From 9c95bb6f25ff802081125f24bf0c756252fa27b2 Mon Sep 17 00:00:00 2001
From: Michael Arndt <michael@scriptkiller.de>
Date: Sun, 17 Feb 2013 20:31:27 +0100
Subject: w1: ds2482: Added 1-Wire pull-up support to the driver

Signed-off-by: Michael Arndt <michael@scriptkiller.de>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/w1/masters/ds2482.c b/drivers/w1/masters/ds2482.c
index 6429b9e..e033491 100644
--- a/drivers/w1/masters/ds2482.c
+++ b/drivers/w1/masters/ds2482.c
@@ -51,10 +51,10 @@
  * The top 4 bits always read 0.
  * To write, the top nibble must be the 1's compl. of the low nibble.
  */
-#define DS2482_REG_CFG_1WS		0x08
-#define DS2482_REG_CFG_SPU		0x04
-#define DS2482_REG_CFG_PPM		0x02
-#define DS2482_REG_CFG_APU		0x01
+#define DS2482_REG_CFG_1WS		0x08	/* 1-wire speed */
+#define DS2482_REG_CFG_SPU		0x04	/* strong pull-up */
+#define DS2482_REG_CFG_PPM		0x02	/* presence pulse masking */
+#define DS2482_REG_CFG_APU		0x01	/* active pull-up */
 
 
 /**
@@ -132,6 +132,17 @@ struct ds2482_data {
 
 
 /**
+ * Helper to calculate values for configuration register
+ * @param conf the raw config value
+ * @return the value w/ complements that can be written to register
+ */
+static inline u8 ds2482_calculate_config(u8 conf)
+{
+	return conf | ((~conf & 0x0f) << 4);
+}
+
+
+/**
  * Sets the read pointer.
  * @param pdev		The ds2482 client pointer
  * @param read_ptr	see DS2482_PTR_CODE_xxx above
@@ -399,7 +410,7 @@ static u8 ds2482_w1_reset_bus(void *data)
 		/* If the chip did reset since detect, re-config it */
 		if (err & DS2482_REG_STS_RST)
 			ds2482_send_cmd_data(pdev, DS2482_CMD_WRITE_CONFIG,
-					     0xF0);
+					     ds2482_calculate_config(0x00));
 	}
 
 	mutex_unlock(&pdev->access_lock);
@@ -407,6 +418,32 @@ static u8 ds2482_w1_reset_bus(void *data)
 	return retval;
 }
 
+static u8 ds2482_w1_set_pullup(void *data, int delay)
+{
+	struct ds2482_w1_chan *pchan = data;
+	struct ds2482_data    *pdev = pchan->pdev;
+	u8 retval = 1;
+
+	/* if delay is non-zero activate the pullup,
+	 * the strong pullup will be automatically deactivated
+	 * by the master, so do not explicitly deactive it
+	 */
+	if (delay) {
+		/* both waits are crucial, otherwise devices might not be
+		 * powered long enough, causing e.g. a w1_therm sensor to
+		 * provide wrong conversion results
+		 */
+		ds2482_wait_1wire_idle(pdev);
+		/* note: it seems like both SPU and APU have to be set! */
+		retval = ds2482_send_cmd_data(pdev, DS2482_CMD_WRITE_CONFIG,
+			ds2482_calculate_config(DS2482_REG_CFG_SPU |
+						DS2482_REG_CFG_APU));
+		ds2482_wait_1wire_idle(pdev);
+	}
+
+	return retval;
+}
+
 
 static int ds2482_probe(struct i2c_client *client,
 			const struct i2c_device_id *id)
@@ -452,7 +489,8 @@ static int ds2482_probe(struct i2c_client *client,
 		data->w1_count = 8;
 
 	/* Set all config items to 0 (off) */
-	ds2482_send_cmd_data(data, DS2482_CMD_WRITE_CONFIG, 0xF0);
+	ds2482_send_cmd_data(data, DS2482_CMD_WRITE_CONFIG,
+		ds2482_calculate_config(0x00));
 
 	mutex_init(&data->access_lock);
 
@@ -468,6 +506,7 @@ static int ds2482_probe(struct i2c_client *client,
 		data->w1_ch[idx].w1_bm.touch_bit  = ds2482_w1_touch_bit;
 		data->w1_ch[idx].w1_bm.triplet    = ds2482_w1_triplet;
 		data->w1_ch[idx].w1_bm.reset_bus  = ds2482_w1_reset_bus;
+		data->w1_ch[idx].w1_bm.set_pullup = ds2482_w1_set_pullup;
 
 		err = w1_add_master_device(&data->w1_ch[idx].w1_bm);
 		if (err) {
-- 
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