1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Backup battery driver for Wolfson Microelectronics wm831x PMICs
4  *
5  * Copyright 2009 Wolfson Microelectronics PLC.
6  */
7 
8 #include <linux/module.h>
9 #include <linux/err.h>
10 #include <linux/platform_device.h>
11 #include <linux/power_supply.h>
12 #include <linux/slab.h>
13 
14 #include <linux/mfd/wm831x/core.h>
15 #include <linux/mfd/wm831x/auxadc.h>
16 #include <linux/mfd/wm831x/pmu.h>
17 #include <linux/mfd/wm831x/pdata.h>
18 
19 struct wm831x_backup {
20 	struct wm831x *wm831x;
21 	struct power_supply *backup;
22 	struct power_supply_desc backup_desc;
23 	char name[20];
24 };
25 
26 static int wm831x_backup_read_voltage(struct wm831x *wm831x,
27 				     enum wm831x_auxadc src,
28 				     union power_supply_propval *val)
29 {
30 	int ret;
31 
32 	ret = wm831x_auxadc_read_uv(wm831x, src);
33 	if (ret >= 0)
34 		val->intval = ret;
35 
36 	return ret;
37 }
38 
39 /*********************************************************************
40  *		Backup supply properties
41  *********************************************************************/
42 
43 static void wm831x_config_backup(struct wm831x *wm831x)
44 {
45 	struct wm831x_pdata *wm831x_pdata = wm831x->dev->platform_data;
46 	struct wm831x_backup_pdata *pdata;
47 	int ret, reg;
48 
49 	if (!wm831x_pdata || !wm831x_pdata->backup) {
50 		dev_warn(wm831x->dev,
51 			 "No backup battery charger configuration\n");
52 		return;
53 	}
54 
55 	pdata = wm831x_pdata->backup;
56 
57 	reg = 0;
58 
59 	if (pdata->charger_enable)
60 		reg |= WM831X_BKUP_CHG_ENA | WM831X_BKUP_BATT_DET_ENA;
61 	if (pdata->no_constant_voltage)
62 		reg |= WM831X_BKUP_CHG_MODE;
63 
64 	switch (pdata->vlim) {
65 	case 2500:
66 		break;
67 	case 3100:
68 		reg |= WM831X_BKUP_CHG_VLIM;
69 		break;
70 	default:
71 		dev_err(wm831x->dev, "Invalid backup voltage limit %dmV\n",
72 			pdata->vlim);
73 	}
74 
75 	switch (pdata->ilim) {
76 	case 100:
77 		break;
78 	case 200:
79 		reg |= 1;
80 		break;
81 	case 300:
82 		reg |= 2;
83 		break;
84 	case 400:
85 		reg |= 3;
86 		break;
87 	default:
88 		dev_err(wm831x->dev, "Invalid backup current limit %duA\n",
89 			pdata->ilim);
90 	}
91 
92 	ret = wm831x_reg_unlock(wm831x);
93 	if (ret != 0) {
94 		dev_err(wm831x->dev, "Failed to unlock registers: %d\n", ret);
95 		return;
96 	}
97 
98 	ret = wm831x_set_bits(wm831x, WM831X_BACKUP_CHARGER_CONTROL,
99 			      WM831X_BKUP_CHG_ENA_MASK |
100 			      WM831X_BKUP_CHG_MODE_MASK |
101 			      WM831X_BKUP_BATT_DET_ENA_MASK |
102 			      WM831X_BKUP_CHG_VLIM_MASK |
103 			      WM831X_BKUP_CHG_ILIM_MASK,
104 			      reg);
105 	if (ret != 0)
106 		dev_err(wm831x->dev,
107 			"Failed to set backup charger config: %d\n", ret);
108 
109 	wm831x_reg_lock(wm831x);
110 }
111 
112 static int wm831x_backup_get_prop(struct power_supply *psy,
113 				  enum power_supply_property psp,
114 				  union power_supply_propval *val)
115 {
116 	struct wm831x_backup *devdata = dev_get_drvdata(psy->dev.parent);
117 	struct wm831x *wm831x = devdata->wm831x;
118 	int ret = 0;
119 
120 	ret = wm831x_reg_read(wm831x, WM831X_BACKUP_CHARGER_CONTROL);
121 	if (ret < 0)
122 		return ret;
123 
124 	switch (psp) {
125 	case POWER_SUPPLY_PROP_STATUS:
126 		if (ret & WM831X_BKUP_CHG_STS)
127 			val->intval = POWER_SUPPLY_STATUS_CHARGING;
128 		else
129 			val->intval = POWER_SUPPLY_STATUS_NOT_CHARGING;
130 		break;
131 
132 	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
133 		ret = wm831x_backup_read_voltage(wm831x, WM831X_AUX_BKUP_BATT,
134 						val);
135 		break;
136 
137 	case POWER_SUPPLY_PROP_PRESENT:
138 		if (ret & WM831X_BKUP_CHG_STS)
139 			val->intval = 1;
140 		else
141 			val->intval = 0;
142 		break;
143 
144 	default:
145 		ret = -EINVAL;
146 		break;
147 	}
148 
149 	return ret;
150 }
151 
152 static enum power_supply_property wm831x_backup_props[] = {
153 	POWER_SUPPLY_PROP_STATUS,
154 	POWER_SUPPLY_PROP_VOLTAGE_NOW,
155 	POWER_SUPPLY_PROP_PRESENT,
156 };
157 
158 /*********************************************************************
159  *		Initialisation
160  *********************************************************************/
161 
162 static int wm831x_backup_probe(struct platform_device *pdev)
163 {
164 	struct wm831x *wm831x = dev_get_drvdata(pdev->dev.parent);
165 	struct wm831x_pdata *wm831x_pdata = wm831x->dev->platform_data;
166 	struct wm831x_backup *devdata;
167 
168 	devdata = devm_kzalloc(&pdev->dev, sizeof(struct wm831x_backup),
169 				GFP_KERNEL);
170 	if (devdata == NULL)
171 		return -ENOMEM;
172 
173 	devdata->wm831x = wm831x;
174 	platform_set_drvdata(pdev, devdata);
175 
176 	/* We ignore configuration failures since we can still read
177 	 * back the status without enabling the charger (which may
178 	 * already be enabled anyway).
179 	 */
180 	wm831x_config_backup(wm831x);
181 
182 	if (wm831x_pdata && wm831x_pdata->wm831x_num)
183 		snprintf(devdata->name, sizeof(devdata->name),
184 			 "wm831x-backup.%d", wm831x_pdata->wm831x_num);
185 	else
186 		snprintf(devdata->name, sizeof(devdata->name),
187 			 "wm831x-backup");
188 
189 	devdata->backup_desc.name = devdata->name;
190 	devdata->backup_desc.type = POWER_SUPPLY_TYPE_BATTERY;
191 	devdata->backup_desc.properties = wm831x_backup_props;
192 	devdata->backup_desc.num_properties = ARRAY_SIZE(wm831x_backup_props);
193 	devdata->backup_desc.get_property = wm831x_backup_get_prop;
194 	devdata->backup = power_supply_register(&pdev->dev,
195 						&devdata->backup_desc, NULL);
196 
197 	return PTR_ERR_OR_ZERO(devdata->backup);
198 }
199 
200 static int wm831x_backup_remove(struct platform_device *pdev)
201 {
202 	struct wm831x_backup *devdata = platform_get_drvdata(pdev);
203 
204 	power_supply_unregister(devdata->backup);
205 
206 	return 0;
207 }
208 
209 static struct platform_driver wm831x_backup_driver = {
210 	.probe = wm831x_backup_probe,
211 	.remove = wm831x_backup_remove,
212 	.driver = {
213 		.name = "wm831x-backup",
214 	},
215 };
216 
217 module_platform_driver(wm831x_backup_driver);
218 
219 MODULE_DESCRIPTION("Backup battery charger driver for WM831x PMICs");
220 MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com>");
221 MODULE_LICENSE("GPL");
222 MODULE_ALIAS("platform:wm831x-backup");
223