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
 22struct 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
 34static const int qcom_rset_map[] = { 2100, 1700, 1200, 800 };
 35static 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 */
 39static 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
 93static 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
134static const struct of_device_id qcom_coincell_match_table[] = {
135	{ .compatible = "qcom,pm8941-coincell", },
136	{}
137};
138
139MODULE_DEVICE_TABLE(of, qcom_coincell_match_table);
140
141static 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
149module_platform_driver(qcom_coincell_driver);
150
151MODULE_DESCRIPTION("Qualcomm PMIC coincell charger driver");
152MODULE_LICENSE("GPL v2");