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	char name[20];
 26};
 27
 28static int wm831x_backup_read_voltage(struct wm831x *wm831x,
 29				     enum wm831x_auxadc src,
 30				     union power_supply_propval *val)
 31{
 32	int ret;
 33
 34	ret = wm831x_auxadc_read_uv(wm831x, src);
 35	if (ret >= 0)
 36		val->intval = ret;
 37
 38	return ret;
 39}
 40
 41/*********************************************************************
 42 *		Backup supply properties
 43 *********************************************************************/
 44
 45static void wm831x_config_backup(struct wm831x *wm831x)
 46{
 47	struct wm831x_pdata *wm831x_pdata = wm831x->dev->platform_data;
 48	struct wm831x_backup_pdata *pdata;
 49	int ret, reg;
 50
 51	if (!wm831x_pdata || !wm831x_pdata->backup) {
 52		dev_warn(wm831x->dev,
 53			 "No backup battery charger configuration\n");
 54		return;
 55	}
 56
 57	pdata = wm831x_pdata->backup;
 58
 59	reg = 0;
 60
 61	if (pdata->charger_enable)
 62		reg |= WM831X_BKUP_CHG_ENA | WM831X_BKUP_BATT_DET_ENA;
 63	if (pdata->no_constant_voltage)
 64		reg |= WM831X_BKUP_CHG_MODE;
 65
 66	switch (pdata->vlim) {
 67	case 2500:
 68		break;
 69	case 3100:
 70		reg |= WM831X_BKUP_CHG_VLIM;
 71		break;
 72	default:
 73		dev_err(wm831x->dev, "Invalid backup voltage limit %dmV\n",
 74			pdata->vlim);
 75	}
 76
 77	switch (pdata->ilim) {
 78	case 100:
 79		break;
 80	case 200:
 81		reg |= 1;
 82		break;
 83	case 300:
 84		reg |= 2;
 85		break;
 86	case 400:
 87		reg |= 3;
 88		break;
 89	default:
 90		dev_err(wm831x->dev, "Invalid backup current limit %duA\n",
 91			pdata->ilim);
 92	}
 93
 94	ret = wm831x_reg_unlock(wm831x);
 95	if (ret != 0) {
 96		dev_err(wm831x->dev, "Failed to unlock registers: %d\n", ret);
 97		return;
 98	}
 99
100	ret = wm831x_set_bits(wm831x, WM831X_BACKUP_CHARGER_CONTROL,
101			      WM831X_BKUP_CHG_ENA_MASK |
102			      WM831X_BKUP_CHG_MODE_MASK |
103			      WM831X_BKUP_BATT_DET_ENA_MASK |
104			      WM831X_BKUP_CHG_VLIM_MASK |
105			      WM831X_BKUP_CHG_ILIM_MASK,
106			      reg);
107	if (ret != 0)
108		dev_err(wm831x->dev,
109			"Failed to set backup charger config: %d\n", ret);
110
111	wm831x_reg_lock(wm831x);
112}
113
114static int wm831x_backup_get_prop(struct power_supply *psy,
115				  enum power_supply_property psp,
116				  union power_supply_propval *val)
117{
118	struct wm831x_backup *devdata = dev_get_drvdata(psy->dev->parent);
119	struct wm831x *wm831x = devdata->wm831x;
120	int ret = 0;
121
122	ret = wm831x_reg_read(wm831x, WM831X_BACKUP_CHARGER_CONTROL);
123	if (ret < 0)
124		return ret;
125
126	switch (psp) {
127	case POWER_SUPPLY_PROP_STATUS:
128		if (ret & WM831X_BKUP_CHG_STS)
129			val->intval = POWER_SUPPLY_STATUS_CHARGING;
130		else
131			val->intval = POWER_SUPPLY_STATUS_NOT_CHARGING;
132		break;
133
134	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
135		ret = wm831x_backup_read_voltage(wm831x, WM831X_AUX_BKUP_BATT,
136						val);
137		break;
138
139	case POWER_SUPPLY_PROP_PRESENT:
140		if (ret & WM831X_BKUP_CHG_STS)
141			val->intval = 1;
142		else
143			val->intval = 0;
144		break;
145
146	default:
147		ret = -EINVAL;
148		break;
149	}
150
151	return ret;
152}
153
154static enum power_supply_property wm831x_backup_props[] = {
155	POWER_SUPPLY_PROP_STATUS,
156	POWER_SUPPLY_PROP_VOLTAGE_NOW,
157	POWER_SUPPLY_PROP_PRESENT,
158};
159
160/*********************************************************************
161 *		Initialisation
162 *********************************************************************/
163
164static int wm831x_backup_probe(struct platform_device *pdev)
165{
166	struct wm831x *wm831x = dev_get_drvdata(pdev->dev.parent);
167	struct wm831x_pdata *wm831x_pdata = wm831x->dev->platform_data;
168	struct wm831x_backup *devdata;
169	struct power_supply *backup;
170	int ret;
171
172	devdata = devm_kzalloc(&pdev->dev, sizeof(struct wm831x_backup),
173				GFP_KERNEL);
174	if (devdata == NULL)
175		return -ENOMEM;
176
177	devdata->wm831x = wm831x;
178	platform_set_drvdata(pdev, devdata);
179
180	backup = &devdata->backup;
181
182	/* We ignore configuration failures since we can still read
183	 * back the status without enabling the charger (which may
184	 * already be enabled anyway).
185	 */
186	wm831x_config_backup(wm831x);
187
188	if (wm831x_pdata && wm831x_pdata->wm831x_num)
189		snprintf(devdata->name, sizeof(devdata->name),
190			 "wm831x-backup.%d", wm831x_pdata->wm831x_num);
191	else
192		snprintf(devdata->name, sizeof(devdata->name),
193			 "wm831x-backup");
194
195	backup->name = devdata->name;
196	backup->type = POWER_SUPPLY_TYPE_BATTERY;
197	backup->properties = wm831x_backup_props;
198	backup->num_properties = ARRAY_SIZE(wm831x_backup_props);
199	backup->get_property = wm831x_backup_get_prop;
200	ret = power_supply_register(&pdev->dev, backup);
201
202	return ret;
203}
204
205static int wm831x_backup_remove(struct platform_device *pdev)
206{
207	struct wm831x_backup *devdata = platform_get_drvdata(pdev);
208
209	power_supply_unregister(&devdata->backup);
210
211	return 0;
212}
213
214static struct platform_driver wm831x_backup_driver = {
215	.probe = wm831x_backup_probe,
216	.remove = wm831x_backup_remove,
217	.driver = {
218		.name = "wm831x-backup",
219	},
220};
221
222module_platform_driver(wm831x_backup_driver);
223
224MODULE_DESCRIPTION("Backup battery charger driver for WM831x PMICs");
225MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com>");
226MODULE_LICENSE("GPL");
227MODULE_ALIAS("platform:wm831x-backup");