fix(plat/marvell/a3720/uart): fix UART parent clock rate determination
The UART code for the A3K platform assumes that UART parent clock rate
is always 25 MHz. This is incorrect, because the xtal clock can also run
at 40 MHz (this is board specific).
The frequency of the xtal clock is determined by a value on a strapping
pin during SOC reset. The code to determine this frequency is already in
A3K's comphy driver.
Move the get_ref_clk() function from the comphy driver to a separate
file and use it for UART parent clock rate determination.
Signed-off-by: Pali Rohár <pali@kernel.org>
Change-Id: I8bb18a2d020ef18fe65aa06ffa4ab205c71be92e
diff --git a/plat/marvell/armada/a3k/common/aarch64/a3700_clock.S b/plat/marvell/armada/a3k/common/aarch64/a3700_clock.S
new file mode 100644
index 0000000..f79516f
--- /dev/null
+++ b/plat/marvell/armada/a3k/common/aarch64/a3700_clock.S
@@ -0,0 +1,35 @@
+/*
+ * Copyright (C) 2018 Marvell International Ltd.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ * https://spdx.org/licenses
+ */
+
+#include <asm_macros.S>
+#include <platform_def.h>
+
+/*
+ * Below address in used only for reading, therefore no problem with concurrent
+ * Linux access.
+ */
+#define MVEBU_TEST_PIN_LATCH_N (MVEBU_NB_GPIO_REG_BASE + 0x8)
+ #define MVEBU_XTAL_MODE_MASK BIT(9)
+
+ /* -----------------------------------------------------
+ * uint32_t get_ref_clk (void);
+ *
+ * returns reference clock in MHz (25 or 40)
+ * -----------------------------------------------------
+ */
+.globl get_ref_clk
+func get_ref_clk
+ mov_imm x0, MVEBU_TEST_PIN_LATCH_N
+ ldr w0, [x0]
+ tst w0, #MVEBU_XTAL_MODE_MASK
+ bne 40
+ mov w0, #25
+ ret
+40:
+ mov w0, #40
+ ret
+endfunc get_ref_clk