[PATCH v2] arm: mvebu: update RTC values for PCIe memory wrappers

[Chris Packham]

From: Chris Packham <chris.packham at alliedtelesis.co.nz>

Update the RTC (Read Timing Control) values for PCIe memory wrappers
following an ERRATA (ERRATA# TDB). This means the PCIe accesses will
used slower memory Read Timing, to allow more efficient energy
consumption, in order to lower the minimum VDD of the memory.  Will lead
to more robust memory when voltage drop occurs (VDDSEG)

The code is based on changes from Marvell's U-Boot, specifically:

https://github.com/MarvellEmbeddedProcessors/u-boot-marvell/commit/20cd2704072512de176e048970f2883db901674b
https://github.com/MarvellEmbeddedProcessors/u-boot-marvell/commit/eb608a7c8dd0d42b87601a61b9c0cc5615ab94b2
https://github.com/MarvellEmbeddedProcessors/u-boot-marvell/commit/c4af19ae2bf08cf6e450e741ce4f04d402a5cb6b

Signed-off-by: Chris Packham <chris.packham at alliedtelesis.co.nz>
Signed-off-by: Chris Packham <judge.packham at gmail.com>
---
I've signed-off using both my email addresses. I normally do u-boot
stuff via gmail for convenience but this is definitely a work thing.

Changes in v2:
- drop duplicated link in commit message

 arch/arm/mach-mvebu/include/mach/cpu.h        |  2 ++
 arch/arm/mach-mvebu/serdes/a38x/sys_env_lib.c | 17 +++++++++++++++++
 arch/arm/mach-mvebu/serdes/a38x/sys_env_lib.h | 13 +++++++++++++
 arch/arm/mach-mvebu/spl.c                     |  3 +++
 4 files changed, 35 insertions(+)

diff --git a/arch/arm/mach-mvebu/include/mach/cpu.h b/arch/arm/mach-mvebu/include/mach/cpu.h
index 2e2d72aac892..fa7c81754b8f 100644
--- a/arch/arm/mach-mvebu/include/mach/cpu.h
+++ b/arch/arm/mach-mvebu/include/mach/cpu.h
@@ -166,8 +166,10 @@ int ddr3_init(void);
 /* Auto Voltage Scaling */
 #if defined(CONFIG_ARMADA_38X) || defined(CONFIG_ARMADA_39X)
 void mv_avs_init(void);
+void mv_rtc_config(void);
 #else
 static inline void mv_avs_init(void) {}
+static inline void mv_rtc_config(void) {}
 #endif
 
 /*
diff --git a/arch/arm/mach-mvebu/serdes/a38x/sys_env_lib.c b/arch/arm/mach-mvebu/serdes/a38x/sys_env_lib.c
index e9dd096ad0f5..3c4c7e01a1cd 100644
--- a/arch/arm/mach-mvebu/serdes/a38x/sys_env_lib.c
+++ b/arch/arm/mach-mvebu/serdes/a38x/sys_env_lib.c
@@ -257,6 +257,23 @@ u8 sys_env_device_rev_get(void)
 	return (value & (REVISON_ID_MASK)) >> REVISON_ID_OFFS;
 }
 
+void mv_rtc_config(void)
+{
+	u32 i, val;
+
+	if (!(IS_ENABLED(CONFIG_ARMADA_38X) || IS_ENABLED(CONFIG_ARMADA_39X)))
+		return;
+
+	/* Activate pipe0 for read/write transaction, and set XBAR client number #1 */
+	val = 0x1 << DFX_PIPE_SELECT_PIPE0_ACTIVE_OFFS |
+	      0x1 << DFX_PIPE_SELECT_XBAR_CLIENT_SEL_OFFS;
+	writel(val, MVEBU_DFX_BASE);
+
+	/* Set new RTC value for all memory wrappers */
+	for (i = 0; i < RTC_MEMORY_WRAPPER_COUNT; i++)
+		reg_write(RTC_MEMORY_WRAPPER_REG(i), RTC_MEMORY_WRAPPER_CTRL_VAL);
+}
+
 void mv_avs_init(void)
 {
 	u32 sar_freq;
diff --git a/arch/arm/mach-mvebu/serdes/a38x/sys_env_lib.h b/arch/arm/mach-mvebu/serdes/a38x/sys_env_lib.h
index 1774a5b780ca..17cd811331d2 100644
--- a/arch/arm/mach-mvebu/serdes/a38x/sys_env_lib.h
+++ b/arch/arm/mach-mvebu/serdes/a38x/sys_env_lib.h
@@ -150,6 +150,19 @@
 #define MPP_UART1_SET_MASK		(~(0xff000))
 #define MPP_UART1_SET_DATA		(0x66000)
 
+#define DFX_PIPE_SELECT_PIPE0_ACTIVE_OFFS	0
+/* DFX_PIPE_SELECT_XBAR_CLIENT_SEL_OFFS: Since address completion in 14bit
+ * address mode, and given that [14:8] => [19:13], the 2 lower bits [9:8] =>
+ * [14:13] are dismissed. hence field offset is also shifted to 10
+ */
+#define DFX_PIPE_SELECT_XBAR_CLIENT_SEL_OFFS	10
+
+#define RTC_MEMORY_CTRL_REG_BASE	0xE6000
+#define RTC_MEMORY_WRAPPER_COUNT	8
+#define RTC_MEMORY_WRAPPER_REG(i)	(RTC_MEMORY_CTRL_REG_BASE + ((i) * 0x40))
+#define RTC_MEMORY_CTRL_PDLVMC_FIELD_OFFS	6
+#define RTC_MEMORY_WRAPPER_CTRL_VAL	(0x1 << RTC_MEMORY_CTRL_PDLVMC_FIELD_OFFS)
+
 #define AVS_DEBUG_CNTR_REG		0xe4124
 #define AVS_DEBUG_CNTR_DEFAULT_VALUE	0x08008073
 
diff --git a/arch/arm/mach-mvebu/spl.c b/arch/arm/mach-mvebu/spl.c
index a99bf166fd85..70fef3b573d9 100644
--- a/arch/arm/mach-mvebu/spl.c
+++ b/arch/arm/mach-mvebu/spl.c
@@ -130,6 +130,9 @@ void board_init_f(ulong dummy)
 	/* Initialize Auto Voltage Scaling */
 	mv_avs_init();
 
+	/* Update read timing control for PCIe */
+	mv_rtc_config();
+
 	/*
 	 * Return to the BootROM to continue the Marvell xmodem
 	 * UART boot protocol. As initiated by the kwboot tool.
-- 
2.25.1