From: Vaibhav Hiremath <hvaibhav at ti.com>
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 at ti.com>
Signed-off-by: Tom Rini <trini at ti.com>
---
arch/arm/cpu/armv7/am33xx/board.c | 21 ++++++++++++++++++++-
arch/arm/cpu/armv7/am33xx/clock.c | 6 ++++++
arch/arm/include/asm/arch-am33xx/cpu.h | 15 +++++++++++++++
arch/arm/include/asm/arch-am33xx/hardware.h | 4 ++++
4 files changed, 45 insertions(+), 1 deletion(-)
diff --git a/arch/arm/cpu/armv7/am33xx/board.c b/arch/arm/cpu/armv7/am33xx/board.c
index 6de03fd..f6589c2 100644
--- a/arch/arm/cpu/armv7/am33xx/board.c
+++ b/arch/arm/cpu/armv7/am33xx/board.c
@@ -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;
diff --git a/arch/arm/cpu/armv7/am33xx/clock.c b/arch/arm/cpu/armv7/am33xx/clock.c
index 2b19506..f870859 100644
--- a/arch/arm/cpu/armv7/am33xx/clock.c
+++ b/arch/arm/cpu/armv7/am33xx/clock.c
@@ -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)
diff --git a/arch/arm/include/asm/arch-am33xx/cpu.h b/arch/arm/include/asm/arch-am33xx/cpu.h
index 6cfbef7..88057a3 100644
--- a/arch/arm/include/asm/arch-am33xx/cpu.h
+++ b/arch/arm/include/asm/arch-am33xx/cpu.h
@@ -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[6];
+ unsigned int kick0r; /* offset 0x6c */
+ unsigned int kick1r; /* offset 0x70 */
+};
+
/* UART Registers */
struct uart_sys {
unsigned int resv1[21];
diff --git a/arch/arm/include/asm/arch-am33xx/hardware.h b/arch/arm/include/asm/arch-am33xx/hardware.h
index 62332f2..5bd4bc8 100644
--- a/arch/arm/include/asm/arch-am33xx/hardware.h
+++ b/arch/arm/include/asm/arch-am33xx/hardware.h
@@ -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 */
--
1.7.9.5