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am335x: Enable RTC 32K OSC clock

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In order to support low power state, you must source kernel system
timers to persistent clock, available across suspend/resume.  In case of
AM335x device, the only source we have is, RTC32K, available in
wakeup/always-on domain.  Having said that, during validation it has
been observed that, RTC clock need couple of seconds delay to stabilize
the RTC OSC clock; and such a huge delay is not acceptable in kernel
especially during early init and also it will impact quick/fast boot
use-cases.

So, RTC32k OSC enable dependency has been shifted to
SPL/first-bootloader.

Signed-off-by: Vaibhav Hiremath <hvaibhav@ti.com>
Signed-off-by: Tom Rini <trini@ti.com>
This commit is contained in:
Vaibhav Hiremath 2012-03-08 17:15:47 +05:30 committed by Tom Rini
parent 3530a35d74
commit 000820b583
4 changed files with 45 additions and 1 deletions
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21
arch/arm/cpu/armv7/am33xx/board.c
View File

@ -116,11 +116,27 @@ static int read_eeprom(void)
return 0;
}
/* UART Defines */
#ifdef CONFIG_SPL_BUILD
/* UART Defines */
#define UART_RESET (0x1 << 1)
#define UART_CLK_RUNNING_MASK 0x1
#define UART_SMART_IDLE_EN (0x1 << 0x3)
static void rtc32k_enable(void)
{
struct rtc_regs *rtc = (struct rtc_regs *)AM335X_RTC_BASE;
/*
* Unlock the RTC's registers. For more details please see the
* RTC_SS section of the TRM. In order to unlock we need to
* write these specific values (keys) in this order.
*/
writel(0x83e70b13, &rtc->kick0r);
writel(0x95a4f1e0, &rtc->kick1r);
/* Enable the RTC 32K OSC by setting bits 3 and 6. */
writel((1 << 3) | (1 << 6), &rtc->osc);
}
#endif
/*
@ -154,6 +170,9 @@ void s_init(void)
/* Setup the PLLs and the clocks for the peripherals */
pll_init();
/* Enable RTC32K clock */
rtc32k_enable();
/* UART softreset */
u32 regVal;

6
arch/arm/cpu/armv7/am33xx/clock.c
View File

@ -44,6 +44,7 @@
const struct cm_perpll *cmper = (struct cm_perpll *)CM_PER;
const struct cm_wkuppll *cmwkup = (struct cm_wkuppll *)CM_WKUP;
const struct cm_dpll *cmdpll = (struct cm_dpll *)CM_DPLL;
const struct cm_rtc *cmrtc = (struct cm_rtc *)CM_RTC;
static void enable_interface_clocks(void)
{
@ -153,6 +154,11 @@ static void enable_per_clocks(void)
writel(PRCM_MOD_EN, &cmper->spi0clkctrl);
while (readl(&cmper->spi0clkctrl) != PRCM_MOD_EN)
;
/* RTC */
writel(PRCM_MOD_EN, &cmrtc->rtcclkctrl);
while (readl(&cmrtc->rtcclkctrl) != PRCM_MOD_EN)
;
}
static void mpu_pll_config(void)

15
arch/arm/include/asm/arch-am33xx/cpu.h
View File

@ -169,6 +169,12 @@ struct cm_dpll {
unsigned int clktimer2clk; /* offset 0x08 */
};
/* Control Module RTC registers */
struct cm_rtc {
unsigned int rtcclkctrl; /* offset 0x0 */
unsigned int clkstctrl; /* offset 0x4 */
};
/* Watchdog timer registers */
struct wd_timer {
unsigned int resv1[4];
@ -218,6 +224,15 @@ struct gptimer {
unsigned int tcar2; /* offset 0x58 */
};
/* RTC Registers */
struct rtc_regs {
unsigned int res[21];
unsigned int osc; /* offset 0x54 */
unsigned int res2[5];
unsigned int kick0r; /* offset 0x6c */
unsigned int kick1r; /* offset 0x70 */
};
/* UART Registers */
struct uart_sys {
unsigned int resv1[21];

4
arch/arm/include/asm/arch-am33xx/hardware.h
View File

@ -61,6 +61,7 @@
#define CM_WKUP 0x44E00400
#define CM_DPLL 0x44E00500
#define CM_DEVICE 0x44E00700
#define CM_RTC 0x44E00800
#define CM_CEFUSE 0x44E00A00
#define PRM_DEVICE 0x44E00F00
@ -83,4 +84,7 @@
#define AM335X_CPSW_BASE 0x4A100000
#define AM335X_CPSW_MDIO_BASE 0x4A101000
/* RTC base address */
#define AM335X_RTC_BASE 0x44E3E000
#endif /* __AM33XX_HARDWARE_H */