contiki/cpu/cc26xx/clock.c
Benoît Thébaudeau 19fd7a3551 Use additive offsets
OR-ing an offset to a base address instead of adding it is dangerous
because it can only work if the base address is aligned enough for the
offset.

Moreover, if the base address or the offset has a value unknown at
compile time, then the assembly instructions dedicated to 'base +
offset' addressing on most CPUs can't be emitted by the compiler because
this would require the alignment of the base address against the offset
to be known in order to optimize 'base | offset' into 'base + offset'.
In that case, the compiler has to emit more instructions in order to
compute 'base | offset' on most CPUs, e.g. on ARM, which means larger
binary size and slower execution.

Hence, replace all occurrences of 'base | offset' with 'base + offset'.
This must become a coding rule.

Here are the results for the cc2538-demo example:
 - Compilation of uart_init():
    * before:
        REG(regs->base | UART_CC) = 0;
        200b78:	f446 637c 	orr.w	r3, r6, #4032	; 0xfc0
        200b7c:	f043 0308 	orr.w	r3, r3, #8
        200b80:	2200      	movs	r2, #0
        200b82:	601a      	str	r2, [r3, #0]

    * now:
        REG(regs->base + UART_CC) = 0;
        200b7a:	2300      	movs	r3, #0
        200b7c:	f8c4 3fc8 	str.w	r3, [r4, #4040]	; 0xfc8

 - Size of the .text section:
    * before:	0x4c7c
    * now:	0x4c28
    * saved:	84 bytes

Signed-off-by: Benoît Thébaudeau <benoit.thebaudeau.dev@gmail.com>
2015-03-28 17:28:15 +01:00

190 lines
5.7 KiB
C

/*
* Copyright (c) 2014, Texas Instruments Incorporated - http://www.ti.com/
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the copyright holder nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*---------------------------------------------------------------------------*/
/**
* \addtogroup platform
* @{
*
* \defgroup cc26xx-platforms TI CC26xx-powered Platforms
* @{
*
* \defgroup cc26xx The TI CC26xx CPU
* @{
*
* \addtogroup cc26xx-clocks
* @{
*
* \defgroup cc26xx-software-clock CC26xx Software Clock
*
* Implementation of the clock module for the cc26xx.
*
* The software clock uses the facilities provided by the AON RTC driver
* @{
*
* \file
* Software clock implementation for the TI CC26xx
*/
/*---------------------------------------------------------------------------*/
#include "contiki.h"
#include "ti-lib.h"
/*---------------------------------------------------------------------------*/
static volatile clock_time_t count;
static volatile clock_time_t second_countdown;
static volatile unsigned long secs;
/*---------------------------------------------------------------------------*/
static void
power_domain_on(void)
{
ti_lib_prcm_power_domain_on(PRCM_DOMAIN_PERIPH);
while(ti_lib_prcm_power_domain_status(PRCM_DOMAIN_PERIPH) !=
PRCM_DOMAIN_POWER_ON);
}
/*---------------------------------------------------------------------------*/
void
clock_init(void)
{
count = 0;
secs = 0;
second_countdown = CLOCK_SECOND;
/*
* Here, we configure GPT0 Timer A, which we subsequently use in
* clock_delay_usec
*
* First, enable GPT0 in run mode. We don't need it in sleep mode
*/
ti_lib_prcm_peripheral_run_enable(PRCM_PERIPH_TIMER0);
ti_lib_prcm_load_set();
while(!ti_lib_prcm_load_get());
/* Disable both GPT0 timers */
HWREG(GPT0_BASE + GPT_O_CTL) &= ~(GPT_CTL_TAEN | GPT_CTL_TBEN);
/*
* We assume that the clock is running at 48MHz, we use GPT0 Timer A,
* one-shot, countdown, prescaled by 48 gives us 1 tick per usec
*/
ti_lib_timer_configure(GPT0_BASE,
TIMER_CFG_SPLIT_PAIR | TIMER_CFG_B_ONE_SHOT);
/* Global config: split pair (2 x 16-bit wide) */
HWREG(GPT0_BASE + GPT_O_CFG) = TIMER_CFG_SPLIT_PAIR >> 24;
/*
* Pre-scale value 47 pre-scales by 48
*
* ToDo: The theoretical value here should be 47 (to provide x48 prescale)
* However, 49 seems to give results much closer to the desired delay
*/
ti_lib_timer_prescale_set(GPT0_BASE, TIMER_B, 49);
/* GPT0 / Timer B: One shot, PWM interrupt enable */
HWREG(GPT0_BASE + GPT_O_TBMR) =
((TIMER_CFG_B_ONE_SHOT >> 8) & 0xFF) | GPT_TBMR_TBPWMIE;
}
/*---------------------------------------------------------------------------*/
CCIF clock_time_t
clock_time(void)
{
return count;
}
/*---------------------------------------------------------------------------*/
void
clock_update(void)
{
count++;
if(etimer_pending()) {
etimer_request_poll();
}
if(--second_countdown == 0) {
secs++;
second_countdown = CLOCK_SECOND;
}
}
/*---------------------------------------------------------------------------*/
void
clock_set_seconds(unsigned long sec)
{
secs = sec;
}
/*---------------------------------------------------------------------------*/
CCIF unsigned long
clock_seconds(void)
{
return secs;
}
/*---------------------------------------------------------------------------*/
void
clock_wait(clock_time_t i)
{
clock_time_t start;
start = clock_time();
while(clock_time() - start < (clock_time_t)i);
}
/*---------------------------------------------------------------------------*/
void
clock_delay_usec(uint16_t len)
{
if(ti_lib_prcm_power_domain_status(PRCM_DOMAIN_PERIPH) !=
PRCM_DOMAIN_POWER_ON) {
power_domain_on();
}
ti_lib_timer_load_set(GPT0_BASE, TIMER_B, len);
ti_lib_timer_enable(GPT0_BASE, TIMER_B);
/*
* Wait for TBEN to clear. CC26xxware does not provide us with a convenient
* function, hence the direct register access here
*/
while(HWREG(GPT0_BASE + GPT_O_CTL) & GPT_CTL_TBEN);
}
/*---------------------------------------------------------------------------*/
/**
* \brief Obsolete delay function but we implement it here since some code
* still uses it
*/
void
clock_delay(unsigned int i)
{
clock_delay_usec(i);
}
/*---------------------------------------------------------------------------*/
/**
* @}
* @}
* @}
* @}
* @}
*/