TPS65911: Comparator: Add comparator driver

This driver adds functionality to the tps65911 chip driver.

Two of the comparators are configurable by software and measures
VCCS voltage to detect high or low voltage scenarios.
Signed-off-by: Jorge Eduardo Candelaria <jedu@slimlogic.co.uk>
Acked-by: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>

drivers/mfd/tps65911-comparator.c

+/*
+ * tps65910.c  --  TI TPS6591x
+ *
+ * Copyright 2010 Texas Instruments Inc.
+ *
+ * Author: Jorge Eduardo Candelaria <jedu@slimlogic.co.uk>
+ *
+ *  This program is free software; you can redistribute it and/or modify it
+ *  under  the terms of the GNU General  Public License as published by the
+ *  Free Software Foundation;  either version 2 of the License, or (at your
+ *  option) any later version.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+#include <linux/platform_device.h>
+#include <linux/debugfs.h>
+#include <linux/gpio.h>
+#include <linux/mfd/tps65910.h>
+
+#define COMP					0
+#define COMP1					1
+#define COMP2					2
+
+/* Comparator 1 voltage selection table in milivolts */
+static const u16 COMP_VSEL_TABLE[] = {
+	0, 2500, 2500, 2500, 2500, 2550, 2600, 2650,
+	2700, 2750, 2800, 2850, 2900, 2950, 3000, 3050,
+	3100, 3150, 3200, 3250, 3300, 3350, 3400, 3450,
+	3500,
+};
+
+struct comparator {
+	const char *name;
+	int reg;
+	int uV_max;
+	const u16 *vsel_table;
+};
+
+static struct comparator tps_comparators[] = {
+	{
+		.name = "COMP1",
+		.reg = TPS65911_VMBCH,
+		.uV_max = 3500,
+		.vsel_table = COMP_VSEL_TABLE,
+	},
+	{
+		.name = "COMP2",
+		.reg = TPS65911_VMBCH2,
+		.uV_max = 3500,
+		.vsel_table = COMP_VSEL_TABLE,
+	},
+};
+
+static int comp_threshold_set(struct tps65910 *tps65910, int id, int voltage)
+{
+	struct comparator tps_comp = tps_comparators[id];
+	int curr_voltage = 0;
+	int ret;
+	u8 index = 0, val;
+
+	if (id == COMP)
+		return 0;
+
+	while (curr_voltage < tps_comp.uV_max) {
+		curr_voltage = tps_comp.vsel_table[index];
+		if (curr_voltage >= voltage)
+			break;
+		else if (curr_voltage < voltage)
+			index ++;
+	}
+
+	if (curr_voltage > tps_comp.uV_max)
+		return -EINVAL;
+
+	val = index << 1;
+	ret = tps65910->write(tps65910, tps_comp.reg, 1, &val);
+
+	return ret;
+}
+
+static int comp_threshold_get(struct tps65910 *tps65910, int id)
+{
+	struct comparator tps_comp = tps_comparators[id];
+	int ret;
+	u8 val;
+
+	if (id == COMP)
+		return 0;
+
+	ret = tps65910->read(tps65910, tps_comp.reg, 1, &val);
+	if (ret < 0)
+		return ret;
+
+	val >>= 1;
+	return tps_comp.vsel_table[val];
+}
+
+static ssize_t comp_threshold_show(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct tps65910 *tps65910 = dev_get_drvdata(dev->parent);
+	struct attribute comp_attr = attr->attr;
+	int id, uVolt;
+
+	if (!strcmp(comp_attr.name, "comp1_threshold"))
+		id = COMP1;
+	else if (!strcmp(comp_attr.name, "comp2_threshold"))
+		id = COMP2;
+	else
+		return -EINVAL;
+
+	uVolt = comp_threshold_get(tps65910, id);
+
+	return sprintf(buf, "%d\n", uVolt);
+}
+
+static DEVICE_ATTR(comp1_threshold, S_IRUGO, comp_threshold_show, NULL);
+static DEVICE_ATTR(comp2_threshold, S_IRUGO, comp_threshold_show, NULL);
+
+static __devinit int tps65911_comparator_probe(struct platform_device *pdev)
+{
+	struct tps65910 *tps65910 = dev_get_drvdata(pdev->dev.parent);
+	struct tps65910_platform_data *pdata = dev_get_platdata(tps65910->dev);
+	int ret;
+
+	ret = comp_threshold_set(tps65910, COMP1,  pdata->vmbch_threshold);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "cannot set COMP1 threshold\n");
+		return ret;
+	}
+
+	ret = comp_threshold_set(tps65910, COMP2, pdata->vmbch2_threshold);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "cannot set COMP2 theshold\n");
+		return ret;
+	}
+
+	/* Create sysfs entry */
+	ret = device_create_file(&pdev->dev, &dev_attr_comp1_threshold);
+	if (ret < 0)
+		dev_err(&pdev->dev, "failed to add COMP1 sysfs file\n");
+
+	ret = device_create_file(&pdev->dev, &dev_attr_comp2_threshold);
+	if (ret < 0)
+		dev_err(&pdev->dev, "failed to add COMP2 sysfs file\n");
+
+	return ret;
+}
+
+static __devexit int tps65911_comparator_remove(struct platform_device *pdev)
+{
+	struct tps65910 *tps65910;
+
+	tps65910 = dev_get_drvdata(pdev->dev.parent);
+
+	return 0;
+}
+
+static struct platform_driver tps65911_comparator_driver = {
+	.driver = {
+		.name = "tps65911-comparator",
+		.owner = THIS_MODULE,
+	},
+	.probe = tps65911_comparator_probe,
+	.remove = __devexit_p(tps65911_comparator_remove),
+};
+
+static int __init tps65911_comparator_init(void)
+{
+	return platform_driver_register(&tps65911_comparator_driver);
+}
+subsys_initcall(tps65911_comparator_init);
+
+static void __exit tps65911_comparator_exit(void)
+{
+	platform_driver_unregister(&tps65911_comparator_driver);
+}
+module_exit(tps65911_comparator_exit);
+
+MODULE_AUTHOR("Jorge Eduardo Candelaria <jedu@slimlogic.co.uk>");
+MODULE_DESCRIPTION("TPS65911 comparator driver");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:tps65911-comparator");

include/linux/mfd/tps65910.h

@@ -121,6 +121,8 @@
 #define TPS65911_LDO6					0x35
 #define TPS65911_LDO4					0x36
 #define TPS65911_LDO3					0x37
+#define TPS65911_VMBCH					0x6A
+#define TPS65911_VMBCH2					0x6B
 
 /*
  * List of register bitfields for component TPS65910
@@ -746,6 +748,8 @@ struct tps65910_board {
 	int gpio_base;
 	int irq;
 	int irq_base;
+	int vmbch_threshold;
+	int vmbch2_threshold;
 	struct regulator_init_data *tps65910_pmic_init_data;
 };