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-rw-r--r--kernel/arch/cris/arch-v10/lib/dram_init.S146
1 files changed, 146 insertions, 0 deletions
diff --git a/kernel/arch/cris/arch-v10/lib/dram_init.S b/kernel/arch/cris/arch-v10/lib/dram_init.S
new file mode 100644
index 000000000..e541d3d8f
--- /dev/null
+++ b/kernel/arch/cris/arch-v10/lib/dram_init.S
@@ -0,0 +1,146 @@
+/*
+ * DRAM/SDRAM initialization - alter with care
+ * This file is intended to be included from other assembler files
+ *
+ * Note: This file may not modify r9 because r9 is used to carry
+ * information from the decompresser to the kernel
+ *
+ * Copyright (C) 2000-2012 Axis Communications AB
+ *
+ */
+
+/* Just to be certain the config file is included, we include it here
+ * explicitly instead of depending on it being included in the file that
+ * uses this code.
+ */
+
+
+ ;; WARNING! The registers r8 and r9 are used as parameters carrying
+ ;; information from the decompressor (if the kernel was compressed).
+ ;; They should not be used in the code below.
+
+ move.d CONFIG_ETRAX_DEF_R_WAITSTATES, $r0
+ move.d $r0, [R_WAITSTATES]
+
+ move.d CONFIG_ETRAX_DEF_R_BUS_CONFIG, $r0
+ move.d $r0, [R_BUS_CONFIG]
+
+#ifndef CONFIG_ETRAX_SDRAM
+ move.d CONFIG_ETRAX_DEF_R_DRAM_CONFIG, $r0
+ move.d $r0, [R_DRAM_CONFIG]
+
+ move.d CONFIG_ETRAX_DEF_R_DRAM_TIMING, $r0
+ move.d $r0, [R_DRAM_TIMING]
+#else
+ ;; Samsung SDRAMs seem to require to be initialized twice to work properly.
+ moveq 2, $r6
+_sdram_init:
+
+ ; Refer to ETRAX 100LX Designers Reference for a description of SDRAM initialization
+
+ ; Bank configuration
+ move.d CONFIG_ETRAX_DEF_R_SDRAM_CONFIG, $r0
+ move.d $r0, [R_SDRAM_CONFIG]
+
+ ; Calculate value of mrs_data
+ ; CAS latency = 2 && bus_width = 32 => 0x40
+ ; CAS latency = 3 && bus_width = 32 => 0x60
+ ; CAS latency = 2 && bus_width = 16 => 0x20
+ ; CAS latency = 3 && bus_width = 16 => 0x30
+
+ ; Check if value is already supplied in kernel config
+ move.d CONFIG_ETRAX_DEF_R_SDRAM_TIMING, $r2
+ and.d 0x00ff0000, $r2
+ bne _set_timing
+ lsrq 16, $r2
+
+ move.d 0x40, $r2 ; Assume 32 bits and CAS latency = 2
+ move.d CONFIG_ETRAX_DEF_R_SDRAM_TIMING, $r1
+ move.d $r1, $r3
+ and.d 0x03, $r1 ; Get CAS latency
+ and.d 0x1000, $r3 ; 50 or 100 MHz?
+ beq _speed_50
+ nop
+_speed_100:
+ cmp.d 0x00, $r1 ; CAS latency = 2?
+ beq _bw_check
+ nop
+ or.d 0x20, $r2 ; CAS latency = 3
+ ba _bw_check
+ nop
+_speed_50:
+ cmp.d 0x01, $r1 ; CAS latency = 2?
+ beq _bw_check
+ nop
+ or.d 0x20, $r2 ; CAS latency = 3
+_bw_check:
+ move.d CONFIG_ETRAX_DEF_R_SDRAM_CONFIG, $r1
+ and.d 0x800000, $r1 ; DRAM width is bit 23
+ bne _set_timing
+ nop
+ lsrq 1, $r2 ; 16 bits. Shift down value.
+
+ ; Set timing parameters. Starts master clock
+_set_timing:
+ move.d CONFIG_ETRAX_DEF_R_SDRAM_TIMING, $r1
+ and.d 0x8000f9ff, $r1 ; Make sure mrs data and command is 0
+ or.d 0x80000000, $r1 ; Make sure sdram enable bit is set
+ move.d $r1, $r5
+ or.d 0x0000c000, $r1 ; ref = disable
+ lslq 16, $r2 ; mrs data starts at bit 16
+ or.d $r2, $r1
+ move.d $r1, [R_SDRAM_TIMING]
+
+ ; Wait 200us
+ move.d 10000, $r2
+1: bne 1b
+ subq 1, $r2
+
+ ; Issue initialization command sequence
+ move.d _sdram_commands_start, $r2
+ and.d 0x000fffff, $r2 ; Make sure commands are read from flash
+ move.d _sdram_commands_end, $r3
+ and.d 0x000fffff, $r3
+1: clear.d $r4
+ move.b [$r2+], $r4
+ lslq 9, $r4 ; Command starts at bit 9
+ or.d $r1, $r4
+ move.d $r4, [R_SDRAM_TIMING]
+ nop ; Wait five nop cycles between each command
+ nop
+ nop
+ nop
+ nop
+ cmp.d $r2, $r3
+ bne 1b
+ nop
+ move.d $r5, [R_SDRAM_TIMING]
+ subq 1, $r6
+ bne _sdram_init
+ nop
+ ba _sdram_commands_end
+ nop
+
+_sdram_commands_start:
+ .byte 3 ; Precharge
+ .byte 0 ; nop
+ .byte 2 ; refresh
+ .byte 0 ; nop
+ .byte 2 ; refresh
+ .byte 0 ; nop
+ .byte 2 ; refresh
+ .byte 0 ; nop
+ .byte 2 ; refresh
+ .byte 0 ; nop
+ .byte 2 ; refresh
+ .byte 0 ; nop
+ .byte 2 ; refresh
+ .byte 0 ; nop
+ .byte 2 ; refresh
+ .byte 0 ; nop
+ .byte 2 ; refresh
+ .byte 0 ; nop
+ .byte 1 ; mrs
+ .byte 0 ; nop
+_sdram_commands_end:
+#endif