (!kbatt->next_update || time_after(jiffies, kbatt->next_update)) {
42 /* switch load on */
43 iowrite8(KBATT_CONTROL_BAT_TEST,
44 kbatt->base + KBATT_CONTROL_REG);
45
46 /* wait some time to let things settle */
47 fsleep(KBATT_SETTLE_TIME_US);
48
49 /* check battery state */
50 if (ioread8(kbatt->base + KBATT_STATUS_REG) &
51 KBATT_STATUS_BAT_OK)
52 kbatt->alarm = false;
53 else
54 kbatt->alarm = true;
55
56 /* switch load off */
57 iowrite8(0, kbatt->base + KBATT_CONTROL_REG);
58
59 kbatt->next_update = jiffies + KBATT_MAX_UPD_INTERVAL;
60 }
61
62 mutex_unlock(&kbatt->lock);
63
64 return kbatt->alarm;
65}
66
67static int kbatt_read(struct device *dev, enum hwmon_sensor_types type,
68 u32 attr, int channel, long *val)
69{
70 struct kbatt *kbatt = dev_get_drvdata(dev);
71
72 *val = kbatt_alarm(kbatt) ? 1 : 0;
73
74 return 0;
75}
76
77static umode_t kbatt_is_visible(const void *data, enum hwmon_sensor_types type,
78 u32 attr, int channel)
79{
80 if (channel == 0 && attr == hwmon_in_min_alarm)
81 return 0444;
82
83 return 0;
84}
85
86static const struct hwmon_channel_info *kbatt_info[] = {
87 HWMON_CHANNEL_INFO(in,
88 /* 0: input minimum alarm channel */
89 HWMON_I_MIN_ALARM),
90 NULL
91};
92
93static const struct hwmon_ops kbatt_hwmon_ops = {
94 .is_visible = kbatt_is_visible,
95 .read = kbatt_read,
96};
97
98static const struct hwmon_chip_info kbatt_chip_info = {
99 .ops = &kbatt_hwmon_ops,
100 .info = kbatt_info,
101};
102
103static int kbatt_probe(struct auxiliary_device *auxdev,
104 const struct auxiliary_device_id *id)
105{
106 struct keba_batt_auxdev *kbatt_auxdev =
107 container_of(auxdev, struct keba_batt_auxdev, auxdev);
108 struct device *dev = &auxdev->dev;
109 struct device *hwmon_dev;
110 struct kbatt *kbatt;
111 int retval;
112
113 kbatt = devm_kzalloc(dev, sizeof(*kbatt), GFP_KERNEL);
114 if (!kbatt)
115 return -ENOMEM;
116
117 retval = devm_mutex_init(dev, &kbatt->lock);
118 if (retval)
119 return retval;
120
121 kbatt->base = devm_ioremap_resource(dev, &kbatt_auxdev->io);
122 if (IS_ERR(kbatt->base))
123 return PTR_ERR(kbatt->base);
124
125 hwmon_dev = devm_hwmon_device_register_with_info(dev, KBATT, kbatt,
126 &kbatt_chip_info,
127 NULL);
128 return PTR_ERR_OR_ZERO(hwmon_dev);
129}
130
131static const struct auxiliary_device_id kbatt_devtype_aux[] = {
132 { .name = "keba.batt" },
133 {}
134};
135MODULE_DEVICE_TABLE(auxiliary, kbatt_devtype_aux);
136
137static struct auxiliary_driver kbatt_driver_aux = {
138 .name = KBATT,
139 .id_table = kbatt_devtype_aux,
140 .probe = kbatt_probe,
141};
142module_auxiliary_driver(kbatt_driver_aux);
143
144MODULE_AUTHOR("Petar Bojanic <[email protected]>");
145MODULE_AUTHOR("Gerhard Engleder <[email protected]>");
146MODULE_DESCRIPTION("KEBA battery monitoring controller driver");
147MODULE_LICENSE("GPL");