w1: ds1wm: add a reset recovery parameter [Linux 3.0]

This Linux kernel change "w1: ds1wm: add a reset recovery parameter" is included in the Linux 3.0 release. This change is authored by Jean-François Dagenais <dagenaisj [at] sonatest.com> on Fri Jul 8 15:39:44 2011 -0700. The commit for this change in Linux stable tree is f607e7f (patch).

w1: ds1wm: add a reset recovery parameter

This fixes a regression in 3.0 reported by Paul Parsons regarding the
removal of the msleep(1) in the ds1wm_reset() function:

: The linux-3.0-rc4 DS1WM 1-wire driver is logging "bus error, retrying"
: error messages on an HP iPAQ hx4700 PDA (XScale-PXA270):
:
: <snip>
: Driver for 1-wire Dallas network protocol.
: DS1WM w1 busmaster driver - (c) 2004 Szabolcs Gyurko
: 1-Wire driver for the DS2760 battery monitor  chip  - (c) 2004-2005, Szabolcs Gyurko
: ds1wm ds1wm: pass: 1 bus error, retrying
: ds1wm ds1wm: pass: 2 bus error, retrying
: ds1wm ds1wm: pass: 3 bus error, retrying
: ds1wm ds1wm: pass: 4 bus error, retrying
: ds1wm ds1wm: pass: 5 bus error, retrying
: ...
:
: The visible result is that the battery charging LED is erratic; sometimes
: it works, mostly it doesn't.
:
: The linux-2.6.39 DS1WM 1-wire driver worked OK.  I haven't tried 3.0-rc1,
: 3.0-rc2, or 3.0-rc3.

This sleep should not be required on normal circuitry provided the
pull-ups on the bus are correctly adapted to the slaves.  Unfortunately,
this is not always the case.  The sleep is restored but as a parameter to
the probe function in the pdata.

[akpm@linux-foundation.org: coding-style fixes]
Reported-by: Paul Parsons <lost.distance@yahoo.com>
Tested-by: Paul Parsons <lost.distance@yahoo.com>
Signed-off-by: Jean-François Dagenais <dagenaisj@sonatest.com>
Cc: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

There are 14 lines of Linux source code added/deleted in this change. Code changes to Linux kernel are as follows.

 drivers/mfd/asic3.c        | 1 +
 drivers/mfd/htc-pasic3.c   | 1 +
 drivers/w1/masters/ds1wm.c | 5 +++++
 include/linux/mfd/ds1wm.h  | 7 +++++++
 4 files changed, 14 insertions(+)

diff --git a/drivers/mfd/asic3.c b/drivers/mfd/asic3.c
index c27fd1f..c71ae09 100644
--- a/drivers/mfd/asic3.c
+++ b/drivers/mfd/asic3.c
@@ -619,6 +619,7 @@ static void asic3_clk_disable(struct asic3 *asic, struct asic3_clk *clk)
 /* MFD cells (SPI, PWM, LED, DS1WM, MMC) */
 static struct ds1wm_driver_data ds1wm_pdata = {
    .active_high = 1,
+   .reset_recover_delay = 1,
 };

 static struct resource ds1wm_resources[] = {
diff --git a/drivers/mfd/htc-pasic3.c b/drivers/mfd/htc-pasic3.c
index 2808bd1..04c7093 100644
--- a/drivers/mfd/htc-pasic3.c
+++ b/drivers/mfd/htc-pasic3.c
@@ -99,6 +99,7 @@ static int ds1wm_disable(struct platform_device *pdev)

 static struct ds1wm_driver_data ds1wm_pdata = {
    .active_high = 0,
+   .reset_recover_delay = 1,
 };

 static struct resource ds1wm_resources[] __initdata = {
diff --git a/drivers/w1/masters/ds1wm.c b/drivers/w1/masters/ds1wm.c
index ad57593..a0c8965 100644
--- a/drivers/w1/masters/ds1wm.c
+++ b/drivers/w1/masters/ds1wm.c
@@ -109,6 +109,7 @@ struct ds1wm_data {
    /* byte to write that makes all intr disabled, */
    /* considering active_state (IAS) (optimization) */
    u8       int_en_reg_none;
+   unsigned int reset_recover_delay; /* see ds1wm.h */
 };

 static inline void ds1wm_write_register(struct ds1wm_data *ds1wm_data, u32 reg,
@@ -187,6 +188,9 @@ static int ds1wm_reset(struct ds1wm_data *ds1wm_data)
        return 1;
    }

+   if (ds1wm_data->reset_recover_delay)
+       msleep(ds1wm_data->reset_recover_delay);
+
    return 0;
 }

@@ -490,6 +494,7 @@ static int ds1wm_probe(struct platform_device *pdev)
    }
    ds1wm_data->irq = res->start;
    ds1wm_data->int_en_reg_none = (plat->active_high ? DS1WM_INTEN_IAS : 0);
+   ds1wm_data->reset_recover_delay = plat->reset_recover_delay;

    if (res->flags & IORESOURCE_IRQ_HIGHEDGE)
        irq_set_irq_type(ds1wm_data->irq, IRQ_TYPE_EDGE_RISING);
diff --git a/include/linux/mfd/ds1wm.h b/include/linux/mfd/ds1wm.h
index be469a3..38a372a 100644
--- a/include/linux/mfd/ds1wm.h
+++ b/include/linux/mfd/ds1wm.h
@@ -3,4 +3,11 @@
 struct ds1wm_driver_data {
    int active_high;
    int clock_rate;
+   /* in milliseconds, the amount of time to */
+   /* sleep following a reset pulse. Zero    */
+   /* should work if your bus devices recover*/
+   /* time respects the 1-wire spec since the*/
+   /* ds1wm implements the precise timings of*/
+   /* a reset pulse/presence detect sequence.*/
+   unsigned int reset_recover_delay;
 };

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