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 
28 struct 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 
37 static 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 
67 static 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 
77 static 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 
86 static 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 
93 static const struct hwmon_ops kbatt_hwmon_ops = {
94 	.is_visible = kbatt_is_visible,
95 	.read = kbatt_read,
96 };
97 
98 static const struct hwmon_chip_info kbatt_chip_info = {
99 	.ops = &kbatt_hwmon_ops,
100 	.info = kbatt_info,
101 };
102 
103 static 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 
131 static const struct auxiliary_device_id kbatt_devtype_aux[] = {
132 	{ .name = "keba.batt" },
133 	{}
134 };
135 MODULE_DEVICE_TABLE(auxiliary, kbatt_devtype_aux);
136 
137 static struct auxiliary_driver kbatt_driver_aux = {
138 	.name = KBATT,
139 	.id_table = kbatt_devtype_aux,
140 	.probe = kbatt_probe,
141 };
142 module_auxiliary_driver(kbatt_driver_aux);
143 
144 MODULE_AUTHOR("Petar Bojanic <boja@keba.com>");
145 MODULE_AUTHOR("Gerhard Engleder <eg@keba.com>");
146 MODULE_DESCRIPTION("KEBA battery monitoring controller driver");
147 MODULE_LICENSE("GPL");
148