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Gigabeat S: Implement a genuine udelay function. Timer is gated to not run in WFI mode to save power and as such time until rollover is variable.

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git-svn-id: svn://svn.rockbox.org/rockbox/trunk@19820 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Michael Sevakis 2009-01-23 01:23:25 +00:00
parent da76a34694
commit 7bcfc38b42
4 changed files with 123 additions and 19 deletions
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8
firmware/target/arm/imx31/gigabeat-s/button-imx31.c
View file

@ -68,8 +68,6 @@ static __attribute__((interrupt("IRQ"))) void KPP_HANDLER(void)
for (col = 0; col < 3; col++) /* Col */
{
int i;
/* 2. Write 1s to KPDR[10:8] setting column data to 1s */
KPP_KPDR |= (0x7 << 8);
@ -78,8 +76,7 @@ static __attribute__((interrupt("IRQ"))) void KPP_HANDLER(void)
KPP_KPCR &= ~(0x7 << 8);
/* Give the columns time to discharge */
for (i = 0; i < 128; i++) /* TODO: find minimum safe delay */
asm volatile ("");
udelay(2);
/* 4. Configure columns as open-drain */
KPP_KPCR |= (0x7 << 8);
@ -94,8 +91,7 @@ static __attribute__((interrupt("IRQ"))) void KPP_HANDLER(void)
/* Delay added to avoid propagating the 0 from column to row
* when scanning. */
for (i = 0; i < 128; i++) /* TODO: find minimum safe delay */
asm volatile ("");
udelay(2);
/* Read row input */
button |= (~KPP_KPDR & kms[col].mask) << kms[col].shift;

31
firmware/target/arm/imx31/gigabeat-s/system-imx31.c
View file

@ -32,6 +32,8 @@
#include "clkctl-imx31.h"
#include "mc13783.h"
/** Watchdog timer routines **/
/* Initialize the watchdog timer */
void watchdog_init(unsigned int half_seconds)
{
@ -57,6 +59,33 @@ void watchdog_service(void)
WDOG_WSR = 0xaaaa;
}
/** GPT timer routines - basis for udelay **/
/* Start the general-purpose timer (1MHz) */
void gpt_start(void)
{
imx31_clkctl_module_clock_gating(CG_GPT, CGM_ON_RUN_WAIT);
unsigned int ipg_mhz = imx31_clkctl_get_ipg_clk() / 1000000;
GPTCR &= ~GPTCR_EN; /* Disable counter */
GPTCR |= GPTCR_SWR; /* Reset module */
while (GPTCR & GPTCR_SWR);
/* No output
* No capture
* Enable in run mode only (doesn't tick while in WFI)
* Freerun mode (count to 0xFFFFFFFF and roll-over to 0x00000000)
*/
GPTCR = GPTCR_FRR | GPTCR_CLKSRC_IPG_CLK;
GPTPR = ipg_mhz - 1;
GPTCR |= GPTCR_EN;
}
/* Stop the general-purpose timer */
void gpt_stop(void)
{
GPTCR &= ~GPTCR_EN;
}
int system_memory_guard(int newmode)
{
(void)newmode;
@ -84,7 +113,6 @@ void system_init(void)
/* CGR0 */
CG_SD_MMC1,
CG_SD_MMC2,
CG_GPT,
CG_IIM,
CG_SDMA,
CG_CSPI3,
@ -140,6 +168,7 @@ void system_init(void)
imx31_clkctl_module_clock_gating(disable_clocks[i], CGM_OFF);
avic_init();
gpt_start();
gpio_init();
}

17
firmware/target/arm/imx31/gigabeat-s/system-target.h
View file

@ -31,25 +31,18 @@
#define CPUFREQ_MAX CPU_FREQ
#endif
/* For USB driver - no accuracy assurance */
static inline void udelay(unsigned int usecs)
{
unsigned int x;
for (x = 0; x < 300*usecs; x++)
asm volatile ("");
unsigned stop = GPTCNT + usecs;
while (TIME_BEFORE(GPTCNT, stop));
}
#if 0
static inline void udelay(unsigned int usecs)
{
volatile signed int stop = EPITCNT1 - usecs;
while ((signed int)EPITCNT1 > stop);
}
#endif
void watchdog_init(unsigned int half_seconds);
void watchdog_service(void);
void gpt_start(void);
void gpt_stop(void);
/* Prepare for transition to firmware */
void system_prepare_fw_start(void);
void tick_stop(void);