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Linux/drivers/power/wm831x_backup.c

  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 
 22 struct wm831x_backup {
 23         struct wm831x *wm831x;
 24         struct power_supply *backup;
 25         struct power_supply_desc backup_desc;
 26         char name[20];
 27 };
 28 
 29 static 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 
 46 static 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 
115 static 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 
155 static 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 
165 static 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 
203 static 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 
212 static 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 
220 module_platform_driver(wm831x_backup_driver);
221 
222 MODULE_DESCRIPTION("Backup battery charger driver for WM831x PMICs");
223 MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com>");
224 MODULE_LICENSE("GPL");
225 MODULE_ALIAS("platform:wm831x-backup");
226 

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