ARM: qcom: Add coincell charger driver

This driver is used to configure the coincell charger found in
Qualcomm PMICs.

The driver allows configuring the current-limiting resistor for
the charger, as well as the voltage to apply to the coincell
(or capacitor) when charging.

Signed-off-by: Tim Bird <tim.bird@sonymobile.com>
Reviewed-by: Andy Gross <agross@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index 42c38525904b854d8e6a3b5051dbfb133f226f84..ccccc2943f2fde2d06955bdf5453a327f60dc153 100644 (file)
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -271,6 +271,16 @@ config HP_ILO
          To compile this driver as a module, choose M here: the
          module will be called hpilo.
 
+config QCOM_COINCELL
+       tristate "Qualcomm coincell charger support"
+       depends on MFD_SPMI_PMIC || COMPILE_TEST
+       help
+         This driver supports the coincell block found inside of
+         Qualcomm PMICs.  The coincell charger provides a means to
+         charge a coincell battery or backup capacitor which is used
+         to maintain PMIC register and RTC state in the absence of
+         external power.
+
 config SGI_GRU
        tristate "SGI GRU driver"
        depends on X86_UV && SMP

diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index d056fb7186fe1b31867457abb3e56b18ab1beb10..537d7f3b78da9a35afcf4fe41053bbcbef1dd1f2 100644 (file)
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -18,6 +18,7 @@ obj-$(CONFIG_LKDTM)           += lkdtm.o
 obj-$(CONFIG_TIFM_CORE)        += tifm_core.o
 obj-$(CONFIG_TIFM_7XX1)        += tifm_7xx1.o
 obj-$(CONFIG_PHANTOM)          += phantom.o
+obj-$(CONFIG_QCOM_COINCELL)    += qcom-coincell.o
 obj-$(CONFIG_SENSORS_BH1780)   += bh1780gli.o
 obj-$(CONFIG_SENSORS_BH1770)   += bh1770glc.o
 obj-$(CONFIG_SENSORS_APDS990X) += apds990x.o

diff --git a/drivers/misc/qcom-coincell.c b/drivers/misc/qcom-coincell.c
new file mode 100644 (file)
index 0000000..7b4a2da
--- /dev/null
+++ b/drivers/misc/qcom-coincell.c
@@ -0,0 +1,152 @@
+/* Copyright (c) 2013, The Linux Foundation. All rights reserved.
+ * Copyright (c) 2015, Sony Mobile Communications Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/of.h>
+#include <linux/regmap.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+
+struct qcom_coincell {
+       struct device   *dev;
+       struct regmap   *regmap;
+       u32             base_addr;
+};
+
+#define QCOM_COINCELL_REG_RSET         0x44
+#define QCOM_COINCELL_REG_VSET         0x45
+#define QCOM_COINCELL_REG_ENABLE       0x46
+
+#define QCOM_COINCELL_ENABLE           BIT(7)
+
+static const int qcom_rset_map[] = { 2100, 1700, 1200, 800 };
+static const int qcom_vset_map[] = { 2500, 3200, 3100, 3000 };
+/* NOTE: for pm8921 and others, voltage of 2500 is 16 (10000b), not 0 */
+
+/* if enable==0, rset and vset are ignored */
+static int qcom_coincell_chgr_config(struct qcom_coincell *chgr, int rset,
+                                    int vset, bool enable)
+{
+       int i, j, rc;
+
+       /* if disabling, just do that and skip other operations */
+       if (!enable)
+               return regmap_write(chgr->regmap,
+                         chgr->base_addr + QCOM_COINCELL_REG_ENABLE, 0);
+
+       /* find index for current-limiting resistor */
+       for (i = 0; i < ARRAY_SIZE(qcom_rset_map); i++)
+               if (rset == qcom_rset_map[i])
+                       break;
+
+       if (i >= ARRAY_SIZE(qcom_rset_map)) {
+               dev_err(chgr->dev, "invalid rset-ohms value %d\n", rset);
+               return -EINVAL;
+       }
+
+       /* find index for charge voltage */
+       for (j = 0; j < ARRAY_SIZE(qcom_vset_map); j++)
+               if (vset == qcom_vset_map[j])
+                       break;
+
+       if (j >= ARRAY_SIZE(qcom_vset_map)) {
+               dev_err(chgr->dev, "invalid vset-millivolts value %d\n", vset);
+               return -EINVAL;
+       }
+
+       rc = regmap_write(chgr->regmap,
+                         chgr->base_addr + QCOM_COINCELL_REG_RSET, i);
+       if (rc) {
+               /*
+                * This is mainly to flag a bad base_addr (reg) from dts.
+                * Other failures writing to the registers should be
+                * extremely rare, or indicative of problems that
+                * should be reported elsewhere (eg. spmi failure).
+                */
+               dev_err(chgr->dev, "could not write to RSET register\n");
+               return rc;
+       }
+
+       rc = regmap_write(chgr->regmap,
+               chgr->base_addr + QCOM_COINCELL_REG_VSET, j);
+       if (rc)
+               return rc;
+
+       /* set 'enable' register */
+       return regmap_write(chgr->regmap,
+                           chgr->base_addr + QCOM_COINCELL_REG_ENABLE,
+                           QCOM_COINCELL_ENABLE);
+}
+
+static int qcom_coincell_probe(struct platform_device *pdev)
+{
+       struct device_node *node = pdev->dev.of_node;
+       struct qcom_coincell chgr;
+       u32 rset, vset;
+       bool enable;
+       int rc;
+
+       chgr.dev = &pdev->dev;
+
+       chgr.regmap = dev_get_regmap(pdev->dev.parent, NULL);
+       if (!chgr.regmap) {
+               dev_err(chgr.dev, "Unable to get regmap\n");
+               return -EINVAL;
+       }
+
+       rc = of_property_read_u32(node, "reg", &chgr.base_addr);
+       if (rc)
+               return rc;
+
+       enable = !of_property_read_bool(node, "qcom,charger-disable");
+
+       if (enable) {
+               rc = of_property_read_u32(node, "qcom,rset-ohms", &rset);
+               if (rc) {
+                       dev_err(chgr.dev,
+                               "can't find 'qcom,rset-ohms' in DT block");
+                       return rc;
+               }
+
+               rc = of_property_read_u32(node, "qcom,vset-millivolts", &vset);
+               if (rc) {
+                       dev_err(chgr.dev,
+                           "can't find 'qcom,vset-millivolts' in DT block");
+                       return rc;
+               }
+       }
+
+       return qcom_coincell_chgr_config(&chgr, rset, vset, enable);
+}
+
+static const struct of_device_id qcom_coincell_match_table[] = {
+       { .compatible = "qcom,pm8941-coincell", },
+       {}
+};
+
+MODULE_DEVICE_TABLE(of, qcom_coincell_match_table);
+
+static struct platform_driver qcom_coincell_driver = {
+       .driver = {
+               .name           = "qcom-spmi-coincell",
+               .of_match_table = qcom_coincell_match_table,
+       },
+       .probe          = qcom_coincell_probe,
+};
+
+module_platform_driver(qcom_coincell_driver);
+
+MODULE_DESCRIPTION("Qualcomm PMIC coincell charger driver");
+MODULE_LICENSE("GPL v2");