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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         char name[20];
 26 };
 27 
 28 static 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 
 45 static 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 
114 static 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 
154 static 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 
164 static 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 
205 static 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 
214 static 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 
222 module_platform_driver(wm831x_backup_driver);
223 
224 MODULE_DESCRIPTION("Backup battery charger driver for WM831x PMICs");
225 MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com>");
226 MODULE_LICENSE("GPL");
227 MODULE_ALIAS("platform:wm831x-backup");
228 

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