drivers/misc/qcom-coincell.c

   1 /* Copyright (c) 2013, The Linux Foundation. All rights reserved.
   2  * Copyright (c) 2015, Sony Mobile Communications Inc.
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 and
   6  * only version 2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  */
  13
  14 #include <linux/kernel.h>
  15 #include <linux/module.h>
  16 #include <linux/slab.h>
  17 #include <linux/of.h>
  18 #include <linux/regmap.h>
  19 #include <linux/of_device.h>
  20 #include <linux/platform_device.h>
  21
  22 struct qcom_coincell {
  23         struct device   *dev;
  24         struct regmap   *regmap;
  25         u32             base_addr;
  26 };
  27
  28 #define QCOM_COINCELL_REG_RSET          0x44
  29 #define QCOM_COINCELL_REG_VSET          0x45
  30 #define QCOM_COINCELL_REG_ENABLE        0x46
  31
  32 #define QCOM_COINCELL_ENABLE            BIT(7)
  33
  34 static const int qcom_rset_map[] = { 2100, 1700, 1200, 800 };
  35 static const int qcom_vset_map[] = { 2500, 3200, 3100, 3000 };
  36 /* NOTE: for pm8921 and others, voltage of 2500 is 16 (10000b), not 0 */
  37
  38 /* if enable==0, rset and vset are ignored */
  39 static int qcom_coincell_chgr_config(struct qcom_coincell *chgr, int rset,
  40                                      int vset, bool enable)
  41 {
  42         int i, j, rc;
  43
  44         /* if disabling, just do that and skip other operations */
  45         if (!enable)
  46                 return regmap_write(chgr->regmap,
  47                           chgr->base_addr + QCOM_COINCELL_REG_ENABLE, 0);
  48
  49         /* find index for current-limiting resistor */
  50         for (i = 0; i < ARRAY_SIZE(qcom_rset_map); i++)
  51                 if (rset == qcom_rset_map[i])
  52                         break;
  53
  54         if (i >= ARRAY_SIZE(qcom_rset_map)) {
  55                 dev_err(chgr->dev, "invalid rset-ohms value %d\n", rset);
  56                 return -EINVAL;
  57         }
  58
  59         /* find index for charge voltage */
  60         for (j = 0; j < ARRAY_SIZE(qcom_vset_map); j++)
  61                 if (vset == qcom_vset_map[j])
  62                         break;
  63
  64         if (j >= ARRAY_SIZE(qcom_vset_map)) {
  65                 dev_err(chgr->dev, "invalid vset-millivolts value %d\n", vset);
  66                 return -EINVAL;
  67         }
  68
  69         rc = regmap_write(chgr->regmap,
  70                           chgr->base_addr + QCOM_COINCELL_REG_RSET, i);
  71         if (rc) {
  72                 /*
  73                  * This is mainly to flag a bad base_addr (reg) from dts.
  74                  * Other failures writing to the registers should be
  75                  * extremely rare, or indicative of problems that
  76                  * should be reported elsewhere (eg. spmi failure).
  77                  */
  78                 dev_err(chgr->dev, "could not write to RSET register\n");
  79                 return rc;
  80         }
  81
  82         rc = regmap_write(chgr->regmap,
  83                 chgr->base_addr + QCOM_COINCELL_REG_VSET, j);
  84         if (rc)
  85                 return rc;
  86
  87         /* set 'enable' register */
  88         return regmap_write(chgr->regmap,
  89                             chgr->base_addr + QCOM_COINCELL_REG_ENABLE,
  90                             QCOM_COINCELL_ENABLE);
  91 }
  92
  93 static int qcom_coincell_probe(struct platform_device *pdev)
  94 {
  95         struct device_node *node = pdev->dev.of_node;
  96         struct qcom_coincell chgr;
  97         u32 rset, vset;
  98         bool enable;
  99         int rc;
 100
 101         chgr.dev = &pdev->dev;
 102
 103         chgr.regmap = dev_get_regmap(pdev->dev.parent, NULL);
 104         if (!chgr.regmap) {
 105                 dev_err(chgr.dev, "Unable to get regmap\n");
 106                 return -EINVAL;
 107         }
 108
 109         rc = of_property_read_u32(node, "reg", &chgr.base_addr);
 110         if (rc)
 111                 return rc;
 112
 113         enable = !of_property_read_bool(node, "qcom,charger-disable");
 114
 115         if (enable) {
 116                 rc = of_property_read_u32(node, "qcom,rset-ohms", &rset);
 117                 if (rc) {
 118                         dev_err(chgr.dev,
 119                                 "can't find 'qcom,rset-ohms' in DT block");
 120                         return rc;
 121                 }
 122
 123                 rc = of_property_read_u32(node, "qcom,vset-millivolts", &vset);
 124                 if (rc) {
 125                         dev_err(chgr.dev,
 126                             "can't find 'qcom,vset-millivolts' in DT block");
 127                         return rc;
 128                 }
 129         }
 130
 131         return qcom_coincell_chgr_config(&chgr, rset, vset, enable);
 132 }
 133
 134 static const struct of_device_id qcom_coincell_match_table[] = {
 135         { .compatible = "qcom,pm8941-coincell", },
 136         {}
 137 };
 138
 139 MODULE_DEVICE_TABLE(of, qcom_coincell_match_table);
 140
 141 static struct platform_driver qcom_coincell_driver = {
 142         .driver = {
 143                 .name           = "qcom-spmi-coincell",
 144                 .of_match_table = qcom_coincell_match_table,
 145         },
 146         .probe          = qcom_coincell_probe,
 147 };
 148
 149 module_platform_driver(qcom_coincell_driver);
 150
 151 MODULE_DESCRIPTION("Qualcomm PMIC coincell charger driver");
 152 MODULE_LICENSE("GPL v2");