[LEDE-DEV] [PATCH 2/2] mvebu: Add Solidrun RTC init patch.

[Rosen Penev]

Some boards like the Turris Omnia have an RTC chip that does not get initialized. Initializing the RTC at the driver level helps get rid of bootloader hacks that write special register values.

Signed-off-by: Rosen Penev <rosenp at gmail.com>
---
 .../mvebu/patches-4.14/421-rtc-initialize.patch    | 70 ++++++++++++++++++++++
 1 file changed, 70 insertions(+)
 create mode 100644 target/linux/mvebu/patches-4.14/421-rtc-initialize.patch

diff --git a/target/linux/mvebu/patches-4.14/421-rtc-initialize.patch b/target/linux/mvebu/patches-4.14/421-rtc-initialize.patch
new file mode 100644
index 0000000000..b6b96c985c
--- /dev/null
+++ b/target/linux/mvebu/patches-4.14/421-rtc-initialize.patch
@@ -0,0 +1,70 @@
+--- a/drivers/rtc/rtc-armada38x.c	2017-12-11 18:32:22.329841869 +0200
++++ b/drivers/rtc/rtc-armada38x.c	2017-12-11 19:01:40.677854645 +0200
+@@ -30,6 +30,9 @@
+ #define RTC_IRQ_FREQ_1HZ	    BIT(2)
+ #define RTC_CCR		    0x18
+ #define RTC_CCR_MODE		    BIT(15)
++#define RTC_CCR_NORMAL_PPB	    0x2000
++#define RTC_TEST_CONF	    0x1c
++#define RTC_TEST_CONF_MASK  0xff
+ 
+ #define RTC_TIME	    0xC
+ #define RTC_ALARM1	    0x10
+@@ -91,6 +94,7 @@
+ 	void (*clear_isr)(struct armada38x_rtc *rtc);
+ 	void (*unmask_interrupt)(struct armada38x_rtc *rtc);
+ 	u32 alarm;
++	void (*init_rtc)(struct armada38x_rtc *rtc);
+ };
+ 
+ /*
+@@ -202,6 +206,23 @@
+ 	writel(val | SOC_RTC_ALARM1_MASK, rtc->regs_soc + SOC_RTC_INTERRUPT);
+ }
+ 
++static void armada38x_rtc_init(struct armada38x_rtc *rtc)
++{
++	u32 reg;
++	
++	/* Test RTC test configuration register bits [7:0] */
++	reg = readl(rtc->regs + RTC_TEST_CONF);
++	/* If bits [7:0] are non-zero, assume RTC was uninitialized */
++	if (reg & RTC_TEST_CONF_MASK) {
++		rtc_delayed_write(0, rtc, RTC_TEST_CONF);
++		rtc_delayed_write(0, rtc, RTC_TIME);
++		rtc_delayed_write((RTC_STATUS_ALARM1 | RTC_STATUS_ALARM2),
++			rtc, RTC_STATUS);
++		rtc_delayed_write(RTC_CCR_NORMAL_PPB, rtc, RTC_CCR);
++	}
++	return;
++}
++
+ static void armada8k_clear_isr(struct armada38x_rtc *rtc)
+ {
+ 	writel(RTC_8K_ALARM2, rtc->regs_soc + RTC_8K_ISR);
+@@ -464,6 +485,7 @@
+ 	.clear_isr = armada38x_clear_isr,
+ 	.unmask_interrupt = armada38x_unmask_interrupt,
+ 	.alarm = ALARM1,
++	.init_rtc = armada38x_rtc_init,
+ };
+ 
+ static const struct armada38x_rtc_data armada8k_data = {
+@@ -558,6 +580,17 @@
+ 		dev_err(&pdev->dev, "Failed to register RTC device: %d\n", ret);
+ 		return ret;
+ 	}
++
++	/*
++	 * Try to detect if RTC is in uninitialized state.
++	 * It is not definitive to know if the RTC is in an uninialized state or not,
++	 * but the following call will read some bits in the RTC unit and guess if
++	 * if it's in that state, and accordingly set it to sane default values.
++	 */
++	if (rtc->data->init_rtc) {
++		rtc->data->init_rtc(rtc);
++	}
++
+ 	return 0;
+ }
+ 
-- 
2.16.2