head.s

linux内核源码

	move.d	[$r9], $r0	; cramfs_super.magic
	cmp.d	CRAMFS_MAGIC, $r0
	bne	_no_romfs_in_flash
	nop
	move.d	[$r9+4], $r0	; cramfs_super.length
	move.d	$r0, [romfs_length]
#ifdef CONFIG_CRIS_LOW_MAP
	add.d   0x50000000, $r9	; add flash start in virtual memory (cached)
#else
	add.d   0xf0000000, $r9	; add flash start in virtual memory (cached)
#endif
	move.d	$r9, [romfs_start]

	moveq	1, $r0
	move.d	$r0, [romfs_in_flash]

	jump	_start_it	; enter code, cached this time

_no_romfs_in_flash:
	
	;; Check if there is a cramfs (magic value).
	;; Notice that we check for cramfs magic value - which is
	;; the "rom fs" we'll possibly use in 2.4 if not JFFS (which does
	;; not need this mechanism anyway)

	move.d	__vmlinux_end, $r0; the image will be after the vmlinux end address
	move.d	[$r0], $r1	; cramfs assumes same endian on host/target
	cmp.d	CRAMFS_MAGIC, $r1; magic value in cramfs superblock
	bne	2f
	nop

	;; Ok. What is its size ? 
	
	move.d	[$r0 + 4], $r2	; cramfs_super.size (again, no need to swapwb)

	;; We want to copy it to the end of the BSS

	move.d	_end, $r1

	;; Remember values so cramfs and setup can find this info

	move.d	$r1, [romfs_start]	; new romfs location
	move.d	$r2, [romfs_length]

	;; We need to copy it backwards, since they can be overlapping

	add.d	$r2, $r0
	add.d	$r2, $r1
		
	;; Go ahead. Make my loop.

	lsrq	1, $r2		; size is in bytes, we copy words

1:	move.w	[$r0=$r0-2],$r3
	move.w	$r3,[$r1=$r1-2]
	subq	1, $r2
	bne	1b
	nop

2:		
	;; Dont worry that the BSS is tainted. It will be cleared later.

	moveq	0, $r0
	move.d	$r0, [romfs_in_flash]

	jump	_start_it	; better skip the additional cramfs check below
	
_start_it:

	;; Check if kernel command line is supplied
	cmp.d	COMMAND_LINE_MAGIC, $r10
	bne	no_command_line
	nop

	move.d	256, $r13
	move.d  cris_command_line, $r10
	or.d	0x80000000, $r11 ; Make it virtual
1:
	move.b  [$r11+], $r12
	move.b  $r12, [$r10+]
	subq	1, $r13
	bne	1b
	nop

no_command_line:

	;; the kernel stack is overlayed with the task structure for each
	;; task. thus the initial kernel stack is in the same page as the
	;; init_task (but starts in the top of the page, size 8192)
	move.d	init_thread_union + 8192, $sp
	move.d	ibr_start,$r0	; this symbol is set by the linker script 
	move	$r0,$ibr
	move.d	$r0,[etrax_irv]	; set the interrupt base register and pointer
	
	;; Clear BSS region, from _bss_start to _end

	move.d	__bss_start, $r0
	move.d	_end, $r1
1:	clear.d	[$r0+]
	cmp.d	$r1, $r0
	blo	1b
	nop
	
#ifdef CONFIG_BLK_DEV_ETRAXIDE
	;; disable ATA before enabling it in genconfig below
	moveq	0,$r0
	move.d	$r0,[R_ATA_CTRL_DATA]
	move.d	$r0,[R_ATA_TRANSFER_CNT]
	move.d	$r0,[R_ATA_CONFIG]
#if 0
	move.d	R_PORT_G_DATA, $r1
	move.d	$r0, [$r1]; assert ATA bus-reset
	nop
	nop
	nop
	nop
	nop
	nop
	move.d	0x08000000,$r0
	move.d	$r0,[$r1]
#endif
#endif

#ifdef CONFIG_JULIETTE
	;; configure external DMA channel 0 before enabling it in genconfig
	
	moveq	0,$r0
	move.d	$r0,[R_EXT_DMA_0_ADDR]
	; cnt enable, word size, output, stop, size 0
	move.d	  IO_STATE (R_EXT_DMA_0_CMD, cnt, enable)	\
		| IO_STATE (R_EXT_DMA_0_CMD, rqpol, ahigh)	\
		| IO_STATE (R_EXT_DMA_0_CMD, apol, ahigh)	\
		| IO_STATE (R_EXT_DMA_0_CMD, rq_ack, burst)	\
		| IO_STATE (R_EXT_DMA_0_CMD, wid, word)		\
		| IO_STATE (R_EXT_DMA_0_CMD, dir, output)	\
		| IO_STATE (R_EXT_DMA_0_CMD, run, stop)		\
		| IO_FIELD (R_EXT_DMA_0_CMD, trf_count, 0),$r0
	move.d	$r0,[R_EXT_DMA_0_CMD]

	;; reset dma4 and wait for completion
	
	moveq	IO_STATE (R_DMA_CH4_CMD, cmd, reset),$r0
	move.b	$r0,[R_DMA_CH4_CMD]
1:	move.b	[R_DMA_CH4_CMD],$r0
	and.b	IO_MASK (R_DMA_CH4_CMD, cmd),$r0
	cmp.b	IO_STATE (R_DMA_CH4_CMD, cmd, reset),$r0
	beq	1b
	nop

	;; reset dma5 and wait for completion
	
	moveq	IO_STATE (R_DMA_CH5_CMD, cmd, reset),$r0
	move.b	$r0,[R_DMA_CH5_CMD]
1:	move.b	[R_DMA_CH5_CMD],$r0
	and.b	IO_MASK (R_DMA_CH5_CMD, cmd),$r0
	cmp.b	IO_STATE (R_DMA_CH5_CMD, cmd, reset),$r0
	beq	1b
	nop
#endif	
			
	;; Etrax product HW genconfig setup

	moveq	0,$r0

	;; Init interfaces (disable them).
	or.d	  IO_STATE (R_GEN_CONFIG, scsi0, disable) \
		| IO_STATE (R_GEN_CONFIG, ata, disable) \
		| IO_STATE (R_GEN_CONFIG, par0, disable) \
		| IO_STATE (R_GEN_CONFIG, ser2, disable) \
		| IO_STATE (R_GEN_CONFIG, mio, disable) \
		| IO_STATE (R_GEN_CONFIG, scsi1, disable) \
		| IO_STATE (R_GEN_CONFIG, scsi0w, disable) \
		| IO_STATE (R_GEN_CONFIG, par1, disable) \
		| IO_STATE (R_GEN_CONFIG, ser3, disable) \
		| IO_STATE (R_GEN_CONFIG, mio_w, disable) \
		| IO_STATE (R_GEN_CONFIG, usb1, disable) \
		| IO_STATE (R_GEN_CONFIG, usb2, disable) \
		| IO_STATE (R_GEN_CONFIG, par_w, disable),$r0

	;; Init DMA channel muxing (set to unused clients).
	or.d	  IO_STATE (R_GEN_CONFIG, dma2, ata)	\
		| IO_STATE (R_GEN_CONFIG, dma3, ata) \
		| IO_STATE (R_GEN_CONFIG, dma4, scsi1) \
		| IO_STATE (R_GEN_CONFIG, dma5, scsi1) \
		| IO_STATE (R_GEN_CONFIG, dma6, unused) \
		| IO_STATE (R_GEN_CONFIG, dma7, unused) \
		| IO_STATE (R_GEN_CONFIG, dma8, usb) \
		| IO_STATE (R_GEN_CONFIG, dma9, usb),$r0


#if defined(CONFIG_ETRAX_DEF_R_PORT_G0_DIR_OUT)
        or.d      IO_STATE (R_GEN_CONFIG, g0dir, out),$r0
#endif

#if defined(CONFIG_ETRAX_DEF_R_PORT_G8_15_DIR_OUT)
        or.d      IO_STATE (R_GEN_CONFIG, g8_15dir, out),$r0
#endif
#if defined(CONFIG_ETRAX_DEF_R_PORT_G16_23_DIR_OUT)
       or.d      IO_STATE (R_GEN_CONFIG, g16_23dir, out),$r0
#endif

#if defined(CONFIG_ETRAX_DEF_R_PORT_G24_DIR_OUT)
       or.d      IO_STATE (R_GEN_CONFIG, g24dir, out),$r0
#endif

	move.d	$r0,[genconfig_shadow] ; init a shadow register of R_GEN_CONFIG

#ifndef CONFIG_SVINTO_SIM
	move.d	$r0,[R_GEN_CONFIG]

#if 0
	moveq	4,$r0
	move.b	$r0,[R_DMA_CH6_CMD]	; reset (ser0 dma out)
	move.b	$r0,[R_DMA_CH7_CMD]	; reset (ser0 dma in)
1:	move.b	[R_DMA_CH6_CMD],$r0	; wait for reset cycle to finish
	and.b	7,$r0
	cmp.b	4,$r0
	beq	1b
	nop
1:	move.b	[R_DMA_CH7_CMD],$r0	; wait for reset cycle to finish
	and.b	7,$r0
	cmp.b	4,$r0
	beq	1b
	nop
#endif
	
	moveq	IO_STATE (R_DMA_CH8_CMD, cmd, reset),$r0
	move.b	$r0,[R_DMA_CH8_CMD]	; reset (ser1 dma out)
	move.b	$r0,[R_DMA_CH9_CMD]	; reset (ser1 dma in)
1:	move.b	[R_DMA_CH8_CMD],$r0	; wait for reset cycle to finish
	andq	IO_MASK (R_DMA_CH8_CMD, cmd),$r0
	cmpq	IO_STATE (R_DMA_CH8_CMD, cmd, reset),$r0
	beq	1b
	nop
1:	move.b	[R_DMA_CH9_CMD],$r0	; wait for reset cycle to finish
	andq	IO_MASK (R_DMA_CH9_CMD, cmd),$r0
	cmpq	IO_STATE (R_DMA_CH9_CMD, cmd, reset),$r0
	beq	1b
	nop

	;; setup port PA and PB default initial directions and data
	;; including their shadow registers
		
	move.b	CONFIG_ETRAX_DEF_R_PORT_PA_DIR,$r0
#if defined(CONFIG_BLUETOOTH) && defined(CONFIG_BLUETOOTH_RESET_PA7)
	or.b	IO_STATE (R_PORT_PA_DIR, dir7, output),$r0
#endif
	move.b	$r0,[port_pa_dir_shadow]
	move.b	$r0,[R_PORT_PA_DIR]
	move.b	CONFIG_ETRAX_DEF_R_PORT_PA_DATA,$r0
#if defined(CONFIG_BLUETOOTH) && defined(CONFIG_BLUETOOTH_RESET_PA7)
#if defined(CONFIG_BLUETOOTH_RESET_ACTIVE_HIGH)
	and.b	~(1 << 7),$r0
#else
	or.b	(1 << 7),$r0
#endif
#endif
	move.b	$r0,[port_pa_data_shadow]
	move.b	$r0,[R_PORT_PA_DATA]
	
	move.b	CONFIG_ETRAX_DEF_R_PORT_PB_CONFIG,$r0
	move.b	$r0,[port_pb_config_shadow]
	move.b	$r0,[R_PORT_PB_CONFIG]
	move.b	CONFIG_ETRAX_DEF_R_PORT_PB_DIR,$r0
#if defined(CONFIG_BLUETOOTH) && defined(CONFIG_BLUETOOTH_RESET_PB5)
	or.b	IO_STATE (R_PORT_PB_DIR, dir5, output),$r0
#endif
	move.b	$r0,[port_pb_dir_shadow]
	move.b	$r0,[R_PORT_PB_DIR]
	move.b	CONFIG_ETRAX_DEF_R_PORT_PB_DATA,$r0
#if defined(CONFIG_BLUETOOTH) && defined(CONFIG_BLUETOOTH_RESET_PB5)
#if defined(CONFIG_BLUETOOTH_RESET_ACTIVE_HIGH)
	and.b	~(1 << 5),$r0
#else
	or.b	(1 << 5),$r0
#endif
#endif
	move.b	$r0,[port_pb_data_shadow]
	move.b	$r0,[R_PORT_PB_DATA]

	moveq   0, $r0
	move.d  $r0,[port_pb_i2c_shadow]
	move.d  $r0, [R_PORT_PB_I2C]

	moveq	0,$r0
#if defined(CONFIG_BLUETOOTH) && defined(CONFIG_BLUETOOTH_RESET_G10)
#if defined(CONFIG_BLUETOOTH_RESET_ACTIVE_HIGH)
	and.d	~(1 << 10),$r0
#else
	or.d	(1 << 10),$r0
#endif
#endif
#if defined(CONFIG_BLUETOOTH) && defined(CONFIG_BLUETOOTH_RESET_G11)
#if defined(CONFIG_BLUETOOTH_RESET_ACTIVE_HIGH)
	and.d	~(1 << 11),$r0
#else
	or.d	(1 << 11),$r0
#endif
#endif
	move.d	$r0,[port_g_data_shadow]
	move.d	$r0,[R_PORT_G_DATA]
	
	;; setup the serial port 0 at 115200 baud for debug purposes
	
	moveq	  IO_STATE (R_SERIAL0_XOFF, tx_stop, enable)		\
		| IO_STATE (R_SERIAL0_XOFF, auto_xoff, disable)		\
		| IO_FIELD (R_SERIAL0_XOFF, xoff_char, 0),$r0
	move.d	$r0,[R_SERIAL0_XOFF] 

	; 115.2kbaud for both transmit and receive
	move.b	  IO_STATE (R_SERIAL0_BAUD, tr_baud, c115k2Hz)		\
		| IO_STATE (R_SERIAL0_BAUD, rec_baud, c115k2Hz),$r0
	move.b	$r0,[R_SERIAL0_BAUD]

	; Set up and enable the serial0 receiver.
	move.b	  IO_STATE (R_SERIAL0_REC_CTRL, dma_err, stop)		\
		| IO_STATE (R_SERIAL0_REC_CTRL, rec_enable, enable)	\
		| IO_STATE (R_SERIAL0_REC_CTRL, rts_, active)		\
		| IO_STATE (R_SERIAL0_REC_CTRL, sampling, middle)	\
		| IO_STATE (R_SERIAL0_REC_CTRL, rec_stick_par, normal)	\
		| IO_STATE (R_SERIAL0_REC_CTRL, rec_par, even)		\
		| IO_STATE (R_SERIAL0_REC_CTRL, rec_par_en, disable)	\
		| IO_STATE (R_SERIAL0_REC_CTRL, rec_bitnr, rec_8bit),$r0
	move.b	$r0,[R_SERIAL0_REC_CTRL] 
	
	; Set up and enable the serial0 transmitter.
	move.b	  IO_FIELD (R_SERIAL0_TR_CTRL, txd, 0)			\
		| IO_STATE (R_SERIAL0_TR_CTRL, tr_enable, enable)	\
		| IO_STATE (R_SERIAL0_TR_CTRL, auto_cts, disabled)	\
		| IO_STATE (R_SERIAL0_TR_CTRL, stop_bits, one_bit)	\
		| IO_STATE (R_SERIAL0_TR_CTRL, tr_stick_par, normal)	\
		| IO_STATE (R_SERIAL0_TR_CTRL, tr_par, even)		\
		| IO_STATE (R_SERIAL0_TR_CTRL, tr_par_en, disable)	\
		| IO_STATE (R_SERIAL0_TR_CTRL, tr_bitnr, tr_8bit),$r0
	move.b	$r0,[R_SERIAL0_TR_CTRL]

	;; setup the serial port 1 at 115200 baud for debug purposes
	
	moveq	  IO_STATE (R_SERIAL1_XOFF, tx_stop, enable)		\
		| IO_STATE (R_SERIAL1_XOFF, auto_xoff, disable)		\
		| IO_FIELD (R_SERIAL1_XOFF, xoff_char, 0),$r0
	move.d	$r0,[R_SERIAL1_XOFF] 

	; 115.2kbaud for both transmit and receive
	move.b	  IO_STATE (R_SERIAL1_BAUD, tr_baud, c115k2Hz)		\
		| IO_STATE (R_SERIAL1_BAUD, rec_baud, c115k2Hz),$r0
	move.b	$r0,[R_SERIAL1_BAUD]

	; Set up and enable the serial1 receiver.
	move.b	  IO_STATE (R_SERIAL1_REC_CTRL, dma_err, stop)		\
		| IO_STATE (R_SERIAL1_REC_CTRL, rec_enable, enable)	\
		| IO_STATE (R_SERIAL1_REC_CTRL, rts_, active)		\
		| IO_STATE (R_SERIAL1_REC_CTRL, sampling, middle)	\
		| IO_STATE (R_SERIAL1_REC_CTRL, rec_stick_par, normal)	\
		| IO_STATE (R_SERIAL1_REC_CTRL, rec_par, even)		\
		| IO_STATE (R_SERIAL1_REC_CTRL, rec_par_en, disable)	\
		| IO_STATE (R_SERIAL1_REC_CTRL, rec_bitnr, rec_8bit),$r0
	move.b	$r0,[R_SERIAL1_REC_CTRL] 
	
	; Set up and enable the serial1 transmitter.
	move.b	  IO_FIELD (R_SERIAL1_TR_CTRL, txd, 0)			\
		| IO_STATE (R_SERIAL1_TR_CTRL, tr_enable, enable)	\
		| IO_STATE (R_SERIAL1_TR_CTRL, auto_cts, disabled)	\
		| IO_STATE (R_SERIAL1_TR_CTRL, stop_bits, one_bit)	\
		| IO_STATE (R_SERIAL1_TR_CTRL, tr_stick_par, normal)	\
		| IO_STATE (R_SERIAL1_TR_CTRL, tr_par, even)		\
		| IO_STATE (R_SERIAL1_TR_CTRL, tr_par_en, disable)	\
		| IO_STATE (R_SERIAL1_TR_CTRL, tr_bitnr, tr_8bit),$r0
	move.b	$r0,[R_SERIAL1_TR_CTRL]

	
#ifdef CONFIG_ETRAX_SERIAL_PORT3	
	;; setup the serial port 3 at 115200 baud for debug purposes
	
	moveq	  IO_STATE (R_SERIAL3_XOFF, tx_stop, enable)		\
		| IO_STATE (R_SERIAL3_XOFF, auto_xoff, disable)		\
		| IO_FIELD (R_SERIAL3_XOFF, xoff_char, 0),$r0
	move.d	$r0,[R_SERIAL3_XOFF] 

	; 115.2kbaud for both transmit and receive
	move.b	  IO_STATE (R_SERIAL3_BAUD, tr_baud, c115k2Hz)		\
		| IO_STATE (R_SERIAL3_BAUD, rec_baud, c115k2Hz),$r0
	move.b	$r0,[R_SERIAL3_BAUD]

	; Set up and enable the serial3 receiver.
	move.b	  IO_STATE (R_SERIAL3_REC_CTRL, dma_err, stop)		\
		| IO_STATE (R_SERIAL3_REC_CTRL, rec_enable, enable)	\
		| IO_STATE (R_SERIAL3_REC_CTRL, rts_, active)		\
		| IO_STATE (R_SERIAL3_REC_CTRL, sampling, middle)	\
		| IO_STATE (R_SERIAL3_REC_CTRL, rec_stick_par, normal)	\
		| IO_STATE (R_SERIAL3_REC_CTRL, rec_par, even)		\
		| IO_STATE (R_SERIAL3_REC_CTRL, rec_par_en, disable)	\
		| IO_STATE (R_SERIAL3_REC_CTRL, rec_bitnr, rec_8bit),$r0
	move.b	$r0,[R_SERIAL3_REC_CTRL] 
	
	; Set up and enable the serial3 transmitter.
	move.b	  IO_FIELD (R_SERIAL3_TR_CTRL, txd, 0)			\
		| IO_STATE (R_SERIAL3_TR_CTRL, tr_enable, enable)	\
		| IO_STATE (R_SERIAL3_TR_CTRL, auto_cts, disabled)	\
		| IO_STATE (R_SERIAL3_TR_CTRL, stop_bits, one_bit)	\
		| IO_STATE (R_SERIAL3_TR_CTRL, tr_stick_par, normal)	\
		| IO_STATE (R_SERIAL3_TR_CTRL, tr_par, even)		\
		| IO_STATE (R_SERIAL3_TR_CTRL, tr_par_en, disable)	\
		| IO_STATE (R_SERIAL3_TR_CTRL, tr_bitnr, tr_8bit),$r0
	move.b	$r0,[R_SERIAL3_TR_CTRL]
#endif
	
#endif /* CONFIG_SVINTO_SIM */

	jump	start_kernel	; jump into the C-function start_kernel in init/main.c
		
	.data
etrax_irv:	
	.dword	0
romfs_start:
	.dword	0
romfs_length:
	.dword	0
romfs_in_flash:
	.dword	0
	
	;; put some special pages at the beginning of the kernel aligned
	;; to page boundaries - the kernel cannot start until after this

#ifdef CONFIG_CRIS_LOW_MAP
swapper_pg_dir = 0x60002000
#else	
swapper_pg_dir = 0xc0002000
#endif

	.section ".init.data", "aw"
#include "../lib/hw_settings.S"