On 06.05.22 14:16, Stefan Roese wrote:
On 06.05.22 14:09, Pali Rohár wrote:
On Friday 06 May 2022 14:04:53 Stefan Roese wrote:
On 06.05.22 11:05, Pali Rohár wrote:
Moving of internal registers from INTREG_BASE_ADDR_REG to SOC_REGS_PHY_BASE
needs to be done very early, prior calling any function which may touch
internal registers, like debug_uart_init().

So do it earlier in arch_very_early_init() instead of arch_cpu_init().

Movement is done in proper U-Boot, not in SPL. SPL may return to bootrom
and bootrom requires internal registers at (old) expected location.

Signed-off-by: Pali Rohár <p...@kernel.org>
---
   arch/arm/mach-mvebu/Kconfig    |  1 +
   arch/arm/mach-mvebu/Makefile   |  1 +
   arch/arm/mach-mvebu/cpu.c      | 31 -------------------------------
   arch/arm/mach-mvebu/lowlevel.S | 27 +++++++++++++++++++++++++++
   4 files changed, 29 insertions(+), 31 deletions(-)
   create mode 100644 arch/arm/mach-mvebu/lowlevel.S

diff --git a/arch/arm/mach-mvebu/Kconfig b/arch/arm/mach-mvebu/Kconfig
index a3f273f4f949..98b13d1e336d 100644
--- a/arch/arm/mach-mvebu/Kconfig
+++ b/arch/arm/mach-mvebu/Kconfig
@@ -16,6 +16,7 @@ config ARMADA_32BIT
       select SUPPORT_SPL
       select TRANSLATION_OFFSET
       select SPL_SYS_NO_VECTOR_TABLE if SPL
+    select ARCH_VERY_EARLY_INIT
   config ARMADA_64BIT
       bool
diff --git a/arch/arm/mach-mvebu/Makefile b/arch/arm/mach-mvebu/Makefile
index 1b451889d242..8bd2246325ca 100644
--- a/arch/arm/mach-mvebu/Makefile
+++ b/arch/arm/mach-mvebu/Makefile
@@ -21,6 +21,7 @@ else # CONFIG_ARCH_KIRKWOOD
   obj-y    = cpu.o
   obj-y    += dram.o
+obj-y    += lowlevel.o
   obj-$(CONFIG_DM_RESET) += system-controller.o
   ifndef CONFIG_SPL_BUILD
   obj-$(CONFIG_ARMADA_375) += ../../../drivers/ddr/marvell/axp/xor.o
diff --git a/arch/arm/mach-mvebu/cpu.c b/arch/arm/mach-mvebu/cpu.c
index 1e893777b292..173d95a760a3 100644
--- a/arch/arm/mach-mvebu/cpu.c
+++ b/arch/arm/mach-mvebu/cpu.c
@@ -413,20 +413,7 @@ static void update_sdram_window_sizes(void)
       }
   }
-void mmu_disable(void)
-{
-    asm volatile(
-        "mrc p15, 0, r0, c1, c0, 0\n"
-        "bic r0, #1\n"
-        "mcr p15, 0, r0, c1, c0, 0\n");
-}
-
   #ifdef CONFIG_ARCH_CPU_INIT
-static void set_cbar(u32 addr)
-{
-    asm("mcr p15, 4, %0, c15, c0" : : "r" (addr));
-}
-
   #define MV_USB_PHY_BASE            (MVEBU_AXP_USB_BASE + 0x800)
   #define MV_USB_PHY_PLL_REG(reg)        (MV_USB_PHY_BASE | (((reg) & 0xF) << 2))    #define MV_USB_X3_BASE(addr)        (MVEBU_AXP_USB_BASE | BIT(11) | \
@@ -476,24 +463,6 @@ int arch_cpu_init(void)
       struct pl310_regs *const pl310 =
           (struct pl310_regs *)CONFIG_SYS_PL310_BASE;
-    /*
-     * Only with disabled MMU its possible to switch the base
-     * register address on Armada 38x. Without this the SDRAM
-     * located at >= 0x4000.0000 is also not accessible, as its
-     * still locked to cache.
-     */
-    mmu_disable();
-
-    /* Linux expects the internal registers to be at 0xf1000000 */
-    writel(SOC_REGS_PHY_BASE, INTREG_BASE_ADDR_REG);
-    set_cbar(SOC_REGS_PHY_BASE + 0xC000);
-
-    /*
-     * From this stage on, the SoC detection is working. As we have
-     * configured the internal register base to the value used
-     * in the macros / defines in the U-Boot header (soc.h).
-     */
-
       if (mvebu_soc_family() == MVEBU_SOC_A38X) {
           /*
            * To fully release / unlock this area from cache, we need
diff --git a/arch/arm/mach-mvebu/lowlevel.S b/arch/arm/mach-mvebu/lowlevel.S
new file mode 100644
index 000000000000..2491310eb0c1
--- /dev/null
+++ b/arch/arm/mach-mvebu/lowlevel.S
@@ -0,0 +1,27 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+
+#include <config.h>
+#include <linux/linkage.h>
+
+ENTRY(arch_very_early_init)
+#ifdef CONFIG_ARMADA_38X
+    /*
+     * Only with disabled MMU its possible to switch the base
+     * register address on Armada 38x. Without this the SDRAM
+     * located at >= 0x4000.0000 is also not accessible, as its
+     * still locked to cache.
+     */
+    mrc    p15, 0, r0, c1, c0, 0
+    bic    r0, #1
+    mcr    p15, 0, r0, c1, c0, 0
+#endif

You are disabling the MMU here only for CONFIG_ARMADA_38X. In the
non-asm version removed above, it's disabled in all cases in
arch_cpu_init(). Is this correct? I might be missing something - it's
been quite some time, since I worked on this code.

I'm not sure. I was in impression from that comment that disabling MMU
is needed only for A38x. But runtime detection of the board was not
possible until registers are relocated to the new location, so code
disabling MMU was called always.

So, this change should be tested on some AXP, A370 or A375 board to
verify that everything is working correctly.

Okay, understood. I can do some testing on AXP.

Some quick tests on theadorable_debug (AXP) have shown, that it makes
no difference, if the MMU is disabled or not AFAICT.

While doing this I noticed though, that kwboot UART booting only worked
in roughly 1 out of 2 cases. With no progress after this line:

Sending boot message. Please reboot the target...\

IIRC, this worked more reliable a few weeks ago. Any idea, what might
have caused this regression - if I am correct here?

Thanks,
Stefan

Thanks,
Stefan

I tested it only on A385 Turris Omnia.

Thanks,
Stefan

+
+    /* Move internal registers from INTREG_BASE_ADDR_REG to SOC_REGS_PHY_BASE */
+    ldr    r0, =SOC_REGS_PHY_BASE
+    ldr    r1, =INTREG_BASE_ADDR_REG
+    str    r0, [r1]
+    add    r0, r0, #0xC000
+    mcr    p15, 4, r0, c15, c0
+
+    bx lr
+ENDPROC(arch_very_early_init)

Viele Grüße,
Stefan Roese

--
DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-51 Fax: (+49)-8142-66989-80 Email: s...@denx.de

Viele Grüße,
Stefan Roese


Viele Grüße,
Stefan Roese

--
DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-51 Fax: (+49)-8142-66989-80 Email: s...@denx.de

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