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>

1 files changed, 45 insertions, 6 deletions

diff --git a/drivers/w1/masters/ds2482.c b/drivers/w1/masters/ds2482.c
index 6429b9e9fb82..e033491fe308 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) {