diff options
Diffstat (limited to 'common/onewire.c')
| -rw-r--r-- | common/onewire.c | 30 |
1 files changed, 16 insertions, 14 deletions
diff --git a/common/onewire.c b/common/onewire.c index cdb5837255..0b109bbdcd 100644 --- a/common/onewire.c +++ b/common/onewire.c @@ -1,4 +1,4 @@ -/* Copyright 2012 The Chromium OS Authors. All rights reserved. +/* Copyright 2012 The ChromiumOS Authors * Use of this source code is governed by a BSD-style license that can be * found in the LICENSE file. */ @@ -16,16 +16,19 @@ * Note that these timing are actually _longer_ than legacy 1-wire standard * speed because we're running the 1-wire bus at 3.3V instead of 5V. */ -#define T_RSTL 602 /* Reset low pulse; 600-960 us */ -#define T_MSP 72 /* Presence detect sample time; 70-75 us */ -#define T_RSTH (68 + 260 + 5 + 2) /* Reset high; tPDHmax + tPDLmax + tRECmin */ -#define T_SLOT 70 /* Timeslot; >67 us */ -#define T_W0L 63 /* Write 0 low; 62-120 us */ -#define T_W1L 7 /* Write 1 low; 5-15 us */ -#define T_RL 7 /* Read low; 5-15 us */ -#define T_MSR 9 /* Read sample time; <15 us. Must be at least 200 ns after - * T_RL since that's how long the signal takes to be pulled - * up on our board. */ +#define T_RSTL 602 /* Reset low pulse; 600-960 us */ +#define T_MSP 72 /* Presence detect sample time; 70-75 us */ +#define T_RSTH \ + (68 + 260 + 5 + 2) /* Reset high; tPDHmax + tPDLmax + tRECmin \ + */ +#define T_SLOT 70 /* Timeslot; >67 us */ +#define T_W0L 63 /* Write 0 low; 62-120 us */ +#define T_W1L 7 /* Write 1 low; 5-15 us */ +#define T_RL 7 /* Read low; 5-15 us */ +#define T_MSR \ + 9 /* Read sample time; <15 us. Must be at least 200 ns after \ + * T_RL since that's how long the signal takes to be pulled \ + * up on our board. */ /** * Output low on the bus for <usec> us, then switch back to open-drain input. @@ -98,7 +101,6 @@ static void writebit(int bit) interrupt_enable(); udelay(T_SLOT - T_W0L); } - } int onewire_reset(void) @@ -133,7 +135,7 @@ int onewire_read(void) int i; for (i = 0; i < 8; i++) - data |= readbit() << i; /* LSB first */ + data |= readbit() << i; /* LSB first */ return data; } @@ -143,5 +145,5 @@ void onewire_write(int data) int i; for (i = 0; i < 8; i++) - writebit((data >> i) & 0x01); /* LSB first */ + writebit((data >> i) & 0x01); /* LSB first */ } |