1/*
2 * Backup battery driver for Wolfson Microelectronics wm831x PMICs
3 *
4 * Copyright 2009 Wolfson Microelectronics PLC.
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 */
10
11#include <linux/module.h>
12#include <linux/err.h>
13#include <linux/platform_device.h>
14#include <linux/power_supply.h>
15#include <linux/slab.h>
16
17#include <linux/mfd/wm831x/core.h>
18#include <linux/mfd/wm831x/auxadc.h>
19#include <linux/mfd/wm831x/pmu.h>
20#include <linux/mfd/wm831x/pdata.h>
21
22struct wm831x_backup {
23	struct wm831x *wm831x;
24	struct power_supply *backup;
25	struct power_supply_desc backup_desc;
26	char name[20];
27};
28
29static int wm831x_backup_read_voltage(struct wm831x *wm831x,
30				     enum wm831x_auxadc src,
31				     union power_supply_propval *val)
32{
33	int ret;
34
35	ret = wm831x_auxadc_read_uv(wm831x, src);
36	if (ret >= 0)
37		val->intval = ret;
38
39	return ret;
40}
41
42/*********************************************************************
43 *		Backup supply properties
44 *********************************************************************/
45
46static void wm831x_config_backup(struct wm831x *wm831x)
47{
48	struct wm831x_pdata *wm831x_pdata = wm831x->dev->platform_data;
49	struct wm831x_backup_pdata *pdata;
50	int ret, reg;
51
52	if (!wm831x_pdata || !wm831x_pdata->backup) {
53		dev_warn(wm831x->dev,
54			 "No backup battery charger configuration\n");
55		return;
56	}
57
58	pdata = wm831x_pdata->backup;
59
60	reg = 0;
61
62	if (pdata->charger_enable)
63		reg |= WM831X_BKUP_CHG_ENA | WM831X_BKUP_BATT_DET_ENA;
64	if (pdata->no_constant_voltage)
65		reg |= WM831X_BKUP_CHG_MODE;
66
67	switch (pdata->vlim) {
68	case 2500:
69		break;
70	case 3100:
71		reg |= WM831X_BKUP_CHG_VLIM;
72		break;
73	default:
74		dev_err(wm831x->dev, "Invalid backup voltage limit %dmV\n",
75			pdata->vlim);
76	}
77
78	switch (pdata->ilim) {
79	case 100:
80		break;
81	case 200:
82		reg |= 1;
83		break;
84	case 300:
85		reg |= 2;
86		break;
87	case 400:
88		reg |= 3;
89		break;
90	default:
91		dev_err(wm831x->dev, "Invalid backup current limit %duA\n",
92			pdata->ilim);
93	}
94
95	ret = wm831x_reg_unlock(wm831x);
96	if (ret != 0) {
97		dev_err(wm831x->dev, "Failed to unlock registers: %d\n", ret);
98		return;
99	}
100
101	ret = wm831x_set_bits(wm831x, WM831X_BACKUP_CHARGER_CONTROL,
102			      WM831X_BKUP_CHG_ENA_MASK |
103			      WM831X_BKUP_CHG_MODE_MASK |
104			      WM831X_BKUP_BATT_DET_ENA_MASK |
105			      WM831X_BKUP_CHG_VLIM_MASK |
106			      WM831X_BKUP_CHG_ILIM_MASK,
107			      reg);
108	if (ret != 0)
109		dev_err(wm831x->dev,
110			"Failed to set backup charger config: %d\n", ret);
111
112	wm831x_reg_lock(wm831x);
113}
114
115static int wm831x_backup_get_prop(struct power_supply *psy,
116				  enum power_supply_property psp,
117				  union power_supply_propval *val)
118{
119	struct wm831x_backup *devdata = dev_get_drvdata(psy->dev.parent);
120	struct wm831x *wm831x = devdata->wm831x;
121	int ret = 0;
122
123	ret = wm831x_reg_read(wm831x, WM831X_BACKUP_CHARGER_CONTROL);
124	if (ret < 0)
125		return ret;
126
127	switch (psp) {
128	case POWER_SUPPLY_PROP_STATUS:
129		if (ret & WM831X_BKUP_CHG_STS)
130			val->intval = POWER_SUPPLY_STATUS_CHARGING;
131		else
132			val->intval = POWER_SUPPLY_STATUS_NOT_CHARGING;
133		break;
134
135	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
136		ret = wm831x_backup_read_voltage(wm831x, WM831X_AUX_BKUP_BATT,
137						val);
138		break;
139
140	case POWER_SUPPLY_PROP_PRESENT:
141		if (ret & WM831X_BKUP_CHG_STS)
142			val->intval = 1;
143		else
144			val->intval = 0;
145		break;
146
147	default:
148		ret = -EINVAL;
149		break;
150	}
151
152	return ret;
153}
154
155static enum power_supply_property wm831x_backup_props[] = {
156	POWER_SUPPLY_PROP_STATUS,
157	POWER_SUPPLY_PROP_VOLTAGE_NOW,
158	POWER_SUPPLY_PROP_PRESENT,
159};
160
161/*********************************************************************
162 *		Initialisation
163 *********************************************************************/
164
165static int wm831x_backup_probe(struct platform_device *pdev)
166{
167	struct wm831x *wm831x = dev_get_drvdata(pdev->dev.parent);
168	struct wm831x_pdata *wm831x_pdata = wm831x->dev->platform_data;
169	struct wm831x_backup *devdata;
170
171	devdata = devm_kzalloc(&pdev->dev, sizeof(struct wm831x_backup),
172				GFP_KERNEL);
173	if (devdata == NULL)
174		return -ENOMEM;
175
176	devdata->wm831x = wm831x;
177	platform_set_drvdata(pdev, devdata);
178
179	/* We ignore configuration failures since we can still read
180	 * back the status without enabling the charger (which may
181	 * already be enabled anyway).
182	 */
183	wm831x_config_backup(wm831x);
184
185	if (wm831x_pdata && wm831x_pdata->wm831x_num)
186		snprintf(devdata->name, sizeof(devdata->name),
187			 "wm831x-backup.%d", wm831x_pdata->wm831x_num);
188	else
189		snprintf(devdata->name, sizeof(devdata->name),
190			 "wm831x-backup");
191
192	devdata->backup_desc.name = devdata->name;
193	devdata->backup_desc.type = POWER_SUPPLY_TYPE_BATTERY;
194	devdata->backup_desc.properties = wm831x_backup_props;
195	devdata->backup_desc.num_properties = ARRAY_SIZE(wm831x_backup_props);
196	devdata->backup_desc.get_property = wm831x_backup_get_prop;
197	devdata->backup = power_supply_register(&pdev->dev,
198						&devdata->backup_desc, NULL);
199
200	return PTR_ERR_OR_ZERO(devdata->backup);
201}
202
203static int wm831x_backup_remove(struct platform_device *pdev)
204{
205	struct wm831x_backup *devdata = platform_get_drvdata(pdev);
206
207	power_supply_unregister(devdata->backup);
208
209	return 0;
210}
211
212static struct platform_driver wm831x_backup_driver = {
213	.probe = wm831x_backup_probe,
214	.remove = wm831x_backup_remove,
215	.driver = {
216		.name = "wm831x-backup",
217	},
218};
219
220module_platform_driver(wm831x_backup_driver);
221
222MODULE_DESCRIPTION("Backup battery charger driver for WM831x PMICs");
223MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com>");
224MODULE_LICENSE("GPL");
225MODULE_ALIAS("platform:wm831x-backup");
226