From 345b19bca4b1c336f61f17b9aa6a180d934b299f Mon Sep 17 00:00:00 2001
From: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Date: Thu, 15 Sep 2016 10:32:03 +0200
Subject: mfd: axp20x: Provide interface for add-on drivers

Add-on drivers (e.g. hwmon) utilising a AXP20x, AXP22x or AXP80x need
access to the regmap provided by the device, but no interface for
retrieving the device/interface exists.

This adds a new function axp20x_node_to_regmap(), modelled after the
similar syscon_node_to_regmap(), to gain access to the regmap for
a AXP-node with a fully loaded driver.

Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
---
 drivers/mfd/axp20x.c       | 29 ++++++++++++++++++++++++++++-
 include/linux/mfd/axp20x.h | 13 +++++++++++++
 2 files changed, 41 insertions(+), 1 deletion(-)

diff --git a/drivers/mfd/axp20x.c b/drivers/mfd/axp20x.c
index 96102753847f..b8324f5dc078 100644
--- a/drivers/mfd/axp20x.c
+++ b/drivers/mfd/axp20x.c
@@ -28,9 +28,11 @@
 #include <linux/mfd/core.h>
 #include <linux/of_device.h>
 #include <linux/acpi.h>
-
 #define AXP20X_OFF	0x80
 
+static DEFINE_SPINLOCK(axp20x_list_slock);
+static LIST_HEAD(axp20x_list);
+
 static const char * const axp20x_model_names[] = {
 	"AXP152",
 	"AXP202",
@@ -821,6 +823,27 @@ int axp20x_match_device(struct axp20x_dev *axp20x)
 }
 EXPORT_SYMBOL(axp20x_match_device);
 
+struct regmap *axp20x_node_to_regmap(struct device_node *np)
+{
+	struct axp20x_dev *entry, *axp20x = NULL;
+
+	spin_lock(&axp20x_list_slock);
+
+	list_for_each_entry(entry, &axp20x_list, list)
+		if (entry->dev && entry->dev->of_node == np) {
+			axp20x = entry;
+			break;
+		}
+
+	spin_unlock(&axp20x_list_slock);
+
+	if (axp20x)
+		return axp20x->regmap;
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(syscon_node_to_regmap);
+
 int axp20x_device_probe(struct axp20x_dev *axp20x)
 {
 	int ret;
@@ -848,6 +871,10 @@ int axp20x_device_probe(struct axp20x_dev *axp20x)
 		pm_power_off = axp20x_power_off;
 	}
 
+	spin_lock(&axp20x_list_slock);
+	list_add_tail(&axp20x->list, &axp20x_list);
+	spin_unlock(&axp20x_list_slock);
+
 	dev_info(axp20x->dev, "AXP20X driver loaded\n");
 
 	return 0;
diff --git a/include/linux/mfd/axp20x.h b/include/linux/mfd/axp20x.h
index fec597fb34cb..2ecf8c0b13d1 100644
--- a/include/linux/mfd/axp20x.h
+++ b/include/linux/mfd/axp20x.h
@@ -11,6 +11,7 @@
 #ifndef __LINUX_MFD_AXP20X_H
 #define __LINUX_MFD_AXP20X_H
 
+#include <linux/list.h>
 #include <linux/regmap.h>
 
 enum {
@@ -524,6 +525,7 @@ struct axp20x_dev {
 	struct mfd_cell                 *cells;
 	const struct regmap_config	*regmap_cfg;
 	const struct regmap_irq_chip	*regmap_irq_chip;
+	struct list_head                list;
 };
 
 #define BATTID_LEN				64
@@ -593,6 +595,17 @@ static inline int axp20x_read_variable_width(struct regmap *regmap,
  */
 int axp20x_match_device(struct axp20x_dev *axp20x);
 
+/**
+ * axp20x_node_to_regmap(): Find the regmap for a axp20x device
+ *
+ * @np: node-pointer to the axp20x device
+ *
+ * This function lets add-on drivers (e.g. axp809-thermal) retrieve
+ * a registered axp20x device's regmap. The device must be fully
+ * configured or NULL will be returned.
+ */
+struct regmap *axp20x_node_to_regmap(struct device_node *np);
+
 /**
  * axp20x_device_probe(): Probe a configured axp20x device
  *
-- 
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